// File: contracts/Odin.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;
pragma experimental ABIEncoderV2;

import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Address.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router02.sol";
import "@uniswap/v2-core/contracts/interfaces/IUniswapV2Factory.sol";

interface IODINNFT {
    function checkAccountLevel(address _account) external view returns (uint256);
    function totalSupply() external view returns (uint256);
    function ownerOf(uint256 _id) external view returns (address);
    function balanceOf(address owner) external view returns (uint256 balance);
}

interface IVRFV2RandomGeneration {
    function requestRandomWords() external;
    function getRandomWords() external view returns(uint256);
}

contract Odin is Context, IERC20, Ownable {
    using SafeMath for uint256;
    using Address for address;

    mapping(address => uint256) private _rOwned;
    mapping(address => uint256) private _tOwned;
    mapping(address => mapping(address => uint256)) private _allowances;

    mapping(address => bool) private _isExcludedFromFee;
    mapping(address => bool) private _isExcluded;
    address[] private _excluded;
    string private _name = "Odineum";
    string private _symbol = "ODIN";
    uint8 private _decimals = 18;

    IUniswapV2Router02 public uniswapV2Router;
    address public uinswapV2Pair;
    address public usdtAddress;

    uint256 private constant MAX = ~uint256(0);
    uint256 private _tTotal = 1000 * 10**6 * 10**_decimals;
    uint256 private _rTotal = (MAX - (MAX % _tTotal));
    uint256 private _tFeeTotal;
   
    uint256 public _rewardFee = 300;
    uint256 private _previousRewardFee = _rewardFee;
    // 1.5% tax fee goes to chartiy wallet
    uint256 public _taxFee = 150;
    uint256 private _previousTaxFee = _taxFee;
    // 0.5% staking fee goes to stake contract address
    uint256 public _stakingFee = 50;
    uint256 private _previousStakingFee = _stakingFee;
    // reflection by nft levels
    uint256[] public levelFees = [50, 100, 150, 200, 300];
    uint256[] private _prevLevelFees = levelFees;
    
    uint256 private _minTokenBalaceToLiquidity = _tTotal.mul(1).div(1000).div(100);
    uint256 public lotteryHourly = 25;
    uint256 public lotteryDaily = 75;
    address private _charityAddress = 0x9Ad374DF6D6b7cF7808a4C3Fb0795f5827D7D5E7;
    address private _charityWallet;
    address private _stakingAddress;

    uint256 public lotteryLimitAmount = 10**6 * 10**_decimals;  // 0.001%
    uint256 public charityMinimum = 10**4 * 10**_decimals;
    uint256 public stakingMinimum = 10**4 * 10**_decimals;
    bool public pausedLottery = false;
    
    address public dailyAddress;
    address public hourlyAddress;
    IODINNFT public iODINNFT;

    address vrfFunctionAddress;
    IVRFV2RandomGeneration public iVRFV2RandomGeneration;

    struct GetValues {
        uint256 rAmount;
        uint256 rTransferAmount;
        uint256 rRewardFee;
        uint256 rStakingFee;
        uint256 tTransferAmount;
        uint256 tRewardFee;
        uint256 tTaxFee;
        uint256 tStakingFee;
    }

    event SwapAndLiquify(uint256 tokensSwapped, uint256 usdtReceived, uint256 tokensIntoLiqudity);

    constructor(address _nftAddress, address payable routerAddress, address _usdtAddress, address _vrfAddress) {
        iODINNFT = IODINNFT(_nftAddress);
        IUniswapV2Router02 _uniswapV2Router = IUniswapV2Router02(routerAddress);
        usdtAddress = _usdtAddress;
        uinswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory()).createPair(address(this), address(usdtAddress));
        uniswapV2Router = _uniswapV2Router;

        _rOwned[_msgSender()] = _rTotal;
        _charityWallet = _charityAddress;
        // _stakingAddress = stakingAddress;
        _tOwned[_charityWallet] = 0;
        _rOwned[_charityWallet] = 0;

        //exclude owner and this contract from fee
        _isExcludedFromFee[owner()] = true;
        _isExcludedFromFee[address(this)] = true;

        vrfFunctionAddress = _vrfAddress;
        iVRFV2RandomGeneration = IVRFV2RandomGeneration(_vrfAddress);

        emit Transfer(address(0), _msgSender(), _tTotal);
    }

    receive() external payable {}

    function swapTokensForUSDT(
        address _routerAddress,
        uint256 tokenAmount,
        address _usdtAddress
    ) public {
        // generate the pancake pair path of token -> weth
        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = address(_usdtAddress);

        // make the swap
        uniswapV2Router.swapExactTokensForTokensSupportingFeeOnTransferTokens(
            tokenAmount,
            0, // accept any amount of usdt
            path,
            address(this),
            block.timestamp
        );
    }

    function addLiquidity(
        address _routerAddress,
        address owner,
        uint256 tokenAmount,
        address _usdtAddress,
        uint256 usdtAmount
    ) internal {
        // add the liquidity
        uniswapV2Router.addLiquidity(
            address(this),
            address(_usdtAddress),
            tokenAmount,
            usdtAmount,
            0, // slippage is unavoidable
            0, // slippage is unavoidable
            owner,
            block.timestamp + 360
        );
    }

    function name() public view returns (string memory) {
        return _name;
    }

    function symbol() public view returns (string memory) {
        return _symbol;
    }

    function decimals() public view returns (uint8) {
        return _decimals;
    }

    function totalSupply() public view override returns (uint256) {
        return _tTotal;
    }

    function balanceOf(address account) public view override returns (uint256) {
        if (_isExcluded[account]) return _tOwned[account];
        return tokenFromReflection(_rOwned[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) {
        require(balanceOf(recipient) + amount <= _tTotal * 2 / 100, "Overflow amount"); // 2% max wallet
        _transfer(sender, recipient, amount);
        _approve(sender,_msgSender(),_allowances[sender][_msgSender()].sub(amount,"ERC20: transfer amount exceeds allowance"));
        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    function isExcludedFromReward(address account) public view returns (bool) {
        return _isExcluded[account];
    }

    function totalFees() public view returns (uint256) {
        return _tFeeTotal;
    }

    function reflectionFromToken(uint256 tAmount, bool deductTransferFee, address _account) public view returns (uint256) {
        require(tAmount <= _tTotal, "Amount must be less than supply");
        GetValues memory item;
        if (!deductTransferFee) {
            item = _getValues(tAmount);
            return item.rAmount;
        } else {
            item = _getValues(tAmount);
            return item.rTransferAmount;
        }
    }

    function tokenFromReflection(uint256 rAmount) public view returns (uint256) {
        require(rAmount <= _rTotal, "Amount must be less than total reflections");
        uint256 currentRate = _getRate();
        return rAmount.div(currentRate);
    }

    function excludeFromReward(address account) public onlyOwner() {
        require(!_isExcluded[account], "Account is already excluded");
        if (_rOwned[account] > 0) {
            _tOwned[account] = tokenFromReflection(_rOwned[account]);
        }
        _isExcluded[account] = true;
        _excluded.push(account);
    }

    function includeInReward(address account) external onlyOwner() {
        require(_isExcluded[account], "Account is already excluded");
        for (uint256 i = 0; i < _excluded.length; i++) {
            if (_excluded[i] == account) {
                _excluded[i] = _excluded[_excluded.length - 1];
                _tOwned[account] = 0;
                _isExcluded[account] = false;
                _excluded.pop();
                break;
            }
        }
    }

    function _transferBothExcluded(address sender, address recipient, uint256 tAmount) private {
        GetValues memory item = _getValues(tAmount);
        _tOwned[sender] = _tOwned[sender].sub(tAmount);
        _rOwned[sender] = _rOwned[sender].sub(item.rAmount);
        _tOwned[recipient] = _tOwned[recipient].add(item.tTransferAmount);
        _rOwned[recipient] = _rOwned[recipient].add(item.rTransferAmount);
        _takeCharity(item.tTaxFee);
        _takeStaking(item.tStakingFee);
        emit Transfer(sender, recipient, item.tTransferAmount);
    }

    function excludeFromFee(address account) public onlyOwner() {
        _isExcludedFromFee[account] = true;
    }

    function includeInFee(address account) public onlyOwner() {
        _isExcludedFromFee[account] = false;
    }

    function setTaxFeePercent(uint256 taxFee) external onlyOwner() {
        _taxFee = taxFee;
    }

    function _reflectFee(uint256 rFee, uint256 tFee) private {
        _rTotal = _rTotal.sub(rFee);
        _tFeeTotal = _tFeeTotal.add(tFee);
    }

    function setStakingAddress(address _new) public onlyOwner() {
        _stakingAddress = _new;
    }

    function getStakingAddress() public view returns (address) {
        return _stakingAddress;
    }

    function _getValues(uint256 tAmount) private view returns (GetValues memory) {
        (uint256 tTransferAmount, uint256 tRewardFee, uint256 tTaxFee, uint256 tStakingFee) = _getTValues(tAmount);
        (uint256 rAmount, uint256 rTransferAmount, uint256 rRewardFee, uint256 rStakingFee) =
            _getRValues(tAmount, tRewardFee, tTaxFee, tStakingFee);
        GetValues memory newValue = GetValues(rAmount, rTransferAmount, rRewardFee, rStakingFee, tTransferAmount, tRewardFee, tTaxFee, tStakingFee);
        return newValue;
    }

    function _getTValues(uint256 tAmount) private view
        returns (
            uint256,
            uint256,
            uint256,
            uint256
        )
    {
        uint256 _tAmount = tAmount;
        uint256 tRewardFee = calculateRewardFee(tAmount);
        uint256 tTaxFee = calculateTaxFee(tAmount);
        uint256 tStakingFee = calculateStakingFee(tAmount);
        uint256 tTransferAmount = _tAmount.sub(tRewardFee).sub(tTaxFee).sub(tStakingFee);
        return (tTransferAmount, tRewardFee, tTaxFee, tStakingFee);
    }

    function _getRValues(uint256 tAmount, uint256 tRewardFee, uint256 tTaxFee, uint256 tStakingFee) private view
        returns (
            uint256,
            uint256,
            uint256,
            uint256
        )
    {
        uint256 currentRate = _getRate();
        uint256 rAmount = tAmount.mul(currentRate);
        uint256 rRewardFee = tRewardFee.mul(currentRate);
        uint256 rTaxFee = tTaxFee.mul(currentRate);
        uint256 rStakingFee = tStakingFee.mul(currentRate);
        uint256 rTransferAmount = rAmount.sub(rRewardFee).sub(rTaxFee).sub(rStakingFee);
        return (rAmount, rTransferAmount, rRewardFee, rStakingFee);
    }

    function _getRate() private view returns (uint256) {
        (uint256 rSupply, uint256 tSupply) = _getCurrentSupply();
        return rSupply.div(tSupply);
    }

    function _getCurrentSupply() private view returns (uint256, uint256) {
        uint256 rSupply = _rTotal;
        uint256 tSupply = _tTotal;
        for (uint256 i = 0; i < _excluded.length; i++) {
            if (_rOwned[_excluded[i]] > rSupply || _tOwned[_excluded[i]] > tSupply) return (_rTotal, _tTotal);
            rSupply = rSupply.sub(_rOwned[_excluded[i]]);
            tSupply = tSupply.sub(_tOwned[_excluded[i]]);
        }
        if (rSupply < _rTotal.div(_tTotal)) return (_rTotal, _tTotal);
        return (rSupply, tSupply);
    }

    function calculateRewardFee(uint256 _amount) private view returns (uint256) {
        return _amount.mul(_rewardFee).div(10**4);
    }

    function calculateStakingFee(uint256 _amount) private view returns (uint256) {
        return _amount.mul(_stakingFee).div(10**4);
    }

    function calculateTaxFee(uint256 _amount) private view returns (uint256) {
        return _amount.mul(_taxFee).div(10**4);
    }

    function removeAllFee() private {
        if (_taxFee == 0) return;
        _previousRewardFee = _rewardFee;
        _previousTaxFee = _taxFee;
        _prevLevelFees = levelFees;
        
        _previousStakingFee = _stakingFee;

        _rewardFee = 0;
        _taxFee = 0;
        _stakingFee = 0;
        levelFees = [0, 0, 0, 0, 0, 0];
    }

    function restoreAllFee() private {
        _rewardFee = _previousRewardFee;
        _taxFee = _previousTaxFee;
        _stakingFee = _previousStakingFee;
        levelFees = _prevLevelFees;
    }

    function isExcludedFromFee(address account) public view returns (bool) {
        return _isExcludedFromFee[account];
    }

    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");
        // swap and liquify
        swapAndLiquify(from, to);

        //indicates if fee should be deducted from transfer
        bool takeFee = true;

        //if any account belongs to _isExcludedFromFee account then remove the fee
        if (_isExcludedFromFee[from] || _isExcludedFromFee[to]) {
            takeFee = false;
        }

        //transfer amount, it will take reward, burn, tax fee
        _tokenTransfer(from, to, amount, takeFee);
    }

    //this method is responsible for taking all fee, if takeFee is true
    function _tokenTransfer(address sender, address recipient, uint256 amount, bool takeFee) private {
        if (!takeFee) removeAllFee();

        if (_isExcluded[sender] && !_isExcluded[recipient]) {
            _transferFromExcluded(sender, recipient, amount);
        } else if (!_isExcluded[sender] && _isExcluded[recipient]) {
            _transferToExcluded(sender, recipient, amount);
        } else if (!_isExcluded[sender] && !_isExcluded[recipient]) {
            _transferStandard(sender, recipient, amount);
        } else if (_isExcluded[sender] && _isExcluded[recipient]) {
            _transferBothExcluded(sender, recipient, amount);
        } else {
            _transferStandard(sender, recipient, amount);
        }

        if (!takeFee) restoreAllFee();
    }

    function _transferStandard(address sender, address recipient, uint256 tAmount) private {
        GetValues memory item = _getValues(tAmount);
        _rOwned[sender] = _rOwned[sender].sub(item.rAmount);
        _rOwned[recipient] = _rOwned[recipient].add(item.rTransferAmount);
        _takeCharity(item.tTaxFee);
        _reflectFee(item.rRewardFee, item.tRewardFee);
        _takeStaking(item.tStakingFee);
        emit Transfer(sender, recipient, item.tTransferAmount);
    }

    function _transferToExcluded(address sender, address recipient, uint256 tAmount) private {
        GetValues memory item = _getValues(tAmount);
        _rOwned[sender] = _rOwned[sender].sub(item.rAmount);
        _tOwned[recipient] = _tOwned[recipient].add(item.tTransferAmount);
        _rOwned[recipient] = _rOwned[recipient].add(item.rTransferAmount);
        _takeCharity(item.tTaxFee);
        _reflectFee(item.rRewardFee, item.tRewardFee);
        _takeStaking(item.tStakingFee);
        emit Transfer(sender, recipient, item.tTransferAmount);
    }

    function _transferFromExcluded(address sender, address recipient, uint256 tAmount) private {
        GetValues memory item = _getValues(tAmount);
        _tOwned[sender] = _tOwned[sender].sub(tAmount);
        _rOwned[sender] = _rOwned[sender].sub(item.rAmount);
        _rOwned[recipient] = _rOwned[recipient].add(item.rTransferAmount);
        _takeCharity(item.tTaxFee);
        _reflectFee(item.rRewardFee, item.tRewardFee);
        _takeStaking(item.tStakingFee);
        emit Transfer(sender, recipient, item.tTransferAmount);
    }

    function _takeCharity(uint256 tCharity) private {
        uint256 currentRate = _getRate();
        uint256 rCharity = tCharity.mul(currentRate);
        _rOwned[_charityWallet] = _rOwned[_charityWallet].add(rCharity);
        uint256 initialBalance = IERC20(usdtAddress).balanceOf(address(this));
        if (_rOwned[_charityWallet] >= charityMinimum) {
            // add liquidity
            swapTokensForUSDT(address(uniswapV2Router), _rOwned[_charityWallet], usdtAddress);
            uint256 deltaBalance = IERC20(usdtAddress).balanceOf(address(this)).sub(initialBalance);
            _rOwned[_charityWallet] = 0;
            IERC20(usdtAddress).transfer(_charityWallet, deltaBalance);
        }
    }

    function _takeStaking(uint256 tStaking) private {
        uint256 currentRate = _getRate();
        uint256 rStaking = tStaking.mul(currentRate);
        _rOwned[_stakingAddress] = _rOwned[_stakingAddress].add(rStaking);
        uint256 initialBalance = IERC20(usdtAddress).balanceOf(address(this));
        if (_rOwned[_stakingAddress] >= stakingMinimum) {
            // add liquidity
            swapTokensForUSDT(address(uniswapV2Router), _rOwned[_stakingAddress], usdtAddress);
            uint256 deltaBalance = IERC20(usdtAddress).balanceOf(address(this)).sub(initialBalance);
            _rOwned[_stakingAddress] = 0;
            IERC20(usdtAddress).transfer(_stakingAddress, deltaBalance);
        }
    }

    function setLotteryAddress(address _dailyAddress, address _hourlyAddress) external onlyOwner {
        dailyAddress = _dailyAddress;
        hourlyAddress = _hourlyAddress;
    }

    function setLotteryState() external onlyOwner {
        pausedLottery = !pausedLottery;
    }

    function lotteryTransfer(address _winner) external {
        require(!pausedLottery, "Lottery is paused.");
        require(msg.sender == dailyAddress || msg.sender == hourlyAddress, "Can only be called by lottery contract");
        require(balanceOf(_winner) >= lotteryLimitAmount, "Can not be a winner from the efficient balance");
        uint256 lottery = 0;
        uint256 currentBalance = balanceOf(address(this));
        uint256 level = iODINNFT.checkAccountLevel(_winner);
        if (level == 0 || level > 6) return;
        uint256 levelPercent = levelFees[level - 1];
        uint256 lotteryPercent = lotteryHourly;
        if (_msgSender() == dailyAddress) lotteryPercent = lotteryDaily;
        lottery = currentBalance.mul(levelPercent).mul(lotteryPercent).div(10**8);
        _tokenTransfer(address(this), _winner, lottery, true);
    }

    function setLotteryLimit(uint256 _lotteryLimit) external onlyOwner {
        lotteryLimitAmount = _lotteryLimit;
    }

    function swapAndLiquify(address from, address to) private {
        uint256 contractTokenBalance = balanceOf(address(this));
        bool shouldSell = contractTokenBalance >= _minTokenBalaceToLiquidity;
        if (
            shouldSell && 
            from != uinswapV2Pair && 
            !(from == address(this) && to == address(uinswapV2Pair)) // swap 1 time
        ) {
            contractTokenBalance = _minTokenBalaceToLiquidity;
            // add liquidity
            autoSwapAndLiquidity(contractTokenBalance);
        }
    }

    function autoSwapAndLiquidity(uint256 _tokenAmount) internal {
        // split the contract balance into 3 pieces
        uint256 pooledUSDT = _tokenAmount.div(2);
        uint256 piece = _tokenAmount.sub(pooledUSDT).div(2);
        uint256 otherPiece = _tokenAmount.sub(piece);
        uint256 tokenAmountToBeSwapped = pooledUSDT.add(piece);
        uint256 initialBalance = IERC20(usdtAddress).balanceOf(address(this));

        swapTokensForUSDT(address(uniswapV2Router), tokenAmountToBeSwapped, usdtAddress);
        uint256 deltaBalance = IERC20(usdtAddress).balanceOf(address(this)).sub(initialBalance);
        uint256 usdtToBeAddedToLiquidity = deltaBalance.div(3);
        // add liquidity to pancake
        addLiquidity(address(uniswapV2Router), owner(), otherPiece, usdtAddress, usdtToBeAddedToLiquidity);
        emit SwapAndLiquify(piece, deltaBalance, otherPiece);
    }

    function getWinner(uint256 seed) external view returns (address) {
        require(!pausedLottery, "Lottery is paused.");
        require(msg.sender == dailyAddress || msg.sender == hourlyAddress, "Can only be called by lottery contract");
        uint256 tSupply = iODINNFT.totalSupply();
        require(tSupply > 1, "Holders are not enough to run lottery");
        uint256 mod = tSupply - 1;

        uint256 rndNum = iVRFV2RandomGeneration.getRandomWords().mod(mod); // uint256(keccak256(abi.encode(block.timestamp, block.difficulty, block.coinbase, blockhash(block.number + 1), seed, block.number))).mod(mod);
        address winner = iODINNFT.ownerOf(rndNum);
        return winner;
    }

    function setWinner() external onlyOwner {
        iVRFV2RandomGeneration.requestRandomWords();
    }
}

// File: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT
// 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;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
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 `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);

    /**
     * @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);
}

// File: @openzeppelin/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (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 Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing 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);
    }
}

// File: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin/contracts/utils/math/SafeMath.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (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 substraction 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;
        }
    }
}

// File: @uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router02.sol



pragma solidity >=0.6.2;

import './IUniswapV2Router01.sol';

interface IUniswapV2Router02 is IUniswapV2Router01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountETH);
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountETH);

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external payable;
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
}

// File: @uniswap/v2-core/contracts/interfaces/IUniswapV2Factory.sol



pragma solidity >=0.5.0;

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    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(uint) external view returns (address pair);
    function allPairsLength() external view returns (uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);

    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
}

// File: @uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router01.sol



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,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB, uint liquidity);
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountToken, uint amountETH);
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountToken, uint amountETH);
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);

    function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
    function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
    function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}