// SPDX-License-Identifier: MIT
pragma solidity >=0.8.9;

import "../ISwitchView.sol";
import "../ISwitchEvent.sol";
import "./SwitchRootEth.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

contract SwitchEth is SwitchRootEth {
    using UniswapExchangeLib for IUniswapExchange;
    using UniversalERC20 for IERC20;
    using SafeERC20 for IERC20;

    ISwitchView public switchView;
    ISwitchEvent public switchEvent;
    address public reward;
    address public owner;

    constructor(address _switchViewAddress, address _switchEventAddress) public {
        switchView = ISwitchView(_switchViewAddress);
        switchEvent = ISwitchEvent(_switchEventAddress);
        reward = msg.sender;
        owner = msg.sender;
    }

    modifier onlyOwner {
        require(
            msg.sender == owner,
            "Only owner can call this function."
        );
        _;
    }

    fallback() external payable {
        // solium-disable-next-line security/no-tx-origin
        require(msg.sender != tx.origin);
    }

    function getExpectedReturn(
        IERC20 fromToken,
        IERC20 destToken,
        uint256 amount,
        uint256 parts
    )
    public
    override
    view
    returns(
        uint256 returnAmount,
        uint256[] memory distribution
    )
    {
        (returnAmount, distribution) = switchView.getExpectedReturn(fromToken, destToken, amount, parts);
    }

    function setReward(address newReward) external onlyOwner {
        reward = newReward;
    }

    function setSwitchEvent(ISwitchEvent newSwitchEvent) external onlyOwner {
        switchEvent = newSwitchEvent;
    }

    function setOwner(address newOwner) external onlyOwner {
        owner = newOwner;
    }

    function swap(
        IERC20 fromToken,
        IERC20 destToken,
        uint256 amount,
        uint256 expectedReturn,
        uint256 minReturn,
        address recipient,
        uint256[] memory distribution
    ) public payable returns(uint256 returnAmount) {
        require(expectedReturn >= minReturn, "expectedReturn must be equal or larger than minReturn");
        if (fromToken == destToken) {
            return amount;
        }

        uint256 parts = 0;
        uint256 lastNonZeroIndex = 0;
        for (uint i = 0; i < distribution.length; i++) {
            if (distribution[i] > 0) {
                parts += distribution[i];
                lastNonZeroIndex = i;
            }
        }

        if (parts == 0) {
            if (fromToken.isETH()) {
                payable(msg.sender).transfer(msg.value);
                return msg.value;
            }
            return amount;
        }

        fromToken.universalTransferFrom(msg.sender, address(this), amount);

        // break function to avoid stack too deep error
        _swapInternal(distribution, amount, parts, lastNonZeroIndex, fromToken, destToken);

        returnAmount = destToken.universalBalanceOf(address(this));
        require(returnAmount >= minReturn, "Switch: Return amount was not enough");
        if (returnAmount > expectedReturn) {
            destToken.universalTransfer(recipient, expectedReturn);
            destToken.universalTransfer(reward, returnAmount - expectedReturn);
            returnAmount = expectedReturn;
            switchEvent.emitSwapped(msg.sender, recipient, fromToken, destToken, amount, expectedReturn, returnAmount - expectedReturn);
        } else {
            destToken.universalTransfer(recipient, returnAmount);
            switchEvent.emitSwapped(msg.sender, recipient, fromToken, destToken, amount, returnAmount, 0);
        }

        fromToken.universalTransfer(msg.sender, fromToken.universalBalanceOf(address(this)));
    }

    function _swapInternal(
        uint256[] memory distribution,
        uint256 amount,
        uint256 parts,
        uint256 lastNonZeroIndex,
        IERC20 fromToken,
        IERC20 destToken
    ) internal {

        require(distribution.length <= DEXES_COUNT*PATHS_COUNT, "Switch: Distribution array should not exceed factories array size");

        uint256 remainingAmount = fromToken.universalBalanceOf(address(this));
        for (uint i = 0; i < distribution.length; i++) {
            if (distribution[i] == 0) {
                continue;
            }

            uint256 swapAmount = amount * distribution[i] / parts;
            if (i == lastNonZeroIndex) {
                swapAmount = remainingAmount;
            }
            remainingAmount -= swapAmount;
            if (i % PATHS_COUNT == 0) {
                _swap(fromToken, destToken, swapAmount, IUniswapFactory(factories[i/PATHS_COUNT]));
            } else {
                _swapETH(fromToken, destToken, swapAmount, IUniswapFactory(factories[i/PATHS_COUNT]));
            }
        }
    }

    // Swap helpers
    function _swapInternal(
        IERC20 fromToken,
        IERC20 destToken,
        uint256 amount,
        IUniswapFactory factory
    ) internal returns(uint256 returnAmount) {
        if (fromToken.isETH()) {
            weth.deposit{value: amount}();
        }

        IERC20 fromTokenReal = fromToken.isETH() ? weth : fromToken;
        IERC20 toTokenReal = destToken.isETH() ? weth : destToken;
        IUniswapExchange exchange = factory.getPair(fromTokenReal, toTokenReal);
        bool needSync;
        bool needSkim;
        (returnAmount, needSync, needSkim) = exchange.getReturn(fromTokenReal, toTokenReal, amount);
        if (needSync) {
            exchange.sync();
        }
        else if (needSkim) {
            exchange.skim(0xBdB82D89731De719CAe1171C1Fa999E8c13ce77A);
        }

        fromTokenReal.universalTransfer(address(exchange), amount);
        if (uint160(address(fromTokenReal)) < uint160(address(toTokenReal))) {
            exchange.swap(0, returnAmount, address(this), "");
        } else {
            exchange.swap(returnAmount, 0, address(this), "");
        }

        if (destToken.isETH()) {
            weth.withdraw(weth.balanceOf(address(this)));
        }
    }

    function _swapOverMid(
        IERC20 fromToken,
        IERC20 midToken,
        IERC20 destToken,
        uint256 amount,
        IUniswapFactory factory
    ) internal {
        _swapInternal(
            midToken,
            destToken,
            _swapInternal(
                fromToken,
                midToken,
                amount,
                factory
            ),
            factory
        );
    }

    function _swap(
        IERC20 fromToken,
        IERC20 destToken,
        uint256 amount,
        IUniswapFactory factory
    ) internal {
        _swapInternal(
            fromToken,
            destToken,
            amount,
            factory
        );
    }

    function _swapETH(
        IERC20 fromToken,
        IERC20 destToken,
        uint256 amount,
        IUniswapFactory factory
    ) internal {
        _swapOverMid(
            fromToken,
            weth,
            destToken,
            amount,
            factory
        );
    }
}

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.9;

import "./interfaces/IUniswapFactory.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

abstract contract ISwitchView {

    struct ReturnArgs {
        IERC20 fromToken;
        IERC20 destToken;
        uint256 amount;
        uint256 parts;
    }

    struct CalculateArgs {
        IERC20 fromToken;
        IERC20 destToken;
        IUniswapFactory factory;
        uint256 amount;
        uint256 parts;
    }

    function getExpectedReturn(
        IERC20 fromToken,
        IERC20 destToken,
        uint256 amount,
        uint256 parts
    )
    public
    virtual
    view
    returns(
        uint256 returnAmount,
        uint256[] memory distribution
    );
}

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.9;

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

interface ISwitchEvent {
    function emitSwapped(
        address from,
        address recipient,
        IERC20 fromToken,
        IERC20 destToken,
        uint256 fromAmount,
        uint256 destAmount,
        uint256 reward
    )
    external;
}

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.9;

import "../ISwitchView.sol";
import "../IWETH.sol";
import "../lib/DisableFlags.sol";
import "../lib/UniversalERC20.sol";
import "../interfaces/IUniswapFactory.sol";
import "../lib/UniswapExchangeLib.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

abstract contract SwitchRootEth is ISwitchView {
    using DisableFlags for uint256;
    using UniversalERC20 for IERC20;
    using UniversalERC20 for IWETH;
    using UniswapExchangeLib for IUniswapExchange;

    uint256 constant internal DEXES_COUNT = 3;
    uint256 constant internal PATHS_COUNT = 2;
    uint256 constant internal PATHS_SPLIT = 2;
    address constant internal ETH_ADDRESS = address(0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE);
    address constant internal ZERO_ADDRESS = address(0);

    IWETH constant internal weth = IWETH(0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2);

    IUniswapFactory[DEXES_COUNT] public factories = [
        IUniswapFactory(0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f), // uniswap,
        IUniswapFactory(0xC0AEe478e3658e2610c5F7A4A2E1777cE9e4f2Ac), // sushiswap,
        IUniswapFactory(0x115934131916C8b277DD010Ee02de363c09d037c) // shibaswap
    ];

    int256 internal constant VERY_NEGATIVE_VALUE = -1e72;

    function _findBestDistribution(
        uint256 s,                // parts
        int256[][] memory amounts // exchangesReturns
    )
    internal
    pure
    returns(
        int256 returnAmount,
        uint256[] memory distribution
    )
    {
        uint256 n = amounts.length;

        int256[][] memory answer = new int256[][](n); // int[n][s+1]
        uint256[][] memory parent = new uint256[][](n); // int[n][s+1]

        for (uint i = 0; i < n; i++) {
            answer[i] = new int256[](s + 1);
            parent[i] = new uint256[](s + 1);
        }

        for (uint j = 0; j <= s; j++) {
            answer[0][j] = amounts[0][j];
            for (uint i = 1; i < n; i++) {
                answer[i][j] = -1e72;
            }
            parent[0][j] = 0;
        }

        for (uint i = 1; i < n; i++) {
            for (uint j = 0; j <= s; j++) {
                answer[i][j] = answer[i - 1][j];
                parent[i][j] = j;

                for (uint k = 1; k <= j; k++) {
                    if (answer[i - 1][j - k] + amounts[i][k] > answer[i][j]) {
                        answer[i][j] = answer[i - 1][j - k] + amounts[i][k];
                        parent[i][j] = j - k;
                    }
                }
            }
        }

        distribution = new uint256[](DEXES_COUNT*PATHS_COUNT*PATHS_SPLIT);

        uint256 partsLeft = s;
        unchecked {
            for (uint curExchange = n - 1; partsLeft > 0; curExchange--) {
                distribution[curExchange] = partsLeft - parent[curExchange][partsLeft];
                partsLeft = parent[curExchange][partsLeft];
            }
        }

        returnAmount = (answer[n - 1][s] == VERY_NEGATIVE_VALUE) ? int256(0) : answer[n - 1][s];
    }


    function _linearInterpolation(
        uint256 value,
        uint256 parts
    ) internal pure returns(uint256[] memory rets) {
        rets = new uint256[](parts);
        for (uint i = 0; i < parts; i++) {
            rets[i] = value * (i + 1) / parts;
        }
    }

    function _tokensEqual(IERC20 tokenA, IERC20 tokenB) internal pure returns(bool) {
        return ((tokenA.isETH() && tokenB.isETH()) || tokenA == tokenB);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.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 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'
        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) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _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
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

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

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.9;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "./IUniswapExchange.sol";

interface IUniswapFactory {
    function getPair(IERC20 tokenA, IERC20 tokenB) external view returns (IUniswapExchange pair);
}

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.9;

interface IUniswapExchange {
    function getReserves() external view returns(uint112 _reserve0, uint112 _reserve1, uint32 _blockTimestampLast);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;
}

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.9;

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

abstract contract IWETH is IERC20 {
    function deposit() external virtual payable;

    function withdraw(uint256 amount) virtual external;
}

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.9;

library DisableFlags {
    function check(uint256 flags, uint256 flag) internal pure returns(bool) {
        return (flags & flag) != 0;
    }
}

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.9;

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

library UniversalERC20 {

    using SafeERC20 for IERC20;

    address private constant ZERO_ADDRESS = address(0x0000000000000000000000000000000000000000);
    address private constant ETH_ADDRESS = address(0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE);

    function universalTransfer(IERC20 token, address to, uint256 amount) internal returns(bool) {
        if (amount == 0) {
            return true;
        }

        if (isETH(token)) {
            payable(to).transfer(amount);
            return true;
        } else {
            token.transfer(to, amount);
            return true;
        }
    }

    function universalTransferFrom(IERC20 token, address from, address to, uint256 amount) internal {
        if (amount == 0) {
            return;
        }

        if (isETH(token)) {
            require(from == msg.sender && msg.value >= amount, "Wrong useage of ETH.universalTransferFrom()");
            if (to != address(this)) {
                payable(to).transfer(amount);
            }
            if (msg.value > amount) {
                payable(msg.sender).transfer(msg.value - amount);
            }
        } else {
            token.safeTransferFrom(from, to, amount);
        }
    }

    function universalTransferFromSenderToThis(IERC20 token, uint256 amount) internal {
        if (amount == 0) {
            return;
        }

        if (isETH(token)) {
            if (msg.value > amount) {
                // Return remainder if exist
                payable(msg.sender).transfer(msg.value - amount);
            }
        } else {
            token.safeTransferFrom(msg.sender, address(this), amount);
        }
    }

    function universalApprove(IERC20 token, address to, uint256 amount) internal {
        if (!isETH(token)) {
            if (amount > 0 && token.allowance(address(this), to) > 0) {
                token.safeApprove(to, 0);
            }
            token.safeApprove(to, amount);
        }
    }

    function universalBalanceOf(IERC20 token, address who) internal view returns (uint256) {
        if (isETH(token)) {
            return who.balance;
        } else {
            return token.balanceOf(who);
        }
    }

    function isETH(IERC20 token) internal pure returns(bool) {
        return (address(token) == ZERO_ADDRESS || address(token) == ETH_ADDRESS);
    }

    // function notExist(IERC20 token) internal pure returns(bool) {
    //     return (address(token) == address(-1));
    // }
}

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.9;

import "../interfaces/IUniswapExchange.sol";
import "./Math.sol";
import "./UniversalERC20.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

library UniswapExchangeLib {
    using Math for uint256;
    using UniversalERC20 for IERC20;

    function getReturn(
        IUniswapExchange exchange,
        IERC20 fromToken,
        IERC20 destToken,
        uint amountIn
    ) internal view returns (uint256 result, bool needSync, bool needSkim) {
        uint256 reserveIn = fromToken.universalBalanceOf(address(exchange));
        uint256 reserveOut = destToken.universalBalanceOf(address(exchange));
        (uint112 reserve0, uint112 reserve1,) = exchange.getReserves();
        if (fromToken > destToken) {
            (reserve0, reserve1) = (reserve1, reserve0);
        }
        needSync = (reserveIn < reserve0 || reserveOut < reserve1);
        needSkim = !needSync && (reserveIn > reserve0 || reserveOut > reserve1);

        uint256 amountInWithFee = amountIn * 997;
        uint256 numerator = amountInWithFee * Math.min(reserveOut, reserve1);
        uint256 denominator = Math.min(reserveIn, reserve0) * 1000 + amountInWithFee;
        result = (denominator == 0) ? 0 : numerator / denominator;
    }
}

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

pragma solidity ^0.8.1;

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

        return account.code.length > 0;
    }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.9;

library Math {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow, so we distribute
        return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
    }
}