TokenSale

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

interface IERC20 {
    function transfer(address recipient, uint256 amount) external returns (bool);
    function balanceOf(address account) external view returns (uint256);
}

contract TokenSale {
    address public owner;
    IERC20 public token;
    uint256 public rate; // 1 ETH 당 토큰 개수 (token decimals 포함)

    event TokensPurchased(address indexed buyer, uint256 ethAmount, uint256 tokenAmount);
    event WithdrawnETH(address indexed to, uint256 amount);
    event WithdrawnTokens(address indexed to, uint256 amount);
    event RateUpdated(uint256 newRate);

    modifier onlyOwner() {
        require(msg.sender == owner, "Not owner");
        _;
    }

    uint256 private _status;
    modifier nonReentrant() {
        require(_status != 1, "Reentrancy detected");
        _status = 1;
        _;
        _status = 0;
    }

    // 하드코딩된 토큰 주소와 rate (수정해서 사용하세요!)
    address constant TOKEN_ADDRESS = 0xA01f98deFEA59e079d5Efd2676EC0D16BDfb994b;
    uint256 constant INITIAL_RATE = 1000 * 1e18; // 1 ETH = 1000 토큰 (18 decimals 토큰 기준)

    constructor() {
        owner = msg.sender;
        token = IERC20(TOKEN_ADDRESS);
        rate = INITIAL_RATE;
        _status = 0;
    }

    receive() external payable {
        buyTokens();
    }

    function buyTokens() public payable nonReentrant {
        require(msg.value > 0, "Send ETH to buy tokens");

        uint256 tokenAmount = (msg.value * rate) / 1 ether;

        require(token.balanceOf(address(this)) >= tokenAmount, "Not enough tokens in contract");
        require(token.transfer(msg.sender, tokenAmount), "Token transfer failed");

        emit TokensPurchased(msg.sender, msg.value, tokenAmount);
    }

    function setRate(uint256 newRate) external onlyOwner {
        require(newRate > 0, "Rate must be > 0");
        rate = newRate;
        emit RateUpdated(newRate);
    }

    function withdrawETH(address payable to) external onlyOwner nonReentrant {
        require(to != address(0), "Invalid address");
        uint256 balance = address(this).balance;
        require(balance > 0, "No ETH to withdraw");

        (bool success, ) = to.call{value: balance}("");
        require(success, "ETH transfer failed");

        emit WithdrawnETH(to, balance);
    }

    function withdrawTokens(address to, uint256 amount) external onlyOwner nonReentrant {
        require(to != address(0), "Invalid address");
        require(token.balanceOf(address(this)) >= amount, "Not enough tokens");

        require(token.transfer(to, amount), "Token transfer failed");

        emit WithdrawnTokens(to, amount);
    }

    function withdrawAllTokens(address to) external onlyOwner nonReentrant {
        require(to != address(0), "Invalid address");
        uint256 amount = token.balanceOf(address(this));
        require(amount > 0, "No tokens to withdraw");

        require(token.transfer(to, amount), "Token transfer failed");

        emit WithdrawnTokens(to, amount);
    }
}