// File: /contracts/crossChain/Wrapper.sol



// SPDX-License-Identifier: AGPL-3.0

pragma solidity ^0.8.0;

import "../access/Ownable.sol";
import "./interfaces/IBridge.sol";
import "./interfaces/IWrapper.sol";
import "../swap/interfaces/IPool.sol";
import "../assets/interfaces/IWETH.sol";
import "../assets/interfaces/IPToken.sol";
import "@openzeppelin/contracts/security/Pausable.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

contract Wrapper is Ownable, IWrapper, Pausable, ReentrancyGuard {
    using SafeMath for uint;
    using SafeERC20 for IERC20;

    address public bridge;
    address public feeCollector;
    address public wethAddress;

    event PolyWrapperLock (
        address indexed fromAsset,
        address indexed sender,
        uint64 toChainId,
        bytes toAddress,
        uint net,
        uint fee,
        uint id
    );

    event SetBridgeContract(address bridge);
    event SetFeeCollector(address feeCollector);
    event SetWETHAddress(address wethAddress);

    modifier onlyFeeCollector {
        require(_msgSender() == feeCollector, "Not fee collector");
        _;
    }

    function pause() external onlyOwner {
        _pause();
    }

    function unpause() external onlyOwner {
        _unpause();
    }

    function setBridgeContract(address _bridge) public onlyOwner {
        bridge = _bridge;
        emit SetBridgeContract(bridge);
    }

    function setFeeCollector(address _feeCollector) public onlyOwner {
        feeCollector = _feeCollector;
        emit SetFeeCollector(feeCollector);
    }

    function setWETHAddress(address _weth) public onlyOwner {
        wethAddress = _weth;
        emit SetWETHAddress(wethAddress);
    }

    function extractFee() public onlyFeeCollector {
        payable(feeCollector).transfer(address(this).balance);
    }

    function rescueFund(address tokenAddress) public onlyOwner {
        IERC20 token = IERC20(tokenAddress);
        token.safeTransfer(_msgSender(), token.balanceOf(address(this)));
    }

    function bridgeOut(
        address pTokenAddress,
        uint256 amount,
        uint64 toChainId,
        bytes memory toAddress,
        bytes memory callData
    ) public payable nonReentrant whenNotPaused returns(bool) {
        // check
        require(toAddress.length != 0, "empty toAddress");
        address addr;
        assembly { addr := mload(add(toAddress,0x14)) }
        require(addr != address(0), "zero toAddress");

        // pull
        IERC20(pTokenAddress).safeTransferFrom(_msgSender(), address(this), amount);

        // push
        IERC20(pTokenAddress).safeApprove(bridge, 0);
        IERC20(pTokenAddress).safeApprove(bridge, amount);
        require(IBridge(bridge).bridgeOut(pTokenAddress, toChainId, toAddress, amount, callData), "bridgeOut fail");

        // log
        emit PolyWrapperLock(pTokenAddress, _msgSender(), toChainId, toAddress, amount, msg.value, 1);

        return true;
    }

    function swapAndBridgeOut(
        address poolAddress, address tokenFrom, address tokenTo, uint256 dx, uint256 minDy, uint256 deadline, // args for swap
        uint64 toChainId, bytes memory toAddress, bytes memory callData                                       // args for bridge
    ) public payable nonReentrant whenNotPaused returns(bool) {
        uint256 balanceBefore = IERC20(tokenTo).balanceOf(address(this));
        {
            // check
            require(toAddress.length != 0, "empty toAddress");
            address addr;
            assembly { addr := mload(add(toAddress,0x14)) }
            require(addr != address(0), "zero toAddress");
        }
        {
            // pull
            IERC20(tokenFrom).safeTransferFrom(_msgSender(), address(this), dx);
        }
        {
            // swap
            IERC20(tokenFrom).safeApprove(poolAddress, 0);
            IERC20(tokenFrom).safeApprove(poolAddress, dx);
            IPool pool = IPool(poolAddress);
            pool.swap(pool.getTokenIndex(tokenFrom), pool.getTokenIndex(tokenTo), dx, minDy, deadline);
        }

        // push
        uint256 amount = IERC20(tokenTo).balanceOf(address(this)).sub(balanceBefore);
        IERC20(tokenTo).safeApprove(bridge, 0);
        IERC20(tokenTo).safeApprove(bridge, amount);
        require(IBridge(bridge).bridgeOut(tokenTo, toChainId, toAddress, amount, callData), "bridgeOut fail");

        // log
        emit PolyWrapperLock(tokenTo, _msgSender(), toChainId, toAddress, amount, msg.value, 2);

        return true;
    }

    function swapAndBridgeOutNativeToken(
        address poolAddress, address tokenTo, uint256 dx, uint256 minDy, uint256 deadline, // args for swap
        uint64 toChainId, bytes memory toAddress, bytes memory callData                    // args for bridge
    ) public payable nonReentrant whenNotPaused returns(bool) {
        require(msg.value >= dx, "insufficient fund");
        uint256 balanceBefore = IERC20(tokenTo).balanceOf(address(this));
        {
            // check
            require(toAddress.length != 0, "empty toAddress");
            address addr;
            assembly { addr := mload(add(toAddress,0x14)) }
            require(addr != address(0), "zero toAddress");
        }
        {
            // deposit
            IWETH(wethAddress).deposit{value: dx}();
        }
        {
            // swap
            IERC20(wethAddress).safeApprove(poolAddress, 0);
            IERC20(wethAddress).safeApprove(poolAddress, dx);
            IPool pool = IPool(poolAddress);
            pool.swap(pool.getTokenIndex(wethAddress), pool.getTokenIndex(tokenTo), dx, minDy, deadline);
        }

        // push
        uint256 amount = IERC20(tokenTo).balanceOf(address(this)).sub(balanceBefore);
        IERC20(tokenTo).safeApprove(bridge, 0);
        IERC20(tokenTo).safeApprove(bridge, amount);
        require(IBridge(bridge).bridgeOut(tokenTo, toChainId, toAddress, amount, callData), "bridgeOut fail");

        // log
        emit PolyWrapperLock(tokenTo, _msgSender(), toChainId, toAddress, amount, msg.value.sub(dx), 3);

        return true;
    }

    function depositAndBridgeOut(
        address originalToken,
        address pTokenAddress,
        uint256 amount,
        uint64 toChainId,
        bytes memory toAddress,
        bytes memory callData
    ) public payable nonReentrant whenNotPaused returns(bool) {
        {
            // check
            require(IPToken(pTokenAddress).tokenUnderlying() == originalToken, "invalid ptoken / originalToken");
            require(toAddress.length != 0, "empty toAddress");
            address addr;
            assembly { addr := mload(add(toAddress,0x14)) }
            require(addr != address(0), "zero toAddress");
        }
        {
            // pull
            IERC20(originalToken).safeTransferFrom(_msgSender(), address(this), amount);
        }

        // push
        IERC20(originalToken).safeApprove(bridge, 0);
        IERC20(originalToken).safeApprove(bridge, amount);
        require(IBridge(bridge).depositAndBridgeOut(originalToken, pTokenAddress, toChainId, toAddress, amount, callData), "depositAndBridgeOut fail");

        // log
        emit PolyWrapperLock(originalToken, _msgSender(), toChainId, toAddress, amount, msg.value, 4);

        return true;
    }

    function depositAndBridgeOutNativeToken(
        address pTokenAddress,
        uint256 amount,
        uint64 toChainId,
        bytes memory toAddress,
        bytes memory callData
    ) public payable nonReentrant whenNotPaused returns(bool) {
        require(msg.value >= amount, "insufficient fund");
        {
            // check
            require(IPToken(pTokenAddress).tokenUnderlying() == wethAddress, "invalid ptoken");
            require(toAddress.length != 0, "empty toAddress");
            address addr;
            assembly { addr := mload(add(toAddress,0x14)) }
            require(addr != address(0), "zero toAddress");
        }
        {
            // deposit ETH
            IWETH(wethAddress).deposit{value: amount}();
        }

        // push
        IERC20(wethAddress).safeApprove(bridge, 0);
        IERC20(wethAddress).safeApprove(bridge, amount);
        require(IBridge(bridge).depositAndBridgeOut(wethAddress, pTokenAddress, toChainId, toAddress, amount, callData), "depositAndBridgeOut fail");

        // log
        emit PolyWrapperLock(wethAddress, _msgSender(), toChainId, toAddress, amount, msg.value.sub(amount), 5);

        return true;
    }

    function bridgeOutAndWithdraw(
        address pTokenAddress,
        uint64 toChainId,
        bytes memory toAddress,
        uint256 amount
    ) public payable nonReentrant whenNotPaused returns(bool) {
        // check
        require(toAddress.length !=0, "empty toAddress");
        address addr;
        assembly { addr := mload(add(toAddress,0x14)) }
        require(addr != address(0),"zero toAddress");

        // pull
        IERC20(pTokenAddress).safeTransferFrom(_msgSender(), address(this), amount);

        // push
        IERC20(pTokenAddress).safeApprove(bridge, 0);
        IERC20(pTokenAddress).safeApprove(bridge, amount);
        require(IBridge(bridge).bridgeOutAndWithdraw(pTokenAddress, toChainId, toAddress, amount), "bridgeOutAndWithdraw fail");

        // log
        emit PolyWrapperLock(pTokenAddress, _msgSender(), toChainId, toAddress, amount, msg.value, 6);

        return true;
    }
}

// File: /contracts/swap/interfaces/IPool.sol



// SPDX-License-Identifier: AGPL-3.0

pragma solidity ^0.8.0;

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

interface IPool {
    function coins(uint256 index) external view returns(IERC20);
    function getA() external view returns (uint256);
    function getTokenIndex(address token) external view returns (uint8);

    function getVirtualPrice() external view returns (uint256);

    function calculateSwap(uint8 tokenIndexFrom, uint8 tokenIndexTo, uint256 dx) external view returns (uint256 dy);
    function calculateRemoveLiquidity(uint256 amount) external view returns (uint256[] memory);
    function calculateTokenAmount(uint256[] calldata amounts, bool deposit) external view returns (uint256);
    function calculateWithdrawOneToken(uint256 tokenAmount, uint8 tokenIndex) external view returns (uint256 amount);

    function swap(uint8 tokenIndexFrom, uint8 tokenIndexTo, uint256 dx, uint256 minDy, uint256 deadline) external returns (uint256);
    function addLiquidity(uint256[] memory amounts, uint256 minToMint, uint256 deadline) external returns (uint256);
    function removeLiquidity(uint256 amount, uint256[] calldata minAmounts, uint256 deadline) external returns (uint256[] memory);
    function removeLiquidityOneToken(uint256 tokenAmount, uint8 tokenIndex, uint256 minAmount, uint256 deadline) external returns (uint256);
    function removeLiquidityImbalance(uint256[] calldata amounts, uint256 maxBurnAmount, uint256 deadline) external returns (uint256);

    function applySwapFee(uint256 newSwapFee) external;
    function applyAdminFee(uint256 newAdminFee) external;
    function getAdminBalance(uint256 index) external view returns (uint256);
    function withdrawAdminFee(address receiver) external;
    function rampA(uint256 _futureA, uint256 _futureTime) external;
    function stopRampA() external;
}

// File: /contracts/crossChain/interfaces/IWrapper.sol



// SPDX-License-Identifier: AGPL-3.0

pragma solidity ^0.8.0;

interface IWrapper {
    function bridgeOut(
        address pTokenAddress,
        uint256 amount,
        uint64 toChainId,
        bytes memory toAddress,
        bytes memory callData
    ) external payable returns(bool);

    function swapAndBridgeOut(
        address poolAddress, address tokenFrom, address tokenTo, uint256 dx, uint256 minDy, uint256 deadline, // args for swap
        uint64 toChainId, bytes memory toAddress, bytes memory callData                                       // args for bridge
    ) external payable returns(bool);

    function swapAndBridgeOutNativeToken(
        address poolAddress, address tokenTo, uint256 dx, uint256 minDy, uint256 deadline, // args for swap
        uint64 toChainId, bytes memory toAddress, bytes memory callData                    // args for bridge
    ) external payable returns(bool);

    function depositAndBridgeOut(
        address originalToken,
        address pTokenAddress,
        uint256 amount,
        uint64 toChainId,
        bytes memory toAddress,
        bytes memory callData
    ) external payable returns(bool);

    function depositAndBridgeOutNativeToken(
        address pTokenAddress,
        uint256 amount,
        uint64 toChainId,
        bytes memory toAddress,
        bytes memory callData
    ) external payable returns(bool);

    function bridgeOutAndWithdraw(
        address pTokenAddress,
        uint64 toChainId,
        bytes memory toAddress,
        uint256 amount
    ) external payable returns(bool);
}

// File: /contracts/crossChain/interfaces/IBridge.sol



// SPDX-License-Identifier: AGPL-3.0

pragma solidity ^0.8.0;

interface IBridge {
    function bridgeFeeRate() external view returns (uint256);
    function bridgeFeeCollector() external view returns (address);

    function bridgeOut(
        address fromAssetHash,
        uint64 toChainId,
        bytes memory toAddress,
        uint256 amount,
        bytes memory callData
    ) external returns(bool);

    function depositAndBridgeOut(
        address originalTokenAddress,
        address pTokenAddress,
        uint64 toChainId,
        bytes memory toAddress,
        uint256 amount,
        bytes memory callData
    ) external returns(bool);

    function bridgeOutAndWithdraw(
        address pTokenAddress,
        uint64 toChainId,
        bytes memory toAddress,
        uint256 amount
    ) external returns(bool);
}

// File: /contracts/assets/interfaces/IWETH.sol



// SPDX-License-Identifier: AGPL-3.0

pragma solidity ^0.8.0;

interface IWETH {
    function deposit() external payable;
    function withdraw(uint wad) external;

    function transfer(address dst, uint wad) external returns (bool);
}

// File: /contracts/assets/interfaces/IPToken.sol



// SPDX-License-Identifier: AGPL-3.0

pragma solidity ^0.8.0;

interface IPToken {
    function mint(address to, uint256 amount) external;
    function burn(uint256 amount) external;

    function deposit(address to, uint256 amount) external;
    function withdraw(address to, uint256 amount) external;

    function tokenUnderlying() external view returns(address);

    function checkAuthorizedCaller(address caller) external view returns (bool);
    function checkIfDepositWithdrawEnabled() external view returns (bool);
}

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



// SPDX-License-Identifier: AGPL-3.0

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

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

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/math/SafeMath.sol)

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        return a * b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

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



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

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

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



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

pragma solidity ^0.8.1;

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

        return account.code.length > 0;
    }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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



// 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");
        }
    }
}

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



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

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

// File: @openzeppelin/contracts/security/ReentrancyGuard.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (security/ReentrancyGuard.sol)

pragma solidity ^0.8.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// File: @openzeppelin/contracts/security/Pausable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (security/Pausable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor() {
        _paused = false;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        require(!paused(), "Pausable: paused");
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        require(paused(), "Pausable: not paused");
        _;
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}