TokenVesting.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.21;
import "@openzeppelin/contracts/=lib/openzeppelin-contracts/contracts/token/ERC20/IERC20.sol";

contract TokenVesting {
    // 事件
    event ERC20Released(address indexed token, uint256 amount); // 提币事件

    // 状态变量
    mapping(address => uint256) public erc20Released; // 代币地址->释放数量的映射，记录已经释放的代币
    address public immutable beneficiary; // 受益人地址
    uint256 public immutable start; // 起始时间戳
    uint256 public immutable duration; // 归属期

    /**
     * @dev 初始化受益人地址，释放周期(秒), 起始时间戳(当前区块链时间戳)
     */
    constructor(
        address beneficiaryAddress,
        uint256 durationSeconds
    ) {
        require(beneficiaryAddress != address(0), "VestingWallet: beneficiary is zero address");
        beneficiary = beneficiaryAddress;
        start = block.timestamp;
        duration = durationSeconds;
    }

    /**
     * @dev 受益人提取已释放的代币。
     * 调用vestedAmount()函数计算可提取的代币数量，然后transfer给受益人。
     * 释放 {ERC20Released} 事件.
     */
    function release(address token) public {
        // 调用vestedAmount()函数计算可提取的代币数量
        uint256 releasable = vestedAmount(token, uint256(block.timestamp)) - erc20Released[token];
        // 更新已释放代币数量   
        erc20Released[token] += releasable; 
        // 转代币给受益人
        emit ERC20Released(token, releasable);
        IERC20(token).transfer(beneficiary, releasable);
    }

    /**
     * @dev 根据线性释放公式，计算已经释放的数量。开发者可以通过修改这个函数，自定义释放方式。
     * @param token: 代币地址
     * @param timestamp: 查询的时间戳
     */
    function vestedAmount(address token, uint256 timestamp) public view returns (uint256) {
        // 合约里总共收到了多少代币（当前余额 + 已经提取）
        uint256 totalAllocation = IERC20(token).balanceOf(address(this)) + erc20Released[token];
        // 根据线性释放公式，计算已经释放的数量
        if (timestamp < start) {
            return 0;
        } else if (timestamp > start + duration) {
            return totalAllocation;
        } else {
            return (totalAllocation * (timestamp - start)) / duration;
        }
    }
}