ERC-20 智能合约：支持 TRX 和 USDT 兑换

以下是一个支持 TRX 和 USDT 兑换的 ERC-20 智能合约的示例代码：

pragma solidity ^0.8.14;

interface IChainlink {
    function getLatestPrice() external view returns (uint256);
}

contract ERC20 {
    string public name;
    string public symbol;
    uint8 public decimals;
    uint256 public totalSupply;
    address public owner;

    mapping(address => uint256) public balanceOf;
    mapping(address => mapping(address => uint256)) public allowance;

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

    constructor(string memory _name, string memory _symbol, uint8 _decimals, uint256 _initialSupply) {
        name = _name;
        symbol = _symbol;
        decimals = _decimals;
        totalSupply = _initialSupply * 10 ** uint256(_decimals);
        owner = msg.sender;
        balanceOf[owner] = totalSupply;
        emit Transfer(address(0), owner, totalSupply);
    }

    modifier onlyOwner() {
        require(msg.sender == owner, 'Only contract owner can call this function');
        _;
    }

    function transfer(address _to, uint256 _value) external returns (bool success) {
        require(balanceOf[msg.sender] >= _value, 'Insufficient balance');
        balanceOf[msg.sender] -= _value;
        balanceOf[_to] += _value;
        emit Transfer(msg.sender, _to, _value);
        return true;
    }

    function transferFrom(address _from, address _to, uint256 _value) external returns (bool success) {
        require(balanceOf[_from] >= _value, 'Insufficient balance');
        require(allowance[_from][msg.sender] >= _value, 'Insufficient allowance');
        balanceOf[_from] -= _value;
        balanceOf[_to] += _value;
        allowance[_from][msg.sender] -= _value;
        emit Transfer(_from, _to, _value);
        return true;
    }

    function approve(address _spender, uint256 _value) external returns (bool success) {
        allowance[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    function depositTRX() external payable {
        balanceOf[address(this)] += msg.value;
    }

    function depositUSDT(uint256 _amount) external {
        require(_amount > 0, 'Invalid amount');
        // 使用 Chainlink 查询 USDT 与 TRX 的兑换价格
        uint256 trxAmount = _amount * getUSDTtoTRXPrice();
        require(balanceOf[address(this)] >= trxAmount, 'Insufficient TRX balance');
        balanceOf[address(this)] -= trxAmount;
        balanceOf[msg.sender] += trxAmount;
        emit Transfer(address(this), msg.sender, trxAmount);
    }

    function withdrawTRX(uint256 _amount) external onlyOwner {
        require(_amount > 0, 'Invalid amount');
        require(balanceOf[address(this)] >= _amount, 'Insufficient TRX balance');
        balanceOf[address(this)] -= _amount;
        payable(owner).transfer(_amount);
    }

    function withdrawUSDT(uint256 _amount) external onlyOwner {
        require(_amount > 0, 'Invalid amount');
        require(balanceOf[address(this)] >= _amount, 'Insufficient USDT balance');
        balanceOf[address(this)] -= _amount;
        emit Transfer(address(this), owner, _amount);
    }

    function getUSDTtoTRXPrice() private view returns (uint256) {
        // 使用 Chainlink 的合约地址来查询当前 USDT 与 TRX 的兑换价格
        // 假设 Chainlink 合约地址为 0x1234567890
        IChainlink chainlink = IChainlink(0x1234567890);
        return chainlink.getLatestPrice();
    }
}

请注意，此合约仅是一个示例，可能需要进行进一步的测试和优化。在部署和使用合约时，请确保了解和遵守相关的法律和监管要求。