// File: openzeppelin-solidity/contracts/token/ERC20/IERC20.sol

pragma solidity ^0.5.2;

/**
 * @title ERC20 interface
 * @dev see https://eips.ethereum.org/EIPS/eip-20
 */
interface IERC20 {
    function transfer(address to, uint256 value) external returns (bool);

    function approve(address spender, uint256 value) external returns (bool);

    function transferFrom(address from, address to, uint256 value) external returns (bool);

    function totalSupply() external view returns (uint256);

    function balanceOf(address who) external view returns (uint256);

    function allowance(address owner, address spender) external view returns (uint256);

    event Transfer(address indexed from, address indexed to, uint256 value);

    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: openzeppelin-solidity/contracts/math/SafeMath.sol

pragma solidity ^0.5.2;

/**
 * @title SafeMath
 * @dev Unsigned math operations with safety checks that revert on error
 */
library SafeMath {
    /**
     * @dev Multiplies two unsigned integers, reverts on overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring '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;
        }

        uint256 c = a * b;
        require(c / a == b);

        return c;
    }

    /**
     * @dev Integer division of two unsigned integers truncating the quotient, reverts on division by zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Subtracts two unsigned integers, reverts on overflow (i.e. if subtrahend is greater than minuend).
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Adds two unsigned integers, reverts on overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a);

        return c;
    }

    /**
     * @dev Divides two unsigned integers and returns the remainder (unsigned integer modulo),
     * reverts when dividing by zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0);
        return a % b;
    }
}

// File: openzeppelin-solidity/contracts/token/ERC20/ERC20.sol

pragma solidity ^0.5.2;



/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * https://eips.ethereum.org/EIPS/eip-20
 * Originally based on code by FirstBlood:
 * https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 *
 * This implementation emits additional Approval events, allowing applications to reconstruct the allowance status for
 * all accounts just by listening to said events. Note that this isn't required by the specification, and other
 * compliant implementations may not do it.
 */
contract ERC20 is IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowed;

    uint256 private _totalSupply;

    /**
     * @dev Total number of tokens in existence
     */
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev Gets the balance of the specified address.
     * @param owner The address to query the balance of.
     * @return A uint256 representing the amount owned by the passed address.
     */
    function balanceOf(address owner) public view returns (uint256) {
        return _balances[owner];
    }

    /**
     * @dev Function to check the amount of tokens that an owner allowed to a spender.
     * @param owner address The address which owns the funds.
     * @param spender address The address which will spend the funds.
     * @return A uint256 specifying the amount of tokens still available for the spender.
     */
    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowed[owner][spender];
    }

    /**
     * @dev Transfer token to a specified address
     * @param to The address to transfer to.
     * @param value The amount to be transferred.
     */
    function transfer(address to, uint256 value) public returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    /**
     * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
     * Beware that changing an allowance with this method brings the risk that someone may use both the old
     * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
     * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     * @param spender The address which will spend the funds.
     * @param value The amount of tokens to be spent.
     */
    function approve(address spender, uint256 value) public returns (bool) {
        _approve(msg.sender, spender, value);
        return true;
    }

    /**
     * @dev Transfer tokens from one address to another.
     * Note that while this function emits an Approval event, this is not required as per the specification,
     * and other compliant implementations may not emit the event.
     * @param from address The address which you want to send tokens from
     * @param to address The address which you want to transfer to
     * @param value uint256 the amount of tokens to be transferred
     */
    function transferFrom(address from, address to, uint256 value) public returns (bool) {
        _transfer(from, to, value);
        _approve(from, msg.sender, _allowed[from][msg.sender].sub(value));
        return true;
    }

    /**
     * @dev Increase the amount of tokens that an owner allowed to a spender.
     * approve should be called when _allowed[msg.sender][spender] == 0. To increment
     * allowed value is better to use this function to avoid 2 calls (and wait until
     * the first transaction is mined)
     * From MonolithDAO Token.sol
     * Emits an Approval event.
     * @param spender The address which will spend the funds.
     * @param addedValue The amount of tokens to increase the allowance by.
     */
    function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
        _approve(msg.sender, spender, _allowed[msg.sender][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Decrease the amount of tokens that an owner allowed to a spender.
     * approve should be called when _allowed[msg.sender][spender] == 0. To decrement
     * allowed value is better to use this function to avoid 2 calls (and wait until
     * the first transaction is mined)
     * From MonolithDAO Token.sol
     * Emits an Approval event.
     * @param spender The address which will spend the funds.
     * @param subtractedValue The amount of tokens to decrease the allowance by.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
        _approve(msg.sender, spender, _allowed[msg.sender][spender].sub(subtractedValue));
        return true;
    }

    /**
     * @dev Transfer token for a specified addresses
     * @param from The address to transfer from.
     * @param to The address to transfer to.
     * @param value The amount to be transferred.
     */
    function _transfer(address from, address to, uint256 value) internal {
        require(to != address(0));

        _balances[from] = _balances[from].sub(value);
        _balances[to] = _balances[to].add(value);
        emit Transfer(from, to, value);
    }

    /**
     * @dev Internal function that mints an amount of the token and assigns it to
     * an account. This encapsulates the modification of balances such that the
     * proper events are emitted.
     * @param account The account that will receive the created tokens.
     * @param value The amount that will be created.
     */
    function _mint(address account, uint256 value) internal {
        require(account != address(0));

        _totalSupply = _totalSupply.add(value);
        _balances[account] = _balances[account].add(value);
        emit Transfer(address(0), account, value);
    }

    /**
     * @dev Internal function that burns an amount of the token of a given
     * account.
     * @param account The account whose tokens will be burnt.
     * @param value The amount that will be burnt.
     */
    function _burn(address account, uint256 value) internal {
        require(account != address(0));

        _totalSupply = _totalSupply.sub(value);
        _balances[account] = _balances[account].sub(value);
        emit Transfer(account, address(0), value);
    }

    /**
     * @dev Approve an address to spend another addresses' tokens.
     * @param owner The address that owns the tokens.
     * @param spender The address that will spend the tokens.
     * @param value The number of tokens that can be spent.
     */
    function _approve(address owner, address spender, uint256 value) internal {
        require(spender != address(0));
        require(owner != address(0));

        _allowed[owner][spender] = value;
        emit Approval(owner, spender, value);
    }

    /**
     * @dev Internal function that burns an amount of the token of a given
     * account, deducting from the sender's allowance for said account. Uses the
     * internal burn function.
     * Emits an Approval event (reflecting the reduced allowance).
     * @param account The account whose tokens will be burnt.
     * @param value The amount that will be burnt.
     */
    function _burnFrom(address account, uint256 value) internal {
        _burn(account, value);
        _approve(account, msg.sender, _allowed[account][msg.sender].sub(value));
    }
}

// File: openzeppelin-solidity/contracts/token/ERC20/ERC20Detailed.sol

pragma solidity ^0.5.2;


/**
 * @title ERC20Detailed token
 * @dev The decimals are only for visualization purposes.
 * All the operations are done using the smallest and indivisible token unit,
 * just as on Ethereum all the operations are done in wei.
 */
contract ERC20Detailed is IERC20 {
    string private _name;
    string private _symbol;
    uint8 private _decimals;

    constructor (string memory name, string memory symbol, uint8 decimals) public {
        _name = name;
        _symbol = symbol;
        _decimals = decimals;
    }

    /**
     * @return the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @return the symbol of the token.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @return the number of decimals of the token.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }
}

// File: openzeppelin-solidity/contracts/ownership/Ownable.sol

pragma solidity ^0.5.2;

/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 */
contract Ownable {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev The Ownable constructor sets the original `owner` of the contract to the sender
     * account.
     */
    constructor () internal {
        _owner = msg.sender;
        emit OwnershipTransferred(address(0), _owner);
    }

    /**
     * @return the address of the owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner());
        _;
    }

    /**
     * @return true if `msg.sender` is the owner of the contract.
     */
    function isOwner() public view returns (bool) {
        return msg.sender == _owner;
    }

    /**
     * @dev Allows the current owner to relinquish control of the contract.
     * It will not be possible to call the functions with the `onlyOwner`
     * modifier anymore.
     * @notice Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Allows the current owner to transfer control of the contract to a newOwner.
     * @param newOwner The address to transfer ownership to.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers control of the contract to a newOwner.
     * @param newOwner The address to transfer ownership to.
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0));
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: contracts/QDT.sol

pragma solidity 0.5.9;





contract QDT is ERC20, ERC20Detailed, Ownable{
    using SafeMath for uint256;

    uint8 constant LIMIT_FOR_PAYOUT = 200;
    uint32 constant PASSWORD_REVEAL_MIN_DELAY = 2592000;

    string private _name = "Quantfury Data Token";
    string private _symbol = "QDT";
    uint8 private _decimals = 8;

    // Trading data of current epoch
    struct Epoch {
        string hash;
        uint256 epochTime;
        string password;
        uint256 weiAmount;
        uint256 tokenAmount;
        uint256 revealTime;
    }

    uint256 private _currentEpoch;

    // List of trading data
    mapping(uint256 => Epoch) private listOfEpoch;

    // Amount of money in payout pool
    uint256 private _ethPayoutPool;

    // How many token units a buyer gets per wei.
    // The rate is the conversion between wei and the smallest and indivisible token unit.
    uint256 private _tokenPrice;

    constructor() ERC20Detailed(_name, _symbol, _decimals) public {
        _currentEpoch = 0;
        _tokenPrice = 0;
    }

    /**
     * @dev Get balance of contract pool
     * @return A uint256 that indicates amount Eth in contract.
     */
    function getBalance()
    external
    view
    returns(uint256)
    {
        return _ethPayoutPool;
    }

    /**
     * @dev Get current price
     * @return A uint256 that indicates amount Eth per one token.
     */
    function getPrice()
    external
    view
    returns (uint256)
    {
        return _tokenPrice;
    }

    /**
     * @dev Show current epoch
     * @return A uint256 that indicates number of epoch.
     */
    function getCurrentEpoch()
    external
    view
    returns (uint256)
    {
        return _currentEpoch;
    }

    /**
    * @dev Show information about ipfs
    * @param epoch index of data in list of epoch
    * @return A bytes32 that indicates hash of ipfs.
    * @return A string that indicates password of ipfs.
    * @return A uint256 that indicates amount of ether in ipfs.
    * @return A uint256 that indicates amount of tokens in ipfs.
    * @return A uint256 that indicates time of password will show.
    */
    function getEpoch(uint256 epoch)
    external
    view
    returns (
        string memory,
        uint256,
        string memory,
        uint256,
        uint256,
        uint256
    ) {
        return (
                listOfEpoch[epoch].hash,
                listOfEpoch[epoch].epochTime,
                listOfEpoch[epoch].password,
                listOfEpoch[epoch].weiAmount,
                listOfEpoch[epoch].tokenAmount,
                listOfEpoch[epoch].revealTime
               );
    }

    /**
     * @dev Deposit into the payout pool
     * @return A boolean that indicates if the operation was successful.
     */

    function deposit()
    external
    onlyOwner
    payable
    returns (bool)
    {
        require(msg.value > 0);
        _ethPayoutPool = _ethPayoutPool.add(msg.value);
        emit Deposit(msg.sender, msg.value);
        return true;
    }

    /**
     * @dev Withdraw wei from payout pool
     * @param receiver Address who receive ether
     * @param weiAmount Amount of wei
     * @return A boolean that indicates if the operation was successful.
     */
    function withdraw(address payable receiver, uint256 weiAmount)
    external
    onlyOwner
    returns (bool)
    {
        require(receiver != address(0x0));
        _ethPayoutPool = _ethPayoutPool.sub(weiAmount);
        address(receiver).transfer(weiAmount);
        emit Withdraw(receiver, weiAmount);
        return true;
    }

    /**
     * @dev Function create IPFS for new epoch
     * @param ipfsHash Hash of the IPFS link
     * @param epochTime time of creation epoch
     * @param weiAmount Amount of wei
     * @param tokenAmount Amount tokens will mint
     */
    function createEpoch(
        string calldata ipfsHash,
        uint256 epochTime,
        uint256 weiAmount,
        uint256 tokenAmount
    )
    external
    onlyOwner
    {
        require(listOfEpoch[_currentEpoch].epochTime < epochTime);
        uint256 _totalSupply = totalSupply();
        uint256 tokenPriceOld = _tokenPrice;
        _currentEpoch++;
        listOfEpoch[_currentEpoch].hash = ipfsHash;
        listOfEpoch[_currentEpoch].epochTime = epochTime;
        listOfEpoch[_currentEpoch].weiAmount = weiAmount;
        listOfEpoch[_currentEpoch].tokenAmount = tokenAmount;
        listOfEpoch[_currentEpoch].revealTime = epochTime.add(PASSWORD_REVEAL_MIN_DELAY);

        //Change price of token
        _tokenPrice = (weiAmount.add(_totalSupply.mul(_tokenPrice))).div(_totalSupply.add(tokenAmount));
        require(_tokenPrice != 0);

        emit CreateEpoch(
            _currentEpoch,
                weiAmount,
                tokenAmount,
                _tokenPrice,
                _totalSupply,
                tokenPriceOld,
                _ethPayoutPool);
    }

    /**
     * @dev Function calls to swap tokens to wei
     * @param tokenAmount Number of tokens for swap
     */
    function sellTokens(
        uint256 tokenAmount
    )
    external
    {
        uint256 weiAmount = _getWeiAmount(tokenAmount);

        _burn(msg.sender, tokenAmount);

        _ethPayoutPool = _ethPayoutPool.sub(weiAmount);

        address(msg.sender).transfer(weiAmount);

        emit Sell(msg.sender, tokenAmount, weiAmount, _tokenPrice, balanceOf(msg.sender));
    }

    /**
     * @dev Function calls to make payout in epoch
     * @param holderAdresses The array of addresses that will receive the minted tokens.
     * @param tokenAmounts The array of amounts of token that will send to address.
     * @param totalTokenAmount The amount of tokens that will send to address.
     */
    function payout(
        address[] calldata holderAdresses,
        uint256[] calldata tokenAmounts,
        uint256 totalTokenAmount
    )
    external
    onlyOwner
    {
        require(balanceOf(msg.sender) >= totalTokenAmount);
        require(holderAdresses.length == tokenAmounts.length);
        require(holderAdresses.length <= LIMIT_FOR_PAYOUT);

        for (uint i = 0; i < holderAdresses.length; i++) {
            _transfer(msg.sender, holderAdresses[i], tokenAmounts[i]);
        }
    }

    /**
     * @dev Function to mint tokens
     * @param to The address that will receive the minted tokens.
     * @param value The amount of tokens to mint.
     * @return A boolean that indicates if the operation was successful.
     */
    function mint(
        address to,
        uint256 value
    )
    external
    onlyOwner
    returns (bool) {
        _mint(to, value);
        return true;
    }

    /**
     * @dev Function to burn tokens
     * @param value The amount of tokens to burn.
     * @return A boolean that indicates if the operation was successful.
     */
    function burn(
        uint256 value
    )
    external
    onlyOwner
    returns (bool) {
        _burn(msg.sender, value);
        return true;
    }

    /**
     * @dev Function save password of IPFS only after 30 days
     * @param epoch Number of epoch
     * @param password String is password for ipfs
     */
    function commitTradingPassword(
        uint256 epoch,
        string calldata password
    )
    external
    onlyOwner
    {
        require(_currentEpoch >= epoch);
        require(listOfEpoch[epoch].revealTime < now);
        listOfEpoch[epoch].password = password;
        emit OpenPassword(epoch, password);
    }

    /**
     * @dev Override to extend the way in which ether is converted to tokens.
     * @param tokenAmount Value in token to be converted into wei
     * @return Number of wei that can be purchased with the specified _weiAmount
     */
    function _getWeiAmount(uint256 tokenAmount)
    internal
    view
    returns (uint256) {
        return tokenAmount.mul(_tokenPrice);
    }

    event CreateEpoch(
        uint256 epoch,
        uint256 weiAmount,
        uint256 tokenAmount,
        uint256 tokenPrice,
        uint256 totalSupply,
        uint256 tokenPriceOld,
        uint256 ethPayoutPool);
    event OpenPassword(uint256 epoch, string password);
    event Sell(address indexed seller, uint256 tokenAmount, uint256 weiAmount, uint256 tokenPrice, uint256 balances);
    event Withdraw(address indexed receiver, uint256 weiAmount);
    event Deposit(address indexed sender, uint256 weiAmount);
}