// File: contracts/zap/AladdinConvexVaultZap.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.6;
pragma abicoder v2;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";

import "../interfaces/IZap.sol";
import "../interfaces/IConvexCRVDepositor.sol";
import "../interfaces/ICurve3Pool.sol";
import "../interfaces/ICurveFactoryPool.sol";
import "../interfaces/ICurveTriCrypto.sol";
import "../interfaces/ICurveV2Pool.sol";
import "../interfaces/IUniswapV2Pair.sol";
import "../interfaces/IUniswapV3Pool.sol";
import "../interfaces/IUniswapV3Router.sol";
import "../interfaces/IWETH.sol";

// solhint-disable reason-string

/// @dev This is a general zap contract for AladdinConvexVault,
///      everything will zip into ETH or CRV and send back to caller.
contract AladdinConvexVaultZap is Ownable, IZap {
  using SafeERC20 for IERC20;

  event UpdateRoute(address indexed _fromToken, address indexed _toToken, uint256[] route);

  // The address of CRV token.
  address private constant CRV = 0xD533a949740bb3306d119CC777fa900bA034cd52;
  // The address of WETH token.
  address private constant WETH = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
  // The address of Uniswap V3 Router
  address private constant UNIV3_ROUTER = 0xE592427A0AEce92De3Edee1F18E0157C05861564;

  /// @dev This is the list of routes
  /// encoding for single route
  /// |   160 bits   |   4 bits  |  2 bits  |   2 bits  |
  /// | pool address | pool type | index in | index out |
  ///
  /// pool type:
  ///  0: Uniswap V2 like Pair, with fee 0.3%
  ///  1: Uniswap V3 Pair
  ///  2: Curve3Pool
  ///  3: CurveTriCrypto
  ///  4: CurveV2Pool
  ///  5: CurveFactoryPool
  mapping(address => mapping(address => uint256[])) public routes;

  /********************************** Mutated Functions **********************************/

  function zap(
    address _fromToken,
    uint256 _amountIn,
    address _toToken,
    uint256 _minOut
  ) external payable override returns (uint256) {
    require(_toToken == WETH || _toToken == CRV, "AladdinConvexVaultZap: toToken unsupported");

    uint256[] memory _routes = routes[_fromToken][_toToken];
    require(_routes.length > 0, "AladdinConvexVaultZap: route unavailable");

    uint256 _amount = _amountIn;
    for (uint256 i = 0; i < _routes.length; i++) {
      _amount = _swap(_routes[i], _amount);
    }
    require(_amount >= _minOut, "AladdinConvexVaultZap: insufficient output");
    if (_toToken == WETH) {
      _unwrapIfNeeded(_amount);
      // solhint-disable-next-line avoid-low-level-calls
      (bool success, ) = msg.sender.call{ value: _amount }("");
      require(success, "AladdinConvexVaultZap: ETH transfer failed");
    } else {
      IERC20(CRV).safeTransfer(msg.sender, _amount);
    }
    return _amount;
  }

  /********************************** Restricted Functions **********************************/

  function updateRoute(
    address _fromToken,
    address _toToken,
    uint256[] memory route
  ) external onlyOwner {
    delete routes[_fromToken][_toToken];

    routes[_fromToken][_toToken] = route;

    emit UpdateRoute(_fromToken, _toToken, route);
  }

  /********************************** Internal Functions **********************************/
  function _swap(uint256 _route, uint256 _amountIn) internal returns (uint256) {
    address _pool = address(_route & uint256(1461501637330902918203684832716283019655932542975));
    uint256 _poolType = (_route >> 160) & 15;
    uint256 _indexIn = (_route >> 164) & 3;
    uint256 _indexOut = (_route >> 166) & 3;
    if (_poolType == 0) {
      return _swapUniswapV2Pair(_pool, _indexIn, _indexOut, _amountIn);
    } else if (_poolType == 1) {
      return _swapUniswapV3Pool(_pool, _indexIn, _indexOut, _amountIn);
    } else if (_poolType == 2) {
      return _swapCurve3Pool(_pool, _indexIn, _indexOut, _amountIn);
    } else if (_poolType == 3) {
      return _swapTriCryptoPool(_pool, _indexIn, _indexOut, _amountIn);
    } else if (_poolType == 4) {
      return _swapCurveV2Pool(_pool, _indexIn, _indexOut, _amountIn);
    } else if (_poolType == 5) {
      return _swapCurveFactoryPool(_pool, _indexIn, _indexOut, _amountIn);
    } else {
      revert("AladdinConvexVaultZap: invalid poolType");
    }
  }

  function _swapUniswapV2Pair(
    address _pool,
    uint256 _indexIn,
    uint256 _indexOut,
    uint256 _amountIn
  ) internal returns (uint256) {
    uint256 _rIn;
    uint256 _rOut;
    address _tokenIn;
    if (_indexIn < _indexOut) {
      (_rIn, _rOut, ) = IUniswapV2Pair(_pool).getReserves();
      _tokenIn = IUniswapV2Pair(_pool).token0();
    } else {
      (_rOut, _rIn, ) = IUniswapV2Pair(_pool).getReserves();
      _tokenIn = IUniswapV2Pair(_pool).token1();
    }
    // TODO: handle fee on transfer token
    uint256 _amountOut = _amountIn * 997;
    _amountOut = (_amountOut * _rOut) / (_rIn * 1000 + _amountOut);

    _wrapTokenIfNeeded(_tokenIn, _amountIn);
    IERC20(_tokenIn).safeTransfer(_pool, _amountIn);
    if (_indexIn < _indexOut) {
      IUniswapV2Pair(_pool).swap(0, _amountOut, address(this), new bytes(0));
    } else {
      IUniswapV2Pair(_pool).swap(_amountOut, 0, address(this), new bytes(0));
    }
    return _amountOut;
  }

  function _swapUniswapV3Pool(
    address _pool,
    uint256 _indexIn,
    uint256 _indexOut,
    uint256 _amountIn
  ) internal returns (uint256) {
    address _tokenIn;
    address _tokenOut;
    uint24 _fee = IUniswapV3Pool(_pool).fee();
    if (_indexIn < _indexOut) {
      _tokenIn = IUniswapV3Pool(_pool).token0();
      _tokenOut = IUniswapV3Pool(_pool).token1();
    } else {
      _tokenIn = IUniswapV3Pool(_pool).token1();
      _tokenOut = IUniswapV3Pool(_pool).token0();
    }
    _wrapTokenIfNeeded(_tokenIn, _amountIn);
    _approve(_tokenIn, UNIV3_ROUTER, _amountIn);
    IUniswapV3Router.ExactInputSingleParams memory _params = IUniswapV3Router.ExactInputSingleParams(
      _tokenIn,
      _tokenOut,
      _fee,
      address(this),
      // solhint-disable-next-line not-rely-on-time
      block.timestamp + 1,
      _amountIn,
      1,
      0
    );
    return IUniswapV3Router(UNIV3_ROUTER).exactInputSingle(_params);
  }

  function _swapCurve3Pool(
    address _pool,
    uint256 _indexIn,
    uint256 _indexOut,
    uint256 _amountIn
  ) internal returns (uint256) {
    address _tokenIn = ICurve3Pool(_pool).coins(_indexIn);
    address _tokenOut = ICurve3Pool(_pool).coins(_indexOut);

    _wrapTokenIfNeeded(_tokenIn, _amountIn);
    _approve(_tokenIn, _pool, _amountIn);

    uint256 _before = IERC20(_tokenOut).balanceOf(address(this));
    ICurve3Pool(_pool).exchange(int128(_indexIn), int128(_indexOut), _amountIn, 0);
    return IERC20(_tokenOut).balanceOf(address(this)) - _before;
  }

  function _swapTriCryptoPool(
    address _pool,
    uint256 _indexIn,
    uint256 _indexOut,
    uint256 _amountIn
  ) internal returns (uint256) {
    address _tokenIn = ICurveTriCrypto(_pool).coins(_indexIn);
    address _tokenOut = ICurveTriCrypto(_pool).coins(_indexOut);

    _wrapTokenIfNeeded(_tokenIn, _amountIn);
    _approve(_tokenIn, _pool, _amountIn);

    uint256 _before = IERC20(_tokenOut).balanceOf(address(this));
    ICurveTriCrypto(_pool).exchange(_indexIn, _indexOut, _amountIn, 0, false);
    return IERC20(_tokenOut).balanceOf(address(this)) - _before;
  }

  function _swapCurveV2Pool(
    address _pool,
    uint256 _indexIn,
    uint256 _indexOut,
    uint256 _amountIn
  ) internal returns (uint256) {
    address _tokenIn = ICurveV2Pool(_pool).coins(_indexIn);

    _wrapTokenIfNeeded(_tokenIn, _amountIn);
    _approve(_tokenIn, _pool, _amountIn);

    return ICurveV2Pool(_pool).exchange(_indexIn, _indexOut, _amountIn, 0, false);
  }

  function _swapCurveFactoryPool(
    address _pool,
    uint256 _indexIn,
    uint256 _indexOut,
    uint256 _amountIn
  ) internal returns (uint256) {
    address _tokenIn = ICurveFactoryPool(_pool).coins(_indexIn);

    _wrapTokenIfNeeded(_tokenIn, _amountIn);
    _approve(_tokenIn, _pool, _amountIn);

    return ICurveFactoryPool(_pool).exchange(int128(_indexIn), int128(_indexOut), _amountIn, 0, address(this));
  }

  function _wrapTokenIfNeeded(address _token, uint256 _amount) internal {
    if (_token == WETH && IERC20(_token).balanceOf(address(this)) < _amount) {
      IWETH(WETH).deposit{ value: _amount }();
    }
  }

  function _unwrapIfNeeded(uint256 _amount) internal {
    if (address(this).balance < _amount) {
      IWETH(WETH).withdraw(_amount);
    }
  }

  function _approve(
    address _token,
    address _spender,
    uint256 _amount
  ) internal {
    if (IERC20(_token).allowance(address(this), _spender) < _amount) {
      IERC20(_token).safeApprove(_spender, 0);
      IERC20(_token).safeApprove(_spender, _amount);
    }
  }

  // solhint-disable-next-line no-empty-blocks
  receive() external payable {}
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

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 () {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), 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 {
        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/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @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 ^0.7.0;

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: contracts/interfaces/IZap.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.6;

interface IZap {
  function zap(
    address _fromToken,
    uint256 _amountIn,
    address _toToken,
    uint256 _minOut
  ) external payable returns (uint256);
}

// File: contracts/interfaces/IConvexCRVDepositor.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.6;

interface IConvexCRVDepositor {
  function deposit(
    uint256 _amount,
    bool _lock,
    address _stakeAddress
  ) external;

  function deposit(uint256 _amount, bool _lock) external;

  function lockIncentive() external view returns (uint256);
}

// File: contracts/interfaces/ICurve3Pool.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.6;

// solhint-disable var-name-mixedcase, func-name-mixedcase
interface ICurve3Pool {
  function remove_liquidity_one_coin(
    uint256 token_amount,
    int128 i,
    uint256 min_amount
  ) external;

  function calc_withdraw_one_coin(uint256 _token_amount, int128 i) external view returns (uint256);

  function exchange(
    int128 i,
    int128 j,
    uint256 dx,
    uint256 min_dy
  ) external;

  function coins(uint256 index) external returns (address);
}

// File: contracts/interfaces/ICurveFactoryPool.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.6;

// solhint-disable var-name-mixedcase, func-name-mixedcase
interface ICurveFactoryPool {
  function get_dy(
    int128 i,
    int128 j,
    uint256 dx
  ) external view returns (uint256);

  function exchange(
    int128 i,
    int128 j,
    uint256 _dx,
    uint256 _min_dy,
    address _receiver
  ) external returns (uint256);

  function coins(uint256 index) external returns (address);
}

// File: contracts/interfaces/ICurveTriCrypto.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.6;

// solhint-disable var-name-mixedcase, func-name-mixedcase
interface ICurveTriCrypto {
  function exchange(
    uint256 i,
    uint256 j,
    uint256 dx,
    uint256 min_dy,
    bool use_eth
  ) external;

  function get_dy(
    uint256 i,
    uint256 j,
    uint256 dx
  ) external view returns (uint256);

  function coins(uint256 index) external returns (address);
}

// File: contracts/interfaces/ICurveV2Pool.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.6;

// solhint-disable var-name-mixedcase, func-name-mixedcase
interface ICurveV2Pool {
  function get_dy(
    uint256 i,
    uint256 j,
    uint256 dx
  ) external view returns (uint256);

  function coins(uint256 index) external returns (address);

  function exchange(
    uint256 i,
    uint256 j,
    uint256 dx,
    uint256 min_dy,
    bool use_eth
  ) external payable returns (uint256);

  function exchange_underlying(
    uint256 i,
    uint256 j,
    uint256 dx,
    uint256 min_dy
  ) external payable returns (uint256);
}

// File: contracts/interfaces/IUniswapV2Pair.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.6;

interface IUniswapV2Pair {
  function token0() external returns (address);

  function token1() external returns (address);

  function getReserves()
    external
    view
    returns (
      uint112 _reserve0,
      uint112 _reserve1,
      uint32 _blockTimestampLast
    );

  function swap(
    uint256 amount0Out,
    uint256 amount1Out,
    address to,
    bytes calldata data
  ) external;
}

// File: contracts/interfaces/IUniswapV3Pool.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.6;

interface IUniswapV3Pool {
  function token0() external returns (address);

  function token1() external returns (address);

  function fee() external returns (uint24);
}

// File: contracts/interfaces/IUniswapV3Router.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.6;
pragma abicoder v2;

interface IUniswapV3Router {
  struct ExactInputSingleParams {
    address tokenIn;
    address tokenOut;
    uint24 fee;
    address recipient;
    uint256 deadline;
    uint256 amountIn;
    uint256 amountOutMinimum;
    uint160 sqrtPriceLimitX96;
  }

  function exactInputSingle(ExactInputSingleParams calldata params) external returns (uint256 amountOut);
}

// File: contracts/interfaces/IWETH.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.6;

interface IWETH {
  function deposit() external payable;

  function withdraw(uint256 wad) external;
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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 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/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @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, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        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) {
        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) {
        // 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) {
        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) {
        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) {
        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) {
        require(b <= a, "SafeMath: subtraction overflow");
        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) {
        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, reverting 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) {
        require(b > 0, "SafeMath: division by zero");
        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) {
        require(b > 0, "SafeMath: modulo by zero");
        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) {
        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.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * 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);
        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) {
        require(b > 0, errorMessage);
        return a % b;
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @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 on 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");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private 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

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