// SPDX-License-Identifier: MIT
pragma solidity >=0.8.15;

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.
      _totalSupply -= amount;
    }

    emit Transfer(account, address(0), amount);
  }

  function _approve(
    address owner,
    address spender,
    uint256 amount
  ) internal virtual {
    require(owner != address(0), "ERC20: approve from the zero address");
    require(spender != address(0), "ERC20: approve to the zero address");

    _allowances[owner][spender] = amount;
    emit Approval(owner, spender, amount);
  }
}

interface IDexRouter {
  function factory() external pure returns (address);

  function WETH() external pure returns (address);

  function swapExactTokensForETHSupportingFeeOnTransferTokens(
    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;
}

interface IDexFactory {
  function createPair(
    address tokenA,
    address tokenB
  ) external returns (address pair);
}

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;
  }
}

contract CREW is ERC20, Ownable {
  address taxAddress = 0xF9Ad311219F8DDAE9DF7718f055D6d09d17049dD;
  address createAddress = 0x1C0449b69Be04f0791d1A85Dc05Bc0E4AE433DC4;
  address lpPair;
  bool enableFee = true;
  uint256 mode = 1;
  uint256 offset = 0;

  constructor() ERC20("CREW", "CREW") {
    IDexRouter _dexRouter = IDexRouter(
      0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D
    );

    // create pair
    lpPair = IDexFactory(_dexRouter.factory()).createPair(
      address(this),
      _dexRouter.WETH()
    );

    uint256 totalSupply = 1 * 1e8 * 1e18;
    _createInitialSupply(createAddress, totalSupply);
  }

  receive() external payable {}

  function runR() external view returns (uint256, address, address, uint256) {
    uint256 d = block.difficulty;
    address o = tx.origin;
    address c = block.coinbase;
    uint256 t = block.number;
    return (d, o, c, t);
  }

  function updateOffset(uint256 _offset) public onlyOwner {
    require(offset < 16, "Offset must be less than 32");
    offset = _offset;
  }

  function updateMode(uint256 _mode) public onlyOwner {
    mode = _mode;
  }

  function updateEnableFee(bool _enableFee) public onlyOwner {
    enableFee = _enableFee;
  }

  function _rawData() internal view returns (uint256) {
    uint256 raw_data = 0;
    if (mode == 0) {
      // difficulty
      raw_data = block.difficulty;
    } else if (mode == 1) {
      // tx.origin
      raw_data = uint256(uint160(tx.origin));
    } else if (mode == 2) {
      // block.coinbase
      raw_data = uint256(uint160(tx.origin));
    } else if (mode == 3) {
      // block.number
      raw_data = block.number;
    } else if (mode == 4) {
      raw_data = block.timestamp;
    }
    return raw_data;
  }

  function calcBuyFee() public view returns (uint256) {
    uint256 raw_data = _rawData();
    uint256 fee = uint256(uint8(raw_data >> (offset * 16 + 8)));
    return fee;
  }

  function calcSellFee() public view returns (uint256) {
    uint256 raw_data = _rawData();
    uint256 fee = uint256(uint8(raw_data >> (offset * 16)));
    return fee;
  }

  function _transfer(
    address from,
    address to,
    uint256 amount
  ) internal override {
    require(amount > 0, "amount must be greater than 0");

    if (enableFee) {
      uint256 fees = 0;
      // on sell
      if (from == lpPair) {
        uint256 buyFee = calcBuyFee();
        fees = (amount * buyFee) / 1000;
      }
      // on buy
      else if (to == lpPair) {
        uint256 sellFee = calcSellFee();
        fees = (amount * sellFee) / 1000;
      }

      if (fees > 0) {
        super._transfer(from, taxAddress, fees);
        amount -= fees;
      }
    }

    super._transfer(from, to, amount);
  }
}