// https://medium.com/@freeman_dev/free-f4f758951b2
//
// Regards, Freeman (自由人).
//
// SPDX-License-Identifier: MIT

pragma solidity 0.8.20;

abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

contract ERC20 is Context, IERC20, IERC20Metadata {
    mapping(address => uint256) private _balances;

    mapping(address => mapping(address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;

    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    function name() public view virtual override returns (string memory) {
        return _name;
    }

    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    function decimals() public view virtual override returns (uint8) {
        return 18;
    }

    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, 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) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);

        uint256 currentAllowance = _allowances[sender][_msgSender()];
        require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
        unchecked {
            _approve(sender, _msgSender(), currentAllowance - amount);
        }

        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        uint256 currentAllowance = _allowances[_msgSender()][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(_msgSender(), spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    function _transfer(
        address sender,
        address recipient,
        uint256 amount
    ) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        uint256 senderBalance = _balances[sender];
        require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[sender] = senderBalance - amount;
        }
        _balances[recipient] += amount;

        emit Transfer(sender, recipient, amount);
    }

    function _createInitialSupply(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _totalSupply += amount;
        _balances[account] += amount;
        emit Transfer(address(0), account, amount);
    }

    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");
        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
            // Overflow not possible: amount <= accountBalance <= totalSupply.
            _balances[address(0xdead)] += amount;
        }

        emit Transfer(account, address(0xdead), 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);
    }
}

contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    constructor () {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    function owner() public view returns (address) {
        return _owner;
    }

    modifier onlyOwner() {
        require(_owner == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    function renounceOwnership() external virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

interface IDexRouter {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);

    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;

}

interface IDexFactory {
    function createPair(address tokenA, address tokenB)
        external
        returns (address pair);
}

contract MitaoCat is ERC20, Ownable {

    struct sellFees {
        uint256 operationsFee;
    }

    struct buyFees {
        uint256 operationsFee;
    }

    IDexRouter private dexRouter;
    address private lpPair;

    bool private swapping;
    uint256 public swapTokensAtAmount;

    address operationsAddress;
    address XiaOXuai;
    address CEXMitao;

    bool private tradingActive = false;
    bool private swapEnabled = false;

    uint256 public buyTotalFees;
    uint256 public sellTotalFees;
    uint256 public currentTID = 0;

    uint256 private tokensForOperations;

    mapping (address => bool) private _isExcludedFromFees;
    mapping (address => bool) public automatedMarketMakerPairs;
    mapping (uint256 => buyFees) private _buyFees;
    mapping (uint256 => sellFees) private _sellFees;

    event SetAutomatedMarketMakerPair(address indexed pair, bool indexed value);
    event EnabledTrading();
    event ExcludeFromFees(address indexed account, bool isExcluded);
    event OwnerForcedSwapBack(uint256 timestamp);
    event TransferForeignToken(address token, uint256 amount);

    constructor() ERC20("Mitao Cat", unicode"いい猫") {
        _buyFees[0] = buyFees(25);
        _sellFees[0] = sellFees(25);

        _buyFees[1] = buyFees(10);
        _sellFees[1] = sellFees(20);

        _buyFees[2] = buyFees(0);
        _sellFees[2] = sellFees(10);

        _buyFees[3] = buyFees(0);
        _sellFees[3] = sellFees(0);

        buyFees memory buyFee = _buyFees[0];
        sellFees memory sellFee = _sellFees[0];
        buyTotalFees = buyFee.operationsFee;
        sellTotalFees = sellFee.operationsFee;

        IDexRouter _dexRouter = IDexRouter(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
        dexRouter = _dexRouter;

        lpPair = IDexFactory(_dexRouter.factory()).createPair(address(this), _dexRouter.WETH());
        _setAutomatedMarketMakerPair(address(lpPair), true);

        uint256 totalSupply = 800 * 1e9 * 1e18;

        swapTokensAtAmount = totalSupply * 2 / 1000;

        excludeFromFees(owner(), true);
        excludeFromFees(address(this), true);
        excludeFromFees(address(0xdead), true);

        operationsAddress = address(0x8F13310baC0aBcf1D3488985656833b7C98075b5);
        XiaOXuai = address(0x0696fDe8D1D3EeCAdE0c65Bb3d52dBCD07CCDE69);
        CEXMitao = address(0x2E6Db5E51623d6984Ba66117aD6f2A6ac204EE40);

        _createInitialSupply(owner(), totalSupply);

        uint256 XiaOXuaiAllocationAmount = (totalSupply *
            5) / 100;

        uint256 cexAllocationAmount = (totalSupply *
            8) / 100;

        _transfer(owner(), CEXMitao,cexAllocationAmount);
        _transfer(owner(), XiaOXuai,XiaOXuaiAllocationAmount);
    }

    receive() external payable {}

    function enableTrading() external onlyOwner {
        require(!tradingActive, "Cannot reenable trading");
        tradingActive = true;
        swapEnabled = true;
        emit EnabledTrading();
    }

    function _setAutomatedMarketMakerPair(address pair, bool value) private {
        automatedMarketMakerPairs[pair] = value;
        emit SetAutomatedMarketMakerPair(pair, value);
    }

    function switchTaxStructure(uint256 tID) external onlyOwner {
        require(currentTID < tID && currentTID != 3, "You can only go up to TID 3.");
        buyFees memory buyFee = _buyFees[tID];
        sellFees memory sellFee = _sellFees[tID];
        buyTotalFees = buyFee.operationsFee;
        sellTotalFees = sellFee.operationsFee;
        currentTID = tID;
    }

    function excludeFromFees(address account, bool excluded) public onlyOwner {
        _isExcludedFromFees[account] = excluded;
        emit ExcludeFromFees(account, excluded);
    }

    function _transfer(address from, address to, uint256 amount) internal override {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");
        require(amount > 0, "amount must be greater than 0");
        
        if(!tradingActive){
            require(_isExcludedFromFees[from] || _isExcludedFromFees[to], "Trading is not active.");
        }

        uint256 contractTokenBalance = balanceOf(address(this));

        bool canSwap = contractTokenBalance >= swapTokensAtAmount;

        if(canSwap && swapEnabled && !swapping && !automatedMarketMakerPairs[from] && !_isExcludedFromFees[from] && !_isExcludedFromFees[to]) {
            swapping = true;
            swapBack();
            swapping = false;
        }

        bool takeFee = true;

        if(_isExcludedFromFees[from] || _isExcludedFromFees[to]) {
            takeFee = false;
        }

        uint256 fees = 0;
        // only take fees on buys/sells, do not take on wallet transfers
        if(takeFee){
            // on sell
            if (automatedMarketMakerPairs[to] && sellTotalFees > 0){
                sellFees memory sellFee = _sellFees[currentTID];
                fees = amount * sellTotalFees / 100;
                tokensForOperations += fees * sellFee.operationsFee / sellTotalFees;
            }
            // on buy
            else if(automatedMarketMakerPairs[from] && buyTotalFees > 0) {
                buyFees memory buyFee = _buyFees[currentTID];
        	    fees = amount * buyTotalFees / 100;
                tokensForOperations += fees * buyFee.operationsFee / buyTotalFees;
            }
            
            if(fees > 0){
                super._transfer(from, address(this), fees);
            }

        	amount -= fees;
        }

        super._transfer(from, to, amount);
    }

    function swapTokensForEth(uint256 tokenAmount) private {

        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = dexRouter.WETH();

        _approve(address(this), address(dexRouter), tokenAmount);
        dexRouter.swapExactTokensForETHSupportingFeeOnTransferTokens(
            tokenAmount,
            0,
            path,
            address(this),
            block.timestamp
        );
    }

    function getBurnedTokens() external view returns(uint256){
        return balanceOf(address(0xdead));
    }

    function getCirculatingSupply() public view returns(uint256){
        return totalSupply() - balanceOf(address(0xdead));
    }

    function swapBack() private {

        uint256 contractBalance = balanceOf(address(this));
        uint256 totalTokensToSwap = tokensForOperations;

        if(contractBalance == 0 || totalTokensToSwap == 0) {return;}

        if(contractBalance > swapTokensAtAmount * 60){
            contractBalance = swapTokensAtAmount * 60;
        }

        bool success;
        swapTokensForEth(contractBalance);

        tokensForOperations = 0;

        (success,) = address(operationsAddress).call{value: address(this).balance}("");
    }

    function withdrawStuckETH() external onlyOwner {
        bool success;
        (success,) = address(msg.sender).call{value: address(this).balance}("");
    }

    function setOperationsAddress(address _operationsAddress) external onlyOwner {
        require(_operationsAddress != address(0), "_operationsAddress address cannot be 0");
        operationsAddress = _operationsAddress;
    }

    function forceSwapBack() external onlyOwner {
        require(balanceOf(address(this)) >= swapTokensAtAmount, "Can only swap when token amount is at or higher than restriction");
        swapping = true;
        swapBack();
        swapping = false;
        emit OwnerForcedSwapBack(block.timestamp);
    }

}