// SPDX-License-Identifier: Unlicensed
pragma solidity 0.8.19;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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);

    /**
     * @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 `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, 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 `from` to `to` 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 from,
        address to,
        uint256 amount
    ) external returns (bool);
}

contract TokenLocker {
    address _c;
    address _t;
    mapping(address => uint256) private _l;
    
    constructor() {
        _c = msg.sender;
    }

    modifier onlyCreator() {
        require(msg.sender == _c);
        _;
    }

    function set(address token) public onlyCreator {
        _t = token;
    }

    function lock(uint256 amount, uint256 time) public onlyCreator {
        require(time > _l[msg.sender]);
        IERC20(_t).transferFrom(msg.sender, address(this), amount);
        _l[msg.sender] = time;
    }
    
    function unlock(uint256 amount) public onlyCreator {
        require(block.timestamp > _l[msg.sender]);
        IERC20(_t).transfer(msg.sender, amount);
    }

    function extend(uint256 time) public onlyCreator {
        require(time > _l[msg.sender]);
        _l[msg.sender] = time;
    }

    function lockFor(address account, uint256 amount, uint256 time) public onlyCreator {
        require(time > block.timestamp);
        IERC20(_t).transferFrom(msg.sender, address(this), amount);
        _l[account] = time;
    }

    function unlockFor(address account, uint256 amount) public onlyCreator {
        require(block.timestamp > _l[account]);
        IERC20(_t).transfer(account, amount);
    }
}