USDT (Tether USDT)

pragma solidity ^0.4.26;

contract owned {
    address public owner;

    constructor() public {
        owner = msg.sender;
    }

    modifier onlyOwner {
        require(msg.sender == owner, "Only owner can call");
        _;
    }

    function transferOwnership(address newOwner) public onlyOwner {
        owner = newOwner;
    }
}

interface tokenRecipient { 
    function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) external; 
}

contract USDT is owned {
    string public name = "USDT";
    string public symbol = "Tether USDT";
    uint8 public decimals = 6;
    uint256 public totalSupply;

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

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Burn(address indexed from, uint256 value);
    event FrozenFunds(address target, bool frozen);

    // Constructor argument: initial supply in whole tokens
    constructor(uint256 initialSupply) public {
        totalSupply = initialSupply * 10 ** uint256(decimals);
        balanceOf[msg.sender] = totalSupply;
    }

    function _transfer(address _from, address _to, uint _value) internal {
        require(_to != address(0), "Invalid address");
        require(balanceOf[_from] >= _value, "Insufficient balance");
        require(balanceOf[_to] + _value >= balanceOf[_to], "Overflow detected");
        require(!frozenAccount[_from], "Sender account frozen");
        require(!frozenAccount[_to], "Recipient account frozen");

        balanceOf[_from] -= _value;
        balanceOf[_to] += _value;
        emit Transfer(_from, _to, _value);
    }

    function transfer(address _to, uint256 _value) public {
        _transfer(msg.sender, _to, _value);
    }

    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(_value <= allowance[_from][msg.sender], "Allowance exceeded");
        allowance[_from][msg.sender] -= _value;
        _transfer(_from, _to, _value);
        return true;
    }

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

    function approveAndCall(address _spender, uint256 _value, bytes _extraData) public returns (bool success) {
        tokenRecipient spender = tokenRecipient(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value, this, _extraData);
            return true;
        }
        return false;
    }

    function burn(uint256 _value) public returns (bool success) {
        require(balanceOf[msg.sender] >= _value, "Insufficient balance");
        balanceOf[msg.sender] -= _value;
        totalSupply -= _value;
        emit Burn(msg.sender, _value);
        return true;
    }

    function burnFrom(address _from, uint256 _value) public returns (bool success) {
        require(balanceOf[_from] >= _value, "Insufficient balance");
        require(_value <= allowance[_from][msg.sender], "Allowance exceeded");
        balanceOf[_from] -= _value;
        allowance[_from][msg.sender] -= _value;
        totalSupply -= _value;
        emit Burn(_from, _value);
        return true;
    }

    function mintToken(address target, uint256 mintedAmount) public onlyOwner {
        balanceOf[target] += mintedAmount;
        totalSupply += mintedAmount;
        emit Transfer(address(0), this, mintedAmount);
        emit Transfer(this, target, mintedAmount);
    }

    function freezeAccount(address target, bool freeze) public onlyOwner {
        frozenAccount[target] = freeze;
        emit FrozenFunds(target, freeze);
}
}