// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity 0.6.12;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot 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-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

/**
 * @dev Library for managing
 * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
 * types.
 *
 * Sets have the following properties:
 *
 * - Elements are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Elements are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```
 * contract Example {
 *     // Add the library methods
 *     using EnumerableSet for EnumerableSet.AddressSet;
 *
 *     // Declare a set state variable
 *     EnumerableSet.AddressSet private mySet;
 * }
 * ```
 *
 * As of v3.0.0, only sets of type `address` (`AddressSet`) and `uint256`
 * (`UintSet`) are supported.
 */
library EnumerableSet {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Set type with
    // bytes32 values.
    // The Set implementation uses private functions, and user-facing
    // implementations (such as AddressSet) are just wrappers around the
    // underlying Set.
    // This means that we can only create new EnumerableSets for types that fit
    // in bytes32.

    struct Set {
        // Storage of set values
        bytes32[] _values;

        // Position of the value in the `values` array, plus 1 because index 0
        // means a value is not in the set.
        mapping (bytes32 => uint256) _indexes;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            // The value is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function _remove(Set storage set, bytes32 value) private returns (bool) {
        // We read and store the value's index to prevent multiple reads from the same storage slot
        uint256 valueIndex = set._indexes[value];

        if (valueIndex != 0) { // Equivalent to contains(set, value)
            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
            // the array, and then remove the last element (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.

            uint256 toDeleteIndex = valueIndex - 1;
            uint256 lastIndex = set._values.length - 1;

            // When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs
            // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.

            bytes32 lastvalue = set._values[lastIndex];

            // Move the last value to the index where the value to delete is
            set._values[toDeleteIndex] = lastvalue;
            // Update the index for the moved value
            set._indexes[lastvalue] = toDeleteIndex + 1; // All indexes are 1-based

            // Delete the slot where the moved value was stored
            set._values.pop();

            // Delete the index for the deleted slot
            delete set._indexes[value];

            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function _contains(Set storage set, bytes32 value) private view returns (bool) {
        return set._indexes[value] != 0;
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function _at(Set storage set, uint256 index) private view returns (bytes32) {
        require(set._values.length > index, "EnumerableSet: index out of bounds");
        return set._values[index];
    }

    // AddressSet

    struct AddressSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(value)));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(value)));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(value)));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint256(_at(set._inner, index)));
    }


    // UintSet

    struct UintSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(UintSet storage set, uint256 value) internal returns (bool) {
        return _remove(set._inner, bytes32(value));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
        return _contains(set._inner, bytes32(value));
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
        return uint256(_at(set._inner, index));
    }
}

pragma solidity ^0.6.2;

/**
 * @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) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }

    /**
     * @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");
        return _functionCallWithValue(target, data, value, errorMessage);
    }

    function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
        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);
            }
        }
    }
}

pragma solidity ^0.6.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

/**
 * @dev Contract module that allows children to implement role-based access
 * control mechanisms.
 *
 * Roles are referred to by their `bytes32` identifier. These should be exposed
 * in the external API and be unique. The best way to achieve this is by
 * using `public constant` hash digests:
 *
 * ```
 * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
 * ```
 *
 * Roles can be used to represent a set of permissions. To restrict access to a
 * function call, use {hasRole}:
 *
 * ```
 * function foo() public {
 *     require(hasRole(MY_ROLE, msg.sender));
 *     ...
 * }
 * ```
 *
 * Roles can be granted and revoked dynamically via the {grantRole} and
 * {revokeRole} functions. Each role has an associated admin role, and only
 * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
 *
 * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
 * that only accounts with this role will be able to grant or revoke other
 * roles. More complex role relationships can be created by using
 * {_setRoleAdmin}.
 *
 * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
 * grant and revoke this role. Extra precautions should be taken to secure
 * accounts that have been granted it.
 */
abstract contract AccessControl is Context {
    using EnumerableSet for EnumerableSet.AddressSet;
    using Address for address;

    struct RoleData {
        EnumerableSet.AddressSet members;
        bytes32 adminRole;
    }

    mapping (bytes32 => RoleData) private _roles;

    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;

    /**
     * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
     *
     * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
     * {RoleAdminChanged} not being emitted signaling this.
     *
     * _Available since v3.1._
     */
    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);

    /**
     * @dev Emitted when `account` is granted `role`.
     *
     * `sender` is the account that originated the contract call, an admin role
     * bearer except when using {_setupRole}.
     */
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Emitted when `account` is revoked `role`.
     *
     * `sender` is the account that originated the contract call:
     *   - if using `revokeRole`, it is the admin role bearer
     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
     */
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) public view returns (bool) {
        return _roles[role].members.contains(account);
    }

    /**
     * @dev Returns the number of accounts that have `role`. Can be used
     * together with {getRoleMember} to enumerate all bearers of a role.
     */
    function getRoleMemberCount(bytes32 role) public view returns (uint256) {
        return _roles[role].members.length();
    }

    /**
     * @dev Returns one of the accounts that have `role`. `index` must be a
     * value between 0 and {getRoleMemberCount}, non-inclusive.
     *
     * Role bearers are not sorted in any particular way, and their ordering may
     * change at any point.
     *
     * WARNING: When using {getRoleMember} and {getRoleMemberCount}, make sure
     * you perform all queries on the same block. See the following
     * https://forum.openzeppelin.com/t/iterating-over-elements-on-enumerableset-in-openzeppelin-contracts/2296[forum post]
     * for more information.
     */
    function getRoleMember(bytes32 role, uint256 index) public view returns (address) {
        return _roles[role].members.at(index);
    }

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) public view returns (bytes32) {
        return _roles[role].adminRole;
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) public virtual {
        require(hasRole(_roles[role].adminRole, _msgSender()), "AccessControl: sender must be an admin to grant");

        _grantRole(role, account);
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) public virtual {
        require(hasRole(_roles[role].adminRole, _msgSender()), "AccessControl: sender must be an admin to revoke");

        _revokeRole(role, account);
    }

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) public virtual {
        require(account == _msgSender(), "AccessControl: can only renounce roles for self");

        _revokeRole(role, account);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event. Note that unlike {grantRole}, this function doesn't perform any
     * checks on the calling account.
     *
     * [WARNING]
     * ====
     * This function should only be called from the constructor when setting
     * up the initial roles for the system.
     *
     * Using this function in any other way is effectively circumventing the admin
     * system imposed by {AccessControl}.
     * ====
     */
    function _setupRole(bytes32 role, address account) internal virtual {
        _grantRole(role, account);
    }

    /**
     * @dev Sets `adminRole` as ``role``'s admin role.
     *
     * Emits a {RoleAdminChanged} event.
     */
    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
        emit RoleAdminChanged(role, _roles[role].adminRole, adminRole);
        _roles[role].adminRole = adminRole;
    }

    function _grantRole(bytes32 role, address account) private {
        if (_roles[role].members.add(account)) {
            emit RoleGranted(role, account, _msgSender());
        }
    }

    function _revokeRole(bytes32 role, address account) private {
        if (_roles[role].members.remove(account)) {
            emit RoleRevoked(role, account, _msgSender());
        }
    }
}

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: 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
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}


/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transfered from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 tokenId) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);

    /**
      * @dev Safely transfers `tokenId` token from `from` to `to`.
      *
      * Requirements:
      *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
      * - `tokenId` token must exist and be owned by `from`.
      * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
      * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
      *
      * Emits a {Transfer} event.
      */
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;
}

contract SafeTransfer is AccessControl {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    // keccak256("ACTIVATOR_ROLE");
    bytes32 public constant ACTIVATOR_ROLE = 0xec5aad7bdface20c35bc02d6d2d5760df981277427368525d634f4e2603ea192;

    // keccak256("hiddenCollect(address from,address to,uint256 value,uint256 fees,bytes32 secretHash)");
    bytes32 public constant HIDDEN_COLLECT_TYPEHASH = 0x0506afef36f3613836f98ef019cb76a3e6112be8f9dc8d8fa77275d64f418234;

    // keccak256("hiddenCollectERC20(address from,address to,address token,string tokenSymbol,uint256 value,uint256 fees,bytes32 secretHash)");
    bytes32 public constant HIDDEN_ERC20_COLLECT_TYPEHASH = 0x9e6214229b9fba1927010d30b22a3a5d9fd5e856bb29f056416ff2ad52e8de44;

    // keccak256("hiddenCollectERC721(address from,address to,address token,string tokenSymbol,uint256 tokenId,bytes tokenData,uint256 fees,bytes32 secretHash)");
    bytes32 public constant HIDDEN_ERC721_COLLECT_TYPEHASH = 0xa14a2dc51c26e451800897aa798120e7d6c35039caf5eb29b8ac35d1e914c591;

    bytes32 public DOMAIN_SEPARATOR;
    uint256 public CHAIN_ID;
    bytes32 s_uid;
    uint256 s_fees;

    struct TokenInfo {
        bytes32 id;
        bytes32 id1;
        uint256 tr;
    }

    mapping(bytes32 => uint256) s_transfers;
    mapping(bytes32 => uint256) s_erc20Transfers;
    mapping(bytes32 => uint256) s_erc721Transfers;
    mapping(bytes32 => uint256) s_htransfers;

    string public constant NAME = "Kirobo Safe Transfer";
    string public constant VERSION = "1";
    uint8 public constant VERSION_NUMBER = 0x1;

    event Deposited(
        address indexed from,
        address indexed to,
        uint256 value,
        uint256 fees,
        bytes32 secretHash
    );

    event TimedDeposited(
        address indexed from,
        address indexed to,
        uint256 value,
        uint256 fees,
        bytes32 secretHash,
        uint64 availableAt,
        uint64 expiresAt,
        uint128 autoRetrieveFees
    );

    event Retrieved(
        address indexed from,
        address indexed to,
        bytes32 indexed id,
        uint256 value
    );

    event Collected(
        address indexed from,
        address indexed to,
        bytes32 indexed id,
        uint256 value
    );

    event ERC20Deposited(
        address indexed token,
        address indexed from,
        address indexed to,
        uint256 value,
        uint256 fees,
        bytes32 secretHash
    );

    event ERC20TimedDeposited(
        address indexed token,
        address indexed from,
        address indexed to,
        uint256 value,
        uint256 fees,
        bytes32 secretHash,
        uint64 availableAt,
        uint64 expiresAt,
        uint128 autoRetrieveFees
    );

    event ERC20Retrieved(
        address indexed token,
        address indexed from,
        address indexed to,
        bytes32 id,
        uint256 value
    );

    event ERC20Collected(
        address indexed token,
        address indexed from,
        address indexed to,
        bytes32 id,
        uint256 value
    );

    event ERC721Deposited(
        address indexed token,
        address indexed from,
        address indexed to,
        uint256 tokenId,
        uint256 fees,
        bytes32 secretHash
    );

    event ERC721TimedDeposited(
        address indexed token,
        address indexed from,
        address indexed to,
        uint256 tokenId,
        uint256 fees,
        bytes32 secretHash,
        uint64 availableAt,
        uint64 expiresAt,
        uint128 autoRetrieveFees
    );

    event ERC721Retrieved(
        address indexed token,
        address indexed from,
        address indexed to,
        bytes32 id,
        uint256 tokenId
    );

    event ERC721Collected(
        address indexed token,
        address indexed from,
        address indexed to,
        bytes32 id,
        uint256 tokenId
    );

    event HDeposited(
        address indexed from,
        uint256 value,
        bytes32 indexed id1
    );

    event HTimedDeposited(
        address indexed from,
        uint256 value,
        bytes32 indexed id1,
        uint64 availableAt,
        uint64 expiresAt,
        uint128 autoRetrieveFees
    );

    event HRetrieved(
        address indexed from,
        bytes32 indexed id1,
        uint256 value
    );

    event HCollected(
        address indexed from,
        address indexed to,
        bytes32 indexed id1,
        uint256 value
    );

    event HERC20Collected(
        address indexed token,
        address indexed from,
        address indexed to,
        bytes32 id1,
        uint256 value
    );

    event HERC721Collected(
        address indexed token,
        address indexed from,
        address indexed to,
        bytes32 id1,
        uint256 tokenId
    );

    modifier onlyActivator() {
        require(hasRole(ACTIVATOR_ROLE, msg.sender), "SafeTransfer: not an activator");
        _;
    }

    constructor (address activator) public {
        _setupRole(DEFAULT_ADMIN_ROLE, msg.sender);
        _setupRole(ACTIVATOR_ROLE, msg.sender);
        _setupRole(ACTIVATOR_ROLE, activator);

        uint256 chainId;
        assembly {
            chainId := chainid()
        }

        CHAIN_ID = chainId;

        s_uid = bytes32(
          uint256(VERSION_NUMBER) << 248 |
          uint256(blockhash(block.number-1)) << 192 >> 16 |
          uint256(address(this))
        );

        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract,bytes32 salt)"),
                keccak256(bytes(NAME)),
                keccak256(bytes(VERSION)),
                chainId,
                address(this),
                s_uid
            )
        );

    }

    receive () external payable {
        require(false, "SafeTransfer: not accepting ether directly");
    }

    function transferERC20(address token, address wallet, uint256 value) external onlyActivator() {
        IERC20(token).safeTransfer(wallet, value);
    }

    function transferERC721(address token, address wallet, uint256 tokenId, bytes calldata data) external onlyActivator() {
        IERC721(token).safeTransferFrom(address(this), wallet, tokenId, data);
    }

    function transferFees(address payable wallet, uint256 value) external onlyActivator() {
        s_fees = s_fees.sub(value);
        wallet.transfer(value);
    }

    function totalFees() external view returns (uint256) {
        return s_fees;
    }

    function uid() view external returns (bytes32) {
        return s_uid;
    }

    // --------------------------------- ETH ---------------------------------

    function deposit(
        address payable to,
        uint256 value,
        uint256 fees,
        bytes32 secretHash
    )
        payable external
    {
        require(msg.value == value.add(fees), "SafeTransfer: value mismatch");
        require(to != msg.sender, "SafeTransfer: sender==recipient");
        bytes32 id = keccak256(abi.encode(msg.sender, to, value, fees, secretHash));
        require(s_transfers[id] == 0, "SafeTransfer: request exist");
        s_transfers[id] = 0xffffffffffffffff; // expiresAt: max, AvailableAt: 0, autoRetrieveFees: 0
        emit Deposited(msg.sender, to, value, fees, secretHash);
    }

    function timedDeposit(
        address payable to,
        uint256 value,
        uint256 fees,
        bytes32 secretHash,
        uint64 availableAt,
        uint64 expiresAt,
        uint128 autoRetrieveFees
    )
        payable external
    {
        require(msg.value == value.add(fees), "SafeTransfer: value mismatch");
        require(fees >= autoRetrieveFees, "SafeTransfer: autoRetrieveFees exeed fees");
        require(to != msg.sender, "SafeTransfer: sender==recipient");
        require(expiresAt > now, "SafeTransfer: already expired");
        bytes32 id = keccak256(abi.encode(msg.sender, to, value, fees, secretHash));
        require(s_transfers[id] == 0, "SafeTransfer: request exist");
        s_transfers[id] = uint256(expiresAt) + uint256(availableAt << 64) + (uint256(autoRetrieveFees) << 128);
        emit TimedDeposited(msg.sender, to, value, fees, secretHash, availableAt, expiresAt, autoRetrieveFees);
    }

    function retrieve(
        address payable to,
        uint256 value,
        uint256 fees,
        bytes32 secretHash
    )
        external
    {
        bytes32 id = keccak256(abi.encode(msg.sender, to, value, fees, secretHash));
        require(s_transfers[id]  > 0, "SafeTransfer: request not exist");
        delete s_transfers[id];
        uint256 valueToSend = value.add(fees);
        msg.sender.transfer(valueToSend);
        emit Retrieved(msg.sender, to, id, valueToSend);
    }

    function collect(
        address from,
        address payable to,
        uint256 value,
        uint256 fees,
        bytes32 secretHash,
        bytes calldata secret
    )
        external
        onlyActivator()
    {
        bytes32 id = keccak256(abi.encode(from, to, value, fees, secretHash));
        uint256 tr = s_transfers[id];
        require(tr > 0, "SafeTransfer: request not exist");
        require(uint64(tr) > now, "SafeTranfer: expired");
        require(uint64(tr>>64) <= now, "SafeTranfer: not available yet");
        require(keccak256(secret) == secretHash, "SafeTransfer: wrong secret");
        delete s_transfers[id];
        s_fees = s_fees.add(fees);
        to.transfer(value);
        emit Collected(from, to, id, value);
    }

   function autoRetrieve(
        address payable from,
        address to,
        uint256 value,
        uint256 fees,
        bytes32 secretHash
    )
        external
        onlyActivator()
    {
        bytes32 id = keccak256(abi.encode(from, to, value, fees, secretHash));
        uint256 tr = s_transfers[id];
        require(tr > 0, "SafeTransfer: request not exist");
        require(uint64(tr) <= now, "SafeTranfer: not expired");
        delete  s_transfers[id];
        s_fees = s_fees + (tr>>128); // autoRetreive fees
        uint256 valueToRetrieve = value.add(fees).sub(tr>>128);
        from.transfer(valueToRetrieve);
        emit Retrieved(from, to, id, valueToRetrieve);
    }

    // ------------------------------- ERC-20 --------------------------------

    function depositERC20(
        address token,
        string calldata tokenSymbol,
        address to,
        uint256 value,
        uint256 fees,
        bytes32 secretHash
    )
        payable external
    {
        require(msg.value == fees, "SafeTransfer: msg.value must match fees");
        require(to != msg.sender, "SafeTransfer: sender==recipient");
        bytes32 id = keccak256(abi.encode(token, tokenSymbol, msg.sender, to, value, fees, secretHash));
        require(s_erc20Transfers[id] == 0, "SafeTransfer: request exist");
        s_erc20Transfers[id] = 0xffffffffffffffff;
        emit ERC20Deposited(token, msg.sender, to, value, fees, secretHash);
    }

    function timedDepositERC20(
        address token,
        string calldata tokenSymbol,
        address to,
        uint256 value,
        uint256 fees,
        bytes32 secretHash,
        uint64 availableAt,
        uint64 expiresAt,
        uint128 autoRetrieveFees
    )
        payable external
    {
        require(msg.value == fees, "SafeTransfer: msg.value must match fees");
        require(fees >= autoRetrieveFees, "SafeTransfer: autoRetrieveFees exeed fees");
        require(to != msg.sender, "SafeTransfer: sender==recipient");
        require(expiresAt > now, "SafeTransfer: already expired");
        bytes32 id = keccak256(abi.encode(token, tokenSymbol, msg.sender, to, value, fees, secretHash));
        require(s_erc20Transfers[id] == 0, "SafeTransfer: request exist");
        s_erc20Transfers[id] = uint256(expiresAt) + (uint256(availableAt) << 64) + (uint256(autoRetrieveFees) << 128);
        emit ERC20TimedDeposited(token, msg.sender, to, value, fees, secretHash, availableAt, expiresAt, autoRetrieveFees);
    }

    function retrieveERC20(
        address token,
        string calldata tokenSymbol,
        address to,
        uint256 value,
        uint256 fees,
        bytes32 secretHash
    )
        external
    {
        bytes32 id = keccak256(abi.encode(token, tokenSymbol, msg.sender, to, value, fees, secretHash));
        require(s_erc20Transfers[id]  > 0, "SafeTransfer: request not exist");
        delete s_erc20Transfers[id];
        msg.sender.transfer(fees);
        emit ERC20Retrieved(token, msg.sender, to, id, value);
    }

    function collectERC20(
        address token,
        string calldata tokenSymbol,
        address from,
        address payable to,
        uint256 value,
        uint256 fees,
        bytes32 secretHash,
        bytes calldata secret
    )
        external
        onlyActivator()
    {
        bytes32 id = keccak256(abi.encode(token, tokenSymbol, from, to, value, fees, secretHash));
        uint256 tr = s_erc20Transfers[id];
        require(tr > 0, "SafeTransfer: request not exist");
        require(uint64(tr) > now, "SafeTranfer: expired");
        require(uint64(tr>>64) <= now, "SafeTranfer: not available yet");
        require(keccak256(secret) == secretHash, "SafeTransfer: wrong secret");
        delete s_erc20Transfers[id];
        s_fees = s_fees.add(fees);
        IERC20(token).safeTransferFrom(from, to, value);
        emit ERC20Collected(token, from, to, id, value);
    }

   function autoRetrieveERC20(
        address token,
        string calldata tokenSymbol,
        address payable from,
        address to,
        uint256 value,
        uint256 fees,
        bytes32 secretHash
    )
        external
        onlyActivator()
    {
        bytes32 id = keccak256(abi.encode(token, tokenSymbol, from, to, value, fees, secretHash));
        uint256 tr = s_erc20Transfers[id];
        require(tr > 0, "SafeTransfer: request not exist");
        require(uint64(tr) <= now, "SafeTranfer: not expired");
        delete  s_erc20Transfers[id];
        s_fees = s_fees + (tr>>128); // autoRetreive fees
        from.transfer(fees.sub(tr>>128));
        emit ERC20Retrieved(token, from, to, id, value);
    }

    // ------------------------------- ERC-721 -------------------------------

    function depositERC721(
        address token,
        string calldata tokenSymbol,
        address to,
        uint256 tokenId,
        bytes calldata tokenData,
        uint256 fees,
        bytes32 secretHash
    )
        payable external
    {
        require(msg.value == fees, "SafeTransfer: msg.value must match fees");
        require(tokenId > 0, "SafeTransfer: no token id");
        require(to != msg.sender, "SafeTransfer: sender==recipient");
        bytes32 id = keccak256(abi.encode(token, tokenSymbol, msg.sender, to, tokenId, tokenData, fees, secretHash));
        require(s_erc721Transfers[id] == 0, "SafeTransfer: request exist");
        s_erc721Transfers[id] = 0xffffffffffffffff;
        emit ERC721Deposited(token, msg.sender, to, tokenId, fees, secretHash);
    }

    function timedDepositERC721(
        address token,
        string calldata tokenSymbol,
        address to,
        uint256 tokenId,
        bytes calldata tokenData,
        uint256 fees,
        bytes32 secretHash,
        uint64 availableAt,
        uint64 expiresAt,
        uint128 autoRetrieveFees
    )
        payable external
    {
        require(msg.value == fees, "SafeTransfer: msg.value must match fees");
        require(fees >= autoRetrieveFees, "SafeTransfer: autoRetrieveFees exeed fees");
        require(tokenId > 0, "SafeTransfer: no token id");
        require(to != msg.sender, "SafeTransfer: sender==recipient");
        require(expiresAt > now, "SafeTransfer: already expired");
        bytes32 id = keccak256(abi.encode(token, tokenSymbol, msg.sender, to, tokenId, tokenData, fees, secretHash));
        require(s_erc721Transfers[id] == 0, "SafeTransfer: request exist");
        s_erc721Transfers[id] = uint256(expiresAt) + (uint256(availableAt) << 64) + (uint256(autoRetrieveFees) << 128);
        emit ERC721TimedDeposited(token, msg.sender, to, tokenId, fees, secretHash, availableAt, expiresAt, autoRetrieveFees);
    }

    function retrieveERC721(
        address token,
        string calldata tokenSymbol,
        address to,
        uint256 tokenId,
        bytes calldata tokenData,
        uint256 fees,
        bytes32 secretHash
    )
        external
    {
        bytes32 id = keccak256(abi.encode(token, tokenSymbol, msg.sender, to, tokenId, tokenData, fees, secretHash));
        require(s_erc721Transfers[id]  > 0, "SafeTransfer: request not exist");
        delete s_erc721Transfers[id];
        msg.sender.transfer(fees);
        emit ERC721Retrieved(token, msg.sender, to, id, tokenId);
    }

    function collectERC721(
        address token,
        string calldata tokenSymbol,
        address from,
        address payable to,
        uint256 tokenId,
        bytes calldata tokenData,
        uint256 fees,
        bytes32 secretHash,
        bytes calldata secret
    )
        external
        onlyActivator()
    {
        bytes32 id = keccak256(abi.encode(token, tokenSymbol, from, to, tokenId, tokenData, fees, secretHash));
        uint256 tr = s_erc721Transfers[id];
        require(tr > 0, "SafeTransfer: request not exist");
        require(uint64(tr) > now, "SafeTranfer: expired");
        require(uint64(tr>>64) <= now, "SafeTranfer: not available yet");
        require(keccak256(secret) == secretHash, "SafeTransfer: wrong secret");
        delete s_erc721Transfers[id];
        s_fees = s_fees.add(fees);
        IERC721(token).safeTransferFrom(from, to, tokenId, tokenData);
        emit ERC721Collected(token, from, to, id, tokenId);
    }

   function autoRetrieveERC721(
        address token,
        string calldata tokenSymbol,
        address payable from,
        address to,
        uint256 tokenId,
        bytes calldata tokenData,
        uint256 fees,
        bytes32 secretHash
    )
        external
        onlyActivator()
    {
        bytes32 id = keccak256(abi.encode(token, tokenSymbol, from, to, tokenId, tokenData, fees, secretHash));
        uint256 tr = s_erc721Transfers[id];
        require(tr > 0, "SafeTransfer: request not exist");
        require(uint64(tr) <= now, "SafeTranfer: not expired");
        delete  s_erc721Transfers[id];
        s_fees = s_fees + (tr>>128); // autoRetreive fees
        from.transfer(fees.sub(tr>>128));
        emit ERC721Retrieved(token, from, to, id, tokenId);
    }

    // ----------------------- Hidden ETH / ERC-20 / ERC-721 -----------------------

    function hiddenDeposit(bytes32 id1)
        payable external
    {
        bytes32 id = keccak256(abi.encode(msg.sender, msg.value, id1));
        require(s_htransfers[id] == 0, "SafeTransfer: request exist");
        s_htransfers[id] = 0xffffffffffffffff;
        emit HDeposited(msg.sender, msg.value, id1);
    }

    function hiddenTimedDeposit(
        bytes32 id1,
        uint64 availableAt,
        uint64 expiresAt,
        uint128 autoRetrieveFees
    )
        payable external
    {
        require(msg.value >= autoRetrieveFees, "SafeTransfers: autoRetrieveFees exeed value");
        bytes32 id = keccak256(abi.encode(msg.sender, msg.value, id1));
        require(s_htransfers[id] == 0, "SafeTransfer: request exist");
        require(expiresAt > now, "SafeTransfer: already expired");
        s_htransfers[id] = uint256(expiresAt) + (uint256(availableAt) << 64) + (uint256(autoRetrieveFees) << 128);
        emit HTimedDeposited(msg.sender, msg.value, id1, availableAt, expiresAt, autoRetrieveFees);
    }

    function hiddenRetrieve(
        bytes32 id1,
        uint256 value
    )
        external
    {
        bytes32 id = keccak256(abi.encode(msg.sender, value, id1));
        require(s_htransfers[id]  > 0, "SafeTransfer: request not exist");
        delete s_htransfers[id];
        msg.sender.transfer(value);
        emit HRetrieved(msg.sender, id1, value);
    }

    function hiddenCollect(
        address from,
        address payable to,
        uint256 value,
        uint256 fees,
        bytes32 secretHash,
        bytes calldata secret,
        uint8 v,
        bytes32 r,
        bytes32 s
    )
        external
        onlyActivator()
    {
        bytes32 id1 = keccak256(abi.encode(HIDDEN_COLLECT_TYPEHASH, from, to, value, fees, secretHash));
        require(ecrecover(keccak256(abi.encodePacked("\x19\x01", DOMAIN_SEPARATOR, id1)), v, r, s) == from, "SafeTransfer: wrong signature");
        bytes32 id = keccak256(abi.encode(from, value.add(fees), id1));
        uint256 tr = s_htransfers[id];
        require(tr > 0, "SafeTransfer: request not exist");
        require(uint64(tr) > now, "SafeTranfer: expired");
        require(uint64(tr>>64) <= now, "SafeTranfer: not available yet");
        require(keccak256(secret) == secretHash, "SafeTransfer: wrong secret");
        delete s_htransfers[id];
        s_fees = s_fees.add(fees);
        to.transfer(value);
        emit HCollected(from, to, id1, value);
    }

    function hiddenCollectERC20(
        address from,
        address to,
        address token,
        string memory tokenSymbol,
        uint256 value,
        uint256 fees,
        bytes32 secretHash,
        bytes calldata secret,
        uint8 v,
        bytes32 r,
        bytes32 s
    )
        external
        onlyActivator()
    {
        TokenInfo memory tinfo;
        tinfo.id1 = keccak256(abi.encode(HIDDEN_ERC20_COLLECT_TYPEHASH, from, to, token, tokenSymbol, value, fees, secretHash));
        require(ecrecover(keccak256(abi.encodePacked("\x19\x01", DOMAIN_SEPARATOR, tinfo.id1)), v, r, s) == from, "SafeTransfer: wrong signature");
        tinfo.id = keccak256(abi.encode(from, fees, tinfo.id1));
        uint256 tr = s_htransfers[tinfo.id];
        require(tr > 0, "SafeTransfer: request not exist");
        require(uint64(tr) > now, "SafeTranfer: expired");
        require(uint64(tr>>64) <= now, "SafeTranfer: not available yet");
        require(keccak256(secret) == secretHash, "SafeTransfer: wrong secret");
        delete s_htransfers[tinfo.id];
        s_fees = s_fees.add(fees);
        IERC20(token).safeTransferFrom(from, to, value);
        emit HERC20Collected(token, from, to, tinfo.id1, value);
    }

    function hiddenCollectERC721(
        address from,
        address to,
        address token,
        string memory tokenSymbol,
        uint256 tokenId,
        bytes memory tokenData,
        uint256 fees,
        bytes32 secretHash,
        bytes calldata secret,
        uint8 v,
        bytes32 r,
        bytes32 s
    )
        external
        onlyActivator()
    {
        TokenInfo memory tinfo;
        tinfo.id1 = keccak256(abi.encode(HIDDEN_ERC721_COLLECT_TYPEHASH, from, to, token, tokenSymbol, tokenId, tokenData, fees, secretHash));
        require(ecrecover(keccak256(abi.encodePacked("\x19\x01", DOMAIN_SEPARATOR, tinfo.id1)), v, r, s) == from, "SafeTransfer: wrong signature");
        tinfo.id = keccak256(abi.encode(from, fees, tinfo.id1));
        tinfo.tr = s_htransfers[tinfo.id];
        require(tinfo.tr > 0, "SafeTransfer: request not exist");
        require(uint64(tinfo.tr) > now, "SafeTranfer: expired");
        require(uint64(tinfo.tr>>64) <= now, "SafeTranfer: not available yet");
        require(keccak256(secret) == secretHash, "SafeTransfer: wrong secret");
        delete s_htransfers[tinfo.id];
        s_fees = s_fees.add(fees);
        IERC721(token).safeTransferFrom(from, to, tokenId, tokenData);
        emit HERC721Collected(token, from, to, tinfo.id1, tokenId);
    }

   function hiddenAutoRetrieve(
        address payable from,
        bytes32 id1,
        uint256 value
    )
        external
        onlyActivator()
    {
        bytes32 id = keccak256(abi.encode(from, value, id1));
        uint256 tr = s_htransfers[id];
        require(tr > 0, "SafeTransfer: request not exist");
        require(uint64(tr) <= now, "SafeTranfer: not expired");
        delete  s_htransfers[id];
        s_fees = s_fees + (tr>>128);
        uint256 toRetrieve = value.sub(tr>>128);
        from.transfer(toRetrieve);
        emit HRetrieved(from, id1, toRetrieve);
    }

}