我写的第一个合约

写了个合约，请看看是做啥的

//SPDX-License-Identifier: MIT
pragma solidity 0.8.17;

import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/utils/Strings.sol";
import "@openzeppelin/contracts/utils/Address.sol";

contract BankLockTest {
    address owner;
    uint128 counter;
    mapping(address => bool) private legalErc20Tokens;
    mapping(string => Receipt) private receiptRepo;
    mapping(string => bool) private hasReceipt;
    struct Receipt {
        address customer;
        address token;
        uint256 amount;
        uint256 unlockTime;
        bool isEther;
    }

    using SafeERC20 for IERC20;

    event Read(
        address customer,
        address token,
        uint256 amount,
        uint256 unlockTime
    );
    event DepositErc20Token(
        string receiptKey,
        address customer,
        address token,
        uint256 amount,
        uint256 lockDays,
        uint256 unlockTime
    );
    event WithdrawErc20Token(
        string receiptKey,
        address customer,
        address token,
        uint256 amount,
        uint256 time
    );
    event DepositEther(
        string receiptKey,
        address customer,
        uint256 amount,
        uint256 lockDays,
        uint256 unlockTime
    );
    event WithdrawEther(
        string receiptKey,
        address customer,
        uint256 amount,
        uint256 time
    );
    event AddToken(address token);

    constructor() {
        owner = msg.sender;
        counter = 0;
    }

    function _computeReceiptKey(Receipt memory _receipt, uint256 _counter)
        private
        view
        returns (string memory)
    {
        return
            Strings.toString(
                uint256(
                    keccak256(
                        abi.encode(
                            _receipt.customer,
                            _counter + block.timestamp
                        )
                    )
                )
            );
    }

    modifier _isLegalErc20Token(address _token) {
        require(legalErc20Tokens[_token], "not legal token");
        _;
    }

    modifier _notContractAddress(address _address) {
        require(!Address.isContract(_address), "not support contract address");
        _;
    }

    function _getUnlockTime(uint256 _lockDays) private view returns (uint256) {
        return _lockDays * 86400 + block.timestamp;
    }

    function addToken(address _token) public {
        require(msg.sender == owner, "only owner can add tokens");
        legalErc20Tokens[_token] = true;
        emit AddToken(_token);
    }

    function getReceipt(string memory _receiptKey) public {
        require(hasReceipt[_receiptKey], "has not receipt or already draw");
        Receipt memory receipt = receiptRepo[_receiptKey];
        emit Read(
            receipt.customer,
            receipt.token,
            receipt.amount,
            receipt.unlockTime
        );
    }

    function depositEther(uint256 lockDays)
        public
        payable
        _notContractAddress(msg.sender)
    {
        require(msg.value > 0, "amount <= 0");
        if ((lockDays <= 0) || (lockDays > 180)) {
            lockDays = 1;
        }
        unchecked {
            counter = counter + 1;
        }
        uint256 unlockTime = _getUnlockTime(lockDays);
        address etherAddress = address(0);
        Receipt memory receipt = Receipt(
            msg.sender,
            etherAddress,
            msg.value,
            unlockTime,
            true
        );
        string memory receiptKey = _computeReceiptKey(receipt, counter);
        require(!hasReceipt[receiptKey], "same receipt key collision");
        receiptRepo[receiptKey] = receipt;
        hasReceipt[receiptKey] = true;

        emit DepositEther(
            receiptKey,
            msg.sender,
            msg.value,
            lockDays,
            unlockTime
        );
    }

    function depositErc20Token(
        address token,
        uint256 amount,
        uint256 lockDays
    ) public _isLegalErc20Token(token) _notContractAddress(msg.sender) {
        require(amount > 0, "amount <= 0");
        require(
            !Address.isContract(msg.sender),
            "not support contract address"
        );
        if ((lockDays <= 0) || (lockDays > 180)) {
            lockDays = 1;
        }
        unchecked {
            counter = counter + 1;
        }

        uint256 unlockTime = _getUnlockTime(lockDays);
        Receipt memory receipt = Receipt(
            msg.sender,
            token,
            amount,
            unlockTime,
            false
        );
        string memory receiptKey = _computeReceiptKey(receipt, counter);
        require(!hasReceipt[receiptKey], "same receipt key collision");
        receiptRepo[receiptKey] = receipt;
        hasReceipt[receiptKey] = true;
        IERC20(token).safeTransferFrom(msg.sender, address(this), amount);

        emit DepositErc20Token(
            receiptKey,
            msg.sender,
            token,
            amount,
            lockDays,
            unlockTime
        );
    }

    function withdraw(string memory receiptKey) public {
        require(hasReceipt[receiptKey], "has not receipt or already draw");
        require(receiptRepo[receiptKey].unlockTime < block.timestamp, "unlock time not reached");
        hasReceipt[receiptKey] = false;
        Receipt memory receipt = receiptRepo[receiptKey];

        if (receipt.isEther) {
            payable(receipt.customer).transfer(receipt.amount);

            emit WithdrawEther(
                receiptKey,
                receipt.customer,
                receipt.amount,
                block.timestamp
            );
        } else {
            IERC20(receipt.token).safeTransfer(
                receipt.customer,
                receipt.amount
            );

            emit WithdrawErc20Token(
                receiptKey,
                receipt.customer,
                receipt.token,
                receipt.amount,
                block.timestamp
            );
        }
        delete hasReceipt[receiptKey];
        delete receiptRepo[receiptKey];
    }
}