// File: /contracts/ExchangeV2.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;
pragma abicoder v2;

import "./ExchangeV2Core.sol";
import "./RaribleTransferManager.sol";
import "@rarible/royalties/contracts/IRoyaltiesProvider.sol";

contract ExchangeV2 is ExchangeV2Core, RaribleTransferManager {
    function __ExchangeV2_init(
        INftTransferProxy _transferProxy,
        IERC20TransferProxy _erc20TransferProxy,
        uint newProtocolFee,
        address newDefaultFeeReceiver,
        IRoyaltiesProvider newRoyaltiesProvider
    ) external initializer {
        __Context_init_unchained();
        __Ownable_init_unchained();
        __TransferExecutor_init_unchained(_transferProxy, _erc20TransferProxy);
        __RaribleTransferManager_init_unchained(newProtocolFee, newDefaultFeeReceiver, newRoyaltiesProvider);
        __OrderValidator_init_unchained();
    }
}

// File: /contracts/lib/LibTransfer.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;

library LibTransfer {
    function transferEth(address to, uint value) internal {
        (bool success,) = to.call{ value: value }("");
        require(success, "transfer failed");
    }
}

// File: /contracts/lib/LibMath.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;

import "@openzeppelin/contracts-upgradeable/math/SafeMathUpgradeable.sol";

library LibMath {
    using SafeMathUpgradeable for uint;

    /// @dev Calculates partial value given a numerator and denominator rounded down.
    ///      Reverts if rounding error is >= 0.1%
    /// @param numerator Numerator.
    /// @param denominator Denominator.
    /// @param target Value to calculate partial of.
    /// @return partialAmount value of target rounded down.
    function safeGetPartialAmountFloor(
        uint256 numerator,
        uint256 denominator,
        uint256 target
    ) internal pure returns (uint256 partialAmount) {
        if (isRoundingErrorFloor(numerator, denominator, target)) {
            revert("rounding error");
        }
        partialAmount = numerator.mul(target).div(denominator);
    }

    /// @dev Checks if rounding error >= 0.1% when rounding down.
    /// @param numerator Numerator.
    /// @param denominator Denominator.
    /// @param target Value to multiply with numerator/denominator.
    /// @return isError Rounding error is present.
    function isRoundingErrorFloor(
        uint256 numerator,
        uint256 denominator,
        uint256 target
    ) internal pure returns (bool isError) {
        if (denominator == 0) {
            revert("division by zero");
        }

        // The absolute rounding error is the difference between the rounded
        // value and the ideal value. The relative rounding error is the
        // absolute rounding error divided by the absolute value of the
        // ideal value. This is undefined when the ideal value is zero.
        //
        // The ideal value is `numerator * target / denominator`.
        // Let's call `numerator * target % denominator` the remainder.
        // The absolute error is `remainder / denominator`.
        //
        // When the ideal value is zero, we require the absolute error to
        // be zero. Fortunately, this is always the case. The ideal value is
        // zero iff `numerator == 0` and/or `target == 0`. In this case the
        // remainder and absolute error are also zero.
        if (target == 0 || numerator == 0) {
            return false;
        }

        // Otherwise, we want the relative rounding error to be strictly
        // less than 0.1%.
        // The relative error is `remainder / (numerator * target)`.
        // We want the relative error less than 1 / 1000:
        //        remainder / (numerator * target)  <  1 / 1000
        // or equivalently:
        //        1000 * remainder  <  numerator * target
        // so we have a rounding error iff:
        //        1000 * remainder  >=  numerator * target
        uint256 remainder = mulmod(
            target,
            numerator,
            denominator
        );
        isError = remainder.mul(1000) >= numerator.mul(target);
    }

    function safeGetPartialAmountCeil(
        uint256 numerator,
        uint256 denominator,
        uint256 target
    ) internal pure returns (uint256 partialAmount) {
        if (isRoundingErrorCeil(numerator, denominator, target)) {
            revert("rounding error");
        }
        partialAmount = numerator.mul(target).add(denominator.sub(1)).div(denominator);
    }

    /// @dev Checks if rounding error >= 0.1% when rounding up.
    /// @param numerator Numerator.
    /// @param denominator Denominator.
    /// @param target Value to multiply with numerator/denominator.
    /// @return isError Rounding error is present.
    function isRoundingErrorCeil(
        uint256 numerator,
        uint256 denominator,
        uint256 target
    ) internal pure returns (bool isError) {
        if (denominator == 0) {
            revert("division by zero");
        }

        // See the comments in `isRoundingError`.
        if (target == 0 || numerator == 0) {
            // When either is zero, the ideal value and rounded value are zero
            // and there is no rounding error. (Although the relative error
            // is undefined.)
            return false;
        }
        // Compute remainder as before
        uint256 remainder = mulmod(
            target,
            numerator,
            denominator
        );
        remainder = denominator.sub(remainder) % denominator;
        isError = remainder.mul(1000) >= numerator.mul(target);
        return isError;
    }
}

// File: /contracts/lib/BpLibrary.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;

import "@openzeppelin/contracts-upgradeable/math/SafeMathUpgradeable.sol";

library BpLibrary {
    using SafeMathUpgradeable for uint;

    function bp(uint value, uint bpValue) internal pure returns (uint) {
        return value.mul(bpValue).div(10000);
    }
}

// File: /contracts/interfaces/ERC1271.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;

interface ERC1271 {

    /**
     * @dev Should return whether the signature provided is valid for the provided data
     * @param _hash Hash of the data signed on the behalf of address(this)
     * @param _signature Signature byte array associated with _data
     *
     * MUST return the bytes4 magic value 0x1626ba7e when function passes.
     * MUST NOT modify state (using STATICCALL for solc < 0.5, view modifier for solc > 0.5)
     * MUST allow external calls
     */
    function isValidSignature(bytes32 _hash, bytes calldata _signature) virtual external view returns (bytes4 magicValue);
}
// File: /contracts/TransferExecutor.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;
pragma abicoder v2;

import "@rarible/lib-asset/contracts/LibAsset.sol";
import "@rarible/exchange-interfaces/contracts/ITransferProxy.sol";
import "@rarible/exchange-interfaces/contracts/INftTransferProxy.sol";
import "@rarible/exchange-interfaces/contracts/IERC20TransferProxy.sol";
import "./ITransferExecutor.sol";
import "@openzeppelin/contracts-upgradeable/proxy/Initializable.sol";
import "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
import "./lib/LibTransfer.sol";

abstract contract TransferExecutor is Initializable, OwnableUpgradeable, ITransferExecutor {
    using LibTransfer for address;

    mapping (bytes4 => address) proxies;

    event ProxyChange(bytes4 indexed assetType, address proxy);

    function __TransferExecutor_init_unchained(INftTransferProxy transferProxy, IERC20TransferProxy erc20TransferProxy) internal {
        proxies[LibAsset.ERC20_ASSET_CLASS] = address(erc20TransferProxy);
        proxies[LibAsset.ERC721_ASSET_CLASS] = address(transferProxy);
        proxies[LibAsset.ERC1155_ASSET_CLASS] = address(transferProxy);
    }

    function setTransferProxy(bytes4 assetType, address proxy) external onlyOwner {
        proxies[assetType] = proxy;
        emit ProxyChange(assetType, proxy);
    }

    function transfer(
        LibAsset.Asset memory asset,
        address from,
        address to,
        bytes4 transferDirection,
        bytes4 transferType
    ) internal override {
        if (asset.assetType.assetClass == LibAsset.ETH_ASSET_CLASS) {
            to.transferEth(asset.value);
        } else if (asset.assetType.assetClass == LibAsset.ERC20_ASSET_CLASS) {
            (address token) = abi.decode(asset.assetType.data, (address));
            IERC20TransferProxy(proxies[LibAsset.ERC20_ASSET_CLASS]).erc20safeTransferFrom(IERC20Upgradeable(token), from, to, asset.value);
        } else if (asset.assetType.assetClass == LibAsset.ERC721_ASSET_CLASS) {
            (address token, uint tokenId) = abi.decode(asset.assetType.data, (address, uint256));
            require(asset.value == 1, "erc721 value error");
            INftTransferProxy(proxies[LibAsset.ERC721_ASSET_CLASS]).erc721safeTransferFrom(IERC721Upgradeable(token), from, to, tokenId);
        } else if (asset.assetType.assetClass == LibAsset.ERC1155_ASSET_CLASS) {
            (address token, uint tokenId) = abi.decode(asset.assetType.data, (address, uint256));
            INftTransferProxy(proxies[LibAsset.ERC1155_ASSET_CLASS]).erc1155safeTransferFrom(IERC1155Upgradeable(token), from, to, tokenId, asset.value, "");
        } else {
            ITransferProxy(proxies[asset.assetType.assetClass]).transfer(asset, from, to);
        }
        emit Transfer(asset, from, to, transferDirection, transferType);
    }

    uint256[49] private __gap;
}

// File: /contracts/RaribleTransferManager.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;
pragma abicoder v2;

import "@openzeppelin/contracts-upgradeable/token/ERC721/IERC721Upgradeable.sol";
import "@openzeppelin/contracts-upgradeable/math/SafeMathUpgradeable.sol";
import "@rarible/lib-asset/contracts/LibAsset.sol";
import "@rarible/royalties/contracts/IRoyaltiesProvider.sol";
import "./LibFill.sol";
import "./LibFeeSide.sol";
import "./LibOrderDataV1.sol";
import "./ITransferManager.sol";
import "./TransferExecutor.sol";
import "./LibOrderData.sol";
import "./lib/BpLibrary.sol";

abstract contract RaribleTransferManager is OwnableUpgradeable, ITransferManager {
    using BpLibrary for uint;
    using SafeMathUpgradeable for uint;

    uint public protocolFee;
    IRoyaltiesProvider public royaltiesRegistry;

    address public defaultFeeReceiver;
    mapping(address => address) public feeReceivers;

    function __RaribleTransferManager_init_unchained(
        uint newProtocolFee,
        address newDefaultFeeReceiver,
        IRoyaltiesProvider newRoyaltiesProvider
    ) internal initializer {
        protocolFee = newProtocolFee;
        defaultFeeReceiver = newDefaultFeeReceiver;
        royaltiesRegistry = newRoyaltiesProvider;
    }

    function setRoyaltiesRegistry(IRoyaltiesProvider newRoyaltiesRegistry) external onlyOwner {
        royaltiesRegistry = newRoyaltiesRegistry;
    }

    function setProtocolFee(uint newProtocolFee) external onlyOwner {
        protocolFee = newProtocolFee;
    }

    function setDefaultFeeReceiver(address payable newDefaultFeeReceiver) external onlyOwner {
        defaultFeeReceiver = newDefaultFeeReceiver;
    }

    function setFeeReceiver(address token, address wallet) external onlyOwner {
        feeReceivers[token] = wallet;
    }

    function getFeeReceiver(address token) internal view returns (address) {
        address wallet = feeReceivers[token];
        if (wallet != address(0)) {
            return wallet;
        }
        return defaultFeeReceiver;
    }

    function doTransfers(
        LibAsset.AssetType memory makeMatch,
        LibAsset.AssetType memory takeMatch,
        LibFill.FillResult memory fill,
        LibOrder.Order memory leftOrder,
        LibOrder.Order memory rightOrder
    ) override internal returns (uint totalMakeValue, uint totalTakeValue) {
        LibFeeSide.FeeSide feeSide = LibFeeSide.getFeeSide(makeMatch.assetClass, takeMatch.assetClass);
        totalMakeValue = fill.makeValue;
        totalTakeValue = fill.takeValue;
        LibOrderDataV1.DataV1 memory leftOrderData = LibOrderData.parse(leftOrder);
        LibOrderDataV1.DataV1 memory rightOrderData = LibOrderData.parse(rightOrder);
        if (feeSide == LibFeeSide.FeeSide.MAKE) {
            totalMakeValue = doTransfersWithFees(fill.makeValue, leftOrder.maker, leftOrderData, rightOrderData, makeMatch, takeMatch,  TO_TAKER);
            transferPayouts(takeMatch, fill.takeValue, rightOrder.maker, leftOrderData.payouts, TO_MAKER);
        } else if (feeSide == LibFeeSide.FeeSide.TAKE) {
            totalTakeValue = doTransfersWithFees(fill.takeValue, rightOrder.maker, rightOrderData, leftOrderData, takeMatch, makeMatch, TO_MAKER);
            transferPayouts(makeMatch, fill.makeValue, leftOrder.maker, rightOrderData.payouts, TO_TAKER);
        }
    }

    function doTransfersWithFees(
        uint amount,
        address from,
        LibOrderDataV1.DataV1 memory dataCalculate,
        LibOrderDataV1.DataV1 memory dataNft,
        LibAsset.AssetType memory matchCalculate,
        LibAsset.AssetType memory matchNft,
        bytes4 transferDirection
    ) internal returns (uint totalAmount) {
        totalAmount = calculateTotalAmount(amount, protocolFee, dataCalculate.originFees);
        uint rest = transferProtocolFee(totalAmount, amount, from, matchCalculate, transferDirection);
        rest = transferRoyalties(matchCalculate, matchNft, rest, amount, from, transferDirection);
        rest = transferFees(matchCalculate, rest, amount, dataCalculate.originFees, from, transferDirection, ORIGIN);
        rest = transferFees(matchCalculate, rest, amount, dataNft.originFees, from, transferDirection, ORIGIN);
        transferPayouts(matchCalculate, rest, from, dataNft.payouts, transferDirection);
    }

    function transferProtocolFee(
        uint totalAmount,
        uint amount,
        address from,
        LibAsset.AssetType memory matchCalculate,
        bytes4 transferDirection
    ) internal returns (uint) {
        (uint rest, uint fee) = subFeeInBp(totalAmount, amount, protocolFee * 2);
        if (fee > 0) {
            address tokenAddress = address(0);
            if (matchCalculate.assetClass == LibAsset.ERC20_ASSET_CLASS) {
                tokenAddress = abi.decode(matchCalculate.data, (address));
            } else  if (matchCalculate.assetClass == LibAsset.ERC1155_ASSET_CLASS) {
                uint tokenId;
                (tokenAddress, tokenId) = abi.decode(matchCalculate.data, (address, uint));
            }
            transfer(LibAsset.Asset(matchCalculate, fee), from, getFeeReceiver(tokenAddress), transferDirection, PROTOCOL);
        }
        return rest;
    }

    function transferRoyalties(
        LibAsset.AssetType memory matchCalculate,
        LibAsset.AssetType memory matchNft,
        uint rest,
        uint amount,
        address from,
        bytes4 transferDirection
    ) internal returns (uint) {
        if (matchNft.assetClass != LibAsset.ERC1155_ASSET_CLASS && matchNft.assetClass != LibAsset.ERC721_ASSET_CLASS) {
            return rest;
        }
        (address token, uint tokenId) = abi.decode(matchNft.data, (address, uint));
        LibPart.Part[] memory fees = royaltiesRegistry.getRoyalties(token, tokenId);
        return transferFees(matchCalculate, rest, amount, fees, from, transferDirection, ROYALTY);
    }

    function transferFees(
        LibAsset.AssetType memory matchCalculate,
        uint rest,
        uint amount,
        LibPart.Part[] memory fees,
        address from,
        bytes4 transferDirection,
        bytes4 transferType
    ) internal returns (uint restValue) {
        restValue = rest;
        for (uint256 i = 0; i < fees.length; i++) {
            (uint newRestValue, uint feeValue) = subFeeInBp(restValue, amount,  fees[i].value);
            restValue = newRestValue;
            if (feeValue > 0) {
                transfer(LibAsset.Asset(matchCalculate, feeValue), from,  fees[i].account, transferDirection, transferType);
            }
        }
    }

    function transferPayouts(
        LibAsset.AssetType memory matchCalculate,
        uint amount,
        address from,
        LibPart.Part[] memory payouts,
        bytes4 transferDirection
    ) internal {
        uint sumBps = 0;
        uint restValue = amount;
        for (uint256 i = 0; i < payouts.length - 1; i++) {
            uint currentAmount = amount.bp(payouts[i].value);
            sumBps += payouts[i].value;
            if (currentAmount > 0) {
                restValue = restValue.sub(currentAmount);
                transfer(LibAsset.Asset(matchCalculate, currentAmount), from, payouts[i].account, transferDirection, PAYOUT);
            }
        }
        LibPart.Part memory lastPayout = payouts[payouts.length - 1];
        sumBps += lastPayout.value;
        require(sumBps == 10000, "Sum payouts Bps not equal 100%");
        if (restValue > 0) {
            transfer(LibAsset.Asset(matchCalculate, restValue), from, lastPayout.account, transferDirection, PAYOUT);
        }
    }

    function calculateTotalAmount(
        uint amount,
        uint feeOnTopBp,
        LibPart.Part[] memory orderOriginFees
    ) internal pure returns (uint total){
        total = amount.add(amount.bp(feeOnTopBp));
        for (uint256 i = 0; i < orderOriginFees.length; i++) {
            total = total.add(amount.bp(orderOriginFees[i].value));
        }
    }

    function subFeeInBp(uint value, uint total, uint feeInBp) internal pure returns (uint newValue, uint realFee) {
        return subFee(value, total.bp(feeInBp));
    }

    function subFee(uint value, uint fee) internal pure returns (uint newValue, uint realFee) {
        if (value > fee) {
            newValue = value - fee;
            realFee = fee;
        } else {
            newValue = 0;
            realFee = value;
        }
    }


    uint256[46] private __gap;
}

// File: /contracts/OrderValidator.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;

import "./interfaces/ERC1271.sol";
import "./LibOrder.sol";
import "@openzeppelin/contracts-upgradeable/utils/AddressUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/cryptography/ECDSAUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/utils/ContextUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/drafts/EIP712Upgradeable.sol";

abstract contract OrderValidator is Initializable, ContextUpgradeable, EIP712Upgradeable {
    using ECDSAUpgradeable for bytes32;
    using AddressUpgradeable for address;

    bytes4 constant internal MAGICVALUE = 0x1626ba7e;

    function __OrderValidator_init_unchained() internal initializer {
        __EIP712_init_unchained("Exchange", "2");
    }

    function validate(LibOrder.Order memory order, bytes memory signature) internal view {
        if (order.salt == 0) {
            require(_msgSender() == order.maker, "maker is not tx sender");
        } else {
            if (_msgSender() != order.maker) {
                bytes32 hash = LibOrder.hash(order);
                if (order.maker.isContract()) {
                    require(
                        ERC1271(order.maker).isValidSignature(_hashTypedDataV4(hash), signature) == MAGICVALUE,
                        "contract order signature verification error"
                    );
                } else {
                    require(
                        _hashTypedDataV4(hash).recover(signature) == order.maker,
                        "order signature verification error"
                    );
                }
            }
        }
    }

    uint256[50] private __gap;
}

// File: /contracts/LibOrderDataV1.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;
pragma abicoder v2;

import "@rarible/royalties/contracts/LibPart.sol";

library LibOrderDataV1 {
    bytes4 constant public V1 = bytes4(keccak256("V1"));

    struct DataV1 {
        LibPart.Part[] payouts;
        LibPart.Part[] originFees;
    }

    function decodeOrderDataV1(bytes memory data) internal pure returns (DataV1 memory orderData) {
        orderData = abi.decode(data, (DataV1));
    }
}

// File: /contracts/LibOrderData.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;

import "./LibOrder.sol";
import "./LibOrderData.sol";
import "./LibOrderDataV1.sol";
import "@rarible/royalties/contracts/LibPart.sol";

library LibOrderData {

    function parse(LibOrder.Order memory order) pure internal returns (LibOrderDataV1.DataV1 memory dataOrder) {
        if (order.dataType == LibOrderDataV1.V1) {
            dataOrder = LibOrderDataV1.decodeOrderDataV1(order.data);
            if (dataOrder.payouts.length == 0) {
                dataOrder = payoutSet(order.maker, dataOrder);
            }
        } else if (order.dataType == 0xffffffff) {
            dataOrder = payoutSet(order.maker, dataOrder);
        } else {
            revert("Unknown Order data type");
        }
    }

    function payoutSet(
        address orderAddress,
        LibOrderDataV1.DataV1 memory dataOrderOnePayoutIn
    ) pure internal returns (LibOrderDataV1.DataV1 memory ) {
        LibPart.Part[] memory payout = new LibPart.Part[](1);
        payout[0].account = payable(orderAddress);
        payout[0].value = 10000;
        dataOrderOnePayoutIn.payouts = payout;
        return dataOrderOnePayoutIn;
    }
}

// File: /contracts/LibOrder.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;

import "./lib/LibMath.sol";
import "@rarible/lib-asset/contracts/LibAsset.sol";

library LibOrder {
    using SafeMathUpgradeable for uint;

    bytes32 constant ORDER_TYPEHASH = keccak256(
        "Order(address maker,Asset makeAsset,address taker,Asset takeAsset,uint256 salt,uint256 start,uint256 end,bytes4 dataType,bytes data)Asset(AssetType assetType,uint256 value)AssetType(bytes4 assetClass,bytes data)"
    );

    struct Order {
        address maker;
        LibAsset.Asset makeAsset;
        address taker;
        LibAsset.Asset takeAsset;
        uint salt;
        uint start;
        uint end;
        bytes4 dataType;
        bytes data;
    }

    function calculateRemaining(Order memory order, uint fill) internal pure returns (uint makeValue, uint takeValue) {
        takeValue = order.takeAsset.value.sub(fill);
        makeValue = LibMath.safeGetPartialAmountFloor(order.makeAsset.value, order.takeAsset.value, takeValue);
    }

    function hashKey(Order memory order) internal pure returns (bytes32) {
        return keccak256(abi.encode(
                order.maker,
                LibAsset.hash(order.makeAsset.assetType),
                LibAsset.hash(order.takeAsset.assetType),
                order.salt
            ));
    }

    function hash(Order memory order) internal pure returns (bytes32) {
        return keccak256(abi.encode(
                ORDER_TYPEHASH,
                order.maker,
                LibAsset.hash(order.makeAsset),
                order.taker,
                LibAsset.hash(order.takeAsset),
                order.salt,
                order.start,
                order.end,
                order.dataType,
                keccak256(order.data)
            ));
    }

    function validate(LibOrder.Order memory order) internal view {
        require(order.start == 0 || order.start < block.timestamp, "Order start validation failed");
        require(order.end == 0 || order.end > block.timestamp, "Order end validation failed");
    }
}

// File: /contracts/LibFill.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;

import "./LibOrder.sol";
import "@openzeppelin/contracts-upgradeable/math/SafeMathUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/math/MathUpgradeable.sol";

library LibFill {
    using SafeMathUpgradeable for uint;

    struct FillResult {
        uint makeValue;
        uint takeValue;
    }

    /**
     * @dev Should return filled values
     * @param leftOrder left order
     * @param rightOrder right order
     * @param leftOrderFill current fill of the left order (0 if order is unfilled)
     * @param rightOrderFill current fill of the right order (0 if order is unfilled)
     */
    function fillOrder(LibOrder.Order memory leftOrder, LibOrder.Order memory rightOrder, uint leftOrderFill, uint rightOrderFill) internal pure returns (FillResult memory) {
        (uint leftMakeValue, uint leftTakeValue) = LibOrder.calculateRemaining(leftOrder, leftOrderFill);
        (uint rightMakeValue, uint rightTakeValue) = LibOrder.calculateRemaining(rightOrder, rightOrderFill);

        //We have 3 cases here:
        if (rightTakeValue > leftMakeValue) { //1nd: left order should be fully filled
            return fillLeft(leftMakeValue, leftTakeValue, rightOrder.makeAsset.value, rightOrder.takeAsset.value);
        }//2st: right order should be fully filled or 3d: both should be fully filled if required values are the same
        return fillRight(leftOrder.makeAsset.value, leftOrder.takeAsset.value, rightMakeValue, rightTakeValue);
    }

    function fillRight(uint leftMakeValue, uint leftTakeValue, uint rightMakeValue, uint rightTakeValue) internal pure returns (FillResult memory result) {
        uint makerValue = LibMath.safeGetPartialAmountFloor(rightTakeValue, leftMakeValue, leftTakeValue);
        require(makerValue <= rightMakeValue, "fillRight: unable to fill");
        return FillResult(rightTakeValue, makerValue);
    }

    function fillLeft(uint leftMakeValue, uint leftTakeValue, uint rightMakeValue, uint rightTakeValue) internal pure returns (FillResult memory result) {
        uint rightTake = LibMath.safeGetPartialAmountFloor(leftTakeValue, rightMakeValue, rightTakeValue);
        require(rightTake <= leftMakeValue, "fillLeft: unable to fill");
        return FillResult(leftMakeValue, leftTakeValue);
    }
}

// File: /contracts/LibFeeSide.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;

import "@rarible/lib-asset/contracts/LibAsset.sol";

library LibFeeSide {

    enum FeeSide {NONE, MAKE, TAKE}

    function getFeeSide(bytes4 make, bytes4 take) internal pure returns (FeeSide) {
        if (make == LibAsset.ETH_ASSET_CLASS) {
            return FeeSide.MAKE;
        }
        if (take == LibAsset.ETH_ASSET_CLASS) {
            return FeeSide.TAKE;
        }
        if (make == LibAsset.ERC20_ASSET_CLASS) {
            return FeeSide.MAKE;
        }
        if (take == LibAsset.ERC20_ASSET_CLASS) {
            return FeeSide.TAKE;
        }
        if (make == LibAsset.ERC1155_ASSET_CLASS) {
            return FeeSide.MAKE;
        }
        if (take == LibAsset.ERC1155_ASSET_CLASS) {
            return FeeSide.TAKE;
        }
        return FeeSide.NONE;
    }
}

// File: /contracts/ITransferManager.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;
pragma abicoder v2;

import "@rarible/lib-asset/contracts/LibAsset.sol";
import "./LibFill.sol";
import "./TransferExecutor.sol";

abstract contract ITransferManager is ITransferExecutor {
    bytes4 constant TO_MAKER = bytes4(keccak256("TO_MAKER"));
    bytes4 constant TO_TAKER = bytes4(keccak256("TO_TAKER"));
    bytes4 constant PROTOCOL = bytes4(keccak256("PROTOCOL"));
    bytes4 constant ROYALTY = bytes4(keccak256("ROYALTY"));
    bytes4 constant ORIGIN = bytes4(keccak256("ORIGIN"));
    bytes4 constant PAYOUT = bytes4(keccak256("PAYOUT"));

    function doTransfers(
        LibAsset.AssetType memory makeMatch,
        LibAsset.AssetType memory takeMatch,
        LibFill.FillResult memory fill,
        LibOrder.Order memory leftOrder,
        LibOrder.Order memory rightOrder
    ) internal virtual returns (uint totalMakeValue, uint totalTakeValue);
}

// File: /contracts/ITransferExecutor.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;
pragma abicoder v2;

import "@rarible/lib-asset/contracts/LibAsset.sol";

abstract contract ITransferExecutor {

    //events
    event Transfer(LibAsset.Asset asset, address from, address to, bytes4 transferDirection, bytes4 transferType);

    function transfer(
        LibAsset.Asset memory asset,
        address from,
        address to,
        bytes4 transferDirection,
        bytes4 transferType
    ) internal virtual;

}

// File: /contracts/IAssetMatcher.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;
pragma abicoder v2;

import "@rarible/lib-asset/contracts/LibAsset.sol";

interface IAssetMatcher {
    function matchAssets(
        LibAsset.AssetType memory leftAssetType,
        LibAsset.AssetType memory rightAssetType
    ) external view returns (LibAsset.AssetType memory);
}

// File: /contracts/ExchangeV2Core.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;
pragma abicoder v2;

import "./LibFill.sol";
import "./LibOrder.sol";
import "./OrderValidator.sol";
import "./AssetMatcher.sol";
import "./TransferExecutor.sol";
import "./ITransferManager.sol";
import "./lib/LibTransfer.sol";

abstract contract ExchangeV2Core is Initializable, OwnableUpgradeable, AssetMatcher, TransferExecutor, OrderValidator, ITransferManager {
    using SafeMathUpgradeable for uint;
    using LibTransfer for address;

    uint256 private constant UINT256_MAX = 2 ** 256 - 1;

    //state of the orders
    mapping(bytes32 => uint) public fills;

    //events
    event Cancel(bytes32 hash, address maker, LibAsset.AssetType makeAssetType, LibAsset.AssetType takeAssetType);
    event Match(bytes32 leftHash, bytes32 rightHash, address leftMaker, address rightMaker, uint newLeftFill, uint newRightFill, LibAsset.AssetType leftAsset, LibAsset.AssetType rightAsset);

    function cancel(LibOrder.Order memory order) external {
        require(_msgSender() == order.maker, "not a maker");
        bytes32 orderKeyHash = LibOrder.hashKey(order);
        fills[orderKeyHash] = UINT256_MAX;
        emit Cancel(orderKeyHash, order.maker, order.makeAsset.assetType, order.takeAsset.assetType);
    }

    function matchOrders(
        LibOrder.Order memory orderLeft,
        bytes memory signatureLeft,
        LibOrder.Order memory orderRight,
        bytes memory signatureRight
    ) external payable {
        validateFull(orderLeft, signatureLeft);
        validateFull(orderRight, signatureRight);
        if (orderLeft.taker != address(0)) {
            require(orderRight.maker == orderLeft.taker, "leftOrder.taker verification failed");
        }
        if (orderRight.taker != address(0)) {
            require(orderRight.taker == orderLeft.maker, "rightOrder.taker verification failed");
        }
        matchAndTransfer(orderLeft, orderRight);
    }

    function matchAndTransfer(LibOrder.Order memory orderLeft, LibOrder.Order memory orderRight) internal {
        (LibAsset.AssetType memory makeMatch, LibAsset.AssetType memory takeMatch) = matchAssets(orderLeft, orderRight);
        bytes32 leftOrderKeyHash = LibOrder.hashKey(orderLeft);
        bytes32 rightOrderKeyHash = LibOrder.hashKey(orderRight);
        uint leftOrderFill = fills[leftOrderKeyHash];
        uint rightOrderFill = fills[rightOrderKeyHash];
        LibFill.FillResult memory newFill = LibFill.fillOrder(orderLeft, orderRight, leftOrderFill, rightOrderFill);
        require(newFill.takeValue > 0, "nothing to fill");

        if (orderLeft.salt != 0) {
            fills[leftOrderKeyHash] = leftOrderFill + newFill.takeValue;
        }
        if (orderRight.salt != 0) {
            fills[rightOrderKeyHash] = rightOrderFill + newFill.makeValue;
        }

        (uint totalMakeValue, uint totalTakeValue) = doTransfers(makeMatch, takeMatch, newFill, orderLeft, orderRight);
        if (makeMatch.assetClass == LibAsset.ETH_ASSET_CLASS) {
            require(takeMatch.assetClass != LibAsset.ETH_ASSET_CLASS);
            require(msg.value >= totalMakeValue, "not enough eth");
            if (msg.value > totalMakeValue) {
                address(msg.sender).transferEth(msg.value - totalMakeValue);
            }
        } else if (takeMatch.assetClass == LibAsset.ETH_ASSET_CLASS) {
            require(msg.value >= totalTakeValue, "not enough eth");
            if (msg.value > totalTakeValue) {
                address(msg.sender).transferEth(msg.value - totalTakeValue);
            }
        }
        emit Match(leftOrderKeyHash, rightOrderKeyHash, orderLeft.maker, orderRight.maker, newFill.takeValue, newFill.makeValue, makeMatch, takeMatch);
    }

    function matchAssets(LibOrder.Order memory orderLeft, LibOrder.Order memory orderRight) internal view returns (LibAsset.AssetType memory makeMatch, LibAsset.AssetType memory takeMatch) {
        makeMatch = matchAssets(orderLeft.makeAsset.assetType, orderRight.takeAsset.assetType);
        require(makeMatch.assetClass != 0, "assets don't match");
        takeMatch = matchAssets(orderLeft.takeAsset.assetType, orderRight.makeAsset.assetType);
        require(takeMatch.assetClass != 0, "assets don't match");
    }

    function validateFull(LibOrder.Order memory order, bytes memory signature) internal view {
        LibOrder.validate(order);
        validate(order, signature);
    }

    uint256[49] private __gap;
}

// File: /contracts/AssetMatcher.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;
pragma abicoder v2;

import "./IAssetMatcher.sol";
import "@openzeppelin/contracts-upgradeable/proxy/Initializable.sol";
import "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";

abstract contract AssetMatcher is Initializable, OwnableUpgradeable {

    bytes constant EMPTY = "";
    mapping(bytes4 => address) matchers;

    event MatcherChange(bytes4 indexed assetType, address matcher);

    function setAssetMatcher(bytes4 assetType, address matcher) external onlyOwner {
        matchers[assetType] = matcher;
        emit MatcherChange(assetType, matcher);
    }

    function matchAssets(LibAsset.AssetType memory leftAssetType, LibAsset.AssetType memory rightAssetType) internal view returns (LibAsset.AssetType memory) {
        LibAsset.AssetType memory result = matchAssetOneSide(leftAssetType, rightAssetType);
        if (result.assetClass == 0) {
            return matchAssetOneSide(rightAssetType, leftAssetType);
        } else {
            return result;
        }
    }

    function matchAssetOneSide(LibAsset.AssetType memory leftAssetType, LibAsset.AssetType memory rightAssetType) private view returns (LibAsset.AssetType memory) {
        bytes4 classLeft = leftAssetType.assetClass;
        bytes4 classRight = rightAssetType.assetClass;
        if (classLeft == LibAsset.ETH_ASSET_CLASS) {
            if (classRight == LibAsset.ETH_ASSET_CLASS) {
                return leftAssetType;
            }
            return LibAsset.AssetType(0, EMPTY);
        }
        if (classLeft == LibAsset.ERC20_ASSET_CLASS) {
            if (classRight == LibAsset.ERC20_ASSET_CLASS) {
                (address addressLeft) = abi.decode(leftAssetType.data, (address));
                (address addressRight) = abi.decode(rightAssetType.data, (address));
                if (addressLeft == addressRight) {
                    return leftAssetType;
                }
            }
            return LibAsset.AssetType(0, EMPTY);
        }
        if (classLeft == LibAsset.ERC721_ASSET_CLASS) {
            if (classRight == LibAsset.ERC721_ASSET_CLASS) {
                (address addressLeft, uint tokenIdLeft) = abi.decode(leftAssetType.data, (address, uint));
                (address addressRight, uint tokenIdRight) = abi.decode(rightAssetType.data, (address, uint));
                if (addressLeft == addressRight && tokenIdLeft == tokenIdRight) {
                    return leftAssetType;
                }
            }
            return LibAsset.AssetType(0, EMPTY);
        }
        if (classLeft == LibAsset.ERC1155_ASSET_CLASS) {
            if (classRight == LibAsset.ERC1155_ASSET_CLASS) {
                (address addressLeft, uint tokenIdLeft) = abi.decode(leftAssetType.data, (address, uint));
                (address addressRight, uint tokenIdRight) = abi.decode(rightAssetType.data, (address, uint));
                if (addressLeft == addressRight && tokenIdLeft == tokenIdRight) {
                    return leftAssetType;
                }
            }
            return LibAsset.AssetType(0, EMPTY);
        }
        address matcher = matchers[classLeft];
        if (matcher != address(0)) {
            return IAssetMatcher(matcher).matchAssets(leftAssetType, rightAssetType);
        }
        if (classLeft == classRight) {
            bytes32 leftHash = keccak256(leftAssetType.data);
            bytes32 rightHash = keccak256(rightAssetType.data);
            if (leftHash == rightHash) {
                return leftAssetType;
            }
        }
        revert("not found IAssetMatcher");
    }

    uint256[49] private __gap;
}

// File: @rarible/royalties/contracts/LibPart.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

library LibPart {
    bytes32 public constant TYPE_HASH = keccak256("Part(address account,uint96 value)");

    struct Part {
        address payable account;
        uint96 value;
    }

    function hash(Part memory part) internal pure returns (bytes32) {
        return keccak256(abi.encode(TYPE_HASH, part.account, part.value));
    }
}

// File: @rarible/royalties/contracts/IRoyaltiesProvider.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;
pragma abicoder v2;

import "./LibPart.sol";

interface IRoyaltiesProvider {
    function getRoyalties(address token, uint tokenId) external returns (LibPart.Part[] memory);
}

// File: @rarible/lib-asset/contracts/LibAsset.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;

library LibAsset {
    bytes4 constant public ETH_ASSET_CLASS = bytes4(keccak256("ETH"));
    bytes4 constant public ERC20_ASSET_CLASS = bytes4(keccak256("ERC20"));
    bytes4 constant public ERC721_ASSET_CLASS = bytes4(keccak256("ERC721"));
    bytes4 constant public ERC1155_ASSET_CLASS = bytes4(keccak256("ERC1155"));

    bytes32 constant ASSET_TYPE_TYPEHASH = keccak256(
        "AssetType(bytes4 assetClass,bytes data)"
    );

    bytes32 constant ASSET_TYPEHASH = keccak256(
        "Asset(AssetType assetType,uint256 value)AssetType(bytes4 assetClass,bytes data)"
    );

    struct AssetType {
        bytes4 assetClass;
        bytes data;
    }

    struct Asset {
        AssetType assetType;
        uint value;
    }

    function hash(AssetType memory assetType) internal pure returns (bytes32) {
        return keccak256(abi.encode(
                ASSET_TYPE_TYPEHASH,
                assetType.assetClass,
                keccak256(assetType.data)
            ));
    }

    function hash(Asset memory asset) internal pure returns (bytes32) {
        return keccak256(abi.encode(
                ASSET_TYPEHASH,
                hash(asset.assetType),
                asset.value
            ));
    }

}

// File: @rarible/exchange-interfaces/contracts/ITransferProxy.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;
pragma abicoder v2;

import "@rarible/lib-asset/contracts/LibAsset.sol";

interface ITransferProxy {
    function transfer(LibAsset.Asset calldata asset, address from, address to) external;
}

// File: @rarible/exchange-interfaces/contracts/INftTransferProxy.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;
pragma abicoder v2;

import "@openzeppelin/contracts-upgradeable/token/ERC721/IERC721Upgradeable.sol";
import "@openzeppelin/contracts-upgradeable/token/ERC1155/IERC1155Upgradeable.sol";

interface INftTransferProxy {
    function erc721safeTransferFrom(IERC721Upgradeable token, address from, address to, uint256 tokenId) external;

    function erc1155safeTransferFrom(IERC1155Upgradeable token, address from, address to, uint256 id, uint256 value, bytes calldata data) external;
}

// File: @rarible/exchange-interfaces/contracts/IERC20TransferProxy.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.9 <0.8.0;
pragma abicoder v2;

import "@openzeppelin/contracts-upgradeable/token/ERC20/IERC20Upgradeable.sol";

interface IERC20TransferProxy {
    function erc20safeTransferFrom(IERC20Upgradeable token, address from, address to, uint256 value) external;
}

// File: @openzeppelin/contracts-upgradeable/utils/ContextUpgradeable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;
import "../proxy/Initializable.sol";

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

    function __Context_init_unchained() internal initializer {
    }
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
    uint256[50] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/utils/AddressUpgradeable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library AddressUpgradeable {
    /**
     * @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);
    }

    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);
            }
        }
    }
}

// File: @openzeppelin/contracts-upgradeable/token/ERC721/IERC721Upgradeable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

import "../../introspection/IERC165Upgradeable.sol";

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721Upgradeable is IERC165Upgradeable {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 tokenId) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);

    /**
      * @dev Safely transfers `tokenId` token from `from` to `to`.
      *
      * Requirements:
      *
      * - `from` cannot be the zero address.
      * - `to` cannot be the zero address.
      * - `tokenId` token must exist and be owned by `from`.
      * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
      * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
      *
      * Emits a {Transfer} event.
      */
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;
}

// File: @openzeppelin/contracts-upgradeable/token/ERC20/IERC20Upgradeable.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 IERC20Upgradeable {
    /**
     * @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-upgradeable/token/ERC1155/IERC1155Upgradeable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

import "../../introspection/IERC165Upgradeable.sol";

/**
 * @dev Required interface of an ERC1155 compliant contract, as defined in the
 * https://eips.ethereum.org/EIPS/eip-1155[EIP].
 *
 * _Available since v3.1._
 */
interface IERC1155Upgradeable is IERC165Upgradeable {
    /**
     * @dev Emitted when `value` tokens of token type `id` are transferred from `from` to `to` by `operator`.
     */
    event TransferSingle(address indexed operator, address indexed from, address indexed to, uint256 id, uint256 value);

    /**
     * @dev Equivalent to multiple {TransferSingle} events, where `operator`, `from` and `to` are the same for all
     * transfers.
     */
    event TransferBatch(address indexed operator, address indexed from, address indexed to, uint256[] ids, uint256[] values);

    /**
     * @dev Emitted when `account` grants or revokes permission to `operator` to transfer their tokens, according to
     * `approved`.
     */
    event ApprovalForAll(address indexed account, address indexed operator, bool approved);

    /**
     * @dev Emitted when the URI for token type `id` changes to `value`, if it is a non-programmatic URI.
     *
     * If an {URI} event was emitted for `id`, the standard
     * https://eips.ethereum.org/EIPS/eip-1155#metadata-extensions[guarantees] that `value` will equal the value
     * returned by {IERC1155MetadataURI-uri}.
     */
    event URI(string value, uint256 indexed id);

    /**
     * @dev Returns the amount of tokens of token type `id` owned by `account`.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function balanceOf(address account, uint256 id) external view returns (uint256);

    /**
     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {balanceOf}.
     *
     * Requirements:
     *
     * - `accounts` and `ids` must have the same length.
     */
    function balanceOfBatch(address[] calldata accounts, uint256[] calldata ids) external view returns (uint256[] memory);

    /**
     * @dev Grants or revokes permission to `operator` to transfer the caller's tokens, according to `approved`,
     *
     * Emits an {ApprovalForAll} event.
     *
     * Requirements:
     *
     * - `operator` cannot be the caller.
     */
    function setApprovalForAll(address operator, bool approved) external;

    /**
     * @dev Returns true if `operator` is approved to transfer ``account``'s tokens.
     *
     * See {setApprovalForAll}.
     */
    function isApprovedForAll(address account, address operator) external view returns (bool);

    /**
     * @dev Transfers `amount` tokens of token type `id` from `from` to `to`.
     *
     * Emits a {TransferSingle} event.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - If the caller is not `from`, it must be have been approved to spend ``from``'s tokens via {setApprovalForAll}.
     * - `from` must have a balance of tokens of type `id` of at least `amount`.
     * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
     * acceptance magic value.
     */
    function safeTransferFrom(address from, address to, uint256 id, uint256 amount, bytes calldata data) external;

    /**
     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {safeTransferFrom}.
     *
     * Emits a {TransferBatch} event.
     *
     * Requirements:
     *
     * - `ids` and `amounts` must have the same length.
     * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155BatchReceived} and return the
     * acceptance magic value.
     */
    function safeBatchTransferFrom(address from, address to, uint256[] calldata ids, uint256[] calldata amounts, bytes calldata data) external;
}

// File: @openzeppelin/contracts-upgradeable/proxy/Initializable.sol



// SPDX-License-Identifier: MIT

// solhint-disable-next-line compiler-version
pragma solidity >=0.4.24 <0.8.0;

import "../utils/AddressUpgradeable.sol";

/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {UpgradeableProxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 */
abstract contract Initializable {

    /**
     * @dev Indicates that the contract has been initialized.
     */
    bool private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Modifier to protect an initializer function from being invoked twice.
     */
    modifier initializer() {
        require(_initializing || _isConstructor() || !_initialized, "Initializable: contract is already initialized");

        bool isTopLevelCall = !_initializing;
        if (isTopLevelCall) {
            _initializing = true;
            _initialized = true;
        }

        _;

        if (isTopLevelCall) {
            _initializing = false;
        }
    }

    /// @dev Returns true if and only if the function is running in the constructor
    function _isConstructor() private view returns (bool) {
        return !AddressUpgradeable.isContract(address(this));
    }
}

// File: @openzeppelin/contracts-upgradeable/math/SafeMathUpgradeable.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 SafeMathUpgradeable {
    /**
     * @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-upgradeable/math/MathUpgradeable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library MathUpgradeable {
    /**
     * @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);
    }
}

// File: @openzeppelin/contracts-upgradeable/introspection/IERC165Upgradeable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165Upgradeable {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: @openzeppelin/contracts-upgradeable/drafts/EIP712Upgradeable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;
import "../proxy/Initializable.sol";

/**
 * @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
 *
 * The encoding specified in the EIP is very generic, and such a generic implementation in Solidity is not feasible,
 * thus this contract does not implement the encoding itself. Protocols need to implement the type-specific encoding
 * they need in their contracts using a combination of `abi.encode` and `keccak256`.
 *
 * This contract implements the EIP 712 domain separator ({_domainSeparatorV4}) that is used as part of the encoding
 * scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
 * ({_hashTypedDataV4}).
 *
 * The implementation of the domain separator was designed to be as efficient as possible while still properly updating
 * the chain id to protect against replay attacks on an eventual fork of the chain.
 *
 * NOTE: This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
 * https://docs.metamask.io/guide/signing-data.html[`eth_signTypedDataV4` in MetaMask].
 *
 * _Available since v3.4._
 */
abstract contract EIP712Upgradeable is Initializable {
    /* solhint-disable var-name-mixedcase */
    bytes32 private _HASHED_NAME;
    bytes32 private _HASHED_VERSION;
    bytes32 private constant _TYPE_HASH = keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)");
    /* solhint-enable var-name-mixedcase */

    /**
     * @dev Initializes the domain separator and parameter caches.
     *
     * The meaning of `name` and `version` is specified in
     * https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator[EIP 712]:
     *
     * - `name`: the user readable name of the signing domain, i.e. the name of the DApp or the protocol.
     * - `version`: the current major version of the signing domain.
     *
     * NOTE: These parameters cannot be changed except through a xref:learn::upgrading-smart-contracts.adoc[smart
     * contract upgrade].
     */
    function __EIP712_init(string memory name, string memory version) internal initializer {
        __EIP712_init_unchained(name, version);
    }

    function __EIP712_init_unchained(string memory name, string memory version) internal initializer {
        bytes32 hashedName = keccak256(bytes(name));
        bytes32 hashedVersion = keccak256(bytes(version));
        _HASHED_NAME = hashedName;
        _HASHED_VERSION = hashedVersion;
    }

    /**
     * @dev Returns the domain separator for the current chain.
     */
    function _domainSeparatorV4() internal view returns (bytes32) {
        return _buildDomainSeparator(_TYPE_HASH, _EIP712NameHash(), _EIP712VersionHash());
    }

    function _buildDomainSeparator(bytes32 typeHash, bytes32 name, bytes32 version) private view returns (bytes32) {
        return keccak256(
            abi.encode(
                typeHash,
                name,
                version,
                _getChainId(),
                address(this)
            )
        );
    }

    /**
     * @dev Given an already https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct[hashed struct], this
     * function returns the hash of the fully encoded EIP712 message for this domain.
     *
     * This hash can be used together with {ECDSA-recover} to obtain the signer of a message. For example:
     *
     * ```solidity
     * bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
     *     keccak256("Mail(address to,string contents)"),
     *     mailTo,
     *     keccak256(bytes(mailContents))
     * )));
     * address signer = ECDSA.recover(digest, signature);
     * ```
     */
    function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
        return keccak256(abi.encodePacked("\x19\x01", _domainSeparatorV4(), structHash));
    }

    function _getChainId() private view returns (uint256 chainId) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        // solhint-disable-next-line no-inline-assembly
        assembly {
            chainId := chainid()
        }
    }

    /**
     * @dev The hash of the name parameter for the EIP712 domain.
     *
     * NOTE: This function reads from storage by default, but can be redefined to return a constant value if gas costs
     * are a concern.
     */
    function _EIP712NameHash() internal virtual view returns (bytes32) {
        return _HASHED_NAME;
    }

    /**
     * @dev The hash of the version parameter for the EIP712 domain.
     *
     * NOTE: This function reads from storage by default, but can be redefined to return a constant value if gas costs
     * are a concern.
     */
    function _EIP712VersionHash() internal virtual view returns (bytes32) {
        return _HASHED_VERSION;
    }
    uint256[50] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/cryptography/ECDSAUpgradeable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSAUpgradeable {
    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature`. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     */
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        // Check the signature length
        if (signature.length != 65) {
            revert("ECDSA: invalid signature length");
        }

        // Divide the signature in r, s and v variables
        bytes32 r;
        bytes32 s;
        uint8 v;

        // ecrecover takes the signature parameters, and the only way to get them
        // currently is to use assembly.
        // solhint-disable-next-line no-inline-assembly
        assembly {
            r := mload(add(signature, 0x20))
            s := mload(add(signature, 0x40))
            v := byte(0, mload(add(signature, 0x60)))
        }

        return recover(hash, v, r, s);
    }

    /**
     * @dev Overload of {ECDSA-recover-bytes32-bytes-} that receives the `v`,
     * `r` and `s` signature fields separately.
     */
    function recover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal pure returns (address) {
        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (281): 0 < s < secp256k1n ÷ 2 + 1, and for v in (282): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        require(uint256(s) <= 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0, "ECDSA: invalid signature 's' value");
        require(v == 27 || v == 28, "ECDSA: invalid signature 'v' value");

        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(hash, v, r, s);
        require(signer != address(0), "ECDSA: invalid signature");

        return signer;
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from a `hash`. This
     * replicates the behavior of the
     * https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_sign[`eth_sign`]
     * JSON-RPC method.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
        // 32 is the length in bytes of hash,
        // enforced by the type signature above
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
    }
}

// File: @openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "../utils/ContextUpgradeable.sol";
import "../proxy/Initializable.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 OwnableUpgradeable is Initializable, ContextUpgradeable {
    address private _owner;

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    function __Ownable_init() internal initializer {
        __Context_init_unchained();
        __Ownable_init_unchained();
    }

    function __Ownable_init_unchained() internal initializer {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

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

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

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
    uint256[49] private __gap;
}