// File: contracts/Zap.sol



pragma solidity 0.6.11;

import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import {SafeERC20, SafeMath} from "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";

contract Zap {
    using SafeMath for uint;
    using SafeERC20 for IERC20;
    using SafeERC20 for IbDUSD;

    uint constant N_COINS = 4;
    string constant ERR_SLIPPAGE = "ERR_SLIPPAGE";

    ICurveDeposit immutable yDeposit;
    ICurve immutable ySwap;
    IERC20 immutable yCrv;
    IERC20 immutable dusd;
    IbDUSD immutable ibdusd;
    IYVaultPeak immutable yVaultPeak;

    address[N_COINS] coins;
    address[N_COINS] underlyingCoins;
    uint[N_COINS] ZEROES = [uint(0),uint(0),uint(0),uint(0)];

    constructor(
        ICurveDeposit _yDeposit,
        ICurve _ySwap,
        IERC20 _yCrv,
        IERC20 _dusd,
        IbDUSD _ibdusd,
        IYVaultPeak _yVaultPeak,
        address[N_COINS] memory _underlyingCoins,
        address[N_COINS] memory _coins
    ) public {
        yDeposit = _yDeposit;
        ySwap = _ySwap;
        yCrv = _yCrv;
        dusd = _dusd;
        ibdusd = _ibdusd;
        yVaultPeak = _yVaultPeak;
        underlyingCoins = _underlyingCoins;
        coins = _coins;
    }

    /**
    * @notice Mint DUSD
    * @param inAmounts Exact inAmounts in the same order as required by the curve pool
    * @param minDusdAmount Minimum DUSD to mint, used for capping slippage
    */
    function mint(uint[N_COINS] memory inAmounts, uint minDusdAmount)
        public
        returns (uint dusdAmount)
    {
        dusdAmount = _mint(inAmounts, minDusdAmount);
        dusd.safeTransfer(msg.sender, dusdAmount);
    }

    function _mint(uint[N_COINS] memory inAmounts, uint minDusdAmount)
        internal
        returns (uint dusdAmount)
    {
        address[N_COINS] memory _coins = underlyingCoins;
        for (uint i = 0; i < N_COINS; i++) {
            if (inAmounts[i] > 0) {
                IERC20(_coins[i]).safeTransferFrom(msg.sender, address(this), inAmounts[i]);
                IERC20(_coins[i]).safeApprove(address(yDeposit), inAmounts[i]);
            }
        }
        yDeposit.add_liquidity(inAmounts, 0);
        uint inAmount = yCrv.balanceOf(address(this));
        yCrv.safeApprove(address(yVaultPeak), 0);
        yCrv.safeApprove(address(yVaultPeak), inAmount);
        dusdAmount = yVaultPeak.mintWithYcrv(inAmount);
        require(dusdAmount >= minDusdAmount, ERR_SLIPPAGE);
    }

    function calcMint(uint[N_COINS] memory inAmounts)
        public
        view
        returns (uint dusdAmount)
    {
        for(uint i = 0; i < N_COINS; i++) {
            inAmounts[i] = inAmounts[i].mul(1e18).div(yERC20(coins[i]).getPricePerFullShare());
        }
        uint _yCrv = ySwap.calc_token_amount(inAmounts, true /* deposit */);
        return yVaultPeak.calcMintWithYcrv(_yCrv);
    }

    /**
    * @dev Redeem DUSD
    * @param dusdAmount Exact dusdAmount to burn
    * @param minAmounts Min expected amounts to cap slippage
    */
    function redeem(uint dusdAmount, uint[N_COINS] memory minAmounts)
        public
    {
        redeemTo(dusdAmount, minAmounts, msg.sender);
    }

    function redeemTo(uint dusdAmount, uint[N_COINS] memory minAmounts, address destination)
        public
    {
        dusd.safeTransferFrom(msg.sender, address(this), dusdAmount);
        _redeemTo(dusdAmount, minAmounts, destination);
    }

    function _redeemTo(uint dusdAmount, uint[N_COINS] memory minAmounts, address destination)
        internal
    {
        uint r = yVaultPeak.redeemInYcrv(dusdAmount, 0);
        yCrv.safeApprove(address(yDeposit), r);
        yDeposit.remove_liquidity(r, ZEROES);
        address[N_COINS] memory _coins = underlyingCoins;
        uint toTransfer;
        for (uint i = 0; i < N_COINS; i++) {
            toTransfer = IERC20(_coins[i]).balanceOf(address(this));
            if (toTransfer > 0) {
                require(toTransfer >= minAmounts[i], ERR_SLIPPAGE);
                IERC20(_coins[i]).safeTransfer(destination, toTransfer);
            }
        }
    }

    function calcRedeem(uint dusdAmount)
        public view
        returns (uint[N_COINS] memory amounts)
    {
        uint _yCrv = yVaultPeak.calcRedeemInYcrv(dusdAmount);
        uint totalSupply = yCrv.totalSupply();
        for(uint i = 0; i < N_COINS; i++) {
            amounts[i] = ySwap.balances(int128(i))
                .mul(_yCrv)
                .div(totalSupply)
                .mul(yERC20(coins[i]).getPricePerFullShare())
                .div(1e18);
        }
    }

    function redeemInSingleCoin(uint dusdAmount, uint i, uint minOut)
        public
        returns (uint amount)
    {
        return redeemInSingleCoinTo(dusdAmount, i, minOut, msg.sender);
    }

    function redeemInSingleCoinTo(uint dusdAmount, uint i, uint minOut, address destination)
        public
        returns (uint)
    {
        dusd.safeTransferFrom(msg.sender, address(this), dusdAmount);
        return _redeemInSingleCoinTo(dusdAmount, i, minOut, destination);
    }

    function _redeemInSingleCoinTo(uint dusdAmount, uint i, uint minOut, address destination)
        internal
        returns (uint amount)
    {
        uint r = yVaultPeak.redeemInYcrv(dusdAmount, 0);
        yCrv.safeApprove(address(yDeposit), r);
        yDeposit.remove_liquidity_one_coin(r, int128(i), minOut); // checks for slippage
        IERC20 coin = IERC20(underlyingCoins[i]);
        amount = coin.balanceOf(address(this));
        coin.safeTransfer(destination, amount);
    }

    function calcRedeemInSingleCoin(uint dusdAmount, uint i)
        public view
        returns(uint)
    {
        uint _yCrv = yVaultPeak.calcRedeemInYcrv(dusdAmount);
        return yDeposit.calc_withdraw_one_coin(_yCrv, int128(i));
    }

    function deposit(uint[N_COINS] calldata inAmounts, uint minDusdAmount)
        external
        returns (uint dusdAmount)
    {
        dusdAmount = _mint(inAmounts, minDusdAmount);
        dusd.safeApprove(address(ibdusd), dusdAmount);
        ibdusd.deposit(dusdAmount);
        ibdusd.safeTransfer(msg.sender, ibdusd.balanceOf(address(this)));
    }

    function withdraw(uint shares, uint i, uint minOut)
        external
        returns (uint)
    {
        ibdusd.safeTransferFrom(msg.sender, address(this), shares);
        ibdusd.withdraw(shares);
        return _redeemInSingleCoinTo(
            dusd.balanceOf(address(this)),
            i,
            minOut,
            msg.sender
        );
    }

    function withdrawInAll(uint shares, uint[N_COINS] calldata minAmounts)
        external
    {
        ibdusd.safeTransferFrom(msg.sender, address(this), shares);
        ibdusd.withdraw(shares);
        _redeemTo(
            dusd.balanceOf(address(this)),
            minAmounts,
            msg.sender
        );
    }
}

interface IYVaultPeak {
    function mintWithYcrv(uint inAmount) external returns(uint dusdAmount);
    function calcMintWithYcrv(uint inAmount) external view returns (uint dusdAmount);
    function redeemInYcrv(uint dusdAmount, uint minOut) external returns(uint _yCrv);
    function calcRedeemInYcrv(uint dusdAmount) external view returns (uint _yCrv);
}

interface yERC20 {
    function getPricePerFullShare() external view returns(uint);
}

interface ICurveDeposit {
    function add_liquidity(uint[4] calldata uamounts, uint min_mint_amount) external;
    function remove_liquidity(uint amount, uint[4] calldata min_uamounts) external;
    function remove_liquidity_imbalance(uint[4] calldata uamounts, uint max_burn_amount) external;
    function remove_liquidity_one_coin(uint _token_amount, int128 i, uint min_uamount) external;
    function calc_withdraw_one_coin(uint _token_amount, int128 i) external view returns(uint);
}

interface ICurve {
    function add_liquidity(uint[4] calldata uamounts, uint min_mint_amount) external;
    function remove_liquidity_imbalance(uint[4] calldata uamounts, uint max_burn_amount) external;
    function remove_liquidity(uint amount, uint[4] calldata min_amounts) external;
    function calc_token_amount(uint[4] calldata inAmounts, bool deposit) external view returns(uint);
    function balances(int128 i) external view returns(uint);
    function get_virtual_price() external view returns(uint);
    function exchange(int128 i, int128 j, uint256 dx, uint256 min_dy) external;
}

interface IbDUSD is IERC20 {
    function deposit(uint) external;
    function withdraw(uint) external;
    function getPricePerFullShare() external view returns (uint);
    function balance() external view returns (uint);
}


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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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 `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 <0.8.0;

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/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @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 >=0.6.2 <0.8.0;

/**
 * @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);
            }
        }
    }
}