// File: /C/dev/repos/coti-cvix-contracts/contracts/Staking.sol



// SPDX-License-Identifier: GPL-3.0
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router02.sol";
import "./interfaces/IStaking.sol";
import "./interfaces/IFeesCollector.sol";
import "./interfaces/IWETH.sol";

contract Staking is IStaking, IFeesCollector, Ownable {

    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    uint256 public constant PRECISION_DECIMALS = 1e18;

    uint256 public totalStaked;

    IERC20[] private claimableTokens;
    IERC20[] private otherTokens;

	mapping(IERC20 => bool) private claimableTokensSupported;
    mapping(IERC20 => bool) private otherTokensSupported;

	mapping(IERC20 => uint256) public totalProfits;

    mapping(address => mapping(IERC20 => uint256)) private lastProfits;
    mapping(address => mapping(IERC20 => uint256)) private savedProfits;

    mapping(address => uint256) public stakes;
    mapping(address => uint256) public stakeTimestamps;

    IERC20 private immutable cviToken;
    IWETH private immutable wethToken;
    address public immutable fallbackRecipient;

    IUniswapV2Router02 private immutable uniswapRouter;

    uint256 public stakeLockupTime = 1 hours;

	uint256 public creationTimestamp;

    constructor(IERC20 _cviToken, IUniswapV2Router02 _uniswapRouter) public {
    	cviToken = _cviToken;
    	uniswapRouter = _uniswapRouter;
    	wethToken = IWETH(_uniswapRouter.WETH());
    	fallbackRecipient = msg.sender;
		creationTimestamp = block.timestamp;
    }

    receive() external payable override {

    }

    function sendProfit(uint256 _amount, IERC20 _token) external override {
        bool isClaimableToken = claimableTokensSupported[_token];
        bool isOtherToken = otherTokensSupported[_token];
    	require(isClaimableToken || isOtherToken, "Token not supported");

    	if (totalStaked > 0) {
            if (isClaimableToken) {
    		  addProfit(_amount, _token);
            }
    		_token.safeTransferFrom(msg.sender, address(this), _amount);
    	} else {
    		_token.safeTransferFrom(msg.sender, fallbackRecipient, _amount);
    	}
    }

    function stake(uint256 _amount) external override {
    	require(_amount > 0, "Amount must be positive");

    	if (stakes[msg.sender] > 0) {
    		saveProfit(claimableTokens, msg.sender, stakes[msg.sender]);
    	}

    	stakes[msg.sender] = stakes[msg.sender].add(_amount);
    	stakeTimestamps[msg.sender] = block.timestamp;
    	totalStaked = totalStaked.add(_amount);

    	for (uint256 tokenIndex = 0; tokenIndex < claimableTokens.length; tokenIndex = tokenIndex.add(1)) {
    		IERC20 token = claimableTokens[tokenIndex];
	    	lastProfits[msg.sender][token] = totalProfits[token];	    	
	    }

	    cviToken.safeTransferFrom(msg.sender, address(this), _amount);
    }

    function unstake(uint256 _amount) external override {
    	require(_amount > 0, "Amount must be positive");
    	require(_amount <= stakes[msg.sender], "Not enough staked");
    	require(stakeTimestamps[msg.sender].add(stakeLockupTime) <= block.timestamp, "Funds locked");

    	totalStaked = totalStaked.sub(_amount);
    	stakes[msg.sender] = stakes[msg.sender].sub(_amount);
    	saveProfit(claimableTokens, msg.sender, _amount);
    	cviToken.safeTransfer(msg.sender, _amount);
    }

    function claimProfit(IERC20 token) external override returns (uint256 profit) {
    	_saveProfit(token, msg.sender, stakes[msg.sender]);
    	
    	profit = _claimProfit(token);
    	require(profit > 0, "No profit for token");
    }

    function claimAllProfits() external override returns (uint256[] memory) {
        uint256[] memory profits = new uint256[](claimableTokens.length); 
    	saveProfit(claimableTokens, msg.sender, stakes[msg.sender]);

    	uint256 totalProfit = 0;
    	for (uint256 tokenIndex = 0; tokenIndex < claimableTokens.length; tokenIndex++) {
            uint256 currProfit = _claimProfit(claimableTokens[tokenIndex]);
    		profits[tokenIndex] = currProfit;
            totalProfit = totalProfit.add(currProfit);
    	}

    	require(totalProfit > 0, "No profit");

        return profits;
    }

    function addClaimableToken(IERC20 _newClaimableToken) external override onlyOwner {
        _addToken(claimableTokens, claimableTokensSupported, _newClaimableToken);
    }

    function removeClaimableToken(IERC20 _removedClaimableToken) external override onlyOwner {
        _removeToken(claimableTokens, claimableTokensSupported, _removedClaimableToken);
    }

    function addToken(IERC20 _newToken) external override onlyOwner {
        _addToken(otherTokens, otherTokensSupported, _newToken);
        _newToken.safeApprove(address(uniswapRouter), uint256(-1));
    }

    function removeToken(IERC20 _removedToken) external override onlyOwner {
        _removeToken(otherTokens, otherTokensSupported, _removedToken);
        _removedToken.safeApprove(address(uniswapRouter), 0);
    }

    function convertFunds() external override {
        bool didConvert = false;
    	for (uint256 tokenIndex = 0; tokenIndex < otherTokens.length; tokenIndex++) {
    		IERC20 token = otherTokens[tokenIndex];
            uint256 balance = token.balanceOf(address(this));

            if (balance > 0) {
                didConvert = true;

        		address[] memory path = new address[](2);
            	path[0] = address(token);
            	path[1] = address(wethToken);

        		uint256[] memory amounts = 
        			uniswapRouter.swapExactTokensForTokens(token.balanceOf(address(this)), 
        				0, path, address(this), block.timestamp);
                addProfit(amounts[1], IERC20(address(wethToken)));
            }
    	}

        require(didConvert, "No funds to convert");
    }

    function setStakingLockupTime(uint256 _newLockupTime) external override onlyOwner {
        stakeLockupTime = _newLockupTime;
    }

    function profitOf(address _account, IERC20 _token) external view override returns (uint256) {
        return savedProfits[_account][_token].add(unsavedProfit(_account, stakes[_account], _token));
    }

    function getClaimableTokens() external view override returns (IERC20[] memory) {
        return claimableTokens;
    }

    function getOtherTokens() external view override returns (IERC20[] memory) {
        return otherTokens;
    }

    function _claimProfit(IERC20 _token) private returns (uint256 profit) {
    	require(claimableTokensSupported[_token], "Token not supported");
		profit = savedProfits[msg.sender][_token];

		if (profit > 0) {
			savedProfits[msg.sender][_token] = 0;
			lastProfits[msg.sender][_token] = totalProfits[_token];

			if (address(_token) == address(wethToken)) {
				wethToken.withdraw(profit);
                msg.sender.transfer(profit);
			} else {
				_token.safeTransfer(msg.sender, profit);
			}
		}
    }

    function _addToken(IERC20[] storage _tokens, mapping(IERC20 => bool) storage _supportedTokens, IERC20 _newToken) private {
    	require(!_supportedTokens[_newToken], "Token already added");
    	_supportedTokens[_newToken] = true;
    	_tokens.push(_newToken);
    }

    function _removeToken(IERC20[] storage _tokens, mapping(IERC20 => bool) storage _supportedTokens, IERC20 _removedTokenAddress) private {
    	require(_supportedTokens[_removedTokenAddress], "Token not supported");

    	bool isFound = false;
    	for (uint256 tokenIndex = 0; tokenIndex < _tokens.length; tokenIndex = tokenIndex.add(1)) {
    		if (_tokens[tokenIndex] == _removedTokenAddress) {
    			isFound = true;
    			_tokens[tokenIndex] = _tokens[_tokens.length.sub(1)];
    			_tokens.pop();
    			break;
    		}
    	}
    	require(isFound, "Token not found");

    	_supportedTokens[_removedTokenAddress] = false;
    }

    function addProfit(uint256 _amount, IERC20 _token) private {
    	totalProfits[_token] = totalProfits[_token].add(_amount.mul(PRECISION_DECIMALS).div(totalStaked));
    }

    function saveProfit(IERC20[] storage _claimableTokens, address _account, uint256 _amount) private {
    	for (uint256 tokenIndex = 0; tokenIndex < _claimableTokens.length; tokenIndex = tokenIndex.add(1)) {
    		IERC20 token = _claimableTokens[tokenIndex];
    		_saveProfit(token, _account, _amount);
    	}
    }

    function _saveProfit(IERC20 _token, address _account, uint256 _amount) private {
    	savedProfits[_account][_token] = 
    			savedProfits[_account][_token].add(unsavedProfit(_account, _amount, _token));
    }

    function unsavedProfit(address _account, uint256 _amount, IERC20 _token) private view returns (uint256) {
    	return totalProfits[_token].sub(lastProfits[_account][_token]).mul(_amount).div(PRECISION_DECIMALS);
    }
}
// File: /C/dev/repos/coti-cvix-contracts/contracts/interfaces/IFeesCollector.sol



// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.6.2;
pragma experimental ABIEncoderV2;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

interface IFeesCollector {
    function sendProfit(uint256 amount, IERC20 token) external;
}

// File: /C/dev/repos/coti-cvix-contracts/contracts/interfaces/IStaking.sol



// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.6.2;
pragma experimental ABIEncoderV2;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

interface IStaking {
	function stake(uint256 amount) external;
	function unstake(uint256 amount) external;

    function claimProfit(IERC20 token) external returns (uint256);
    function claimAllProfits() external returns (uint256[] memory profits);

    function addClaimableToken(IERC20 newClaimableToken) external;
    function removeClaimableToken(IERC20 removedClaimableToken) external;

    function addToken(IERC20 newToken) external;
    function removeToken(IERC20 removedToken) external;

    function convertFunds() external;

    function setStakingLockupTime(uint256 newLockupTime) external;

    function profitOf(address account, IERC20 token) external view returns (uint256);

    function getClaimableTokens() external view returns (IERC20[] memory);
    function getOtherTokens() external view returns (IERC20[] memory);

    receive() external payable;
}

// File: /C/dev/repos/coti-cvix-contracts/contracts/interfaces/IWETH.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.6.2;

interface IWETH {
    function deposit() external payable;
    function withdraw(uint256) external;
}
// File: @openzeppelin/contracts/GSN/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

/*
 * @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 GSN 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 payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

import "../GSN/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.
 */
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 () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view 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 {
        emit OwnershipTransferred(_owner, address(0));
        _owner = 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");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

/**
 * @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) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        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;
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

/**
 * @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 `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);
}

// File: @openzeppelin/contracts/token/ERC20/SafeERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

import "./IERC20.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.6.2;

/**
 * @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
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies in extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 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");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (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");
        return _functionCallWithValue(target, data, value, errorMessage);
    }

    function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
        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

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// 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);
}

// 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;
}