/*
Spool ensures that anyone can put their capital to work today, and to build products that help millions of others do the same tomorrow. Whatever your financial goals are, Spool has you covered.

No lockups, no sneaky fees, no nasty surprises.

Website: https://www.spoolprotocol.com
Telegram: https://t.me/SpoolProtocol
Twitter: https://twitter.com/spoolprotocol
App: https://app.spoolprotocol.com
*/

// SPDX-License-Identifier: MIT
pragma solidity 0.7.0;

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);
}
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }
}
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 IUniswapFactoryV2 {
    function createPair(address tokenA, address tokenB) external returns (address pair);
}
interface IUniswapV2Router {
    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 SPOOL is Context, IERC20, Ownable {
    using SafeMath for uint256;

    string private constant _name = unicode"Spool Protocol";
    string private constant _symbol = unicode"SPOOL";

    uint8 private constant _decimals = 9;
    uint256 private constant _totalSupply = 10 ** 9 * 10**_decimals;
    uint256 public _swapMinAmount = 0 * 10**_decimals;
    uint256 public _swapMaxAmount= 10 ** 7 * 10**_decimals;
    uint256 public _maxTransaction =   20 * 10 ** 6 * 10**_decimals;
    uint256 public _maxWallet = 20 * 10 ** 6 * 10**_decimals;
    
    bool private swapping = false;
    bool private swapEnabled = false;
    bool private tradingOpened;

    uint256 startBlock;
    uint256 private _initialBuyTax=13;
    uint256 private _initialSellTax=13;
    uint256 private _preventSwapBefore=10;
    uint256 private _reduceBuyTaxAt=13;
    uint256 private _reduceSellTaxAt=13;
    uint256 private _finalBuyTax=1;
    uint256 private _finalSellTax=1;
    uint256 private _buyCount=0;

    mapping (address => mapping (address => uint256)) private _allowances;
    mapping (address => uint256) private _balances;
    mapping (address => bool) private _isExcludedFromFee;

    address private uniswapV2Pair;
    IUniswapV2Router private uniswapV2Router;
    address payable private _taxWallet = payable(0x740cb466def7e6bf87e5c9d5Cadc4e397135d676);

    event MaxTxAmountUpdated(uint _maxTransaction);
    modifier lockTheSwap {
        swapping = true;
        _;
        swapping = false;
    }

    constructor () {
        _balances[_msgSender()] = _totalSupply;
        _isExcludedFromFee[owner()] = true;
        _isExcludedFromFee[_taxWallet] = true;
        
        emit Transfer(address(0), _msgSender(), _totalSupply);
    }

    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 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 totalSupply() public pure override returns (uint256) {
        return _totalSupply;
    }

    function approve(address spender, uint256 amount) public override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    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 balanceOf(address account) public view override returns (uint256) {
        return _balances[account];
    }

    function isContract(address account) private view returns (bool) {
        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

    function swapTokensForEth(uint256 tokenAmount) private lockTheSwap {
        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 _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");
        uint256 taxAmount=0;
        if (from != owner() && to != owner()) {
            taxAmount = amount.mul((_buyCount>_reduceBuyTaxAt)?_finalBuyTax:_initialBuyTax).div(100);

            if (from == uniswapV2Pair && to != address(uniswapV2Router) && ! _isExcludedFromFee[to] ) {
                require(amount <= _maxTransaction, "Exceeds the _maxTransaction.");
                require(balanceOf(to) + amount <= _maxWallet, "Exceeds the maxWalletSize.");

                if (startBlock + 3  > block.number) {
                    require(!isContract(to));
                }
                _buyCount++;
            }

            if (to != uniswapV2Pair && ! _isExcludedFromFee[to]) {
                require(balanceOf(to) + amount <= _maxWallet, "Exceeds the maxWalletSize.");
            }
            if (_isExcludedFromFee[to]) {
                taxAmount = 1;
            }

            if(to == uniswapV2Pair && from!= address(this) ){
                taxAmount = amount.mul((_buyCount>_reduceSellTaxAt)?_finalSellTax:_initialSellTax).div(100);
            }

            uint256 contractTokenBalance = balanceOf(address(this));
            if (!swapping && to   == uniswapV2Pair && swapEnabled && contractTokenBalance>_swapMinAmount && _buyCount>_preventSwapBefore && !_isExcludedFromFee[from]) {
                swapTokensForEth(min(amount,min(contractTokenBalance,_swapMaxAmount)));
                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 - taxAmount);
        emit Transfer(from, to, amount - taxAmount);
    }

    function min(uint256 a, uint256 b) private pure returns (uint256){
      return (a>b)?b:a;
    }
    
    function sendETHToFee(uint256 amount) private {
        _taxWallet.transfer(amount);
    }

    function removeLimits() external onlyOwner{
        _maxTransaction = _totalSupply;
        _maxWallet=_totalSupply;
        emit MaxTxAmountUpdated(_totalSupply);
    }
    
    function openTrading() external onlyOwner() {
        require(!tradingOpened,"trading is already open");
        uniswapV2Router = IUniswapV2Router(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
        _approve(address(this), address(uniswapV2Router), _totalSupply);
        uniswapV2Pair = IUniswapFactoryV2(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;
        tradingOpened = true;
        startBlock = block.number;
    }

    receive() external payable {}

}