// SPDX-License-Identifier: MIT
pragma solidity 0.8.19;

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
    );
}

contract Vesting {
    uint16 private withdrawIndex;
    address public immutable tokenAddress;
    address public immutable beneficiary;
    uint256[] public monthlyRelease;
    uint256[] public withdrawTime;
    string public name;

    constructor(
        address _token,
        uint256[] memory _monthlyReleaseAmount,
        uint256[] memory _withdrawTime,
        address _beneficiary,
        string memory _name
    ) {
        tokenAddress = _token;
        monthlyRelease = _monthlyReleaseAmount;
        withdrawTime = _withdrawTime;
        beneficiary = _beneficiary;
        name = _name;
        withdrawIndex = 0;
    }

    function release() public {
        require(
            block.timestamp >= withdrawTime[withdrawIndex],
            "TokenTimelock: Unlock time error."
        );
        IERC20 token = IERC20(tokenAddress);
        uint256 contractBalance = token.balanceOf(address(this));
        require(contractBalance > 0, "TokenTimelock: Nothing to withdraw.");
        if (contractBalance >= monthlyRelease[withdrawIndex]) {
            token.transfer(beneficiary, monthlyRelease[withdrawIndex]);
        } else {
            token.transfer(beneficiary, contractBalance);
        }
        withdrawIndex += 1;
    }
}