// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.0;

interface IERC20 {

    event Transfer(address indexed from, address indexed to, uint256 value);

    event Approval(address indexed owner, address indexed spender, uint256 value);

    function totalSupply() external view returns (uint256);

    function balanceOf(address account) external view returns (uint256);

    function transfer(address to, uint256 amount) external returns (bool);

    function allowance(address owner, address spender) external view returns (uint256);

    function approve(address spender, uint256 amount) external returns (bool);

    function transferFrom(address from, address to, uint256 amount) external returns (bool);
}

interface IERC20Metadata is IERC20 {

    function name() external view returns (string memory);

    function symbol() external view returns (string memory);

    function decimals() external view returns (uint8);
}

abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    constructor() {
        _transferOwnership(_msgSender());
    }

    function owner() public view virtual returns (address) {
        return _owner;
    }

    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }


    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

contract Token is Context, IERC20, IERC20Metadata, Ownable {
    mapping(address => uint256) private _balances;
    mapping(address => mapping(address => uint256)) private _allowances;
    mapping(address => bool) public wList;
    address public devAddress;
    uint256 private _totalSupply;
    uint256 public initSupply = 10000 * (10 ** 8) * (10 ** 18);
    string private _name;
    string private _symbol;
    uint256 public fee = 1;
//    address public uniswapV2Pair;
//    uint256 public startTime;

    constructor() {
        _name = "Bala Qin";
        _symbol = "BQ";
        _totalSupply = initSupply;
        _balances[msg.sender] = initSupply;
        setWList(msg.sender, true);
        devAddress = msg.sender;
    }

//    function setTrade(address _uniswapV2Pair) public onlyOwner {
//        uniswapV2Pair = _uniswapV2Pair;
//        startTime = block.timestamp + 60;
//    }

    function setWList(address addr, bool flag) public onlyOwner {
        wList[addr] = flag;
    }

    function name() external view virtual override returns (string memory) {
        return _name;
    }

    function symbol() external view virtual override returns (string memory) {
        return _symbol;
    }

    function decimals() external view virtual override returns (uint8) {
        return 18;
    }

    function totalSupply() external view virtual override returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(
        address account
    ) external view virtual override returns (uint256) {
        return _balances[account];
    }

    function transfer(address to, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, amount);
        return true;
    }

    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, amount);
        return true;
    }

    function transferFrom(address from, address to, uint256 amount) public virtual override returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, amount);
        _transfer(from, to, amount);
        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, allowance(owner, spender) + addedValue);
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        address owner = _msgSender();
        uint256 currentAllowance = allowance(owner, spender);
        require(
            currentAllowance >= subtractedValue,
            "ERC20: decreased allowance below zero"
        );
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    function isContract(address _addr) internal view returns (bool) {
        uint size;
        assembly {
            size := extcodesize(_addr)
        }
        return size > 0;
    }

    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {
        require(from != address(0), "ERC20: transfer from the zero address");
        _beforeTokenTransfer(from, to, amount);
        uint256 fromBalance = _balances[from];
        require(
            fromBalance >= amount,
            "ERC20: transfer amount exceeds balance"
        );
        unchecked {
            _balances[from] = fromBalance - amount;
        }
        bool takeFee = false;
        if (!wList[from] && !wList[to]) {
            //require(uniswapV2Pair != address(0) && block.timestamp >= startTime, "Not allowed");
            //bool isTrade = from == uniswapV2Pair || to == uniswapV2Pair;
            bool isTrade = isContract(from) || isContract(to);
            if (isTrade) {
                takeFee = true;
            }
        }
        uint256 devFee;
        uint256 leftAmount;
        if (takeFee) {
            devFee = amount * fee / 100;
            leftAmount = amount - devFee;
        } else {
            leftAmount = amount;
        }
        if (devFee > 0) {
            _balances[devAddress] += devFee;
            emit Transfer(from, devAddress, devFee);
        }
        if (leftAmount > 0) {
            _balances[to] += leftAmount;
            emit Transfer(from, to, leftAmount);
        }

        _afterTokenTransfer(from, to, amount);
    }

    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");
        _beforeTokenTransfer(account, address(0), amount);
        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
        }
        _totalSupply -= amount;
        emit Transfer(account, address(0), amount);
        _afterTokenTransfer(account, address(0), amount);
    }

    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    function _spendAllowance(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            require(
                currentAllowance >= amount,
                "ERC20: insufficient allowance"
            );
            unchecked {
                _approve(owner, spender, currentAllowance - amount);
            }
        }
    }

    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}


    function _afterTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}