contract Broker is
    IBroker,
    MixinWethUtils
{
    // Contract addresses

    // Address of the 0x Exchange contract
    address internal EXCHANGE;
    // Address of the 0x ERC1155 Asset Proxy contract
    address internal ERC1155_PROXY;

    // The following storage variables are used to cache data for the duration of the transcation.
    // They should always cleared at the end of the transaction.

    // Token IDs specified by the taker to be used to fill property-based orders.
    uint256[] internal _cachedTokenIds;
    // An index to the above array keeping track of which assets have been transferred.
    uint256 internal _cacheIndex;
    // The address that called `brokerTrade` or `batchBrokerTrade`. Assets will be transferred to
    // and from this address as the effectual taker of the orders.
    address internal _sender;

    using LibSafeMath for uint256;
    using LibBytes for bytes;
    using LibAssetDataTransfer for bytes;

    /// @param exchange Address of the 0x Exchange contract.
    /// @param exchange Address of the Wrapped Ether contract.
    /// @param exchange Address of the 0x ERC1155 Asset Proxy contract.
    constructor (
        address exchange,
        address weth
    )
        public
        MixinWethUtils(
            exchange,
            weth
        )
    {
        EXCHANGE = exchange;
        ERC1155_PROXY = IExchange(EXCHANGE).getAssetProxy(IAssetData(address(0)).ERC1155Assets.selector);
    }

    /// @dev The Broker implements the ERC1155 transfer function to be compatible with the ERC1155 asset proxy
    /// @param from Since the Broker serves as the taker of the order, this should equal `address(this)`
    /// @param to This should be the maker of the order.
    /// @param amounts Should be an array of just one `uint256`, specifying the amount of the brokered assets to transfer.
    /// @param data Encodes the validator contract address and any auxiliary data it needs for property validation.
    function safeBatchTransferFrom(
        address from,
        address to,
        uint256[] calldata /* ids */,
        uint256[] calldata amounts,
        bytes calldata data
    )
        external
    {
        // Only the ERC1155 asset proxy contract should be calling this function.
        if (msg.sender != ERC1155_PROXY) {
            LibRichErrors.rrevert(LibBrokerRichErrors.OnlyERC1155ProxyError(
                msg.sender
            ));
        }
        // Only `takerAssetData` should be using Broker assets
        if (from != address(this)) {
            LibRichErrors.rrevert(
                LibBrokerRichErrors.InvalidFromAddressError(from)
            );
        }
        // Only one asset amount should be specified.
        if (amounts.length != 1) {
            LibRichErrors.rrevert(
                LibBrokerRichErrors.AmountsLengthMustEqualOneError(amounts.length)
            );
        }

        uint256 cacheIndex = _cacheIndex;
        uint256 remainingAmount = amounts[0];

        // Verify that there are enough broker assets to transfer
        if (_cachedTokenIds.length.safeSub(cacheIndex) < remainingAmount) {
            LibRichErrors.rrevert(
                LibBrokerRichErrors.TooFewBrokerAssetsProvidedError(_cachedTokenIds.length)
            );
        }

        // Decode validator and params from `data`
        (address tokenAddress, address validator, bytes memory propertyData) = abi.decode(
            data,
            (address, address, bytes)
        );

        while (remainingAmount != 0) {
            uint256 tokenId = _cachedTokenIds[cacheIndex];
            cacheIndex++;

            // Validate asset properties
            IPropertyValidator(validator).checkBrokerAsset(
                tokenId,
                propertyData
            );

            // Perform the transfer
            IERC721Token(tokenAddress).transferFrom(
                _sender,
                to,
                tokenId
            );

            remainingAmount--;
        }
        // Update cache index in storage
        _cacheIndex = cacheIndex;
    }

    /// @dev Fills a single property-based order by the given amount using the given assets.
    ///      Pays protocol fees using either the ETH supplied by the taker to the transaction or
    ///      WETH acquired from the maker during settlement. The final WETH balance is sent to the taker.
    /// @param brokeredTokenIds Token IDs specified by the taker to be used to fill the orders.
    /// @param order The property-based order to fill. The format of a property-based order is the
    ///        same as that of a normal order, except the takerAssetData. Instaed of specifying a
    ///        specific ERC721 asset, the takerAssetData should be ERC1155 assetData where the
    ///        underlying tokenAddress is this contract's address and the desired properties are
    ///        encoded in the extra data field. Also note that takerFees must be denominated in
    ///        WETH (or zero).
    /// @param takerAssetFillAmount The amount to fill the order by.
    /// @param signature The maker's signature of the given order.
    /// @param fillFunctionSelector The selector for either `fillOrder` or `fillOrKillOrder`.
    /// @param ethFeeAmounts Amounts of ETH, denominated in Wei, that are paid to corresponding feeRecipients.
    /// @param feeRecipients Addresses that will receive ETH when orders are filled.
    /// @return fillResults Amounts filled and fees paid by the maker and taker.
    function brokerTrade(
        uint256[] memory brokeredTokenIds,
        LibOrder.Order memory order,
        uint256 takerAssetFillAmount,
        bytes memory signature,
        bytes4 fillFunctionSelector,
        uint256[] memory ethFeeAmounts,
        address payable[] memory feeRecipients
    )
        public
        payable
        returns (LibFillResults.FillResults memory fillResults)
    {
        // Cache the taker-supplied asset data
        _cachedTokenIds = brokeredTokenIds;
        // Cache the sender's address
        _sender = msg.sender;

        // Sanity-check the provided function selector
        if (
            fillFunctionSelector != IExchange(address(0)).fillOrder.selector &&
            fillFunctionSelector != IExchange(address(0)).fillOrKillOrder.selector
        ) {
            LibBrokerRichErrors.InvalidFunctionSelectorError(fillFunctionSelector);
        }

        // Pay ETH affiliate fees to all feeRecipient addresses
        _transferEthFeesAndWrapRemaining(ethFeeAmounts, feeRecipients);

        // Perform the fill
        bytes memory fillCalldata = abi.encodeWithSelector(
            fillFunctionSelector,
            order,
            takerAssetFillAmount,
            signature
        );
        // solhint-disable-next-line avoid-call-value
        (bool didSucceed, bytes memory returnData) = EXCHANGE.call(fillCalldata);
        if (didSucceed) {
            fillResults = abi.decode(returnData, (LibFillResults.FillResults));
        } else {
            // Re-throw error
            LibRichErrors.rrevert(returnData);
        }

        // Transfer maker asset to taker
        if (!order.makerAssetData.equals(WETH_ASSET_DATA)) {
            order.makerAssetData.transferOut(fillResults.makerAssetFilledAmount);
        }

        // Refund remaining ETH to msg.sender.
        _unwrapAndTransferEth(WETH.balanceOf(address(this)));

        _clearStorage();

        return fillResults;
    }

    /// @dev Fills multiple property-based orders by the given amounts using the given assets.
    ///      Pays protocol fees using either the ETH supplied by the taker to the transaction or
    ///      WETH acquired from the maker during settlement. The final WETH balance is sent to the taker.
    /// @param brokeredTokenIds Token IDs specified by the taker to be used to fill the orders.
    /// @param orders The property-based orders to fill. The format of a property-based order is the
    ///        same as that of a normal order, except the takerAssetData. Instaed of specifying a
    ///        specific ERC721 asset, the takerAssetData should be ERC1155 assetData where the
    ///        underlying tokenAddress is this contract's address and the desired properties are
    ///        encoded in the extra data field. Also note that takerFees must be denominated in
    ///        WETH (or zero).
    /// @param takerAssetFillAmounts The amounts to fill the orders by.
    /// @param signatures The makers' signatures for the given orders.
    /// @param batchFillFunctionSelector The selector for either `batchFillOrders`,
    ///        `batchFillOrKillOrders`, or `batchFillOrdersNoThrow`.
    /// @param ethFeeAmounts Amounts of ETH, denominated in Wei, that are paid to corresponding feeRecipients.
    /// @param feeRecipients Addresses that will receive ETH when orders are filled.
    /// @return fillResults Amounts filled and fees paid by the makers and taker.
    function batchBrokerTrade(
        uint256[] memory brokeredTokenIds,
        LibOrder.Order[] memory orders,
        uint256[] memory takerAssetFillAmounts,
        bytes[] memory signatures,
        bytes4 batchFillFunctionSelector,
        uint256[] memory ethFeeAmounts,
        address payable[] memory feeRecipients
    )
        public
        payable
        returns (LibFillResults.FillResults[] memory fillResults)
    {
        // Cache the taker-supplied asset data
        _cachedTokenIds = brokeredTokenIds;
        // Cache the sender's address
        _sender = msg.sender;

        // Sanity-check the provided function selector
        if (
            batchFillFunctionSelector != IExchange(address(0)).batchFillOrders.selector &&
            batchFillFunctionSelector != IExchange(address(0)).batchFillOrKillOrders.selector &&
            batchFillFunctionSelector != IExchange(address(0)).batchFillOrdersNoThrow.selector
        ) {
            LibBrokerRichErrors.InvalidFunctionSelectorError(batchFillFunctionSelector);
        }

        // Pay ETH affiliate fees to all feeRecipient addresses
        _transferEthFeesAndWrapRemaining(ethFeeAmounts, feeRecipients);

        // Perform the batch fill
        bytes memory batchFillCalldata = abi.encodeWithSelector(
            batchFillFunctionSelector,
            orders,
            takerAssetFillAmounts,
            signatures
        );
        // solhint-disable-next-line avoid-call-value
        (bool didSucceed, bytes memory returnData) = EXCHANGE.call(batchFillCalldata);
        if (didSucceed) {
            // solhint-disable-next-line indent
            fillResults = abi.decode(returnData, (LibFillResults.FillResults[]));
        } else {
            // Re-throw error
            LibRichErrors.rrevert(returnData);
        }

        // Transfer maker assets to taker
        for (uint256 i = 0; i < orders.length; i++) {
            if (!orders[i].makerAssetData.equals(WETH_ASSET_DATA)) {
                orders[i].makerAssetData.transferOut(fillResults[i].makerAssetFilledAmount);
            }
        }

        // Refund remaining ETH to msg.sender.
        _unwrapAndTransferEth(WETH.balanceOf(address(this)));

        _clearStorage();

        return fillResults;
    }

    function _clearStorage()
        private
    {
        delete _cachedTokenIds;
        _cacheIndex = 0;
        _sender = address(0);
    }
}
// solhint-disable space-after-comma, var-name-mixedcase
function brokerTrade(
        uint256[] memory brokeredTokenIds,
        LibOrder.Order memory order,
        uint256 takerAssetFillAmount,
        bytes memory signature,
        bytes4 fillFunctionSelector,
        uint256[] memory ethFeeAmounts,
        address payable[] memory feeRecipients
    )
        public
        payable
        returns (LibFillResults.FillResults memory fillResults)
    {
        // Cache the taker-supplied asset data
        _cachedTokenIds = brokeredTokenIds;
        // Cache the sender's address
        _sender = msg.sender;

        // Sanity-check the provided function selector
        if (
            fillFunctionSelector != IExchange(address(0)).fillOrder.selector &&
            fillFunctionSelector != IExchange(address(0)).fillOrKillOrder.selector
        ) {
            LibBrokerRichErrors.InvalidFunctionSelectorError(fillFunctionSelector);
        }

        // Pay ETH affiliate fees to all feeRecipient addresses
        _transferEthFeesAndWrapRemaining(ethFeeAmounts, feeRecipients);

        // Perform the fill
        bytes memory fillCalldata = abi.encodeWithSelector(
            fillFunctionSelector,
            order,
            takerAssetFillAmount,
            signature
        );
        // solhint-disable-next-line avoid-call-value
        (bool didSucceed, bytes memory returnData) = EXCHANGE.call(fillCalldata);
        if (didSucceed) {
            fillResults = abi.decode(returnData, (LibFillResults.FillResults));
        } else {
            // Re-throw error
            LibRichErrors.rrevert(returnData);
        }

        // Transfer maker asset to taker
        if (!order.makerAssetData.equals(WETH_ASSET_DATA)) {
            order.makerAssetData.transferOut(fillResults.makerAssetFilledAmount);
        }

        // Refund remaining ETH to msg.sender.
        _unwrapAndTransferEth(WETH.balanceOf(address(this)));

        _clearStorage();

        return fillResults;
    }
/// @dev Fills a single property-based order by the given amount using the given assets.
///      Pays protocol fees using either the ETH supplied by the taker to the transaction or
///      WETH acquired from the maker during settlement. The final WETH balance is sent to the taker.
/// @param brokeredTokenIds Token IDs specified by the taker to be used to fill the orders.
/// @param order The property-based order to fill. The format of a property-based order is the
///        same as that of a normal order, except the takerAssetData. Instaed of specifying a
///        specific ERC721 asset, the takerAssetData should be ERC1155 assetData where the
///        underlying tokenAddress is this contract's address and the desired properties are
///        encoded in the extra data field. Also note that takerFees must be denominated in
///        WETH (or zero).
/// @param takerAssetFillAmount The amount to fill the order by.
/// @param signature The maker's signature of the given order.
/// @param fillFunctionSelector The selector for either `fillOrder` or `fillOrKillOrder`.
/// @param ethFeeAmounts Amounts of ETH, denominated in Wei, that are paid to corresponding feeRecipients.
/// @param feeRecipients Addresses that will receive ETH when orders are filled.
/// @return fillResults Amounts filled and fees paid by the maker and taker.