pragma solidity ^0.5.2;
contract Admin {
    address internal _admin;
    event AdminChanged(address oldAdmin, address newAdmin);
    /// @notice gives the current administrator of this contract.
    /// @return the current administrator of this contract.
    function getAdmin() external view returns (address) {
        return _admin;
    }
    /// @notice change the administrator to be `newAdmin`.
    /// @param newAdmin address of the new administrator.
    function changeAdmin(address newAdmin) external {
        require(msg.sender == _admin, "only admin can change admin");
        emit AdminChanged(_admin, newAdmin);
        _admin = newAdmin;
    }
}
pragma solidity ^0.5.2;
import "./Admin.sol";
contract SuperOperators is Admin {
    mapping(address => bool) internal _superOperators;
    event SuperOperator(address superOperator, bool enabled);
    /// @notice Enable or disable the ability of `superOperator` to transfer tokens of all (superOperator rights).
    /// @param superOperator address that will be given/removed superOperator right.
    /// @param enabled set whether the superOperator is enabled or disabled.
    function setSuperOperator(address superOperator, bool enabled) external {
        require(
            msg.sender == _admin,
            "only admin is allowed to add super operators"
        );
        _superOperators[superOperator] = enabled;
        emit SuperOperator(superOperator, enabled);
    }
    /// @notice check whether address `who` is given superOperator rights.
    /// @param who The address to query.
    /// @return whether the address has superOperator rights.
    function isSuperOperator(address who) public view returns (bool) {
        return _superOperators[who];
    }
}
pragma solidity ^0.5.2;
/* interface */
contract ERC20Events {
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 value
    );
}
pragma solidity ^0.5.2;
library BytesUtil {
    function memcpy(uint256 dest, uint256 src, uint256 len) internal pure {
        // Copy word-length chunks while possible
        for (; len >= 32; len -= 32) {
            assembly {
                mstore(dest, mload(src))
            }
            dest += 32;
            src += 32;
        }
        // Copy remaining bytes
        uint256 mask = 256**(32 - len) - 1;
        assembly {
            let srcpart := and(mload(src), not(mask))
            let destpart := and(mload(dest), mask)
            mstore(dest, or(destpart, srcpart))
        }
    }
    function pointerToBytes(uint256 src, uint256 len)
        internal
        pure
        returns (bytes memory)
    {
        bytes memory ret = new bytes(len);
        uint256 retptr;
        assembly {
            retptr := add(ret, 32)
        }
        memcpy(retptr, src, len);
        return ret;
    }
    function addressToBytes(address a) internal pure returns (bytes memory b) {
        assembly {
            let m := mload(0x40)
            mstore(
                add(m, 20),
                xor(0x140000000000000000000000000000000000000000, a)
            )
            mstore(0x40, add(m, 52))
            b := m
        }
    }
    function uint256ToBytes(uint256 a) internal pure returns (bytes memory b) {
        assembly {
            let m := mload(0x40)
            mstore(add(m, 32), a)
            mstore(0x40, add(m, 64))
            b := m
        }
    }
    function doFirstParamEqualsAddress(bytes memory data, address _address)
        internal
        pure
        returns (bool)
    {
        if (data.length < (36 + 32)) {
            return false;
        }
        uint256 value;
        assembly {
            value := mload(add(data, 36))
        }
        return value == uint256(_address);
    }
    function doParamEqualsUInt256(bytes memory data, uint256 i, uint256 value)
        internal
        pure
        returns (bool)
    {
        if (data.length < (36 + (i + 1) * 32)) {
            return false;
        }
        uint256 offset = 36 + i * 32;
        uint256 valuePresent;
        assembly {
            valuePresent := mload(add(data, offset))
        }
        return valuePresent == value;
    }
    function overrideFirst32BytesWithAddress(
        bytes memory data,
        address _address
    ) internal pure returns (bytes memory) {
        uint256 dest;
        assembly {
            dest := add(data, 48)
        } // 48 = 32 (offset) + 4 (func sig) + 12 (address is only 20 bytes)
        bytes memory addressBytes = addressToBytes(_address);
        uint256 src;
        assembly {
            src := add(addressBytes, 32)
        }
        memcpy(dest, src, 20);
        return data;
    }
    function overrideFirstTwo32BytesWithAddressAndInt(
        bytes memory data,
        address _address,
        uint256 _value
    ) internal pure returns (bytes memory) {
        uint256 dest;
        uint256 src;
        assembly {
            dest := add(data, 48)
        } // 48 = 32 (offset) + 4 (func sig) + 12 (address is only 20 bytes)
        bytes memory bbytes = addressToBytes(_address);
        assembly {
            src := add(bbytes, 32)
        }
        memcpy(dest, src, 20);
        assembly {
            dest := add(data, 68)
        } // 48 = 32 (offset) + 4 (func sig) + 32 (next slot)
        bbytes = uint256ToBytes(_value);
        assembly {
            src := add(bbytes, 32)
        }
        memcpy(dest, src, 32);
        return data;
    }
}
pragma solidity 0.5.9;
import "./Sand/erc20/ERC20ExecuteExtension.sol";
import "./Sand/erc20/ERC20BaseToken.sol";
import "./Sand/erc20/ERC20BasicApproveExtension.sol";
contract Sand is ERC20ExecuteExtension, ERC20BasicApproveExtension, ERC20BaseToken {
    constructor(address sandAdmin, address executionAdmin, address beneficiary) public {
        _admin = sandAdmin;
        _executionAdmin = executionAdmin;
        _mint(beneficiary, 3000000000000000000000000000);
    }
    /// @notice A descriptive name for the tokens
    /// @return name of the tokens
    function name() public view returns (string memory) {
        return "SAND";
    }
    /// @notice An abbreviated name for the tokens
    /// @return symbol of the tokens
    function symbol() public view returns (string memory) {
        return "SAND";
    }
}
pragma solidity 0.5.9;
import "../../../contracts_common/src/Interfaces/ERC20Events.sol";
import "../../../contracts_common/src/BaseWithStorage/SuperOperators.sol";
contract ERC20BaseToken is SuperOperators, ERC20Events {
    uint256 internal _totalSupply;
    mapping(address => uint256) internal _balances;
    mapping(address => mapping(address => uint256)) internal _allowances;
    /// @notice Gets the total number of tokens in existence.
    /// @return the total number of tokens in existence.
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }
    /// @notice Gets the balance of `owner`.
    /// @param owner The address to query the balance of.
    /// @return The amount owned by `owner`.
    function balanceOf(address owner) public view returns (uint256) {
        return _balances[owner];
    }
    /// @notice gets allowance of `spender` for `owner`'s tokens.
    /// @param owner address whose token is allowed.
    /// @param spender address allowed to transfer.
    /// @return the amount of token `spender` is allowed to transfer on behalf of `owner`.
    function allowance(address owner, address spender)
        public
        view
        returns (uint256 remaining)
    {
        return _allowances[owner][spender];
    }
    /// @notice returns the number of decimals for that token.
    /// @return the number of decimals.
    function decimals() public view returns (uint8) {
        return uint8(18);
    }
    /// @notice Transfer `amount` tokens to `to`.
    /// @param to the recipient address of the tokens transfered.
    /// @param amount the number of tokens transfered.
    /// @return true if success.
    function transfer(address to, uint256 amount)
        public
        returns (bool success)
    {
        _transfer(msg.sender, to, amount);
        return true;
    }
    /// @notice Transfer `amount` tokens from `from` to `to`.
    /// @param from whose token it is transferring from.
    /// @param to the recipient address of the tokens transfered.
    /// @param amount the number of tokens transfered.
    /// @return true if success.
    function transferFrom(address from, address to, uint256 amount)
        public
        returns (bool success)
    {
        if (msg.sender != from && !_superOperators[msg.sender]) {
            uint256 currentAllowance = _allowances[from][msg.sender];
            if (currentAllowance != (2**256) - 1) {
                // save gas when allowance is maximal by not reducing it (see https://github.com/ethereum/EIPs/issues/717)
                require(currentAllowance >= amount, "Not enough funds allowed");
                _allowances[from][msg.sender] = currentAllowance - amount;
            }
        }
        _transfer(from, to, amount);
        return true;
    }
    /// @notice burn `amount` tokens.
    /// @param amount the number of tokens to burn.
    /// @return true if success.
    function burn(uint256 amount) external returns (bool) {
        _burn(msg.sender, amount);
        return true;
    }
    /// @notice burn `amount` tokens from `owner`.
    /// @param owner address whose token is to burn.
    /// @param amount the number of token to burn.
    /// @return true if success.
    function burnFor(address owner, uint256 amount) external returns (bool) {
        _burn(owner, amount);
        return true;
    }
    /// @notice approve `spender` to transfer `amount` tokens.
    /// @param spender address to be given rights to transfer.
    /// @param amount the number of tokens allowed.
    /// @return true if success.
    function approve(address spender, uint256 amount)
        public
        returns (bool success)
    {
        _approveFor(msg.sender, spender, amount);
        return true;
    }
    /// @notice approve `spender` to transfer `amount` tokens from `owner`.
    /// @param owner address whose token is allowed.
    /// @param spender  address to be given rights to transfer.
    /// @param amount the number of tokens allowed.
    /// @return true if success.
    function approveFor(address owner, address spender, uint256 amount)
        public
        returns (bool success)
    {
        require(
            msg.sender == owner || _superOperators[msg.sender],
            "msg.sender != owner && !superOperator"
        );
        _approveFor(owner, spender, amount);
        return true;
    }
    function addAllowanceIfNeeded(address owner, address spender, uint256 amountNeeded)
        public
        returns (bool success)
    {
        require(
            msg.sender == owner || _superOperators[msg.sender],
            "msg.sender != owner && !superOperator"
        );
        _addAllowanceIfNeeded(owner, spender, amountNeeded);
        return true;
    }
    function _addAllowanceIfNeeded(address owner, address spender, uint256 amountNeeded)
        internal
    {
        if(amountNeeded > 0 && !isSuperOperator(spender)) {
            uint256 currentAllowance = _allowances[owner][spender];
            if(currentAllowance < amountNeeded) {
                _approveFor(owner, spender, amountNeeded);
            }
        }
    }
    function _approveFor(address owner, address spender, uint256 amount)
        internal
    {
        require(
            owner != address(0) && spender != address(0),
            "Cannot approve with 0x0"
        );
        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }
    function _transfer(address from, address to, uint256 amount) internal {
        require(to != address(0), "Cannot send to 0x0");
        uint256 currentBalance = _balances[from];
        require(currentBalance >= amount, "not enough fund");
        _balances[from] = currentBalance - amount;
        _balances[to] += amount;
        emit Transfer(from, to, amount);
    }
    function _mint(address to, uint256 amount) internal {
        require(to != address(0), "Cannot mint to 0x0");
        require(amount > 0, "cannot mint 0 tokens");
        uint256 currentTotalSupply = _totalSupply;
        uint256 newTotalSupply = currentTotalSupply + amount;
        require(newTotalSupply > currentTotalSupply, "overflow");
        _totalSupply = newTotalSupply;
        _balances[to] += amount;
        emit Transfer(address(0), to, amount);
    }
    function _burn(address from, uint256 amount) internal {
        require(amount > 0, "cannot burn 0 tokens");
        if (msg.sender != from && !_superOperators[msg.sender]) {
            uint256 currentAllowance = _allowances[from][msg.sender];
            require(
                currentAllowance >= amount,
                "Not enough funds allowed"
            );
            if (currentAllowance != (2**256) - 1) {
                // save gas when allowance is maximal by not reducing it (see https://github.com/ethereum/EIPs/issues/717)
                _allowances[from][msg.sender] = currentAllowance - amount;
            }
        }
        uint256 currentBalance = _balances[from];
        require(currentBalance >= amount, "Not enough funds");
        _balances[from] = currentBalance - amount;
        _totalSupply -= amount;
        emit Transfer(from, address(0), amount);
    }
}
pragma solidity 0.5.9;
import "../../../contracts_common/src/Libraries/BytesUtil.sol";
contract ERC20BasicApproveExtension {
    /// @notice approve `target` to spend `amount` and call it with data.
    /// @param target address to be given rights to transfer and destination of the call.
    /// @param amount the number of tokens allowed.
    /// @param data bytes for the call.
    /// @return data of the call.
    function approveAndCall(
        address target,
        uint256 amount,
        bytes calldata data
    ) external payable returns (bytes memory) {
        require(
            BytesUtil.doFirstParamEqualsAddress(data, msg.sender),
            "first param != sender"
        );
        _approveFor(msg.sender, target, amount);
        // solium-disable-next-line security/no-call-value
        (bool success, bytes memory returnData) = target.call.value(msg.value)(data);
        require(success, string(returnData));
        return returnData;
    }
    /// @notice temporarly approve `target` to spend `amount` and call it with data. Previous approvals remains unchanged.
    /// @param target destination of the call, allowed to spend the amount specified
    /// @param amount the number of tokens allowed to spend.
    /// @param data bytes for the call.
    /// @return data of the call.
    function paidCall(
        address target,
        uint256 amount,
        bytes calldata data
    ) external payable returns (bytes memory) {
        require(
            BytesUtil.doFirstParamEqualsAddress(data, msg.sender),
            "first param != sender"
        );
        if (amount > 0) {
            _addAllowanceIfNeeded(msg.sender, target, amount);
        }
        // solium-disable-next-line security/no-call-value
        (bool success, bytes memory returnData) = target.call.value(msg.value)(data);
        require(success, string(returnData));
        return returnData;
    }
    function _approveFor(address owner, address target, uint256 amount) internal;
    function _addAllowanceIfNeeded(address owner, address spender, uint256 amountNeeded) internal;
}
pragma solidity 0.5.9;
contract ERC20ExecuteExtension {
    /// @dev _executionAdmin != _admin so that this super power can be disabled independently
    address internal _executionAdmin;
    event ExecutionAdminAdminChanged(address oldAdmin, address newAdmin);
    /// @notice give the address responsible for adding execution rights.
    /// @return address of the execution administrator.
    function getExecutionAdmin() external view returns (address) {
        return _executionAdmin;
    }
    /// @notice change the execution adminstrator to be `newAdmin`.
    /// @param newAdmin address of the new administrator.
    function changeExecutionAdmin(address newAdmin) external {
        require(msg.sender == _executionAdmin, "only executionAdmin can change executionAdmin");
        emit ExecutionAdminAdminChanged(_executionAdmin, newAdmin);
        _executionAdmin = newAdmin;
    }
    mapping(address => bool) internal _executionOperators;
    event ExecutionOperator(address executionOperator, bool enabled);
    /// @notice set `executionOperator` as executionOperator: `enabled`.
    /// @param executionOperator address that will be given/removed executionOperator right.
    /// @param enabled set whether the executionOperator is enabled or disabled.
    function setExecutionOperator(address executionOperator, bool enabled) external {
        require(
            msg.sender == _executionAdmin,
            "only execution admin is allowed to add execution operators"
        );
        _executionOperators[executionOperator] = enabled;
        emit ExecutionOperator(executionOperator, enabled);
    }
    /// @notice check whether address `who` is given executionOperator rights.
    /// @param who The address to query.
    /// @return whether the address has executionOperator rights.
    function isExecutionOperator(address who) public view returns (bool) {
        return _executionOperators[who];
    }
    /// @notice execute on behalf of the contract.
    /// @param to destination address fo the call.
    /// @param gasLimit exact amount of gas to be passed to the call.
    /// @param data the bytes sent to the destination address.
    /// @return success whether the execution was successful.
    /// @return returnData data resulting from the execution.
    function executeWithSpecificGas(address to, uint256 gasLimit, bytes calldata data) external returns (bool success, bytes memory returnData) {
        require(_executionOperators[msg.sender], "only execution operators allowed to execute on SAND behalf");
        (success, returnData) = to.call.gas(gasLimit)(data);
        assert(gasleft() > gasLimit / 63); // not enough gas provided, assert to throw all gas // TODO use EIP-1930
    }
    /// @notice approve a specific amount of token for `from` and execute on behalf of the contract.
    /// @param from address of which token will be transfered.
    /// @param to destination address fo the call.
    /// @param amount number of tokens allowed that can be transfer by the code at `to`.
    /// @param gasLimit exact amount of gas to be passed to the call.
    /// @param data the bytes sent to the destination address.
    /// @return success whether the execution was successful.
    /// @return returnData data resulting from the execution.
    function approveAndExecuteWithSpecificGas(
        address from,
        address to,
        uint256 amount,
        uint256 gasLimit,
        bytes calldata data
    ) external returns (bool success, bytes memory returnData) {
        require(_executionOperators[msg.sender], "only execution operators allowed to execute on SAND behalf");
        return _approveAndExecuteWithSpecificGas(from, to, amount, gasLimit, data);
    }
    /// @dev the reason for this function is that charging for gas here is more gas-efficient than doing it in the caller.
    /// @notice approve a specific amount of token for `from` and execute on behalf of the contract. Plus charge the gas required to perform it.
    /// @param from address of which token will be transfered.
    /// @param to destination address fo the call.
    /// @param amount number of tokens allowed that can be transfer by the code at `to`.
    /// @param gasLimit exact amount of gas to be passed to the call.
    /// @param tokenGasPrice price in token for the gas to be charged.
    /// @param baseGasCharge amount of gas charged on top of the gas used for the call.
    /// @param tokenReceiver recipient address of the token charged for the gas used.
    /// @param data the bytes sent to the destination address.
    /// @return success whether the execution was successful.
    /// @return returnData data resulting from the execution.
    function approveAndExecuteWithSpecificGasAndChargeForIt(
        address from,
        address to,
        uint256 amount,
        uint256 gasLimit,
        uint256 tokenGasPrice,
        uint256 baseGasCharge,
        address tokenReceiver,
        bytes calldata data
    ) external returns (bool success, bytes memory returnData) {
        uint256 initialGas = gasleft();
        require(_executionOperators[msg.sender], "only execution operators allowed to execute on SAND behalf");
        (success, returnData) = _approveAndExecuteWithSpecificGas(from, to, amount, gasLimit, data);
        if (tokenGasPrice > 0) {
            _charge(from, gasLimit, tokenGasPrice, initialGas, baseGasCharge, tokenReceiver);
        }
    }
    /// @notice transfer 1amount1 token from `from` to `to` and charge the gas required to perform that transfer.
    /// @param from address of which token will be transfered.
    /// @param to destination address fo the call.
    /// @param amount number of tokens allowed that can be transfer by the code at `to`.
    /// @param gasLimit exact amount of gas to be passed to the call.
    /// @param tokenGasPrice price in token for the gas to be charged.
    /// @param baseGasCharge amount of gas charged on top of the gas used for the call.
    /// @param tokenReceiver recipient address of the token charged for the gas used.
    /// @return whether the transfer was successful.
    function transferAndChargeForGas(
        address from,
        address to,
        uint256 amount,
        uint256 gasLimit,
        uint256 tokenGasPrice,
        uint256 baseGasCharge,
        address tokenReceiver
    ) external returns (bool) {
        uint256 initialGas = gasleft();
        require(_executionOperators[msg.sender], "only execution operators allowed to perfrom transfer and charge");
        _transfer(from, to, amount);
        if (tokenGasPrice > 0) {
            _charge(from, gasLimit, tokenGasPrice, initialGas, baseGasCharge, tokenReceiver);
        }
        return true;
    }
    function _charge(
        address from,
        uint256 gasLimit,
        uint256 tokenGasPrice,
        uint256 initialGas,
        uint256 baseGasCharge,
        address tokenReceiver
    ) internal {
        uint256 gasCharge = initialGas - gasleft();
        if(gasCharge > gasLimit) {
            gasCharge = gasLimit;
        }
        gasCharge += baseGasCharge;
        uint256 tokensToCharge = gasCharge * tokenGasPrice;
        require(tokensToCharge / gasCharge == tokenGasPrice, "overflow");
        _transfer(from, tokenReceiver, tokensToCharge);
    }
    function _approveAndExecuteWithSpecificGas(
        address from,
        address to,
        uint256 amount,
        uint256 gasLimit,
        bytes memory data
    ) internal returns (bool success, bytes memory returnData) {
        if (amount > 0) {
            _addAllowanceIfNeeded(from, to, amount);
        }
        (success, returnData) = to.call.gas(gasLimit)(data);
        assert(gasleft() > gasLimit / 63); // not enough gas provided, assert to throw all gas // TODO use EIP-1930
    }
    function _transfer(address from, address to, uint256 amount) internal;
    function _addAllowanceIfNeeded(address owner, address spender, uint256 amountNeeded) internal;
}

pragma solidity ^0.5.3;

/// @title Proxy - Generic proxy contract allows to execute all transactions applying the code of a master contract.
/// @author Stefan George - <[email protected]>
/// @author Richard Meissner - <[email protected]>
contract Proxy {

    // masterCopy always needs to be first declared variable, to ensure that it is at the same location in the contracts to which calls are delegated.
    // To reduce deployment costs this variable is internal and needs to be retrieved via `getStorageAt`
    address internal masterCopy;

    /// @dev Constructor function sets address of master copy contract.
    /// @param _masterCopy Master copy address.
    constructor(address _masterCopy)
        public
    {
        require(_masterCopy != address(0), "Invalid master copy address provided");
        masterCopy = _masterCopy;
    }

    /// @dev Fallback function forwards all transactions and returns all received return data.
    function ()
        external
        payable
    {
        // solium-disable-next-line security/no-inline-assembly
        assembly {
            let masterCopy := and(sload(0), 0xffffffffffffffffffffffffffffffffffffffff)
            // 0xa619486e == keccak("masterCopy()"). The value is right padded to 32-bytes with 0s
            if eq(calldataload(0), 0xa619486e00000000000000000000000000000000000000000000000000000000) {
                mstore(0, masterCopy)
                return(0, 0x20)
            }
            calldatacopy(0, 0, calldatasize())
            let success := delegatecall(gas, masterCopy, 0, calldatasize(), 0, 0)
            returndatacopy(0, 0, returndatasize())
            if eq(success, 0) { revert(0, returndatasize()) }
            return(0, returndatasize())
        }
    }
}

pragma solidity ^0.5.3;

/// @title Proxy - Generic proxy contract allows to execute all transactions applying the code of a master contract.
/// @author Stefan George - <[email protected]>
/// @author Richard Meissner - <[email protected]>
contract Proxy {

    // masterCopy always needs to be first declared variable, to ensure that it is at the same location in the contracts to which calls are delegated.
    // To reduce deployment costs this variable is internal and needs to be retrieved via `getStorageAt`
    address internal masterCopy;

    /// @dev Constructor function sets address of master copy contract.
    /// @param _masterCopy Master copy address.
    constructor(address _masterCopy)
        public
    {
        require(_masterCopy != address(0), "Invalid master copy address provided");
        masterCopy = _masterCopy;
    }

    /// @dev Fallback function forwards all transactions and returns all received return data.
    function ()
        external
        payable
    {
        // solium-disable-next-line security/no-inline-assembly
        assembly {
            let masterCopy := and(sload(0), 0xffffffffffffffffffffffffffffffffffffffff)
            // 0xa619486e == keccak("masterCopy()"). The value is right padded to 32-bytes with 0s
            if eq(calldataload(0), 0xa619486e00000000000000000000000000000000000000000000000000000000) {
                mstore(0, masterCopy)
                return(0, 0x20)
            }
            calldatacopy(0, 0, calldatasize())
            let success := delegatecall(gas, masterCopy, 0, calldatasize(), 0, 0)
            returndatacopy(0, 0, returndatasize())
            if eq(success, 0) { revert(0, returndatasize()) }
            return(0, returndatasize())
        }
    }
}

pragma solidity ^0.5.2;
contract Admin {
    address internal _admin;
    event AdminChanged(address oldAdmin, address newAdmin);
    /// @notice gives the current administrator of this contract.
    /// @return the current administrator of this contract.
    function getAdmin() external view returns (address) {
        return _admin;
    }
    /// @notice change the administrator to be `newAdmin`.
    /// @param newAdmin address of the new administrator.
    function changeAdmin(address newAdmin) external {
        require(msg.sender == _admin, "only admin can change admin");
        emit AdminChanged(_admin, newAdmin);
        _admin = newAdmin;
    }
    modifier onlyAdmin() {
        require (msg.sender == _admin, "only admin allowed");
        _;
    }
}
pragma solidity ^0.5.2;
import "./Admin.sol";
contract MetaTransactionReceiver is Admin{
    mapping(address => bool) internal _metaTransactionContracts;
    event MetaTransactionProcessor(address metaTransactionProcessor, bool enabled);
    /// @notice Enable or disable the ability of `metaTransactionProcessor` to perform meta-tx (metaTransactionProcessor rights).
    /// @param metaTransactionProcessor address that will be given/removed metaTransactionProcessor rights.
    /// @param enabled set whether the metaTransactionProcessor is enabled or disabled.
    function setMetaTransactionProcessor(address metaTransactionProcessor, bool enabled) public {
        require(
            msg.sender == _admin,
            "only admin can setup metaTransactionProcessors"
        );
        _setMetaTransactionProcessor(metaTransactionProcessor, enabled);
    }
    function _setMetaTransactionProcessor(address metaTransactionProcessor, bool enabled) internal {
        _metaTransactionContracts[metaTransactionProcessor] = enabled;
        emit MetaTransactionProcessor(metaTransactionProcessor, enabled);
    }
    /// @notice check whether address `who` is given meta-transaction execution rights.
    /// @param who The address to query.
    /// @return whether the address has meta-transaction execution rights.
    function isMetaTransactionProcessor(address who) external view returns(bool) {
        return _metaTransactionContracts[who];
    }
}pragma solidity ^0.5.2;
import "./Admin.sol";
contract SuperOperators is Admin {
    mapping(address => bool) internal _superOperators;
    event SuperOperator(address superOperator, bool enabled);
    /// @notice Enable or disable the ability of `superOperator` to transfer tokens of all (superOperator rights).
    /// @param superOperator address that will be given/removed superOperator right.
    /// @param enabled set whether the superOperator is enabled or disabled.
    function setSuperOperator(address superOperator, bool enabled) external {
        require(
            msg.sender == _admin,
            "only admin is allowed to add super operators"
        );
        _superOperators[superOperator] = enabled;
        emit SuperOperator(superOperator, enabled);
    }
    /// @notice check whether address `who` is given superOperator rights.
    /// @param who The address to query.
    /// @return whether the address has superOperator rights.
    function isSuperOperator(address who) public view returns (bool) {
        return _superOperators[who];
    }
}
pragma solidity ^0.5.2;
/**
 * @title ERC721 Non-Fungible Token Standard basic interface
 * @dev see https://eips.ethereum.org/EIPS/eip-721
 */
interface ERC721Events {
    event Transfer(
        address indexed _from,
        address indexed _to,
        uint256 indexed _tokenId
    );
    event Approval(
        address indexed _owner,
        address indexed _approved,
        uint256 indexed _tokenId
    );
    event ApprovalForAll(
        address indexed _owner,
        address indexed _operator,
        bool _approved
    );
}
pragma solidity ^0.5.2;
/**
    Note: The ERC-165 identifier for this interface is 0x5e8bf644.
*/
interface ERC721MandatoryTokenReceiver {
    function onERC721BatchReceived(
        address operator,
        address from,
        uint256[] calldata ids,
        bytes calldata data
    ) external returns (bytes4); // needs to return 0x4b808c46
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4); // needs to return 0x150b7a02
    // needs to implements EIP-165
    // function supportsInterface(bytes4 interfaceId)
    //     external
    //     view
    //     returns (bool);
}
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * This code has not been reviewed.
 * Do not use or deploy this code before reviewing it personally first.
 */
// solhint-disable-next-line compiler-fixed
pragma solidity ^0.5.2;
interface ERC721TokenReceiver {
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}
pragma solidity ^0.5.2;
library AddressUtils {
    function toPayable(address _address) internal pure returns (address payable _payable) {
        return address(uint160(_address));
    }
    function isContract(address addr) internal view returns (bool) {
        // for accounts without code, i.e. `keccak256('')`:
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        bytes32 codehash;
        // solium-disable-next-line security/no-inline-assembly
        assembly {
            codehash := extcodehash(addr)
        }
        return (codehash != 0x0 && codehash != accountHash);
    }
}
/* solhint-disable no-empty-blocks */
pragma solidity 0.5.9;
import "./Land/erc721/LandBaseToken.sol";
contract Land is LandBaseToken {
    constructor(
        address metaTransactionContract,
        address admin
    ) public LandBaseToken(
        metaTransactionContract,
        admin
    ) {
    }
    /**
     * @notice Return the name of the token contract
     * @return The name of the token contract
     */
    function name() external pure returns (string memory) {
        return "Sandbox's LANDs";
    }
    /**
     * @notice Return the symbol of the token contract
     * @return The symbol of the token contract
     */
    function symbol() external pure returns (string memory) {
        return "LAND";
    }
    // solium-disable-next-line security/no-assign-params
    function uint2str(uint _i) internal pure returns (string memory) {
        if (_i == 0) {
            return "0";
        }
        uint j = _i;
        uint len;
        while (j != 0) {
            len++;
            j /= 10;
        }
        bytes memory bstr = new bytes(len);
        uint k = len - 1;
        while (_i != 0) {
            bstr[k--] = byte(uint8(48 + _i % 10));
            _i /= 10;
        }
        return string(bstr);
    }
    /**
     * @notice Return the URI of a specific token
     * @param id The id of the token
     * @return The URI of the token
     */
    function tokenURI(uint256 id) public view returns (string memory) {
        require(_ownerOf(id) != address(0), "Id does not exist");
        return
            string(
                abi.encodePacked(
                    "https://api.sandbox.game/lands/",
                    uint2str(id),
                    "/metadata.json"
                )
            );
    }
    /**
     * @notice Check if the contract supports an interface
     * 0x01ffc9a7 is ERC-165
     * 0x80ac58cd is ERC-721
     * 0x5b5e139f is ERC-721 metadata
     * @param id The id of the interface
     * @return True if the interface is supported
     */
    function supportsInterface(bytes4 id) external pure returns (bool) {
        return id == 0x01ffc9a7 || id == 0x80ac58cd || id == 0x5b5e139f;
    }
}
/* solhint-disable func-order, code-complexity */
pragma solidity 0.5.9;
import "../../../contracts_common/src/Libraries/AddressUtils.sol";
import "../../../contracts_common/src/Interfaces/ERC721TokenReceiver.sol";
import "../../../contracts_common/src/Interfaces/ERC721Events.sol";
import "../../../contracts_common/src/BaseWithStorage/SuperOperators.sol";
import "../../../contracts_common/src/BaseWithStorage/MetaTransactionReceiver.sol";
import "../../../contracts_common/src/Interfaces/ERC721MandatoryTokenReceiver.sol";
contract ERC721BaseToken is ERC721Events, SuperOperators, MetaTransactionReceiver {
    using AddressUtils for address;
    bytes4 internal constant _ERC721_RECEIVED = 0x150b7a02;
    bytes4 internal constant _ERC721_BATCH_RECEIVED = 0x4b808c46;
    bytes4 internal constant ERC165ID = 0x01ffc9a7;
    bytes4 internal constant ERC721_MANDATORY_RECEIVER = 0x5e8bf644;
    mapping (address => uint256) public _numNFTPerAddress;
    mapping (uint256 => uint256) public _owners;
    mapping (address => mapping(address => bool)) public _operatorsForAll;
    mapping (uint256 => address) public _operators;
    constructor(
        address metaTransactionContract,
        address admin
    ) internal {
        _admin = admin;
        _setMetaTransactionProcessor(metaTransactionContract, true);
    }
    function _transferFrom(address from, address to, uint256 id) internal {
        _numNFTPerAddress[from]--;
        _numNFTPerAddress[to]++;
        _owners[id] = uint256(to);
        emit Transfer(from, to, id);
    }
    /**
     * @notice Return the number of Land owned by an address
     * @param owner The address to look for
     * @return The number of Land token owned by the address
     */
    function balanceOf(address owner) external view returns (uint256) {
        require(owner != address(0), "owner is zero address");
        return _numNFTPerAddress[owner];
    }
    function _ownerOf(uint256 id) internal view returns (address) {
        return address(_owners[id]);
    }
    function _ownerAndOperatorEnabledOf(uint256 id) internal view returns (address owner, bool operatorEnabled) {
        uint256 data = _owners[id];
        owner = address(data);
        operatorEnabled = (data / 2**255) == 1;
    }
    /**
     * @notice Return the owner of a Land
     * @param id The id of the Land
     * @return The address of the owner
     */
    function ownerOf(uint256 id) external view returns (address owner) {
        owner = _ownerOf(id);
        require(owner != address(0), "token does not exist");
    }
    function _approveFor(address owner, address operator, uint256 id) internal {
        if(operator == address(0)) {
            _owners[id] = uint256(owner); // no need to resset the operator, it will be overriden next time
        } else {
            _owners[id] = uint256(owner) + 2**255;
            _operators[id] = operator;
        }
        emit Approval(owner, operator, id);
    }
    /**
     * @notice Approve an operator to spend tokens on the sender behalf
     * @param sender The address giving the approval
     * @param operator The address receiving the approval
     * @param id The id of the token
     */
    function approveFor(
        address sender,
        address operator,
        uint256 id
    ) external {
        address owner = _ownerOf(id);
        require(sender != address(0), "sender is zero address");
        require(
            msg.sender == sender ||
            _metaTransactionContracts[msg.sender] ||
            _superOperators[msg.sender] ||
            _operatorsForAll[sender][msg.sender],
            "not authorized to approve"
        );
        require(owner == sender, "owner != sender");
        _approveFor(owner, operator, id);
    }
    /**
     * @notice Approve an operator to spend tokens on the sender behalf
     * @param operator The address receiving the approval
     * @param id The id of the token
     */
    function approve(address operator, uint256 id) external {
        address owner = _ownerOf(id);
        require(owner != address(0), "token does not exist");
        require(
            owner == msg.sender ||
            _superOperators[msg.sender] ||
            _operatorsForAll[owner][msg.sender],
            "not authorized to approve"
        );
        _approveFor(owner, operator, id);
    }
    /**
     * @notice Get the approved operator for a specific token
     * @param id The id of the token
     * @return The address of the operator
     */
    function getApproved(uint256 id) external view returns (address) {
        (address owner, bool operatorEnabled) = _ownerAndOperatorEnabledOf(id);
        require(owner != address(0), "token does not exist");
        if (operatorEnabled) {
            return _operators[id];
        } else {
            return address(0);
        }
    }
    function _checkTransfer(address from, address to, uint256 id) internal view returns (bool isMetaTx) {
        (address owner, bool operatorEnabled) = _ownerAndOperatorEnabledOf(id);
        require(owner != address(0), "token does not exist");
        require(owner == from, "not owner in _checkTransfer");
        require(to != address(0), "can't send to zero address");
        isMetaTx = msg.sender != from && _metaTransactionContracts[msg.sender];
        if (msg.sender != from && !isMetaTx) {
            require(
                _superOperators[msg.sender] ||
                _operatorsForAll[from][msg.sender] ||
                (operatorEnabled && _operators[id] == msg.sender),
                "not approved to transfer"
            );
        }
    }
    function _checkInterfaceWith10000Gas(address _contract, bytes4 interfaceId)
        internal
        view
        returns (bool)
    {
        bool success;
        bool result;
        bytes memory call_data = abi.encodeWithSelector(
            ERC165ID,
            interfaceId
        );
        // solium-disable-next-line security/no-inline-assembly
        assembly {
            let call_ptr := add(0x20, call_data)
            let call_size := mload(call_data)
            let output := mload(0x40) // Find empty storage location using "free memory pointer"
            mstore(output, 0x0)
            success := staticcall(
                10000,
                _contract,
                call_ptr,
                call_size,
                output,
                0x20
            ) // 32 bytes
            result := mload(output)
        }
        // (10000 / 63) "not enough for supportsInterface(...)" // consume all gas, so caller can potentially know that there was not enough gas
        assert(gasleft() > 158);
        return success && result;
    }
    /**
     * @notice Transfer a token between 2 addresses
     * @param from The sender of the token
     * @param to The recipient of the token
     * @param id The id of the token
    */
    function transferFrom(address from, address to, uint256 id) external {
        bool metaTx = _checkTransfer(from, to, id);
        _transferFrom(from, to, id);
        if (to.isContract() && _checkInterfaceWith10000Gas(to, ERC721_MANDATORY_RECEIVER)) {
            require(
                _checkOnERC721Received(metaTx ? from : msg.sender, from, to, id, ""),
                "erc721 transfer rejected by to"
            );
        }
    }
    /**
     * @notice Transfer a token between 2 addresses letting the receiver knows of the transfer
     * @param from The sender of the token
     * @param to The recipient of the token
     * @param id The id of the token
     * @param data Additional data
     */
    function safeTransferFrom(address from, address to, uint256 id, bytes memory data) public {
        bool metaTx = _checkTransfer(from, to, id);
        _transferFrom(from, to, id);
        if (to.isContract()) {
            require(
                _checkOnERC721Received(metaTx ? from : msg.sender, from, to, id, data),
                "ERC721: transfer rejected by to"
            );
        }
    }
    /**
     * @notice Transfer a token between 2 addresses letting the receiver knows of the transfer
     * @param from The send of the token
     * @param to The recipient of the token
     * @param id The id of the token
     */
    function safeTransferFrom(address from, address to, uint256 id) external {
        safeTransferFrom(from, to, id, "");
    }
    /**
     * @notice Transfer many tokens between 2 addresses
     * @param from The sender of the token
     * @param to The recipient of the token
     * @param ids The ids of the tokens
     * @param data additional data
    */
    function batchTransferFrom(address from, address to, uint256[] calldata ids, bytes calldata data) external {
        _batchTransferFrom(from, to, ids, data, false);
    }
    function _batchTransferFrom(address from, address to, uint256[] memory ids, bytes memory data, bool safe) internal {
        bool metaTx = msg.sender != from && _metaTransactionContracts[msg.sender];
        bool authorized = msg.sender == from ||
            metaTx ||
            _superOperators[msg.sender] ||
            _operatorsForAll[from][msg.sender];
        require(from != address(0), "from is zero address");
        require(to != address(0), "can't send to zero address");
        uint256 numTokens = ids.length;
        for(uint256 i = 0; i < numTokens; i ++) {
            uint256 id = ids[i];
            (address owner, bool operatorEnabled) = _ownerAndOperatorEnabledOf(id);
            require(owner == from, "not owner in batchTransferFrom");
            require(authorized || (operatorEnabled && _operators[id] == msg.sender), "not authorized");
            _owners[id] = uint256(to);
            emit Transfer(from, to, id);
        }
        if (from != to) {
            _numNFTPerAddress[from] -= numTokens;
            _numNFTPerAddress[to] += numTokens;
        }
        if (to.isContract() && (safe || _checkInterfaceWith10000Gas(to, ERC721_MANDATORY_RECEIVER))) {
            require(
                _checkOnERC721BatchReceived(metaTx ? from : msg.sender, from, to, ids, data),
                "erc721 batch transfer rejected by to"
            );
        }
    }
    /**
     * @notice Transfer many tokens between 2 addresses ensuring the receiving contract has a receiver method
     * @param from The sender of the token
     * @param to The recipient of the token
     * @param ids The ids of the tokens
     * @param data additional data
    */
    function safeBatchTransferFrom(address from, address to, uint256[] calldata ids, bytes calldata data) external {
        _batchTransferFrom(from, to, ids, data, true);
    }
    /**
     * @notice Check if the contract supports an interface
     * 0x01ffc9a7 is ERC-165
     * 0x80ac58cd is ERC-721
     * @param id The id of the interface
     * @return True if the interface is supported
     */
    function supportsInterface(bytes4 id) external pure returns (bool) {
        return id == 0x01ffc9a7 || id == 0x80ac58cd;
    }
    /**
     * @notice Set the approval for an operator to manage all the tokens of the sender
     * @param sender The address giving the approval
     * @param operator The address receiving the approval
     * @param approved The determination of the approval
     */
    function setApprovalForAllFor(
        address sender,
        address operator,
        bool approved
    ) external {
        require(sender != address(0), "Invalid sender address");
        require(
            msg.sender == sender ||
            _metaTransactionContracts[msg.sender] ||
            _superOperators[msg.sender],
            "not authorized to approve for all"
        );
        _setApprovalForAll(sender, operator, approved);
    }
    /**
     * @notice Set the approval for an operator to manage all the tokens of the sender
     * @param operator The address receiving the approval
     * @param approved The determination of the approval
     */
    function setApprovalForAll(address operator, bool approved) external {
        _setApprovalForAll(msg.sender, operator, approved);
    }
    function _setApprovalForAll(
        address sender,
        address operator,
        bool approved
    ) internal {
        require(
            !_superOperators[operator],
            "super operator can't have their approvalForAll changed"
        );
        _operatorsForAll[sender][operator] = approved;
        emit ApprovalForAll(sender, operator, approved);
    }
    /**
     * @notice Check if the sender approved the operator
     * @param owner The address of the owner
     * @param operator The address of the operator
     * @return The status of the approval
     */
    function isApprovedForAll(address owner, address operator)
        external
        view
        returns (bool isOperator)
    {
        return _operatorsForAll[owner][operator] || _superOperators[operator];
    }
    function _burn(address from, address owner, uint256 id) public {
        require(from == owner, "not owner");
        _owners[id] = 2**160; // cannot mint it again
        _numNFTPerAddress[from]--;
        emit Transfer(from, address(0), id);
    }
    /// @notice Burns token `id`.
    /// @param id token which will be burnt.
    function burn(uint256 id) external {
        _burn(msg.sender, _ownerOf(id), id);
    }
    /// @notice Burn token`id` from `from`.
    /// @param from address whose token is to be burnt.
    /// @param id token which will be burnt.
    function burnFrom(address from, uint256 id) external {
        require(from != address(0), "Invalid sender address");
        (address owner, bool operatorEnabled) = _ownerAndOperatorEnabledOf(id);
        require(
            msg.sender == from ||
            _metaTransactionContracts[msg.sender] ||
            (operatorEnabled && _operators[id] == msg.sender) ||
            _superOperators[msg.sender] ||
            _operatorsForAll[from][msg.sender],
            "not authorized to burn"
        );
        _burn(from, owner, id);
    }
    function _checkOnERC721Received(address operator, address from, address to, uint256 tokenId, bytes memory _data)
        internal returns (bool)
    {
        bytes4 retval = ERC721TokenReceiver(to).onERC721Received(operator, from, tokenId, _data);
        return (retval == _ERC721_RECEIVED);
    }
    function _checkOnERC721BatchReceived(address operator, address from, address to, uint256[] memory ids, bytes memory _data)
        internal returns (bool)
    {
        bytes4 retval = ERC721MandatoryTokenReceiver(to).onERC721BatchReceived(operator, from, ids, _data);
        return (retval == _ERC721_BATCH_RECEIVED);
    }
}
/* solhint-disable func-order, code-complexity */
pragma solidity 0.5.9;
import "./ERC721BaseToken.sol";
contract LandBaseToken is ERC721BaseToken {
    // Our grid is 408 x 408 lands
    uint256 internal constant GRID_SIZE = 408;
    uint256 internal constant LAYER =          0xFF00000000000000000000000000000000000000000000000000000000000000;
    uint256 internal constant LAYER_1x1 =      0x0000000000000000000000000000000000000000000000000000000000000000;
    uint256 internal constant LAYER_3x3 =      0x0100000000000000000000000000000000000000000000000000000000000000;
    uint256 internal constant LAYER_6x6 =      0x0200000000000000000000000000000000000000000000000000000000000000;
    uint256 internal constant LAYER_12x12 =    0x0300000000000000000000000000000000000000000000000000000000000000;
    uint256 internal constant LAYER_24x24 =    0x0400000000000000000000000000000000000000000000000000000000000000;
    mapping(address => bool) internal _minters;
    event Minter(address superOperator, bool enabled);
    /// @notice Enable or disable the ability of `minter` to mint tokens
    /// @param minter address that will be given/removed minter right.
    /// @param enabled set whether the minter is enabled or disabled.
    function setMinter(address minter, bool enabled) external {
        require(
            msg.sender == _admin,
            "only admin is allowed to add minters"
        );
        _minters[minter] = enabled;
        emit Minter(minter, enabled);
    }
    /// @notice check whether address `who` is given minter rights.
    /// @param who The address to query.
    /// @return whether the address has minter rights.
    function isMinter(address who) public view returns (bool) {
        return _minters[who];
    }
    constructor(
        address metaTransactionContract,
        address admin
    ) public ERC721BaseToken(metaTransactionContract, admin) {
    }
    /// @notice total width of the map
    /// @return width
    function width() external returns(uint256) {
        return GRID_SIZE;
    }
    /// @notice total height of the map
    /// @return height
    function height() external returns(uint256) {
        return GRID_SIZE;
    }
    /// @notice x coordinate of Land token
    /// @param id tokenId
    /// @return the x coordinates
    function x(uint256 id) external returns(uint256) {
        require(_ownerOf(id) != address(0), "token does not exist");
        return id % GRID_SIZE;
    }
    /// @notice y coordinate of Land token
    /// @param id tokenId
    /// @return the y coordinates
    function y(uint256 id) external returns(uint256) {
        require(_ownerOf(id) != address(0), "token does not exist");
        return id / GRID_SIZE;
    }
    /**
     * @notice Mint a new quad (aligned to a quad tree with size 3, 6, 12 or 24 only)
     * @param to The recipient of the new quad
     * @param size The size of the new quad
     * @param x The top left x coordinate of the new quad
     * @param y The top left y coordinate of the new quad
     * @param data extra data to pass to the transfer
     */
    function mintQuad(address to, uint256 size, uint256 x, uint256 y, bytes calldata data) external {
        require(to != address(0), "to is zero address");
        require(
            isMinter(msg.sender),
            "Only a minter can mint"
        );
        require(x % size == 0 && y % size == 0, "Invalid coordinates");
        require(x <= GRID_SIZE - size && y <= GRID_SIZE - size, "Out of bounds");
        uint256 quadId;
        uint256 id = x + y * GRID_SIZE;
        if (size == 1) {
            quadId = id;
        } else if (size == 3) {
            quadId = LAYER_3x3 + id;
        } else if (size == 6) {
            quadId = LAYER_6x6 + id;
        } else if (size == 12) {
            quadId = LAYER_12x12 + id;
        } else if (size == 24) {
            quadId = LAYER_24x24 + id;
        } else {
            require(false, "Invalid size");
        }
        require(_owners[LAYER_24x24 + (x/24) * 24 + ((y/24) * 24) * GRID_SIZE] == 0, "Already minted as 24x24");
        uint256 toX = x+size;
        uint256 toY = y+size;
        if (size <= 12) {
            require(
                _owners[LAYER_12x12 + (x/12) * 12 + ((y/12) * 12) * GRID_SIZE] == 0,
                "Already minted as 12x12"
            );
        } else {
            for (uint256 x12i = x; x12i < toX; x12i += 12) {
                for (uint256 y12i = y; y12i < toY; y12i += 12) {
                    uint256 id12x12 = LAYER_12x12 + x12i + y12i * GRID_SIZE;
                    require(_owners[id12x12] == 0, "Already minted as 12x12");
                }
            }
        }
        if (size <= 6) {
            require(_owners[LAYER_6x6 + (x/6) * 6 + ((y/6) * 6) * GRID_SIZE] == 0, "Already minted as 6x6");
        } else {
            for (uint256 x6i = x; x6i < toX; x6i += 6) {
                for (uint256 y6i = y; y6i < toY; y6i += 6) {
                    uint256 id6x6 = LAYER_6x6 + x6i + y6i * GRID_SIZE;
                    require(_owners[id6x6] == 0, "Already minted as 6x6");
                }
            }
        }
        if (size <= 3) {
            require(_owners[LAYER_3x3 + (x/3) * 3 + ((y/3) * 3) * GRID_SIZE] == 0, "Already minted as 3x3");
        } else {
            for (uint256 x3i = x; x3i < toX; x3i += 3) {
                for (uint256 y3i = y; y3i < toY; y3i += 3) {
                    uint256 id3x3 = LAYER_3x3 + x3i + y3i * GRID_SIZE;
                    require(_owners[id3x3] == 0, "Already minted as 3x3");
                }
            }
        }
        for (uint256 i = 0; i < size*size; i++) {
            uint256 id = _idInPath(i, size, x, y);
            require(_owners[id] == 0, "Already minted");
            emit Transfer(address(0), to, id);
        }
        _owners[quadId] = uint256(to);
        _numNFTPerAddress[to] += size * size;
        _checkBatchReceiverAcceptQuad(msg.sender, address(0), to, size, x, y, data);
    }
    function _idInPath(uint256 i, uint256 size, uint256 x, uint256 y) internal pure returns(uint256) {
        uint256 row = i / size;
        if(row % 2 == 0) { // alow ids to follow a path in a quad
            return (x + (i%size)) + ((y + row) * GRID_SIZE);
        } else {
            return ((x + size) - (1 + i%size)) + ((y + row) * GRID_SIZE);
        }
    }
    /// @notice transfer one quad (aligned to a quad tree with size 3, 6, 12 or 24 only)
    /// @param from current owner of the quad
    /// @param to destination
    /// @param size size of the quad
    /// @param x The top left x coordinate of the quad
    /// @param y The top left y coordinate of the quad
    /// @param data additional data
    function transferQuad(address from, address to, uint256 size, uint256 x, uint256 y, bytes calldata data) external {
        require(from != address(0), "from is zero address");
        require(to != address(0), "can't send to zero address");
        bool metaTx = msg.sender != from && _metaTransactionContracts[msg.sender];
        if (msg.sender != from && !metaTx) {
            require(
                _superOperators[msg.sender] ||
                _operatorsForAll[from][msg.sender],
                "not authorized to transferQuad"
            );
        }
        _transferQuad(from, to, size, x, y);
        _numNFTPerAddress[from] -= size * size;
        _numNFTPerAddress[to] += size * size;
        _checkBatchReceiverAcceptQuad(metaTx ? from : msg.sender, from, to, size, x, y, data);
    }
    function _checkBatchReceiverAcceptQuad(
        address operator,
        address from,
        address to,
        uint256 size,
        uint256 x,
        uint256 y,
        bytes memory data
    ) internal {
        if (to.isContract() && _checkInterfaceWith10000Gas(to, ERC721_MANDATORY_RECEIVER)) {
            uint256[] memory ids = new uint256[](size*size);
            for (uint256 i = 0; i < size*size; i++) {
                ids[i] = _idInPath(i, size, x, y);
            }
            require(
                _checkOnERC721BatchReceived(operator, from, to, ids, data),
                "erc721 batch transfer rejected by to"
            );
        }
    }
    /// @notice transfer multiple quad (aligned to a quad tree with size 3, 6, 12 or 24 only)
    /// @param from current owner of the quad
    /// @param to destination
    /// @param sizes list of sizes for each quad
    /// @param xs list of top left x coordinates for each quad
    /// @param ys list of top left y coordinates for each quad
    /// @param data additional data
    function batchTransferQuad(
        address from,
        address to,
        uint256[] calldata sizes,
        uint256[] calldata xs,
        uint256[] calldata ys,
        bytes calldata data
    ) external {
        require(from != address(0), "from is zero address");
        require(to != address(0), "can't send to zero address");
        require(sizes.length == xs.length && xs.length == ys.length, "invalid data");
        bool metaTx = msg.sender != from && _metaTransactionContracts[msg.sender];
        if (msg.sender != from && !metaTx) {
            require(
                _superOperators[msg.sender] ||
                _operatorsForAll[from][msg.sender],
                "not authorized to transferMultiQuads"
            );
        }
        uint256 numTokensTransfered = 0;
        for (uint256 i = 0; i < sizes.length; i++) {
            uint256 size = sizes[i];
            _transferQuad(from, to, size, xs[i], ys[i]);
            numTokensTransfered += size * size;
        }
        _numNFTPerAddress[from] -= numTokensTransfered;
        _numNFTPerAddress[to] += numTokensTransfered;
        if (to.isContract() && _checkInterfaceWith10000Gas(to, ERC721_MANDATORY_RECEIVER)) {
            uint256[] memory ids = new uint256[](numTokensTransfered);
            uint256 counter = 0;
            for (uint256 j = 0; j < sizes.length; j++) {
                uint256 size = sizes[j];
                for (uint256 i = 0; i < size*size; i++) {
                    ids[counter] = _idInPath(i, size, xs[j], ys[j]);
                    counter++;
                }
            }
            require(
                _checkOnERC721BatchReceived(metaTx ? from : msg.sender, from, to, ids, data),
                "erc721 batch transfer rejected by to"
            );
        }
    }
    function _transferQuad(address from, address to, uint256 size, uint256 x, uint256 y) internal {
        if (size == 1) {
            uint256 id1x1 = x + y * GRID_SIZE;
            address owner = _ownerOf(id1x1);
            require(owner != address(0), "token does not exist");
            require(owner == from, "not owner in _transferQuad");
            _owners[id1x1] = uint256(to);
        } else {
            _regroup(from, to, size, x, y);
        }
        for (uint256 i = 0; i < size*size; i++) {
            emit Transfer(from, to, _idInPath(i, size, x, y));
        }
    }
    function _checkAndClear(address from, uint256 id) internal returns(bool) {
        uint256 owner = _owners[id];
        if (owner != 0) {
            require(address(owner) == from, "not owner");
            _owners[id] = 0;
            return true;
        }
        return false;
    }
    function _regroup(address from, address to, uint256 size, uint256 x, uint256 y) internal {
        require(x % size == 0 && y % size == 0, "Invalid coordinates");
        require(x <= GRID_SIZE - size && y <= GRID_SIZE - size, "Out of bounds");
        if (size == 3) {
            _regroup3x3(from, to, x, y, true);
        } else if (size == 6) {
            _regroup6x6(from, to, x, y, true);
        } else if (size == 12) {
            _regroup12x12(from, to, x, y, true);
        } else if (size == 24) {
            _regroup24x24(from, to, x, y, true);
        } else {
            require(false, "Invalid size");
        }
    }
    function _regroup3x3(address from, address to, uint256 x, uint256 y, bool set) internal returns (bool) {
        uint256 id = x + y * GRID_SIZE;
        uint256 quadId = LAYER_3x3 + id;
        bool ownerOfAll = true;
        for (uint256 xi = x; xi < x+3; xi++) {
            for (uint256 yi = y; yi < y+3; yi++) {
                ownerOfAll = _checkAndClear(from, xi + yi * GRID_SIZE) && ownerOfAll;
            }
        }
        if(set) {
            if(!ownerOfAll) {
                require(
                    _owners[quadId] == uint256(from) ||
                    _owners[LAYER_6x6 + (x/6) * 6 + ((y/6) * 6) * GRID_SIZE] == uint256(from) ||
                    _owners[LAYER_12x12 + (x/12) * 12 + ((y/12) * 12) * GRID_SIZE] == uint256(from) ||
                    _owners[LAYER_24x24 + (x/24) * 24 + ((y/24) * 24) * GRID_SIZE] == uint256(from),
                    "not owner of all sub quads nor parent quads"
                );
            }
            _owners[quadId] = uint256(to);
            return true;
        }
        return ownerOfAll;
    }
    function _regroup6x6(address from, address to, uint256 x, uint256 y, bool set) internal returns (bool) {
        uint256 id = x + y * GRID_SIZE;
        uint256 quadId = LAYER_6x6 + id;
        bool ownerOfAll = true;
        for (uint256 xi = x; xi < x+6; xi += 3) {
            for (uint256 yi = y; yi < y+6; yi += 3) {
                bool ownAllIndividual = _regroup3x3(from, to, xi, yi, false);
                uint256 id3x3 = LAYER_3x3 + xi + yi * GRID_SIZE;
                uint256 owner3x3 = _owners[id3x3];
                if (owner3x3 != 0) {
                    if(!ownAllIndividual) {
                        require(owner3x3 == uint256(from), "not owner of 3x3 quad");
                    }
                    _owners[id3x3] = 0;
                }
                ownerOfAll = (ownAllIndividual || owner3x3 != 0) && ownerOfAll;
            }
        }
        if(set) {
            if(!ownerOfAll) {
                require(
                    _owners[quadId] == uint256(from) ||
                    _owners[LAYER_12x12 + (x/12) * 12 + ((y/12) * 12) * GRID_SIZE] == uint256(from) ||
                    _owners[LAYER_24x24 + (x/24) * 24 + ((y/24) * 24) * GRID_SIZE] == uint256(from),
                    "not owner of all sub quads nor parent quads"
                );
            }
            _owners[quadId] = uint256(to);
            return true;
        }
        return ownerOfAll;
    }
    function _regroup12x12(address from, address to, uint256 x, uint256 y, bool set) internal returns (bool) {
        uint256 id = x + y * GRID_SIZE;
        uint256 quadId = LAYER_12x12 + id;
        bool ownerOfAll = true;
        for (uint256 xi = x; xi < x+12; xi += 6) {
            for (uint256 yi = y; yi < y+12; yi += 6) {
                bool ownAllIndividual = _regroup6x6(from, to, xi, yi, false);
                uint256 id6x6 = LAYER_6x6 + xi + yi * GRID_SIZE;
                uint256 owner6x6 = _owners[id6x6];
                if (owner6x6 != 0) {
                    if(!ownAllIndividual) {
                        require(owner6x6 == uint256(from), "not owner of 6x6 quad");
                    }
                    _owners[id6x6] = 0;
                }
                ownerOfAll = (ownAllIndividual || owner6x6 != 0) && ownerOfAll;
            }
        }
        if(set) {
            if(!ownerOfAll) {
                require(
                    _owners[quadId] == uint256(from) ||
                    _owners[LAYER_24x24 + (x/24) * 24 + ((y/24) * 24) * GRID_SIZE] == uint256(from),
                    "not owner of all sub quads nor parent quads"
                );
            }
            _owners[quadId] = uint256(to);
            return true;
        }
        return ownerOfAll;
    }
    function _regroup24x24(address from, address to, uint256 x, uint256 y, bool set) internal returns (bool) {
        uint256 id = x + y * GRID_SIZE;
        uint256 quadId = LAYER_24x24 + id;
        bool ownerOfAll = true;
        for (uint256 xi = x; xi < x+24; xi += 12) {
            for (uint256 yi = y; yi < y+24; yi += 12) {
                bool ownAllIndividual = _regroup12x12(from, to, xi, yi, false);
                uint256 id12x12 = LAYER_12x12 + xi + yi * GRID_SIZE;
                uint256 owner12x12 = _owners[id12x12];
                if (owner12x12 != 0) {
                    if(!ownAllIndividual) {
                        require(owner12x12 == uint256(from), "not owner of 12x12 quad");
                    }
                    _owners[id12x12] = 0;
                }
                ownerOfAll = (ownAllIndividual || owner12x12 != 0) && ownerOfAll;
            }
        }
        if(set) {
            if(!ownerOfAll) {
                require(
                    _owners[quadId] == uint256(from),
                    "not owner of all sub quads not parent quad"
                );
            }
            _owners[quadId] = uint256(to);
            return true;
        }
        return ownerOfAll || _owners[quadId] == uint256(from);
    }
    function _ownerOf(uint256 id) internal view returns (address) {
        require(id & LAYER == 0, "Invalid token id");
        uint256 x = id % GRID_SIZE;
        uint256 y = id / GRID_SIZE;
        uint256 owner1x1 = _owners[id];
        if (owner1x1 != 0) {
            return address(owner1x1); // cast to zero
        } else {
            address owner3x3 = address(_owners[LAYER_3x3 + (x/3) * 3 + ((y/3) * 3) * GRID_SIZE]);
            if (owner3x3 != address(0)) {
                return owner3x3;
            } else {
                address owner6x6 = address(_owners[LAYER_6x6 + (x/6) * 6 + ((y/6) * 6) * GRID_SIZE]);
                if (owner6x6 != address(0)) {
                    return owner6x6;
                } else {
                    address owner12x12 = address(_owners[LAYER_12x12 + (x/12) * 12 + ((y/12) * 12) * GRID_SIZE]);
                    if (owner12x12 != address(0)) {
                        return owner12x12;
                    } else {
                        return address(_owners[LAYER_24x24 + (x/24) * 24 + ((y/24) * 24) * GRID_SIZE]);
                    }
                }
            }
        }
    }
    function _ownerAndOperatorEnabledOf(uint256 id) internal view returns (address owner, bool operatorEnabled) {
        require(id & LAYER == 0, "Invalid token id");
        uint256 x = id % GRID_SIZE;
        uint256 y = id / GRID_SIZE;
        uint256 owner1x1 = _owners[id];
        if (owner1x1 != 0) {
            owner = address(owner1x1);
            operatorEnabled = (owner1x1 / 2**255) == 1;
        } else {
            address owner3x3 = address(_owners[LAYER_3x3 + (x/3) * 3 + ((y/3) * 3) * GRID_SIZE]);
            if (owner3x3 != address(0)) {
                owner = owner3x3;
                operatorEnabled = false;
            } else {
                address owner6x6 = address(_owners[LAYER_6x6 + (x/6) * 6 + ((y/6) * 6) * GRID_SIZE]);
                if (owner6x6 != address(0)) {
                    owner = owner6x6;
                    operatorEnabled = false;
                } else {
                    address owner12x12 = address(_owners[LAYER_12x12 + (x/12) * 12 + ((y/12) * 12) * GRID_SIZE]);
                    if (owner12x12 != address(0)) {
                        owner = owner12x12;
                        operatorEnabled = false;
                    } else {
                        owner = address(_owners[LAYER_24x24 + (x/24) * 24 + ((y/24) * 24) * GRID_SIZE]);
                        operatorEnabled = false;
                    }
                }
            }
        }
    }
}

/* solhint-disable not-rely-on-time, func-order */
pragma solidity 0.6.5;
import "../common/Libraries/SafeMathWithRequire.sol";
import "./LandToken.sol";
import "../common/Interfaces/ERC1155.sol";
import "../common/Interfaces/ERC20.sol";
import "../common/BaseWithStorage/MetaTransactionReceiver.sol";
import "../ReferralValidator/ReferralValidator.sol";
import "./AuthValidator.sol";
/// @title Estate Sale contract with referral
/// @notice This contract manages the sale of our lands as Estates
contract EstateSaleWithAuth is MetaTransactionReceiver, ReferralValidator {
    using SafeMathWithRequire for uint256;
    event LandQuadPurchased(
        address indexed buyer,
        address indexed to,
        uint256 indexed topCornerId,
        uint256 size,
        uint256 price,
        address token,
        uint256 amountPaid
    );
    /// @notice set the wallet receiving the proceeds
    /// @param newWallet address of the new receiving wallet
    function setReceivingWallet(address payable newWallet) external {
        require(newWallet != address(0), "ZERO_ADDRESS");
        require(msg.sender == _admin, "NOT_AUTHORIZED");
        _wallet = newWallet;
    }
    /// @notice buy Land with SAND using the merkle proof associated with it
    /// @param buyer address that perform the payment
    /// @param to address that will own the purchased Land
    /// @param reserved the reserved address (if any)
    /// @param info [X_INDEX=0] x coordinate of the Land [Y_INDEX=1] y coordinate of the Land [SIZE_INDEX=2] size of the pack of Land to purchase [PRICE_INDEX=3] price in SAND to purchase that Land
    /// @param proof merkleProof for that particular Land
    function buyLandWithSand(
        address buyer,
        address to,
        address reserved,
        uint256[] calldata info,
        bytes32 salt,
        uint256[] calldata assetIds,
        bytes32[] calldata proof,
        bytes calldata referral,
        bytes calldata signature
    ) external {
        _checkAddressesAndExpiryTime(buyer, reserved);
        _checkAuthAndProofValidity(to, reserved, info, salt, assetIds, proof, signature);
        _handleFeeAndReferral(buyer, info[PRICE_INDEX], referral);
        _mint(buyer, to, info);
        _sendAssets(to, assetIds);
    }
    /// @notice Gets the expiry time for the current sale
    /// @return The expiry time, as a unix epoch
    function getExpiryTime() external view returns (uint256) {
        return _expiryTime;
    }
    /// @notice Gets the Merkle root associated with the current sale
    /// @return The Merkle root, as a bytes32 hash
    function getMerkleRoot() external view returns (bytes32) {
        return _merkleRoot;
    }
    /// @notice enable Admin to withdraw remaining assets from EstateSaleWithFee contract
    /// @param to intended recipient of the asset tokens
    /// @param assetIds the assetIds to be transferred
    /// @param values the quantities of the assetIds to be transferred
    function withdrawAssets(
        address to,
        uint256[] calldata assetIds,
        uint256[] calldata values
    ) external {
        require(msg.sender == _admin, "NOT_AUTHORIZED");
        // require(block.timestamp > _expiryTime, "SALE_NOT_OVER"); // removed to recover in case of misconfigured sales
        _asset.safeBatchTransferFrom(address(this), to, assetIds, values, "");
    }
    function onERC1155Received(
        address, /*operator*/
        address, /*from*/
        uint256, /*id*/
        uint256, /*value*/
        bytes calldata /*data*/
    ) external pure returns (bytes4) {
        return 0xf23a6e61;
    }
    function onERC1155BatchReceived(
        address, /*operator*/
        address, /*from*/
        uint256[] calldata, /*ids*/
        uint256[] calldata, /*values*/
        bytes calldata /*data*/
    ) external pure returns (bytes4) {
        return 0xbc197c81;
    }
    function _sendAssets(address to, uint256[] memory assetIds) internal {
        uint256[] memory values = new uint256[](assetIds.length);
        for (uint256 i = 0; i < assetIds.length; i++) {
            values[i] = 1;
        }
        _asset.safeBatchTransferFrom(address(this), to, assetIds, values, "");
    }
    // NOTE: _checkAddressesAndExpiryTime & _checkAuthAndProofValidity were split due to a stack too deep issue
    function _checkAddressesAndExpiryTime(address buyer, address reserved) internal view {
        /* solium-disable-next-line security/no-block-members */
        require(block.timestamp < _expiryTime, "SALE_IS_OVER");
        require(buyer == msg.sender || _metaTransactionContracts[msg.sender], "NOT_AUTHORIZED");
        require(reserved == address(0) || reserved == buyer, "RESERVED_LAND");
    }
    // NOTE: _checkAddressesAndExpiryTime & _checkAuthAndProofValidity were split due to a stack too deep issue
    function _checkAuthAndProofValidity(
        address to,
        address reserved,
        uint256[] memory info,
        bytes32 salt,
        uint256[] memory assetIds,
        bytes32[] memory proof,
        bytes memory signature
    ) internal view {
        bytes32 hashedData = keccak256(
            abi.encodePacked(
                to,
                reserved,
                info[X_INDEX],
                info[Y_INDEX],
                info[SIZE_INDEX],
                info[PRICE_INDEX],
                salt,
                keccak256(abi.encodePacked(assetIds)),
                keccak256(abi.encodePacked(proof))
            )
        );
        require(_authValidator.isAuthValid(signature, hashedData), "INVALID_AUTH");
        bytes32 leaf = _generateLandHash(
            info[X_INDEX],
            info[Y_INDEX],
            info[SIZE_INDEX],
            info[PRICE_INDEX],
            reserved,
            salt,
            assetIds
        );
        require(_verify(proof, leaf), "INVALID_LAND");
    }
    function _mint(
        address buyer,
        address to,
        uint256[] memory info
    ) internal {
        if (info[SIZE_INDEX] == 1 || _estate == address(0)) {
            _land.mintQuad(to, info[SIZE_INDEX], info[X_INDEX], info[Y_INDEX], "");
        } else {
            _land.mintQuad(_estate, info[SIZE_INDEX], info[X_INDEX], info[Y_INDEX], abi.encode(to));
        }
        emit LandQuadPurchased(
            buyer,
            to,
            info[X_INDEX] + (info[Y_INDEX] * GRID_SIZE),
            info[SIZE_INDEX],
            info[PRICE_INDEX],
            address(_sand),
            info[PRICE_INDEX]
        );
    }
    function _generateLandHash(
        uint256 x,
        uint256 y,
        uint256 size,
        uint256 price,
        address reserved,
        bytes32 salt,
        uint256[] memory assetIds
    ) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked(x, y, size, price, reserved, salt, assetIds));
    }
    function _verify(bytes32[] memory proof, bytes32 leaf) internal view returns (bool) {
        bytes32 computedHash = leaf;
        for (uint256 i = 0; i < proof.length; i++) {
            bytes32 proofElement = proof[i];
            if (computedHash < proofElement) {
                computedHash = keccak256(abi.encodePacked(computedHash, proofElement));
            } else {
                computedHash = keccak256(abi.encodePacked(proofElement, computedHash));
            }
        }
        return computedHash == _merkleRoot;
    }
    function _handleFeeAndReferral(
        address buyer,
        uint256 priceInSand,
        bytes memory referral
    ) internal {
        // send 5% fee to a specially configured instance of FeeDistributor.sol
        uint256 remainingAmountInSand = _handleSandFee(buyer, priceInSand);
        // calculate referral based on 95% of original priceInSand
        handleReferralWithERC20(buyer, remainingAmountInSand, referral, _wallet, address(_sand));
    }
    function _handleSandFee(address buyer, uint256 priceInSand) internal returns (uint256) {
        uint256 feeAmountInSand = priceInSand.mul(FEE).div(100);
        require(_sand.transferFrom(buyer, address(_feeDistributor), feeAmountInSand), "FEE_TRANSFER_FAILED");
        return priceInSand.sub(feeAmountInSand);
    }
    uint256 internal constant GRID_SIZE = 408; // 408 is the size of the Land
    ERC1155 internal immutable _asset;
    LandToken internal immutable _land;
    ERC20 internal immutable _sand;
    address internal immutable _estate;
    address internal immutable _feeDistributor;
    address payable internal _wallet;
    AuthValidator internal _authValidator;
    uint256 internal immutable _expiryTime;
    bytes32 internal immutable _merkleRoot;
    uint256 private constant FEE = 5; // percentage of land sale price to be diverted to a specially configured instance of FeeDistributor, shown as an integer
    // buyLandWithSand info indexes
    uint256 private constant X_INDEX = 0;
    uint256 private constant Y_INDEX = 1;
    uint256 private constant SIZE_INDEX = 2;
    uint256 private constant PRICE_INDEX = 3;
    constructor(
        address landAddress,
        address sandContractAddress,
        address initialMetaTx,
        address admin,
        address payable initialWalletAddress,
        bytes32 merkleRoot,
        uint256 expiryTime,
        address initialSigningWallet,
        uint256 initialMaxCommissionRate,
        address estate,
        address asset,
        address feeDistributor,
        address authValidator
    ) public ReferralValidator(initialSigningWallet, initialMaxCommissionRate) {
        _land = LandToken(landAddress);
        _sand = ERC20(sandContractAddress);
        _setMetaTransactionProcessor(initialMetaTx, true);
        _wallet = initialWalletAddress;
        _merkleRoot = merkleRoot;
        _expiryTime = expiryTime;
        _admin = admin;
        _estate = estate;
        _asset = ERC1155(asset);
        _feeDistributor = feeDistributor;
        _authValidator = AuthValidator(authValidator);
    }
}
pragma solidity 0.6.5;
/**
 * @title SafeMath
 * @dev Math operations with safety checks that revert
 */
library SafeMathWithRequire {
    using SafeMathWithRequire for uint256;
    uint256 constant DECIMALS_18 = 1000000000000000000;
    uint256 constant DECIMALS_12 = 1000000000000;
    uint256 constant DECIMALS_9 = 1000000000;
    uint256 constant DECIMALS_6 = 1000000;
    /**
     * @dev Multiplies two numbers, throws on overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
        // Gas optimization: this is cheaper than asserting 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
        if (a == 0) {
            return 0;
        }
        c = a * b;
        require(c / a == b, "overflow");
        return c;
    }
    /**
     * @dev Integer division of two numbers, truncating the quotient.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0, "divbyzero");
        // uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold
        return a / b;
    }
    /**
     * @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "undeflow");
        return a - b;
    }
    /**
     * @dev Adds two numbers, throws on overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
        c = a + b;
        require(c >= a, "overflow");
        return c;
    }
    function sqrt6(uint256 a) internal pure returns (uint256 c) {
        a = a.mul(DECIMALS_12);
        uint256 tmp = a.add(1) / 2;
        c = a;
        // tmp cannot be zero unless a = 0 which skip the loop
        while (tmp < c) {
            c = tmp;
            tmp = ((a / tmp) + tmp) / 2;
        }
    }
    function sqrt3(uint256 a) internal pure returns (uint256 c) {
        a = a.mul(DECIMALS_6);
        uint256 tmp = a.add(1) / 2;
        c = a;
        // tmp cannot be zero unless a = 0 which skip the loop
        while (tmp < c) {
            c = tmp;
            tmp = ((a / tmp) + tmp) / 2;
        }
    }
    function cbrt6(uint256 a) internal pure returns (uint256 c) {
        a = a.mul(DECIMALS_18);
        uint256 tmp = a.add(2) / 3;
        c = a;
        // tmp cannot be zero unless a = 0 which skip the loop
        while (tmp < c) {
            c = tmp;
            uint256 tmpSquare = tmp**2;
            require(tmpSquare > tmp, "overflow");
            tmp = ((a / tmpSquare) + (tmp * 2)) / 3;
        }
        return c;
    }
    function cbrt3(uint256 a) internal pure returns (uint256 c) {
        a = a.mul(DECIMALS_9);
        uint256 tmp = a.add(2) / 3;
        c = a;
        // tmp cannot be zero unless a = 0 which skip the loop
        while (tmp < c) {
            c = tmp;
            uint256 tmpSquare = tmp**2;
            require(tmpSquare > tmp, "overflow");
            tmp = ((a / tmpSquare) + (tmp * 2)) / 3;
        }
        return c;
    }
    // TODO test
    function rt6_3(uint256 a) internal pure returns (uint256 c) {
        a = a.mul(DECIMALS_18);
        uint256 tmp = a.add(5) / 6;
        c = a;
        // tmp cannot be zero unless a = 0 which skip the loop
        while (tmp < c) {
            c = tmp;
            uint256 tmpFive = tmp**5;
            require(tmpFive > tmp, "overflow");
            tmp = ((a / tmpFive) + (tmp * 5)) / 6;
        }
    }
}
pragma solidity 0.6.5;
interface LandToken {
    function mintQuad(
        address to,
        uint256 size,
        uint256 x,
        uint256 y,
        bytes calldata data
    ) external;
}
pragma solidity 0.6.5;
/**
    @title ERC-1155 Multi Token Standard
    @dev See https://eips.ethereum.org/EIPS/eip-1155
    Note: The ERC-165 identifier for this interface is 0xd9b67a26.
 */
interface ERC1155 {
    event TransferSingle(address indexed operator, address indexed from, address indexed to, uint256 id, uint256 value);
    event TransferBatch(address indexed operator, address indexed from, address indexed to, uint256[] ids, uint256[] values);
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);
    event URI(string value, uint256 indexed id);
    /**
        @notice Transfers `value` amount of an `id` from  `from` to `to`  (with safety call).
        @dev Caller must be approved to manage the tokens being transferred out of the `from` account (see "Approval" section of the standard).
        MUST revert if `to` is the zero address.
        MUST revert if balance of holder for token `id` is lower than the `value` sent.
        MUST revert on any other error.
        MUST emit the `TransferSingle` event to reflect the balance change (see "Safe Transfer Rules" section of the standard).
        After the above conditions are met, this function MUST check if `to` is a smart contract (e.g. code size > 0). If so, it MUST call `onERC1155Received` on `to` and act appropriately (see "Safe Transfer Rules" section of the standard).
        @param from    Source address
        @param to      Target address
        @param id      ID of the token type
        @param value   Transfer amount
        @param data    Additional data with no specified format, MUST be sent unaltered in call to `onERC1155Received` on `to`
    */
    function safeTransferFrom(
        address from,
        address to,
        uint256 id,
        uint256 value,
        bytes calldata data
    ) external;
    /**
        @notice Transfers `values` amount(s) of `ids` from the `from` address to the `to` address specified (with safety call).
        @dev Caller must be approved to manage the tokens being transferred out of the `from` account (see "Approval" section of the standard).
        MUST revert if `to` is the zero address.
        MUST revert if length of `ids` is not the same as length of `values`.
        MUST revert if any of the balance(s) of the holder(s) for token(s) in `ids` is lower than the respective amount(s) in `values` sent to the recipient.
        MUST revert on any other error.
        MUST emit `TransferSingle` or `TransferBatch` event(s) such that all the balance changes are reflected (see "Safe Transfer Rules" section of the standard).
        Balance changes and events MUST follow the ordering of the arrays (_ids[0]/_values[0] before _ids[1]/_values[1], etc).
        After the above conditions for the transfer(s) in the batch are met, this function MUST check if `to` is a smart contract (e.g. code size > 0). If so, it MUST call the relevant `ERC1155TokenReceiver` hook(s) on `to` and act appropriately (see "Safe Transfer Rules" section of the standard).
        @param from    Source address
        @param to      Target address
        @param ids     IDs of each token type (order and length must match _values array)
        @param values  Transfer amounts per token type (order and length must match _ids array)
        @param data    Additional data with no specified format, MUST be sent unaltered in call to the `ERC1155TokenReceiver` hook(s) on `to`
    */
    function safeBatchTransferFrom(
        address from,
        address to,
        uint256[] calldata ids,
        uint256[] calldata values,
        bytes calldata data
    ) external;
    /**
        @notice Get the balance of an account's tokens.
        @param owner  The address of the token holder
        @param id     ID of the token
        @return        The _owner's balance of the token type requested
     */
    function balanceOf(address owner, uint256 id) external view returns (uint256);
    /**
        @notice Get the balance of multiple account/token pairs
        @param owners The addresses of the token holders
        @param ids    ID of the tokens
        @return        The _owner's balance of the token types requested (i.e. balance for each (owner, id) pair)
     */
    function balanceOfBatch(address[] calldata owners, uint256[] calldata ids) external view returns (uint256[] memory);
    /**
        @notice Enable or disable approval for a third party ("operator") to manage all of the caller's tokens.
        @dev MUST emit the ApprovalForAll event on success.
        @param operator  Address to add to the set of authorized operators
        @param approved  True if the operator is approved, false to revoke approval
    */
    function setApprovalForAll(address operator, bool approved) external;
    /**
        @notice Queries the approval status of an operator for a given owner.
        @param owner     The owner of the tokens
        @param operator  Address of authorized operator
        @return           True if the operator is approved, false if not
    */
    function isApprovedForAll(address owner, address operator) external view returns (bool);
}
pragma solidity 0.6.5;
/// @dev see https://eips.ethereum.org/EIPS/eip-20
interface ERC20 {
    /// @notice emitted when tokens are transfered from one address to another.
    /// @param from address from which the token are transfered from (zero means tokens are minted).
    /// @param to destination address which the token are transfered to (zero means tokens are burnt).
    /// @param value amount of tokens transferred.
    event Transfer(address indexed from, address indexed to, uint256 value);
    /// @notice emitted when owner grant transfer rights to another address
    /// @param owner address allowing its token to be transferred.
    /// @param spender address allowed to spend on behalf of `owner`
    /// @param value amount of tokens allowed.
    event Approval(address indexed owner, address indexed spender, uint256 value);
    /// @notice return the current total amount of tokens owned by all holders.
    /// @return supply total number of tokens held.
    function totalSupply() external view returns (uint256 supply);
    /// @notice return the number of tokens held by a particular address.
    /// @param who address being queried.
    /// @return balance number of token held by that address.
    function balanceOf(address who) external view returns (uint256 balance);
    /// @notice transfer tokens to a specific address.
    /// @param to destination address receiving the tokens.
    /// @param value number of tokens to transfer.
    /// @return success whether the transfer succeeded.
    function transfer(address to, uint256 value) external returns (bool success);
    /// @notice transfer tokens from one address to another.
    /// @param from address tokens will be sent from.
    /// @param to destination address receiving the tokens.
    /// @param value number of tokens to transfer.
    /// @return success whether the transfer succeeded.
    function transferFrom(
        address from,
        address to,
        uint256 value
    ) external returns (bool success);
    /// @notice approve an address to spend on your behalf.
    /// @param spender address entitled to transfer on your behalf.
    /// @param value amount allowed to be transfered.
    /// @param success whether the approval succeeded.
    function approve(address spender, uint256 value) external returns (bool success);
    /// @notice return the current allowance for a particular owner/spender pair.
    /// @param owner address allowing spender.
    /// @param spender address allowed to spend.
    /// @return amount number of tokens `spender` can spend on behalf of `owner`.
    function allowance(address owner, address spender) external view returns (uint256 amount);
}
pragma solidity 0.6.5;
import "./Admin.sol";
contract MetaTransactionReceiver is Admin {
    mapping(address => bool) internal _metaTransactionContracts;
    /// @dev emiited when a meta transaction processor is enabled/disabled
    /// @param metaTransactionProcessor address that will be given/removed metaTransactionProcessor rights.
    /// @param enabled set whether the metaTransactionProcessor is enabled or disabled.
    event MetaTransactionProcessor(address metaTransactionProcessor, bool enabled);
    /// @dev Enable or disable the ability of `metaTransactionProcessor` to perform meta-tx (metaTransactionProcessor rights).
    /// @param metaTransactionProcessor address that will be given/removed metaTransactionProcessor rights.
    /// @param enabled set whether the metaTransactionProcessor is enabled or disabled.
    function setMetaTransactionProcessor(address metaTransactionProcessor, bool enabled) public {
        require(msg.sender == _admin, "only admin can setup metaTransactionProcessors");
        _setMetaTransactionProcessor(metaTransactionProcessor, enabled);
    }
    function _setMetaTransactionProcessor(address metaTransactionProcessor, bool enabled) internal {
        _metaTransactionContracts[metaTransactionProcessor] = enabled;
        emit MetaTransactionProcessor(metaTransactionProcessor, enabled);
    }
    /// @dev check whether address `who` is given meta-transaction execution rights.
    /// @param who The address to query.
    /// @return whether the address has meta-transaction execution rights.
    function isMetaTransactionProcessor(address who) external view returns (bool) {
        return _metaTransactionContracts[who];
    }
}
/* solhint-disable not-rely-on-time, func-order */
pragma solidity 0.6.5;
import "../common/Libraries/SigUtil.sol";
import "../common/Libraries/SafeMathWithRequire.sol";
import "../common/Interfaces/ERC20.sol";
import "../common/BaseWithStorage/Admin.sol";
/// @dev This contract verifies if a referral is valid
contract ReferralValidator is Admin {
    address private _signingWallet;
    uint256 private _maxCommissionRate;
    mapping(address => uint256) private _previousSigningWallets;
    uint256 private _previousSigningDelay = 60 * 60 * 24 * 10;
    event ReferralUsed(
        address indexed referrer,
        address indexed referee,
        address indexed token,
        uint256 amount,
        uint256 commission,
        uint256 commissionRate
    );
    constructor(address initialSigningWallet, uint256 initialMaxCommissionRate) public {
        _signingWallet = initialSigningWallet;
        _maxCommissionRate = initialMaxCommissionRate;
    }
    /**
     * @dev Update the signing wallet
     * @param newSigningWallet The new address of the signing wallet
     */
    function updateSigningWallet(address newSigningWallet) external {
        require(_admin == msg.sender, "Sender not admin");
        _previousSigningWallets[_signingWallet] = now + _previousSigningDelay;
        _signingWallet = newSigningWallet;
    }
    /**
     * @dev signing wallet authorized for referral
     * @return the address of the signing wallet
     */
    function getSigningWallet() external view returns (address) {
        return _signingWallet;
    }
    /**
     * @notice the max commision rate
     * @return the maximum commision rate that a referral can give
     */
    function getMaxCommisionRate() external view returns (uint256) {
        return _maxCommissionRate;
    }
    /**
     * @dev Update the maximum commission rate
     * @param newMaxCommissionRate The new maximum commission rate
     */
    function updateMaxCommissionRate(uint256 newMaxCommissionRate) external {
        require(_admin == msg.sender, "Sender not admin");
        _maxCommissionRate = newMaxCommissionRate;
    }
    function handleReferralWithETH(
        uint256 amount,
        bytes memory referral,
        address payable destination
    ) internal {
        uint256 amountForDestination = amount;
        if (referral.length > 0) {
            (bytes memory signature, address referrer, address referee, uint256 expiryTime, uint256 commissionRate) = decodeReferral(referral);
            uint256 commission = 0;
            if (isReferralValid(signature, referrer, referee, expiryTime, commissionRate)) {
                commission = SafeMathWithRequire.div(SafeMathWithRequire.mul(amount, commissionRate), 10000);
                emit ReferralUsed(referrer, referee, address(0), amount, commission, commissionRate);
                amountForDestination = SafeMathWithRequire.sub(amountForDestination, commission);
            }
            if (commission > 0) {
                payable(referrer).transfer(commission);
            }
        }
        destination.transfer(amountForDestination);
    }
    function handleReferralWithERC20(
        address buyer,
        uint256 amount,
        bytes memory referral,
        address payable destination,
        address tokenAddress
    ) internal {
        ERC20 token = ERC20(tokenAddress);
        uint256 amountForDestination = amount;
        if (referral.length > 0) {
            (bytes memory signature, address referrer, address referee, uint256 expiryTime, uint256 commissionRate) = decodeReferral(referral);
            uint256 commission = 0;
            if (isReferralValid(signature, referrer, referee, expiryTime, commissionRate)) {
                commission = SafeMathWithRequire.div(SafeMathWithRequire.mul(amount, commissionRate), 10000);
                emit ReferralUsed(referrer, referee, tokenAddress, amount, commission, commissionRate);
                amountForDestination = SafeMathWithRequire.sub(amountForDestination, commission);
            }
            if (commission > 0) {
                require(token.transferFrom(buyer, referrer, commission), "commision transfer failed");
            }
        }
        require(token.transferFrom(buyer, destination, amountForDestination), "payment transfer failed");
    }
    /**
     * @notice Check if a referral is valid
     * @param signature The signature to check (signed referral)
     * @param referrer The address of the referrer
     * @param referee The address of the referee
     * @param expiryTime The expiry time of the referral
     * @param commissionRate The commissionRate of the referral
     * @return True if the referral is valid
     */
    function isReferralValid(
        bytes memory signature,
        address referrer,
        address referee,
        uint256 expiryTime,
        uint256 commissionRate
    ) public view returns (bool) {
        if (commissionRate > _maxCommissionRate || referrer == referee || now > expiryTime) {
            return false;
        }
        bytes32 hashedData = keccak256(abi.encodePacked(referrer, referee, expiryTime, commissionRate));
        address signer = SigUtil.recover(keccak256(abi.encodePacked("\\x19Ethereum Signed Message:\
32", hashedData)), signature);
        if (_previousSigningWallets[signer] >= now) {
            return true;
        }
        return _signingWallet == signer;
    }
    function decodeReferral(bytes memory referral)
        public
        pure
        returns (
            bytes memory,
            address,
            address,
            uint256,
            uint256
        )
    {
        (bytes memory signature, address referrer, address referee, uint256 expiryTime, uint256 commissionRate) = abi.decode(
            referral,
            (bytes, address, address, uint256, uint256)
        );
        return (signature, referrer, referee, expiryTime, commissionRate);
    }
}
//SPDX-License-Identifier: MIT
pragma solidity 0.6.5; // TODO: update once upgrade is complete
import "../common/Libraries/SigUtil.sol";
import "../common/Libraries/SafeMathWithRequire.sol";
import "../common/BaseWithStorage/Admin.sol";
contract AuthValidator is Admin {
    address public _signingAuthWallet;
    event SigningWallet(address indexed signingWallet);
    constructor(address adminWallet, address initialSigningWallet) public {
        _admin = adminWallet;
        _updateSigningAuthWallet(initialSigningWallet);
    }
    function updateSigningAuthWallet(address newSigningWallet) external onlyAdmin {
        _updateSigningAuthWallet(newSigningWallet);
    }
    function _updateSigningAuthWallet(address newSigningWallet) internal {
        require(newSigningWallet != address(0), "INVALID_SIGNING_WALLET");
        _signingAuthWallet = newSigningWallet;
        emit SigningWallet(newSigningWallet);
    }
    function isAuthValid(bytes memory signature, bytes32 hashedData) public view returns (bool) {
        address signer = SigUtil.recover(keccak256(SigUtil.prefixed(hashedData)), signature);
        return signer == _signingAuthWallet;
    }
}
pragma solidity 0.6.5;
contract Admin {
    address internal _admin;
    /// @dev emitted when the contract administrator is changed.
    /// @param oldAdmin address of the previous administrator.
    /// @param newAdmin address of the new administrator.
    event AdminChanged(address oldAdmin, address newAdmin);
    /// @dev gives the current administrator of this contract.
    /// @return the current administrator of this contract.
    function getAdmin() external view returns (address) {
        return _admin;
    }
    /// @dev change the administrator to be `newAdmin`.
    /// @param newAdmin address of the new administrator.
    function changeAdmin(address newAdmin) external {
        require(msg.sender == _admin, "only admin can change admin");
        emit AdminChanged(_admin, newAdmin);
        _admin = newAdmin;
    }
    modifier onlyAdmin() {
        require(msg.sender == _admin, "only admin allowed");
        _;
    }
}
pragma solidity 0.6.5;
library SigUtil {
    function recover(bytes32 hash, bytes memory sig) internal pure returns (address recovered) {
        require(sig.length == 65);
        bytes32 r;
        bytes32 s;
        uint8 v;
        assembly {
            r := mload(add(sig, 32))
            s := mload(add(sig, 64))
            v := byte(0, mload(add(sig, 96)))
        }
        // Version of signature should be 27 or 28, but 0 and 1 are also possible versions
        if (v < 27) {
            v += 27;
        }
        require(v == 27 || v == 28);
        recovered = ecrecover(hash, v, r, s);
        require(recovered != address(0));
    }
    function recoverWithZeroOnFailure(bytes32 hash, bytes memory sig) internal pure returns (address) {
        if (sig.length != 65) {
            return (address(0));
        }
        bytes32 r;
        bytes32 s;
        uint8 v;
        assembly {
            r := mload(add(sig, 32))
            s := mload(add(sig, 64))
            v := byte(0, mload(add(sig, 96)))
        }
        // Version of signature should be 27 or 28, but 0 and 1 are also possible versions
        if (v < 27) {
            v += 27;
        }
        if (v != 27 && v != 28) {
            return (address(0));
        } else {
            return ecrecover(hash, v, r, s);
        }
    }
    // Builds a prefixed hash to mimic the behavior of eth_sign.
    function prefixed(bytes32 hash) internal pure returns (bytes memory) {
        return abi.encodePacked("\\x19Ethereum Signed Message:\
32", hash);
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
import './UpgradeabilityProxy.sol';
/**
 * @title AdminUpgradeabilityProxy
 * @dev This contract combines an upgradeability proxy with an authorization
 * mechanism for administrative tasks.
 * All external functions in this contract must be guarded by the
 * `ifAdmin` modifier. See ethereum/solidity#3864 for a Solidity
 * feature proposal that would enable this to be done automatically.
 */
contract AdminUpgradeabilityProxy is UpgradeabilityProxy {
  /**
   * Contract constructor.
   * @param _logic address of the initial implementation.
   * @param _admin Address of the proxy administrator.
   * @param _data Data to send as msg.data to the implementation to initialize the proxied contract.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   * This parameter is optional, if no data is given the initialization call to proxied contract will be skipped.
   */
  constructor(address _logic, address _admin, bytes memory _data) UpgradeabilityProxy(_logic, _data) public payable {
    assert(ADMIN_SLOT == bytes32(uint256(keccak256('eip1967.proxy.admin')) - 1));
    _setAdmin(_admin);
  }
  /**
   * @dev Emitted when the administration has been transferred.
   * @param previousAdmin Address of the previous admin.
   * @param newAdmin Address of the new admin.
   */
  event AdminChanged(address previousAdmin, address newAdmin);
  /**
   * @dev Storage slot with the admin of the contract.
   * This is the keccak-256 hash of "eip1967.proxy.admin" subtracted by 1, and is
   * validated in the constructor.
   */
  bytes32 internal constant ADMIN_SLOT = 0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103;
  /**
   * @dev Modifier to check whether the `msg.sender` is the admin.
   * If it is, it will run the function. Otherwise, it will delegate the call
   * to the implementation.
   */
  modifier ifAdmin() {
    if (msg.sender == _admin()) {
      _;
    } else {
      _fallback();
    }
  }
  /**
   * @return The address of the proxy admin.
   */
  function admin() external ifAdmin returns (address) {
    return _admin();
  }
  /**
   * @return The address of the implementation.
   */
  function implementation() external ifAdmin returns (address) {
    return _implementation();
  }
  /**
   * @dev Changes the admin of the proxy.
   * Only the current admin can call this function.
   * @param newAdmin Address to transfer proxy administration to.
   */
  function changeAdmin(address newAdmin) external ifAdmin {
    require(newAdmin != address(0), "Cannot change the admin of a proxy to the zero address");
    emit AdminChanged(_admin(), newAdmin);
    _setAdmin(newAdmin);
  }
  /**
   * @dev Upgrade the backing implementation of the proxy.
   * Only the admin can call this function.
   * @param newImplementation Address of the new implementation.
   */
  function upgradeTo(address newImplementation) external ifAdmin {
    _upgradeTo(newImplementation);
  }
  /**
   * @dev Upgrade the backing implementation of the proxy and call a function
   * on the new implementation.
   * This is useful to initialize the proxied contract.
   * @param newImplementation Address of the new implementation.
   * @param data Data to send as msg.data in the low level call.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   */
  function upgradeToAndCall(address newImplementation, bytes calldata data) payable external ifAdmin {
    _upgradeTo(newImplementation);
    (bool success,) = newImplementation.delegatecall(data);
    require(success);
  }
  /**
   * @return adm The admin slot.
   */
  function _admin() internal view returns (address adm) {
    bytes32 slot = ADMIN_SLOT;
    assembly {
      adm := sload(slot)
    }
  }
  /**
   * @dev Sets the address of the proxy admin.
   * @param newAdmin Address of the new proxy admin.
   */
  function _setAdmin(address newAdmin) internal {
    bytes32 slot = ADMIN_SLOT;
    assembly {
      sstore(slot, newAdmin)
    }
  }
  /**
   * @dev Only fall back when the sender is not the admin.
   */
  function _willFallback() internal override virtual {
    require(msg.sender != _admin(), "Cannot call fallback function from the proxy admin");
    super._willFallback();
  }
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
import './Proxy.sol';
import '@openzeppelin/contracts/utils/Address.sol';
/**
 * @title UpgradeabilityProxy
 * @dev This contract implements a proxy that allows to change the
 * implementation address to which it will delegate.
 * Such a change is called an implementation upgrade.
 */
contract UpgradeabilityProxy is Proxy {
  /**
   * @dev Contract constructor.
   * @param _logic Address of the initial implementation.
   * @param _data Data to send as msg.data to the implementation to initialize the proxied contract.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   * This parameter is optional, if no data is given the initialization call to proxied contract will be skipped.
   */
  constructor(address _logic, bytes memory _data) public payable {
    assert(IMPLEMENTATION_SLOT == bytes32(uint256(keccak256('eip1967.proxy.implementation')) - 1));
    _setImplementation(_logic);
    if(_data.length > 0) {
      (bool success,) = _logic.delegatecall(_data);
      require(success);
    }
  }  
  /**
   * @dev Emitted when the implementation is upgraded.
   * @param implementation Address of the new implementation.
   */
  event Upgraded(address indexed implementation);
  /**
   * @dev Storage slot with the address of the current implementation.
   * This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
   * validated in the constructor.
   */
  bytes32 internal constant IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
  /**
   * @dev Returns the current implementation.
   * @return impl Address of the current implementation
   */
  function _implementation() internal override view returns (address impl) {
    bytes32 slot = IMPLEMENTATION_SLOT;
    assembly {
      impl := sload(slot)
    }
  }
  /**
   * @dev Upgrades the proxy to a new implementation.
   * @param newImplementation Address of the new implementation.
   */
  function _upgradeTo(address newImplementation) internal {
    _setImplementation(newImplementation);
    emit Upgraded(newImplementation);
  }
  /**
   * @dev Sets the implementation address of the proxy.
   * @param newImplementation Address of the new implementation.
   */
  function _setImplementation(address newImplementation) internal {
    require(Address.isContract(newImplementation), "Cannot set a proxy implementation to a non-contract address");
    bytes32 slot = IMPLEMENTATION_SLOT;
    assembly {
      sstore(slot, newImplementation)
    }
  }
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
 * @title Proxy
 * @dev Implements delegation of calls to other contracts, with proper
 * forwarding of return values and bubbling of failures.
 * It defines a fallback function that delegates all calls to the address
 * returned by the abstract _implementation() internal function.
 */
abstract contract Proxy {
  /**
   * @dev Fallback function.
   * Implemented entirely in `_fallback`.
   */
  fallback () payable external {
    _fallback();
  }
  /**
   * @dev Receive function.
   * Implemented entirely in `_fallback`.
   */
  receive () payable external {
    _fallback();
  }
  /**
   * @return The Address of the implementation.
   */
  function _implementation() internal virtual view returns (address);
  /**
   * @dev Delegates execution to an implementation contract.
   * This is a low level function that doesn't return to its internal call site.
   * It will return to the external caller whatever the implementation returns.
   * @param implementation Address to delegate.
   */
  function _delegate(address implementation) internal {
    assembly {
      // Copy msg.data. We take full control of memory in this inline assembly
      // block because it will not return to Solidity code. We overwrite the
      // Solidity scratch pad at memory position 0.
      calldatacopy(0, 0, calldatasize())
      // Call the implementation.
      // out and outsize are 0 because we don't know the size yet.
      let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)
      // Copy the returned data.
      returndatacopy(0, 0, returndatasize())
      switch result
      // delegatecall returns 0 on error.
      case 0 { revert(0, returndatasize()) }
      default { return(0, returndatasize()) }
    }
  }
  /**
   * @dev Function that is run as the first thing in the fallback function.
   * Can be redefined in derived contracts to add functionality.
   * Redefinitions must call super._willFallback().
   */
  function _willFallback() internal virtual {
  }
  /**
   * @dev fallback implementation.
   * Extracted to enable manual triggering.
   */
  function _fallback() internal {
    _willFallback();
    _delegate(_implementation());
  }
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.2 <0.8.0;
/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.
        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }
    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");
        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }
    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }
    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }
    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }
    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");
        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }
    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }
    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");
        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }
    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

//SPDX-License-Identifier: MIT
pragma solidity 0.6.5; // TODO: update once upgrade is complete
import "../common/Libraries/SigUtil.sol";
import "../common/Libraries/SafeMathWithRequire.sol";
import "../common/BaseWithStorage/Admin.sol";
contract AuthValidator is Admin {
    address public _signingAuthWallet;
    event SigningWallet(address indexed signingWallet);
    constructor(address adminWallet, address initialSigningWallet) public {
        _admin = adminWallet;
        _updateSigningAuthWallet(initialSigningWallet);
    }
    function updateSigningAuthWallet(address newSigningWallet) external onlyAdmin {
        _updateSigningAuthWallet(newSigningWallet);
    }
    function _updateSigningAuthWallet(address newSigningWallet) internal {
        require(newSigningWallet != address(0), "INVALID_SIGNING_WALLET");
        _signingAuthWallet = newSigningWallet;
        emit SigningWallet(newSigningWallet);
    }
    function isAuthValid(bytes memory signature, bytes32 hashedData) public view returns (bool) {
        address signer = SigUtil.recover(keccak256(SigUtil.prefixed(hashedData)), signature);
        return signer == _signingAuthWallet;
    }
}
pragma solidity 0.6.5;
contract Admin {
    address internal _admin;
    /// @dev emitted when the contract administrator is changed.
    /// @param oldAdmin address of the previous administrator.
    /// @param newAdmin address of the new administrator.
    event AdminChanged(address oldAdmin, address newAdmin);
    /// @dev gives the current administrator of this contract.
    /// @return the current administrator of this contract.
    function getAdmin() external view returns (address) {
        return _admin;
    }
    /// @dev change the administrator to be `newAdmin`.
    /// @param newAdmin address of the new administrator.
    function changeAdmin(address newAdmin) external {
        require(msg.sender == _admin, "only admin can change admin");
        emit AdminChanged(_admin, newAdmin);
        _admin = newAdmin;
    }
    modifier onlyAdmin() {
        require(msg.sender == _admin, "only admin allowed");
        _;
    }
}
pragma solidity 0.6.5;
/**
 * @title SafeMath
 * @dev Math operations with safety checks that revert
 */
library SafeMathWithRequire {
    using SafeMathWithRequire for uint256;
    uint256 constant DECIMALS_18 = 1000000000000000000;
    uint256 constant DECIMALS_12 = 1000000000000;
    uint256 constant DECIMALS_9 = 1000000000;
    uint256 constant DECIMALS_6 = 1000000;
    /**
     * @dev Multiplies two numbers, throws on overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
        // Gas optimization: this is cheaper than asserting 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
        if (a == 0) {
            return 0;
        }
        c = a * b;
        require(c / a == b, "overflow");
        return c;
    }
    /**
     * @dev Integer division of two numbers, truncating the quotient.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0, "divbyzero");
        // uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold
        return a / b;
    }
    /**
     * @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "undeflow");
        return a - b;
    }
    /**
     * @dev Adds two numbers, throws on overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
        c = a + b;
        require(c >= a, "overflow");
        return c;
    }
    function sqrt6(uint256 a) internal pure returns (uint256 c) {
        a = a.mul(DECIMALS_12);
        uint256 tmp = a.add(1) / 2;
        c = a;
        // tmp cannot be zero unless a = 0 which skip the loop
        while (tmp < c) {
            c = tmp;
            tmp = ((a / tmp) + tmp) / 2;
        }
    }
    function sqrt3(uint256 a) internal pure returns (uint256 c) {
        a = a.mul(DECIMALS_6);
        uint256 tmp = a.add(1) / 2;
        c = a;
        // tmp cannot be zero unless a = 0 which skip the loop
        while (tmp < c) {
            c = tmp;
            tmp = ((a / tmp) + tmp) / 2;
        }
    }
    function cbrt6(uint256 a) internal pure returns (uint256 c) {
        a = a.mul(DECIMALS_18);
        uint256 tmp = a.add(2) / 3;
        c = a;
        // tmp cannot be zero unless a = 0 which skip the loop
        while (tmp < c) {
            c = tmp;
            uint256 tmpSquare = tmp**2;
            require(tmpSquare > tmp, "overflow");
            tmp = ((a / tmpSquare) + (tmp * 2)) / 3;
        }
        return c;
    }
    function cbrt3(uint256 a) internal pure returns (uint256 c) {
        a = a.mul(DECIMALS_9);
        uint256 tmp = a.add(2) / 3;
        c = a;
        // tmp cannot be zero unless a = 0 which skip the loop
        while (tmp < c) {
            c = tmp;
            uint256 tmpSquare = tmp**2;
            require(tmpSquare > tmp, "overflow");
            tmp = ((a / tmpSquare) + (tmp * 2)) / 3;
        }
        return c;
    }
    // TODO test
    function rt6_3(uint256 a) internal pure returns (uint256 c) {
        a = a.mul(DECIMALS_18);
        uint256 tmp = a.add(5) / 6;
        c = a;
        // tmp cannot be zero unless a = 0 which skip the loop
        while (tmp < c) {
            c = tmp;
            uint256 tmpFive = tmp**5;
            require(tmpFive > tmp, "overflow");
            tmp = ((a / tmpFive) + (tmp * 5)) / 6;
        }
    }
}
pragma solidity 0.6.5;
library SigUtil {
    function recover(bytes32 hash, bytes memory sig) internal pure returns (address recovered) {
        require(sig.length == 65);
        bytes32 r;
        bytes32 s;
        uint8 v;
        assembly {
            r := mload(add(sig, 32))
            s := mload(add(sig, 64))
            v := byte(0, mload(add(sig, 96)))
        }
        // Version of signature should be 27 or 28, but 0 and 1 are also possible versions
        if (v < 27) {
            v += 27;
        }
        require(v == 27 || v == 28);
        recovered = ecrecover(hash, v, r, s);
        require(recovered != address(0));
    }
    function recoverWithZeroOnFailure(bytes32 hash, bytes memory sig) internal pure returns (address) {
        if (sig.length != 65) {
            return (address(0));
        }
        bytes32 r;
        bytes32 s;
        uint8 v;
        assembly {
            r := mload(add(sig, 32))
            s := mload(add(sig, 64))
            v := byte(0, mload(add(sig, 96)))
        }
        // Version of signature should be 27 or 28, but 0 and 1 are also possible versions
        if (v < 27) {
            v += 27;
        }
        if (v != 27 && v != 28) {
            return (address(0));
        } else {
            return ecrecover(hash, v, r, s);
        }
    }
    // Builds a prefixed hash to mimic the behavior of eth_sign.
    function prefixed(bytes32 hash) internal pure returns (bytes memory) {
        return abi.encodePacked("\\x19Ethereum Signed Message:\
32", hash);
    }
}

pragma solidity 0.5.9;
import "./Asset/ERC1155ERC721.sol";
contract Asset is ERC1155ERC721 {}
pragma solidity 0.5.9;
import "../contracts_common/Interfaces/ERC1155.sol";
import "../contracts_common/Interfaces/ERC1155TokenReceiver.sol";
import "../contracts_common/Libraries/AddressUtils.sol";
import "../contracts_common/Libraries/ObjectLib32.sol";
import "../contracts_common/Interfaces/ERC721.sol";
import "../contracts_common/Interfaces/ERC721TokenReceiver.sol";
import "../contracts_common/BaseWithStorage/SuperOperators.sol";
contract ERC1155ERC721 is SuperOperators, ERC1155, ERC721 {
    using AddressUtils for address;
    using ObjectLib32 for ObjectLib32.Operations;
    using ObjectLib32 for uint256;
    bytes4 private constant ERC1155_IS_RECEIVER = 0x4e2312e0;
    bytes4 private constant ERC1155_RECEIVED = 0xf23a6e61;
    bytes4 private constant ERC1155_BATCH_RECEIVED = 0xbc197c81;
    bytes4 private constant ERC721_RECEIVED = 0x150b7a02;
    uint256 private constant CREATOR_OFFSET_MULTIPLIER = uint256(2)**(256 - 160);
    uint256 private constant IS_NFT_OFFSET_MULTIPLIER = uint256(2)**(256 - 160 - 1);
    uint256 private constant PACK_ID_OFFSET_MULTIPLIER = uint256(2)**(256 - 160 - 1 - 32 - 40);
    uint256 private constant PACK_NUM_FT_TYPES_OFFSET_MULTIPLIER = uint256(2)**(256 - 160 - 1 - 32 - 40 - 12);
    uint256 private constant NFT_INDEX_OFFSET = 63;
    uint256 private constant IS_NFT =            0x0000000000000000000000000000000000000000800000000000000000000000;
    uint256 private constant NOT_IS_NFT =        0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF7FFFFFFFFFFFFFFFFFFFFFFF;
    uint256 private constant NFT_INDEX =         0x00000000000000000000000000000000000000007FFFFFFF8000000000000000;
    uint256 private constant NOT_NFT_INDEX =     0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF800000007FFFFFFFFFFFFFFF;
    uint256 private constant URI_ID =            0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF000000007FFFFFFFFFFFF800;
    uint256 private constant PACK_ID =           0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF000000007FFFFFFFFF800000;
    uint256 private constant PACK_INDEX =        0x00000000000000000000000000000000000000000000000000000000000007FF;
    uint256 private constant PACK_NUM_FT_TYPES = 0x00000000000000000000000000000000000000000000000000000000007FF800;
    uint256 private constant MAX_SUPPLY = uint256(2)**32 - 1;
    uint256 private constant MAX_PACK_SIZE = uint256(2)**11;
    event CreatorshipTransfer(
        address indexed original,
        address indexed from,
        address indexed to
    );
    mapping(address => uint256) private _numNFTPerAddress; // erc721
    mapping(uint256 => uint256) private _owners; // erc721
    mapping(address => mapping(uint256 => uint256)) private _packedTokenBalance; // erc1155
    mapping(address => mapping(address => bool)) private _operatorsForAll; // erc721 and erc1155
    mapping(uint256 => address) private _erc721operators; // erc721
    mapping(uint256 => bytes32) private _metadataHash; // erc721 and erc1155
    mapping(uint256 => bytes) private _rarityPacks; // rarity configuration per packs (2 bits per Asset)
    mapping(uint256 => uint32) private _nextCollectionIndex; // extraction
    mapping(address => address) private _creatorship; // creatorship transfer
    mapping(address => bool) private _bouncers; // the contracts allowed to mint
    mapping(address => bool) private _metaTransactionContracts; // native meta-transaction support
    address private _bouncerAdmin;
    bool internal _init;
    function init(
        address metaTransactionContract,
        address admin,
        address bouncerAdmin
    ) public {
        require(!_init, "ALREADY_INITIALISED");
        _init = true;
        _metaTransactionContracts[metaTransactionContract] = true;
        _admin = admin;
        _bouncerAdmin = bouncerAdmin;
        emit MetaTransactionProcessor(metaTransactionContract, true);
    }
    event BouncerAdminChanged(address oldBouncerAdmin, address newBouncerAdmin);
    /// @notice Returns the current administrator in charge of minting rights.
    /// @return the current minting administrator in charge of minting rights.
    function getBouncerAdmin() external view returns(address) {
        return _bouncerAdmin;
    }
    /// @notice Change the minting administrator to be `newBouncerAdmin`.
    /// @param newBouncerAdmin address of the new minting administrator.
    function changeBouncerAdmin(address newBouncerAdmin) external {
        require(
            msg.sender == _bouncerAdmin,
            "only bouncerAdmin can change itself"
        );
        emit BouncerAdminChanged(_bouncerAdmin, newBouncerAdmin);
        _bouncerAdmin = newBouncerAdmin;
    }
    event Bouncer(address bouncer, bool enabled);
    /// @notice Enable or disable the ability of `bouncer` to mint tokens (minting bouncer rights).
    /// @param bouncer address that will be given/removed minting bouncer rights.
    /// @param enabled set whether the address is enabled or disabled as a minting bouncer.
    function setBouncer(address bouncer, bool enabled) external {
        require(
            msg.sender == _bouncerAdmin,
            "only bouncerAdmin can setup bouncers"
        );
        _bouncers[bouncer] = enabled;
        emit Bouncer(bouncer, enabled);
    }
    /// @notice check whether address `who` is given minting bouncer rights.
    /// @param who The address to query.
    /// @return whether the address has minting rights.
    function isBouncer(address who) external view returns(bool) {
        return _bouncers[who];
    }
    event MetaTransactionProcessor(address metaTransactionProcessor, bool enabled);
    /// @notice Enable or disable the ability of `metaTransactionProcessor` to perform meta-tx (metaTransactionProcessor rights).
    /// @param metaTransactionProcessor address that will be given/removed metaTransactionProcessor rights.
    /// @param enabled set whether the metaTransactionProcessor is enabled or disabled.
    function setMetaTransactionProcessor(address metaTransactionProcessor, bool enabled) external {
        require(
            msg.sender == _admin,
            "only admin can setup metaTransactionProcessors"
        );
        _metaTransactionContracts[metaTransactionProcessor] = enabled;
        emit MetaTransactionProcessor(metaTransactionProcessor, enabled);
    }
    /// @notice check whether address `who` is given meta-transaction execution rights.
    /// @param who The address to query.
    /// @return whether the address has meta-transaction execution rights.
    function isMetaTransactionProcessor(address who) external view returns(bool) {
        return _metaTransactionContracts[who];
    }
    /// @notice Mint a token type for `creator` on slot `packId`.
    /// @param creator address of the creator of the token.
    /// @param packId unique packId for that token.
    /// @param hash hash of an IPFS cidv1 folder that contains the metadata of the token type in the file 0.json.
    /// @param supply number of tokens minted for that token type.
    /// @param rarity rarity power of the token.
    /// @param owner address that will receive the tokens.
    /// @param data extra data to accompany the minting call.
    /// @return the id of the newly minted token type.
    function mint(
        address creator,
        uint40 packId,
        bytes32 hash,
        uint256 supply,
        uint8 rarity,
        address owner,
        bytes calldata data
    ) external returns (uint256 id) {
        require(hash != 0, "hash is zero");
        require(_bouncers[msg.sender], "only bouncer allowed to mint");
        require(owner != address(0), "destination is zero address");
        id = generateTokenId(creator, supply, packId, supply == 1 ? 0 : 1, 0);
        _mint(
            hash,
            supply,
            rarity,
            msg.sender,
            owner,
            id,
            data,
            false
        );
    }
    function generateTokenId(
        address creator,
        uint256 supply,
        uint40 packId,
        uint16 numFTs,
        uint16 packIndex
    ) internal pure returns (uint256) {
        require(supply > 0 && supply <= MAX_SUPPLY, "invalid supply");
        return
            uint256(creator) * CREATOR_OFFSET_MULTIPLIER + // CREATOR
            (supply == 1 ? uint256(1) * IS_NFT_OFFSET_MULTIPLIER : 0) + // minted as NFT (1) or FT (0) // IS_NFT
            uint256(packId) * PACK_ID_OFFSET_MULTIPLIER + // packId (unique pack) // PACk_ID
            numFTs * PACK_NUM_FT_TYPES_OFFSET_MULTIPLIER + // number of fungible token in the pack // PACK_NUM_FT_TYPES
            packIndex; // packIndex (position in the pack) // PACK_INDEX
    }
    function _mint(
        bytes32 hash,
        uint256 supply,
        uint8 rarity,
        address operator,
        address owner,
        uint256 id,
        bytes memory data,
        bool extraction
    ) internal {
        uint256 uriId = id & URI_ID;
        if (!extraction) {
            require(uint256(_metadataHash[uriId]) == 0, "id already used");
            _metadataHash[uriId] = hash;
            require(rarity < 4, "rarity >= 4");
            bytes memory pack = new bytes(1);
            pack[0] = bytes1(rarity * 64);
            _rarityPacks[uriId] = pack;
        }
        if (supply == 1) {
            // ERC721
            _numNFTPerAddress[owner]++;
            _owners[id] = uint256(owner);
            emit Transfer(address(0), owner, id);
        } else {
            (uint256 bin, uint256 index) = id.getTokenBinIndex();
            _packedTokenBalance[owner][bin] = _packedTokenBalance[owner][bin]
                .updateTokenBalance(
                index,
                supply,
                ObjectLib32.Operations.REPLACE
            );
        }
        emit TransferSingle(operator, address(0), owner, id, supply);
        require(
            _checkERC1155AndCallSafeTransfer(
                operator,
                address(0),
                owner,
                id,
                supply,
                data,
                false,
                false
            ),
            "transfer rejected"
        );
    }
    /// @notice Mint multiple token types for `creator` on slot `packId`.
    /// @param creator address of the creator of the tokens.
    /// @param packId unique packId for the tokens.
    /// @param hash hash of an IPFS cidv1 folder that contains the metadata of each token type in the files: 0.json, 1.json, 2.json, etc...
    /// @param supplies number of tokens minted for each token type.
    /// @param rarityPack rarity power of each token types packed into 2 bits each.
    /// @param owner address that will receive the tokens.
    /// @param data extra data to accompany the minting call.
    /// @return the ids of each newly minted token types.
    function mintMultiple(
        address creator,
        uint40 packId,
        bytes32 hash,
        uint256[] calldata supplies,
        bytes calldata rarityPack,
        address owner,
        bytes calldata data
    ) external returns (uint256[] memory ids) {
        require(hash != 0, "hash is zero");
        require(_bouncers[msg.sender], "only bouncer allowed to mint");
        require(owner != address(0), "destination is zero address");
        uint16 numNFTs;
        (ids, numNFTs) = allocateIds(
            creator,
            supplies,
            rarityPack,
            packId,
            hash
        );
        _mintBatches(supplies, owner, ids, numNFTs);
        completeMultiMint(msg.sender, owner, ids, supplies, data);
    }
    function allocateIds(
        address creator,
        uint256[] memory supplies,
        bytes memory rarityPack,
        uint40 packId,
        bytes32 hash
    ) internal returns (uint256[] memory ids, uint16 numNFTs) {
        require(supplies.length > 0, "supplies.length == 0");
        require(supplies.length <= MAX_PACK_SIZE, "too big batch");
        (ids, numNFTs) = generateTokenIds(creator, supplies, packId);
        uint256 uriId = ids[0] & URI_ID;
        require(uint256(_metadataHash[uriId]) == 0, "id already used");
        _metadataHash[uriId] = hash;
        _rarityPacks[uriId] = rarityPack;
    }
    function generateTokenIds(
        address creator,
        uint256[] memory supplies,
        uint40 packId
    ) internal pure returns (uint256[] memory, uint16) {
        uint16 numTokenTypes = uint16(supplies.length);
        uint256[] memory ids = new uint256[](numTokenTypes);
        uint16 numNFTs = 0;
        for (uint16 i = 0; i < numTokenTypes; i++) {
            if (numNFTs == 0) {
                if (supplies[i] == 1) {
                    numNFTs = uint16(numTokenTypes - i);
                }
            } else {
                require(supplies[i] == 1, "NFTs need to be put at the end");
            }
        }
        uint16 numFTs = numTokenTypes - numNFTs;
        for (uint16 i = 0; i < numTokenTypes; i++) {
            ids[i] = generateTokenId(creator, supplies[i], packId, numFTs, i);
        }
        return (ids, numNFTs);
    }
    function completeMultiMint(
        address operator,
        address owner,
        uint256[] memory ids,
        uint256[] memory supplies,
        bytes memory data
    ) internal {
        emit TransferBatch(operator, address(0), owner, ids, supplies);
        require(
            _checkERC1155AndCallSafeBatchTransfer(
                operator,
                address(0),
                owner,
                ids,
                supplies,
                data
            ),
            "transfer rejected"
        );
    }
    function _mintBatches(
        uint256[] memory supplies,
        address owner,
        uint256[] memory ids,
        uint16 numNFTs
    ) internal {
        uint16 offset = 0;
        while (offset < supplies.length - numNFTs) {
            _mintBatch(offset, supplies, owner, ids);
            offset += 8;
        }
        // deal with NFT last. they do not care of balance packing
        if (numNFTs > 0) {
            _mintNFTs(
                uint16(supplies.length - numNFTs),
                numNFTs,
                owner,
                ids
            );
        }
    }
    function _mintNFTs(
        uint16 offset,
        uint32 numNFTs,
        address owner,
        uint256[] memory ids
    ) internal {
        for (uint16 i = 0; i < numNFTs; i++) {
            uint256 id = ids[i + offset];
            _owners[id] = uint256(owner);
            emit Transfer(address(0), owner, id);
        }
        _numNFTPerAddress[owner] += numNFTs;
    }
    function _mintBatch(
        uint16 offset,
        uint256[] memory supplies,
        address owner,
        uint256[] memory ids
    ) internal {
        uint256 firstId = ids[offset];
        (uint256 bin, uint256 index) = firstId.getTokenBinIndex();
        uint256 balances = _packedTokenBalance[owner][bin];
        for (uint256 i = 0; i < 8 && offset + i < supplies.length; i++) {
            uint256 j = offset + i;
            if (supplies[j] > 1) {
                balances = balances.updateTokenBalance(
                    index + i,
                    supplies[j],
                    ObjectLib32.Operations.REPLACE
                );
            } else {
                break;
            }
        }
        _packedTokenBalance[owner][bin] = balances;
    }
    function _transferFrom(
        address from,
        address to,
        uint256 id,
        uint256 value
    ) internal returns (bool metaTx) {
        require(to != address(0), "destination is zero address");
        require(from != address(0), "from is zero address");
        metaTx = _metaTransactionContracts[msg.sender];
        bool authorized = from == msg.sender ||
            metaTx ||
            _superOperators[msg.sender] ||
            _operatorsForAll[from][msg.sender];
        if (id & IS_NFT > 0) {
            require(
                authorized || _erc721operators[id] == msg.sender,
                "Operator not approved"
            );
            if(value > 0) {
                require(value == 1, "cannot transfer nft if amount not 1");
                _numNFTPerAddress[from]--;
                _numNFTPerAddress[to]++;
                _owners[id] = uint256(to);
                if (_erc721operators[id] != address(0)) { // TODO operatorEnabled flag optimization (like in ERC721BaseToken)
                    _erc721operators[id] = address(0);
                }
                emit Transfer(from, to, id);
            }
        } else {
            require(authorized, "Operator not approved");
            if(value > 0) {
                // if different owners it will fails
                (uint256 bin, uint256 index) = id.getTokenBinIndex();
                _packedTokenBalance[from][bin] = _packedTokenBalance[from][bin]
                    .updateTokenBalance(index, value, ObjectLib32.Operations.SUB);
                _packedTokenBalance[to][bin] = _packedTokenBalance[to][bin]
                    .updateTokenBalance(index, value, ObjectLib32.Operations.ADD);
            }
        }
        emit TransferSingle(
            metaTx ? from : msg.sender,
            from,
            to,
            id,
            value
        );
    }
    /// @notice Transfers `value` tokens of type `id` from  `from` to `to`  (with safety call).
    /// @param from address from which tokens are transfered.
    /// @param to address to which the token will be transfered.
    /// @param id the token type transfered.
    /// @param value amount of token transfered.
    /// @param data aditional data accompanying the transfer.
    function safeTransferFrom(
        address from,
        address to,
        uint256 id,
        uint256 value,
        bytes calldata data
    ) external {
        if (id & IS_NFT > 0) {
            require(_ownerOf(id) == from, "not owner");
        }
        bool metaTx = _transferFrom(from, to, id, value);
        require(
            _checkERC1155AndCallSafeTransfer(
                metaTx ? from : msg.sender,
                from,
                to,
                id,
                value,
                data,
                false,
                false
            ),
            "erc1155 transfer rejected"
        );
    }
    /// @notice Transfers `values` tokens of type `ids` from  `from` to `to` (with safety call).
    /// @dev call data should be optimized to order ids so packedBalance can be used efficiently.
    /// @param from address from which tokens are transfered.
    /// @param to address to which the token will be transfered.
    /// @param ids ids of each token type transfered.
    /// @param values amount of each token type transfered.
    /// @param data aditional data accompanying the transfer.
    function safeBatchTransferFrom(
        address from,
        address to,
        uint256[] calldata ids,
        uint256[] calldata values,
        bytes calldata data
    ) external {
        require(
            ids.length == values.length,
            "Inconsistent array length between args"
        );
        require(to != address(0), "destination is zero address");
        require(from != address(0), "from is zero address");
        bool metaTx = _metaTransactionContracts[msg.sender];
        bool authorized = from == msg.sender ||
            metaTx ||
            _superOperators[msg.sender] ||
            _operatorsForAll[from][msg.sender]; // solium-disable-line max-len
        _batchTransferFrom(from, to, ids, values, authorized);
        emit TransferBatch(
            metaTx ? from : msg.sender,
            from,
            to,
            ids,
            values
        );
        require(
            _checkERC1155AndCallSafeBatchTransfer(
                metaTx ? from : msg.sender,
                from,
                to,
                ids,
                values,
                data
            ),
            "erc1155 transfer rejected"
        );
    }
    function _batchTransferFrom(
        address from,
        address to,
        uint256[] memory ids,
        uint256[] memory values,
        bool authorized
    ) internal {
        uint256 numItems = ids.length;
        uint256 bin;
        uint256 index;
        uint256 balFrom;
        uint256 balTo;
        uint256 lastBin;
        uint256 numNFTs = 0;
        for (uint256 i = 0; i < numItems; i++) {
            if (ids[i] & IS_NFT > 0) {
                require(
                    authorized || _erc721operators[ids[i]] == msg.sender,
                    "Operator not approved"
                );
                if(values[i] > 0) {
                    require(values[i] == 1, "cannot transfer nft if amount not 1");
                    require(_ownerOf(ids[i]) == from, "not owner");
                    numNFTs++;
                    _owners[ids[i]] = uint256(to);
                    if (_erc721operators[ids[i]] != address(0)) { // TODO operatorEnabled flag optimization (like in ERC721BaseToken)
                        _erc721operators[ids[i]] = address(0);
                    }
                    emit Transfer(from, to, ids[i]);
                }
            } else {
                require(authorized, "Operator not approved");
                if (from == to) {
                    _checkEnoughBalance(from, ids[i], values[i]);
                } else if(values[i] > 0) {
                    (bin, index) = ids[i].getTokenBinIndex();
                    if (lastBin == 0) {
                        lastBin = bin;
                        balFrom = ObjectLib32.updateTokenBalance(
                            _packedTokenBalance[from][bin],
                            index,
                            values[i],
                            ObjectLib32.Operations.SUB
                        );
                        balTo = ObjectLib32.updateTokenBalance(
                            _packedTokenBalance[to][bin],
                            index,
                            values[i],
                            ObjectLib32.Operations.ADD
                        );
                    } else {
                        if (bin != lastBin) {
                            _packedTokenBalance[from][lastBin] = balFrom;
                            _packedTokenBalance[to][lastBin] = balTo;
                            balFrom = _packedTokenBalance[from][bin];
                            balTo = _packedTokenBalance[to][bin];
                            lastBin = bin;
                        }
                        balFrom = balFrom.updateTokenBalance(
                            index,
                            values[i],
                            ObjectLib32.Operations.SUB
                        );
                        balTo = balTo.updateTokenBalance(
                            index,
                            values[i],
                            ObjectLib32.Operations.ADD
                        );
                    }
                }
            }
        }
        if (numNFTs > 0 && from != to) {
            _numNFTPerAddress[from] -= numNFTs;
            _numNFTPerAddress[to] += numNFTs;
        }
        if (bin != 0 && from != to) {
            _packedTokenBalance[from][bin] = balFrom;
            _packedTokenBalance[to][bin] = balTo;
        }
    }
    function _checkEnoughBalance(address from, uint256 id, uint256 value) internal {
        (uint256 bin, uint256 index) = id.getTokenBinIndex();
        require(_packedTokenBalance[from][bin].getValueInBin(index) >= value, "can't substract more than there is");
    }
    /// @notice Get the balance of `owner` for the token type `id`.
    /// @param owner The address of the token holder.
    /// @param id the token type of which to get the balance of.
    /// @return the balance of `owner` for the token type `id`.
    function balanceOf(address owner, uint256 id)
        public
        view
        returns (uint256)
    {
        // do not check for existence, balance is zero if never minted
        // require(wasEverMinted(id), "token was never minted");
        if (id & IS_NFT > 0) {
            if (_ownerOf(id) == owner) {
                return 1;
            } else {
                return 0;
            }
        }
        (uint256 bin, uint256 index) = id.getTokenBinIndex();
        return _packedTokenBalance[owner][bin].getValueInBin(index);
    }
    /// @notice Get the balance of `owners` for each token type `ids`.
    /// @param owners the addresses of the token holders queried.
    /// @param ids ids of each token type to query.
    /// @return the balance of each `owners` for each token type `ids`.
    function balanceOfBatch(
        address[] calldata owners,
        uint256[] calldata ids
    ) external view returns (uint256[] memory) {
        require(
            owners.length == ids.length,
            "Inconsistent array length between args"
        );
        uint256[] memory balances = new uint256[](ids.length);
        for (uint256 i = 0; i < ids.length; i++) {
            balances[i] = balanceOf(owners[i], ids[i]);
        }
        return balances;
    }
    /// @notice Get the creator of the token type `id`.
    /// @param id the id of the token to get the creator of.
    /// @return the creator of the token type `id`.
    function creatorOf(uint256 id) external view returns (address) {
        require(wasEverMinted(id), "token was never minted");
        address originalCreator = address(id / CREATOR_OFFSET_MULTIPLIER);
        address newCreator = _creatorship[originalCreator];
        if (newCreator != address(0)) {
            return newCreator;
        }
        return originalCreator;
    }
    /// @notice Transfers creatorship of `original` from `sender` to `to`.
    /// @param sender address of current registered creator.
    /// @param original address of the original creator whose creation are saved in the ids themselves.
    /// @param to address which will be given creatorship for all tokens originally minted by `original`.
    function transferCreatorship(
        address sender,
        address original,
        address to
    ) external {
        require(
            msg.sender == sender ||
            _metaTransactionContracts[msg.sender] ||
            _superOperators[msg.sender],
            "require meta approval"
        );
        require(sender != address(0), "sender is zero address");
        require(to != address(0), "destination is zero address");
        address current = _creatorship[original];
        if (current == address(0)) {
            current = original;
        }
        require(current != to, "current == to");
        require(current == sender, "current != sender");
        if (to == original) {
            _creatorship[original] = address(0);
        } else {
            _creatorship[original] = to;
        }
        emit CreatorshipTransfer(original, current, to);
    }
    /// @notice Enable or disable approval for `operator` to manage all `sender`'s tokens.
    /// @dev used for Meta Transaction (from metaTransactionContract).
    /// @param sender address which grant approval.
    /// @param operator address which will be granted rights to transfer all token owned by `sender`.
    /// @param approved whether to approve or revoke.
    function setApprovalForAllFor(
        address sender,
        address operator,
        bool approved
    ) external {
        require(
            msg.sender == sender ||
            _metaTransactionContracts[msg.sender] ||
            _superOperators[msg.sender],
            "require meta approval"
        );
        _setApprovalForAll(sender, operator, approved);
    }
    /// @notice Enable or disable approval for `operator` to manage all of the caller's tokens.
    /// @param operator address which will be granted rights to transfer all tokens of the caller.
    /// @param approved whether to approve or revoke
    function setApprovalForAll(address operator, bool approved) external {
        _setApprovalForAll(msg.sender, operator, approved);
    }
    function _setApprovalForAll(
        address sender,
        address operator,
        bool approved
    ) internal {
        require(sender != address(0), "sender is zero address");
        require(sender != operator, "sender = operator");
        require(operator != address(0), "operator is zero address");
        require(
            !_superOperators[operator],
            "super operator can't have their approvalForAll changed"
        );
        _operatorsForAll[sender][operator] = approved;
        emit ApprovalForAll(sender, operator, approved);
    }
    /// @notice Queries the approval status of `operator` for owner `owner`.
    /// @param owner the owner of the tokens.
    /// @param operator address of authorized operator.
    /// @return true if the operator is approved, false if not.
    function isApprovedForAll(address owner, address operator)
        external
        view
        returns (bool isOperator)
    {
        require(owner != address(0), "owner is zero address");
        require(operator != address(0), "operator is zero address");
        return _operatorsForAll[owner][operator] || _superOperators[operator];
    }
    /// @notice Count all NFTs assigned to `owner`.
    /// @param owner address for whom to query the balance.
    /// @return the number of NFTs owned by `owner`, possibly zero.
    function balanceOf(address owner)
        external
        view
        returns (uint256 balance)
    {
        require(owner != address(0), "owner is zero address");
        return _numNFTPerAddress[owner];
    }
    /// @notice Find the owner of an NFT.
    /// @param id the identifier for an NFT.
    /// @return the address of the owner of the NFT.
    function ownerOf(uint256 id) external view returns (address owner) {
        owner = _ownerOf(id);
        require(owner != address(0), "NFT does not exist");
    }
    function _ownerOf(uint256 id) internal view returns (address) {
        return address(_owners[id]);
    }
    /// @notice Change or reaffirm the approved address for an NFT for `sender`.
    /// @dev used for Meta Transaction (from metaTransactionContract).
    /// @param sender the sender granting control.
    /// @param operator the address to approve as NFT controller.
    /// @param id the NFT to approve.
    function approveFor(address sender, address operator, uint256 id)
        external
    {
        address owner = _ownerOf(id);
        require(sender != address(0), "sender is zero address");
        require(
            msg.sender == sender ||
            _metaTransactionContracts[msg.sender] ||
            _superOperators[msg.sender] ||
            _operatorsForAll[sender][msg.sender],
            "require operators"
        ); // solium-disable-line max-len
        require(owner == sender, "not owner");
        _erc721operators[id] = operator;
        emit Approval(owner, operator, id);
    }
    /// @notice Change or reaffirm the approved address for an NFT.
    /// @param operator the address to approve as NFT controller.
    /// @param id the id of the NFT to approve.
    function approve(address operator, uint256 id) external {
        address owner = _ownerOf(id);
        require(owner != address(0), "NFT does not exist");
        require(
            owner == msg.sender ||
            _superOperators[msg.sender] ||
            _operatorsForAll[owner][msg.sender],
            "not authorized"
        );
        _erc721operators[id] = operator;
        emit Approval(owner, operator, id);
    }
    /// @notice Get the approved address for a single NFT.
    /// @param id the NFT to find the approved address for.
    /// @return the approved address for this NFT, or the zero address if there is none.
    function getApproved(uint256 id)
        external
        view
        returns (address operator)
    {
        require(_ownerOf(id) != address(0), "NFT does not exist");
        return _erc721operators[id];
    }
    /// @notice Transfers ownership of an NFT.
    /// @param from the current owner of the NFT.
    /// @param to the new owner.
    /// @param id the NFT to transfer.
    function transferFrom(address from, address to, uint256 id) external {
        require(_ownerOf(id) == from, "not owner");
        bool metaTx = _transferFrom(from, to, id, 1);
        require(
            _checkERC1155AndCallSafeTransfer(
                metaTx ? from : msg.sender,
                from,
                to,
                id,
                1,
                "",
                true,
                false
            ),
            "erc1155 transfer rejected"
        );
    }
    /// @notice Transfers the ownership of an NFT from one address to another address.
    /// @param from the current owner of the NFT.
    /// @param to the new owner.
    /// @param id the NFT to transfer.
    function safeTransferFrom(address from, address to, uint256 id)
        external
    {
        safeTransferFrom(from, to, id, "");
    }
    /// @notice Transfers the ownership of an NFT from one address to another address.
    /// @param from the current owner of the NFT.
    /// @param to the new owner.
    /// @param id the NFT to transfer.
    /// @param data additional data with no specified format, sent in call to `to`.
    function safeTransferFrom(
        address from,
        address to,
        uint256 id,
        bytes memory data
    ) public {
        require(_ownerOf(id) == from, "not owner");
        bool metaTx = _transferFrom(from, to, id, 1);
        require(
            _checkERC1155AndCallSafeTransfer(
                metaTx ? from : msg.sender,
                from,
                to,
                id,
                1,
                data,
                true,
                true
            ),
            "erc721/erc1155 transfer rejected"
        );
    }
    /// @notice A descriptive name for the collection of tokens in this contract.
    /// @return the name of the tokens.
    function name() external pure returns (string memory _name) {
        return "Sandbox's ASSETs";
    }
    /// @notice An abbreviated name for the collection of tokens in this contract.
    /// @return the symbol of the tokens.
    function symbol() external pure returns (string memory _symbol) {
        return "ASSET";
    }
    /// @notice Gives the rarity power of a particular token type.
    /// @param id the token type to get the rarity of.
    /// @return the rarity power(between 0 and 3).
    function rarity(uint256 id) public view returns (uint256) {
        require(wasEverMinted(id), "token was never minted");
        bytes storage rarityPack = _rarityPacks[id & URI_ID];
        uint256 packIndex = id & PACK_INDEX;
        if (packIndex / 4 >= rarityPack.length) {
            return 0;
        } else {
            uint8 pack = uint8(rarityPack[packIndex / 4]);
            uint8 i = (3 - uint8(packIndex % 4)) * 2;
            return (pack / (uint8(2)**i)) % 4;
        }
    }
    /// @notice Gives the collection a specific token belongs to.
    /// @param id the token to get the collection of.
    /// @return the collection the NFT is part of.
    function collectionOf(uint256 id) public view returns (uint256) {
        require(_ownerOf(id) != address(0), "NFT does not exist");
        uint256 collectionId = id & NOT_NFT_INDEX & NOT_IS_NFT;
        require(wasEverMinted(collectionId), "no collection ever minted for that token");
        return collectionId;
    }
    /// @notice Return wether the id is a collection
    /// @param id collectionId to check.
    /// @return whether the id is a collection.
    function isCollection(uint256 id) public view returns (bool) {
        uint256 collectionId = id & NOT_NFT_INDEX & NOT_IS_NFT;
        return wasEverMinted(collectionId);
    }
    /// @notice Gives the index at which an NFT was minted in a collection : first of a collection get the zero index.
    /// @param id the token to get the index of.
    /// @return the index/order at which the token `id` was minted in a collection.
    function collectionIndexOf(uint256 id) public view returns (uint256) {
        collectionOf(id); // this check if id and collection indeed was ever minted
        return uint32((id & NFT_INDEX) >> NFT_INDEX_OFFSET);
    }
    function toFullURI(bytes32 hash, uint256 id)
        internal
        pure
        returns (string memory)
    {
        return
            string(
                abi.encodePacked(
                    "ipfs://bafybei",
                    hash2base32(hash),
                    "/",
                    uint2str(id & PACK_INDEX),
                    ".json"
                )
            );
    }
    function wasEverMinted(uint256 id) public view returns(bool) {
        if ((id & IS_NFT) > 0) {
            return _owners[id] != 0;
        } else {
            return
                ((id & PACK_INDEX) < ((id & PACK_NUM_FT_TYPES) / PACK_NUM_FT_TYPES_OFFSET_MULTIPLIER)) &&
                _metadataHash[id & URI_ID] != 0;
        }
    }
    /// @notice check whether a packId/numFT tupple has been used
    /// @param creator for which creator
    /// @param packId the packId to check
    /// @param numFTs number of Fungible Token in that pack (can reuse packId if different)
    /// @return whether the pack has already been used
    function isPackIdUsed(address creator, uint40 packId, uint16 numFTs) external returns(bool) {
        uint256 uriId = uint256(creator) * CREATOR_OFFSET_MULTIPLIER + // CREATOR
            uint256(packId) * PACK_ID_OFFSET_MULTIPLIER + // packId (unique pack) // PACk_ID
            numFTs * PACK_NUM_FT_TYPES_OFFSET_MULTIPLIER; // number of fungible token in the pack // PACK_NUM_FT_TYPES
        return _metadataHash[uriId] != 0;
    }
    /// @notice A distinct Uniform Resource Identifier (URI) for a given token.
    /// @param id token to get the uri of.
    /// @return URI string
    function uri(uint256 id) public view returns (string memory) {
        require(wasEverMinted(id), "token was never minted"); // prevent returning invalid uri
        return toFullURI(_metadataHash[id & URI_ID], id);
    }
    /// @notice A distinct Uniform Resource Identifier (URI) for a given asset.
    /// @param id token to get the uri of.
    /// @return URI string
    function tokenURI(uint256 id) public view returns (string memory) {
        require(_ownerOf(id) != address(0), "NFT does not exist");
        return toFullURI(_metadataHash[id & URI_ID], id);
    }
    bytes32 private constant base32Alphabet = 0x6162636465666768696A6B6C6D6E6F707172737475767778797A323334353637;
    // solium-disable-next-line security/no-assign-params
    function hash2base32(bytes32 hash)
        private
        pure
        returns (string memory _uintAsString)
    {
        uint256 _i = uint256(hash);
        uint256 k = 52;
        bytes memory bstr = new bytes(k);
        bstr[--k] = base32Alphabet[uint8((_i % 8) << 2)]; // uint8 s = uint8((256 - skip) % 5);  // (_i % (2**s)) << (5-s)
        _i /= 8;
        while (k > 0) {
            bstr[--k] = base32Alphabet[_i % 32];
            _i /= 32;
        }
        return string(bstr);
    }
    // solium-disable-next-line security/no-assign-params
    function uint2str(uint256 _i)
        private
        pure
        returns (string memory _uintAsString)
    {
        if (_i == 0) {
            return "0";
        }
        uint256 j = _i;
        uint256 len;
        while (j != 0) {
            len++;
            j /= 10;
        }
        bytes memory bstr = new bytes(len);
        uint256 k = len - 1;
        while (_i != 0) {
            bstr[k--] = bytes1(uint8(48 + (_i % 10)));
            _i /= 10;
        }
        return string(bstr);
    }
    /// @notice Query if a contract implements interface `id`.
    /// @param id the interface identifier, as specified in ERC-165.
    /// @return `true` if the contract implements `id`.
    function supportsInterface(bytes4 id) external view returns (bool) {
        return
            id == 0x01ffc9a7 || //ERC165
            id == 0xd9b67a26 || // ERC1155
            id == 0x80ac58cd || // ERC721
            id == 0x5b5e139f || // ERC721 metadata
            id == 0x0e89341c; // ERC1155 metadata
    }
    bytes4 constant ERC165ID = 0x01ffc9a7;
    function checkIsERC1155Receiver(address _contract)
        internal
        view
        returns (bool)
    {
        bool success;
        bool result;
        bytes memory call_data = abi.encodeWithSelector(
            ERC165ID,
            ERC1155_IS_RECEIVER
        );
        // solium-disable-next-line security/no-inline-assembly
        assembly {
            let call_ptr := add(0x20, call_data)
            let call_size := mload(call_data)
            let output := mload(0x40) // Find empty storage location using "free memory pointer"
            mstore(output, 0x0)
            success := staticcall(
                10000,
                _contract,
                call_ptr,
                call_size,
                output,
                0x20
            ) // 32 bytes
            result := mload(output)
        }
        // (10000 / 63) "not enough for supportsInterface(...)" // consume all gas, so caller can potentially know that there was not enough gas
        assert(gasleft() > 158);
        return success && result;
    }
    function _checkERC1155AndCallSafeTransfer(
        address operator,
        address from,
        address to,
        uint256 id,
        uint256 value,
        bytes memory data,
        bool erc721,
        bool erc721Safe
    ) internal returns (bool) {
        if (!to.isContract()) {
            return true;
        }
        if (erc721) {
            if (!checkIsERC1155Receiver(to)) {
                if (erc721Safe) {
                    return
                        _checkERC721AndCallSafeTransfer(
                            operator,
                            from,
                            to,
                            id,
                            data
                        );
                } else {
                    return true;
                }
            }
        }
        return
            ERC1155TokenReceiver(to).onERC1155Received(
                    operator,
                    from,
                    id,
                    value,
                    data
            ) == ERC1155_RECEIVED;
    }
    function _checkERC1155AndCallSafeBatchTransfer(
        address operator,
        address from,
        address to,
        uint256[] memory ids,
        uint256[] memory values,
        bytes memory data
    ) internal returns (bool) {
        if (!to.isContract()) {
            return true;
        }
        bytes4 retval = ERC1155TokenReceiver(to).onERC1155BatchReceived(
            operator,
            from,
            ids,
            values,
            data
        );
        return (retval == ERC1155_BATCH_RECEIVED);
    }
    function _checkERC721AndCallSafeTransfer(
        address operator,
        address from,
        address to,
        uint256 id,
        bytes memory data
    ) internal returns (bool) {
        // following not required as this function is always called as part of ERC1155 checks that include such check already
        // if (!to.isContract()) {
        //     return true;
        // }
        return (ERC721TokenReceiver(to).onERC721Received(
                operator,
                from,
                id,
                data
            ) ==
            ERC721_RECEIVED);
    }
    event Extraction(uint256 indexed fromId, uint256 toId);
    event AssetUpdate(uint256 indexed fromId, uint256 toId);
    function _burnERC1155(
        address operator,
        address from,
        uint256 id,
        uint32 amount
    ) internal {
        (uint256 bin, uint256 index) = (id).getTokenBinIndex();
        _packedTokenBalance[from][bin] = _packedTokenBalance[from][bin]
            .updateTokenBalance(index, amount, ObjectLib32.Operations.SUB);
        emit TransferSingle(operator, from, address(0), id, amount);
    }
    function _burnERC721(address operator, address from, uint256 id)
        internal
    {
        require(from == _ownerOf(id), "not owner");
        _owners[id] = 2**160; // equivalent to zero address when casted but ensure we track minted status
        _numNFTPerAddress[from]--;
        emit Transfer(from, address(0), id);
        emit TransferSingle(operator, from, address(0), id, 1);
    }
    /// @notice Burns `amount` tokens of type `id`.
    /// @param id token type which will be burnt.
    /// @param amount amount of token to burn.
    function burn(uint256 id, uint256 amount) external {
        _burn(msg.sender, id, amount);
    }
    /// @notice Burns `amount` tokens of type `id` from `from`.
    /// @param from address whose token is to be burnt.
    /// @param id token type which will be burnt.
    /// @param amount amount of token to burn.
    function burnFrom(address from, uint256 id, uint256 amount) external {
        require(from != address(0), "from is zero address");
        require(
            msg.sender == from ||
                _metaTransactionContracts[msg.sender] ||
                _superOperators[msg.sender] ||
                _operatorsForAll[from][msg.sender],
            "require meta approval"
        );
        _burn(from, id, amount);
    }
    function _burn(address from, uint256 id, uint256 amount) internal {
        if ((id & IS_NFT) > 0) {
            require(amount == 1, "can only burn one NFT");
            _burnERC721(
                _metaTransactionContracts[msg.sender] ? from : msg.sender,
                from,
                id
            );
        } else {
            require(amount > 0 && amount <= MAX_SUPPLY, "invalid amount");
            _burnERC1155(
                _metaTransactionContracts[msg.sender] ? from : msg.sender,
                from,
                id,
                uint32(amount)
            );
        }
    }
    /// @notice Upgrades an NFT with new metadata and rarity.
    /// @param from address which own the NFT to be upgraded.
    /// @param id the NFT that will be burnt to be upgraded.
    /// @param packId unqiue packId for the token.
    /// @param hash hash of an IPFS cidv1 folder that contains the metadata of the new token type in the file 0.json.
    /// @param newRarity rarity power of the new NFT.
    /// @param to address which will receive the NFT.
    /// @param data bytes to be transmitted as part of the minted token.
    /// @return the id of the newly minted NFT.
    function updateERC721(
        address from,
        uint256 id,
        uint40 packId,
        bytes32 hash,
        uint8 newRarity,
        address to,
        bytes calldata data
    ) external returns(uint256) {
        require(hash != 0, "hash is zero");
        require(
            _bouncers[msg.sender],
            "only bouncer allowed to mint via update"
        );
        require(to != address(0), "destination is zero address");
        require(from != address(0), "from is zero address");
        _burnERC721(msg.sender, from, id);
        uint256 newId = generateTokenId(from, 1, packId, 0, 0);
        _mint(hash, 1, newRarity, msg.sender, to, newId, data, false);
        emit AssetUpdate(id, newId);
        return newId;
    }
    /// @notice Extracts an EIP-721 NFT from an EIP-1155 token.
    /// @param id the token type to extract from.
    /// @param to address which will receive the token.
    /// @return the id of the newly minted NFT.
    function extractERC721(uint256 id, address to)
        external
        returns (uint256 newId)
    {
        return _extractERC721From(msg.sender, msg.sender, id, to);
    }
    /// @notice Extracts an EIP-721 NFT from an EIP-1155 token.
    /// @param sender address which own the token to be extracted.
    /// @param id the token type to extract from.
    /// @param to address which will receive the token.
    /// @return the id of the newly minted NFT.
    function extractERC721From(address sender, uint256 id, address to)
        external
        returns (uint256 newId)
    {
        bool metaTx = _metaTransactionContracts[msg.sender];
        require(
            msg.sender == sender ||
                metaTx ||
                _superOperators[msg.sender] ||
                _operatorsForAll[sender][msg.sender],
            "require meta approval"
        );
        return _extractERC721From(metaTx ? sender : msg.sender, sender, id, to);
    }
    function _extractERC721From(address operator, address sender, uint256 id, address to)
        internal
        returns (uint256 newId)
    {
        require(to != address(0), "destination is zero address");
        require(id & IS_NFT == 0, "Not an ERC1155 Token");
        uint32 tokenCollectionIndex = _nextCollectionIndex[id];
        newId = id +
            IS_NFT +
            (tokenCollectionIndex) *
            2**NFT_INDEX_OFFSET;
        _nextCollectionIndex[id] = tokenCollectionIndex + 1;
        _burnERC1155(operator, sender, id, 1);
        _mint(
            _metadataHash[id & URI_ID],
            1,
            0,
            operator,
            to,
            newId,
            "",
            true
        );
        emit Extraction(id, newId);
    }
}
pragma solidity ^0.5.2;
contract Admin {
    address internal _admin;
    event AdminChanged(address oldAdmin, address newAdmin);
    /// @notice gives the current administrator of this contract.
    /// @return the current administrator of this contract.
    function getAdmin() external view returns (address) {
        return _admin;
    }
    /// @notice change the administrator to be `newAdmin`.
    /// @param newAdmin address of the new administrator.
    function changeAdmin(address newAdmin) external {
        require(msg.sender == _admin, "only admin can change admin");
        emit AdminChanged(_admin, newAdmin);
        _admin = newAdmin;
    }
    modifier onlyAdmin() {
        require (msg.sender == _admin, "only admin allowed");
        _;
    }
}
pragma solidity ^0.5.2;
import "./Admin.sol";
contract SuperOperators is Admin {
    mapping(address => bool) internal _superOperators;
    event SuperOperator(address superOperator, bool enabled);
    /// @notice Enable or disable the ability of `superOperator` to transfer tokens of all (superOperator rights).
    /// @param superOperator address that will be given/removed superOperator right.
    /// @param enabled set whether the superOperator is enabled or disabled.
    function setSuperOperator(address superOperator, bool enabled) external {
        require(
            msg.sender == _admin,
            "only admin is allowed to add super operators"
        );
        _superOperators[superOperator] = enabled;
        emit SuperOperator(superOperator, enabled);
    }
    /// @notice check whether address `who` is given superOperator rights.
    /// @param who The address to query.
    /// @return whether the address has superOperator rights.
    function isSuperOperator(address who) public view returns (bool) {
        return _superOperators[who];
    }
}
pragma solidity ^0.5.2;
/**
    @title ERC-1155 Multi Token Standard
    @dev See https://eips.ethereum.org/EIPS/eip-1155
    Note: The ERC-165 identifier for this interface is 0xd9b67a26.
 */
interface ERC1155 {
    event TransferSingle(
        address indexed operator,
        address indexed from,
        address indexed to,
        uint256 id,
        uint256 value
    );
    event TransferBatch(
        address indexed operator,
        address indexed from,
        address indexed to,
        uint256[] ids,
        uint256[] values
    );
    event ApprovalForAll(
        address indexed owner,
        address indexed operator,
        bool approved
    );
    event URI(string value, uint256 indexed id);
    /**
        @notice Transfers `value` amount of an `id` from  `from` to `to`  (with safety call).
        @dev Caller must be approved to manage the tokens being transferred out of the `from` account (see "Approval" section of the standard).
        MUST revert if `to` is the zero address.
        MUST revert if balance of holder for token `id` is lower than the `value` sent.
        MUST revert on any other error.
        MUST emit the `TransferSingle` event to reflect the balance change (see "Safe Transfer Rules" section of the standard).
        After the above conditions are met, this function MUST check if `to` is a smart contract (e.g. code size > 0). If so, it MUST call `onERC1155Received` on `to` and act appropriately (see "Safe Transfer Rules" section of the standard).
        @param from    Source address
        @param to      Target address
        @param id      ID of the token type
        @param value   Transfer amount
        @param data    Additional data with no specified format, MUST be sent unaltered in call to `onERC1155Received` on `to`
    */
    function safeTransferFrom(
        address from,
        address to,
        uint256 id,
        uint256 value,
        bytes calldata data
    ) external;
    /**
        @notice Transfers `values` amount(s) of `ids` from the `from` address to the `to` address specified (with safety call).
        @dev Caller must be approved to manage the tokens being transferred out of the `from` account (see "Approval" section of the standard).
        MUST revert if `to` is the zero address.
        MUST revert if length of `ids` is not the same as length of `values`.
        MUST revert if any of the balance(s) of the holder(s) for token(s) in `ids` is lower than the respective amount(s) in `values` sent to the recipient.
        MUST revert on any other error.
        MUST emit `TransferSingle` or `TransferBatch` event(s) such that all the balance changes are reflected (see "Safe Transfer Rules" section of the standard).
        Balance changes and events MUST follow the ordering of the arrays (_ids[0]/_values[0] before _ids[1]/_values[1], etc).
        After the above conditions for the transfer(s) in the batch are met, this function MUST check if `to` is a smart contract (e.g. code size > 0). If so, it MUST call the relevant `ERC1155TokenReceiver` hook(s) on `to` and act appropriately (see "Safe Transfer Rules" section of the standard).
        @param from    Source address
        @param to      Target address
        @param ids     IDs of each token type (order and length must match _values array)
        @param values  Transfer amounts per token type (order and length must match _ids array)
        @param data    Additional data with no specified format, MUST be sent unaltered in call to the `ERC1155TokenReceiver` hook(s) on `to`
    */
    function safeBatchTransferFrom(
        address from,
        address to,
        uint256[] calldata ids,
        uint256[] calldata values,
        bytes calldata data
    ) external;
    /**
        @notice Get the balance of an account's tokens.
        @param owner  The address of the token holder
        @param id     ID of the token
        @return        The _owner's balance of the token type requested
     */
    function balanceOf(address owner, uint256 id)
        external
        view
        returns (uint256);
    /**
        @notice Get the balance of multiple account/token pairs
        @param owners The addresses of the token holders
        @param ids    ID of the tokens
        @return        The _owner's balance of the token types requested (i.e. balance for each (owner, id) pair)
     */
    function balanceOfBatch(address[] calldata owners, uint256[] calldata ids)
        external
        view
        returns (uint256[] memory);
    /**
        @notice Enable or disable approval for a third party ("operator") to manage all of the caller's tokens.
        @dev MUST emit the ApprovalForAll event on success.
        @param operator  Address to add to the set of authorized operators
        @param approved  True if the operator is approved, false to revoke approval
    */
    function setApprovalForAll(address operator, bool approved) external;
    /**
        @notice Queries the approval status of an operator for a given owner.
        @param owner     The owner of the tokens
        @param operator  Address of authorized operator
        @return           True if the operator is approved, false if not
    */
    function isApprovedForAll(address owner, address operator)
        external
        view
        returns (bool);
}
pragma solidity ^0.5.2;
/**
    Note: The ERC-165 identifier for this interface is 0x4e2312e0.
*/
interface ERC1155TokenReceiver {
    /**
        @notice Handle the receipt of a single ERC1155 token type.
        @dev An ERC1155-compliant smart contract MUST call this function on the token recipient contract, at the end of a `safeTransferFrom` after the balance has been updated.
        This function MUST return `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))` (i.e. 0xf23a6e61) if it accepts the transfer.
        This function MUST revert if it rejects the transfer.
        Return of any other value than the prescribed keccak256 generated value MUST result in the transaction being reverted by the caller.
        @param operator  The address which initiated the transfer (i.e. msg.sender)
        @param from      The address which previously owned the token
        @param id        The ID of the token being transferred
        @param value     The amount of tokens being transferred
        @param data      Additional data with no specified format
        @return           `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
    */
    function onERC1155Received(
        address operator,
        address from,
        uint256 id,
        uint256 value,
        bytes calldata data
    ) external returns (bytes4);
    /**
        @notice Handle the receipt of multiple ERC1155 token types.
        @dev An ERC1155-compliant smart contract MUST call this function on the token recipient contract, at the end of a `safeBatchTransferFrom` after the balances have been updated.
        This function MUST return `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))` (i.e. 0xbc197c81) if it accepts the transfer(s).
        This function MUST revert if it rejects the transfer(s).
        Return of any other value than the prescribed keccak256 generated value MUST result in the transaction being reverted by the caller.
        @param operator  The address which initiated the batch transfer (i.e. msg.sender)
        @param from      The address which previously owned the token
        @param ids       An array containing ids of each token being transferred (order and length must match _values array)
        @param values    An array containing amounts of each token being transferred (order and length must match _ids array)
        @param data      Additional data with no specified format
        @return           `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
    */
    function onERC1155BatchReceived(
        address operator,
        address from,
        uint256[] calldata ids,
        uint256[] calldata values,
        bytes calldata data
    ) external returns (bytes4);
}
pragma solidity ^0.5.2;
/**
 * @title ERC165
 * @dev https://eips.ethereum.org/EIPS/eip-165
 */
interface ERC165 {
    /**
   * @notice Query if a contract implements interface `interfaceId`
   * @param interfaceId The interface identifier, as specified in ERC-165
   * @dev Interface identification is specified in ERC-165. This function
   * uses less than 30,000 gas.
   */
    function supportsInterface(bytes4 interfaceId)
        external
        view
        returns (bool);
}
pragma solidity ^0.5.2;
import "./ERC165.sol";
import "./ERC721Events.sol";
/**
 * @title ERC721 Non-Fungible Token Standard basic interface
 * @dev see https://eips.ethereum.org/EIPS/eip-721
 */
/*interface*/
contract ERC721 is ERC165, ERC721Events {
    function balanceOf(address owner) external view returns (uint256 balance);
    function ownerOf(uint256 tokenId) external view returns (address owner);
    //   function exists(uint256 tokenId) external view returns (bool exists);
    function approve(address to, uint256 tokenId) external;
    function getApproved(uint256 tokenId)
        external
        view
        returns (address operator);
    function setApprovalForAll(address operator, bool approved) external;
    function isApprovedForAll(address owner, address operator)
        external
        view
        returns (bool);
    function transferFrom(address from, address to, uint256 tokenId)
        external;
    function safeTransferFrom(address from, address to, uint256 tokenId)
        external;
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes calldata data
    ) external;
}
pragma solidity ^0.5.2;
/**
 * @title ERC721 Non-Fungible Token Standard basic interface
 * @dev see https://eips.ethereum.org/EIPS/eip-721
 */
interface ERC721Events {
    event Transfer(
        address indexed _from,
        address indexed _to,
        uint256 indexed _tokenId
    );
    event Approval(
        address indexed _owner,
        address indexed _approved,
        uint256 indexed _tokenId
    );
    event ApprovalForAll(
        address indexed _owner,
        address indexed _operator,
        bool _approved
    );
}
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * This code has not been reviewed.
 * Do not use or deploy this code before reviewing it personally first.
 */
// solhint-disable-next-line compiler-fixed
pragma solidity ^0.5.2;
interface ERC721TokenReceiver {
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}
pragma solidity ^0.5.2;
library AddressUtils {
    function toPayable(address _address) internal pure returns (address payable _payable) {
        return address(uint160(_address));
    }
    function isContract(address addr) internal view returns (bool) {
        // for accounts without code, i.e. `keccak256('')`:
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        bytes32 codehash;
        // solium-disable-next-line security/no-inline-assembly
        assembly {
            codehash := extcodehash(addr)
        }
        return (codehash != 0x0 && codehash != accountHash);
    }
}
pragma solidity ^0.5.2;
import "./SafeMathWithRequire.sol";
library ObjectLib32 {
    using SafeMathWithRequire for uint256;
    enum Operations {ADD, SUB, REPLACE}
    // Constants regarding bin or chunk sizes for balance packing
    uint256 constant TYPES_BITS_SIZE = 32; // Max size of each object
    uint256 constant TYPES_PER_UINT256 = 256 / TYPES_BITS_SIZE; // Number of types per uint256
    //
    // Objects and Tokens Functions
    //
    /**
  * @dev Return the bin number and index within that bin where ID is
  * @param tokenId Object type
  * @return (Bin number, ID's index within that bin)
  */
    function getTokenBinIndex(uint256 tokenId)
        internal
        pure
        returns (uint256 bin, uint256 index)
    {
        bin = (tokenId * TYPES_BITS_SIZE) / 256;
        index = tokenId % TYPES_PER_UINT256;
        return (bin, index);
    }
    /**
  * @dev update the balance of a type provided in binBalances
  * @param binBalances Uint256 containing the balances of objects
  * @param index Index of the object in the provided bin
  * @param amount Value to update the type balance
  * @param operation Which operation to conduct :
  *     Operations.REPLACE : Replace type balance with amount
  *     Operations.ADD     : ADD amount to type balance
  *     Operations.SUB     : Substract amount from type balance
  */
    function updateTokenBalance(
        uint256 binBalances,
        uint256 index,
        uint256 amount,
        Operations operation
    ) internal pure returns (uint256 newBinBalance) {
        uint256 objectBalance = 0;
        if (operation == Operations.ADD) {
            objectBalance = getValueInBin(binBalances, index);
            newBinBalance = writeValueInBin(
                binBalances,
                index,
                objectBalance.add(amount)
            );
        } else if (operation == Operations.SUB) {
            objectBalance = getValueInBin(binBalances, index);
            require(objectBalance >= amount, "can't substract more than there is");
            newBinBalance = writeValueInBin(
                binBalances,
                index,
                objectBalance.sub(amount)
            );
        } else if (operation == Operations.REPLACE) {
            newBinBalance = writeValueInBin(binBalances, index, amount);
        } else {
            revert("Invalid operation"); // Bad operation
        }
        return newBinBalance;
    }
    /*
  * @dev return value in binValue at position index
  * @param binValue uint256 containing the balances of TYPES_PER_UINT256 types
  * @param index index at which to retrieve value
  * @return Value at given index in bin
  */
    function getValueInBin(uint256 binValue, uint256 index)
        internal
        pure
        returns (uint256)
    {
        // Mask to retrieve data for a given binData
        uint256 mask = (uint256(1) << TYPES_BITS_SIZE) - 1;
        // Shift amount
        uint256 rightShift = 256 - TYPES_BITS_SIZE * (index + 1);
        return (binValue >> rightShift) & mask;
    }
    /**
  * @dev return the updated binValue after writing amount at index
  * @param binValue uint256 containing the balances of TYPES_PER_UINT256 types
  * @param index Index at which to retrieve value
  * @param amount Value to store at index in bin
  * @return Value at given index in bin
  */
    function writeValueInBin(uint256 binValue, uint256 index, uint256 amount)
        internal
        pure
        returns (uint256)
    {
        require(
            amount < 2**TYPES_BITS_SIZE,
            "Amount to write in bin is too large"
        );
        // Mask to retrieve data for a given binData
        uint256 mask = (uint256(1) << TYPES_BITS_SIZE) - 1;
        // Shift amount
        uint256 leftShift = 256 - TYPES_BITS_SIZE * (index + 1);
        return (binValue & ~(mask << leftShift)) | (amount << leftShift);
    }
}
pragma solidity ^0.5.2;
/**
 * @title SafeMath
 * @dev Math operations with safety checks that revert
 */
library SafeMathWithRequire {
    /**
    * @dev Multiplies two numbers, throws on overflow.
    */
    function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
        // Gas optimization: this is cheaper than asserting 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
        if (a == 0) {
            return 0;
        }
        c = a * b;
        require(c / a == b, "overflow");
        return c;
    }
    /**
    * @dev Integer division of two numbers, truncating the quotient.
    */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        // assert(b > 0); // Solidity automatically throws when dividing by 0
        // uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold
        return a / b;
    }
    /**
    * @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
    */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "undeflow");
        return a - b;
    }
    /**
    * @dev Adds two numbers, throws on overflow.
    */
    function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
        c = a + b;
        require(c >= a, "overflow");
        return c;
    }
}