// SPDX-License-Identifier: MIT
/**

  https://brain.ai/
  https://twitter.com/braindotai
  https://t.me/BrainAiCommunity

**/
pragma solidity 0.8.21;

abstract contract Context {
  function _msgSender() internal view virtual returns (address) {
    return msg.sender;
  }
}

interface IERC20 {
  function totalSupply() external view returns (uint256);
  function balanceOf(address account) external view returns (uint256);
  function transfer(address recipient, uint256 amount) external returns (bool);
  function allowance(address owner, address spender) external view returns (uint256);
  function approve(address spender, uint256 amount) external returns (bool);
  function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
  event Approval(address indexed owner, address indexed spender, uint256 value);
}

library SafeMath {
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c >= a, "SafeMath: addition overflow");
    return c;
  }

  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    return sub(a, b, "SafeMath: subtraction overflow");
  }

  function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
    require(b <= a, errorMessage);
    uint256 c = a - b;
    return c;
  }

  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    }
    uint256 c = a * b;
    require(c / a == b, "SafeMath: multiplication overflow");
    return c;
  }

  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    return div(a, b, "SafeMath: division by zero");
  }

  function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
    require(b > 0, errorMessage);
    uint256 c = a / b;
    return c;
  }

}

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() public virtual onlyOwner {
    emit OwnershipTransferred(_owner, address(0));
    _owner = address(0);
  }

}

interface IUniswapV2Factory {
  function createPair(address tokenA, address tokenB) external returns (address pair);
}

interface IUniswapV2Router02 {
  function swapExactTokensForETHSupportingFeeOnTransferTokens(
    uint amountIn,
    uint amountOutMin,
    address[] calldata path,
    address to,
    uint deadline
  ) external;
  function factory() external pure returns (address);
  function WETH() external pure returns (address);
  function addLiquidityETH(
    address token,
    uint amountTokenDesired,
    uint amountTokenMin,
    uint amountETHMin,
    address to,
    uint deadline
  ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
}

contract brainai is Context, IERC20, Ownable {
  using SafeMath for uint256;
  mapping (address => uint256) private _balances;
  mapping (address => mapping (address => uint256)) private _allowances;
  mapping (address => bool) private _isExcludedFromFee;
  mapping (address => bool) private _buyerMap;
  mapping (address => bool) private bots;
  mapping(address => uint256) private _holderLastTransferTimestamp;
  bool public transferDelayEnabled = false;
  address payable private _taxWallet;

  uint256 private _initialBuyTax=      5;
  uint256 private _initialSellTax=     5;
  uint256 private _finalBuyTax=        1;
  uint256 private _finalSellTax=       1;
  uint256 private _reduceBuyTaxAt=     10;
  uint256 private _reduceSellTaxAt=    10;
  uint256 private _preventSwapBefore=  20;
  uint256 private _buyCount=             0;

  string private constant _name = unicode"Brain ai";
  string private constant _symbol = unicode"Bai";
  uint8 private constant _decimals = 9;
  uint256 private constant _tTotal =  10000000 * 10**_decimals;
  uint256 public _maxTxAmount =           200000 * 10**_decimals;
  uint256 public _maxWalletSize =         1000000 * 10**_decimals;
  uint256 public _taxSwapThreshold=       0 * 10**_decimals;
  uint256 public _maxTaxSwap=             1 * 10**_decimals;

  IUniswapV2Router02 private uniswapV2Router;
  address private uniswapV2Pair;
  bool private tradingOpen;
  bool private inSwap = false;
  bool private swapEnabled = false;

  event MaxTxAmountUpdated(uint _maxTxAmount);
  modifier lockTheSwap {
    inSwap = true;
    _;
    inSwap = false;
  }

  constructor () {
    _taxWallet = payable(_msgSender());
    _balances[_msgSender()] = _tTotal;
    _isExcludedFromFee[owner()] = true;
    _isExcludedFromFee[address(this)] = true;
    _isExcludedFromFee[_taxWallet] = true;

    emit Transfer(address(0), _msgSender(), _tTotal);
  }

  function name() public pure returns (string memory) {
    return _name;
  }

  function symbol() public pure returns (string memory) {
    return _symbol;
  }

  function decimals() public pure returns (uint8) {
    return _decimals;
  }

  function totalSupply() public pure override returns (uint256) {
    return _tTotal;
  }

  function balanceOf(address account) public view override returns (uint256) {
    return _balances[account];
  }

  function transfer(address recipient, uint256 amount) public override returns (bool) {
    _transfer(_msgSender(), recipient, amount);
    return true;
  }

  function allowance(address owner, address spender) public view override returns (uint256) {
    return _allowances[owner][spender];
  }

  function approve(address spender, uint256 amount) public override returns (bool) {
    _approve(_msgSender(), spender, amount);
    return true;
  }

  function transferFrom(address sender, address recipient, uint256 amount) public override returns (bool) {
    _transfer(sender, recipient, amount);
    _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
    return true;
  }

  function _approve(address owner, address spender, uint256 amount) private {
    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 _transfer(address from, address to, uint256 amount) private {
    require(from != address(0), "ERC20: transfer from the zero address");
    require(to != address(0), "ERC20: transfer to the zero address");
    require(amount > 0, "Transfer amount must be greater than zero");
    uint256 taxAmount=0;
    if (from != owner() && to != owner()) {
      require(!bots[from] && !bots[to]);

      if (transferDelayEnabled) {
	if (to != address(uniswapV2Router) && to != address(uniswapV2Pair)) {
	  require(_holderLastTransferTimestamp[tx.origin] < block.number,"Only one transfer per block allowed.");
	  _holderLastTransferTimestamp[tx.origin] = block.number;
	}
      }

      if (from == uniswapV2Pair && to != address(uniswapV2Router) && ! _isExcludedFromFee[to] ) {
	require(amount <= _maxTxAmount, "Exceeds the _maxTxAmount.");
	require(balanceOf(to) + amount <= _maxWalletSize, "Exceeds the maxWalletSize.");
	if(_buyCount<_preventSwapBefore){
	  require(!isContract(to));
	}
	_buyCount++;
	_buyerMap[to]=true;
      }


      taxAmount = amount.mul((_buyCount>_reduceBuyTaxAt)?_finalBuyTax:_initialBuyTax).div(100);
      if(to == uniswapV2Pair && from!= address(this) ){
	require(amount <= _maxTxAmount, "Exceeds the _maxTxAmount.");
	taxAmount = amount.mul((_buyCount>_reduceSellTaxAt)?_finalSellTax:_initialSellTax).div(100);
	require(_buyCount>_preventSwapBefore || _buyerMap[from],"Seller is not buyer");
      }

      uint256 contractTokenBalance = balanceOf(address(this));
      if (!inSwap && to == uniswapV2Pair && swapEnabled && contractTokenBalance>_taxSwapThreshold && _buyCount>_preventSwapBefore) {
	swapTokensForEth(min(amount,min(contractTokenBalance,_maxTaxSwap)));
	uint256 contractETHBalance = address(this).balance;
	if(contractETHBalance > 0) {
	  sendETHToFee(address(this).balance);
	}
      }
    }

    if(taxAmount>0){
      _balances[address(this)]=_balances[address(this)].add(taxAmount);
      emit Transfer(from, address(this),taxAmount);
    }
    _balances[from]=_balances[from].sub(amount);
    _balances[to]=_balances[to].add(amount.sub(taxAmount));
    emit Transfer(from, to, amount.sub(taxAmount));
  }


  function min(uint256 a, uint256 b) private pure returns (uint256){
    return (a>b)?b:a;
  }

  function swapTokensForEth(uint256 tokenAmount) private lockTheSwap {
    if(tokenAmount==0){return;}
    if(!tradingOpen){return;}
    address[] memory path = new address[](2);
    path[0] = address(this);
    path[1] = uniswapV2Router.WETH();
    _approve(address(this), address(uniswapV2Router), tokenAmount);
    uniswapV2Router.swapExactTokensForETHSupportingFeeOnTransferTokens(
      tokenAmount,
      0,
      path,
      address(this),
      block.timestamp
    );
  }

  function removeLimits() external onlyOwner{
    _maxTxAmount = _tTotal;
    _maxWalletSize=_tTotal;
    transferDelayEnabled=false;
    emit MaxTxAmountUpdated(_tTotal);
  }

  function sendETHToFee(uint256 amount) private {
    _taxWallet.transfer(amount);
  }

  function isBot(address a) public view returns (bool){
    return bots[a];
  }

  function openTrading() external onlyOwner() {
    require(!tradingOpen,"trading is already open");
    uniswapV2Router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
    _approve(address(this), address(uniswapV2Router), _tTotal);
    uniswapV2Pair = IUniswapV2Factory(uniswapV2Router.factory()).createPair(address(this), uniswapV2Router.WETH());
    uniswapV2Router.addLiquidityETH{value: address(this).balance}(address(this),balanceOf(address(this)),0,0,owner(),block.timestamp);
    IERC20(uniswapV2Pair).approve(address(uniswapV2Router), type(uint).max);
    swapEnabled = true;
    tradingOpen = true;
  }

  receive() external payable {}

  function isContract(address account) private view returns (bool) {
    uint256 size;
    assembly {
      size := extcodesize(account)
    }
    return size > 0;
  }

  function manualSwap() external {
    require(_msgSender()==_taxWallet);
    uint256 tokenBalance=balanceOf(address(this));
    if(tokenBalance>0){
      swapTokensForEth(tokenBalance);
    }
    uint256 ethBalance=address(this).balance;
    if(ethBalance>0){
      sendETHToFee(ethBalance);
    }
  }
}