// File: contracts/helpers/TransferHelper.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

import { IERC721Receiver } from "../interfaces/IERC721Receiver.sol";

import "./TransferHelperStructs.sol";

import { ConduitInterface } from "../interfaces/ConduitInterface.sol";

import {
    ConduitControllerInterface
} from "../interfaces/ConduitControllerInterface.sol";

import { Conduit } from "../conduit/Conduit.sol";

import { ConduitTransfer } from "../conduit/lib/ConduitStructs.sol";

import {
    TransferHelperInterface
} from "../interfaces/TransferHelperInterface.sol";

import { TransferHelperErrors } from "../interfaces/TransferHelperErrors.sol";

/**
 * @title TransferHelper
 * @author stephankmin, stuckinaboot, ryanio
 * @notice TransferHelper is a utility contract for transferring
 *         ERC20/ERC721/ERC1155 items in bulk to specific recipients.
 */
contract TransferHelper is TransferHelperInterface, TransferHelperErrors {
    // Allow for interaction with the conduit controller.
    ConduitControllerInterface internal immutable _CONDUIT_CONTROLLER;

    // Set conduit creation code and runtime code hashes as immutable arguments.
    bytes32 internal immutable _CONDUIT_CREATION_CODE_HASH;
    bytes32 internal immutable _CONDUIT_RUNTIME_CODE_HASH;

    /**
     * @dev Set the supplied conduit controller and retrieve its
     *      conduit creation code hash.
     *
     *
     * @param conduitController A contract that deploys conduits, or proxies
     *                          that may optionally be used to transfer approved
     *                          ERC20/721/1155 tokens.
     */
    constructor(address conduitController) {
        // Get the conduit creation code and runtime code hashes from the
        // supplied conduit controller and set them as an immutable.
        ConduitControllerInterface controller = ConduitControllerInterface(
            conduitController
        );
        (_CONDUIT_CREATION_CODE_HASH, _CONDUIT_RUNTIME_CODE_HASH) = controller
            .getConduitCodeHashes();

        // Set the supplied conduit controller as an immutable.
        _CONDUIT_CONTROLLER = controller;
    }

    /**
     * @notice Transfer multiple ERC20/ERC721/ERC1155 items to
     *         specified recipients.
     *
     * @param items      The items to transfer to an intended recipient.
     * @param conduitKey An optional conduit key referring to a conduit through
     *                   which the bulk transfer should occur.
     *
     * @return magicValue A value indicating that the transfers were successful.
     */
    function bulkTransfer(
        TransferHelperItemsWithRecipient[] calldata items,
        bytes32 conduitKey
    ) external override returns (bytes4 magicValue) {
        // Ensure that a conduit key has been supplied.
        if (conduitKey == bytes32(0)) {
            revert InvalidConduit(conduitKey, address(0));
        }

        // Use conduit derived from supplied conduit key to perform transfers.
        _performTransfersWithConduit(items, conduitKey);

        // Return a magic value indicating that the transfers were performed.
        magicValue = this.bulkTransfer.selector;
    }

    /**
     * @notice Perform multiple transfers to specified recipients via the
     *         conduit derived from the provided conduit key.
     *
     * @param transfers  The items to transfer.
     * @param conduitKey The conduit key referring to the conduit through
     *                   which the bulk transfer should occur.
     */
    function _performTransfersWithConduit(
        TransferHelperItemsWithRecipient[] calldata transfers,
        bytes32 conduitKey
    ) internal {
        // Retrieve total number of transfers and place on stack.
        uint256 numTransfers = transfers.length;

        // Derive the conduit address from the deployer, conduit key
        // and creation code hash.
        address conduit = address(
            uint160(
                uint256(
                    keccak256(
                        abi.encodePacked(
                            bytes1(0xff),
                            address(_CONDUIT_CONTROLLER),
                            conduitKey,
                            _CONDUIT_CREATION_CODE_HASH
                        )
                    )
                )
            )
        );

        // Declare a variable to store the sum of all items across transfers.
        uint256 sumOfItemsAcrossAllTransfers;

        // Skip overflow checks: all for loops are indexed starting at zero.
        unchecked {
            // Iterate over each transfer.
            for (uint256 i = 0; i < numTransfers; ++i) {
                // Retrieve the transfer in question.
                TransferHelperItemsWithRecipient calldata transfer = transfers[
                    i
                ];

                // Increment totalItems by the number of items in the transfer.
                sumOfItemsAcrossAllTransfers += transfer.items.length;
            }
        }

        // Declare a new array in memory with length totalItems to populate with
        // each conduit transfer.
        ConduitTransfer[] memory conduitTransfers = new ConduitTransfer[](
            sumOfItemsAcrossAllTransfers
        );

        // Declare an index for storing ConduitTransfers in conduitTransfers.
        uint256 itemIndex;

        // Skip overflow checks: all for loops are indexed starting at zero.
        unchecked {
            // Iterate over each transfer.
            for (uint256 i = 0; i < numTransfers; ++i) {
                // Retrieve the transfer in question.
                TransferHelperItemsWithRecipient calldata transfer = transfers[
                    i
                ];

                // Retrieve the items of the transfer in question.
                TransferHelperItem[] calldata transferItems = transfer.items;

                // Ensure recipient is not the zero address.
                _checkRecipientIsNotZeroAddress(transfer.recipient);

                // Create a boolean indicating whether validateERC721Receiver
                // is true and recipient is a contract.
                bool callERC721Receiver = transfer.validateERC721Receiver &&
                    transfer.recipient.code.length != 0;

                // Retrieve the total number of items in the transfer and
                // place on stack.
                uint256 numItemsInTransfer = transferItems.length;

                // Iterate over each item in the transfer to create a
                // corresponding ConduitTransfer.
                for (uint256 j = 0; j < numItemsInTransfer; ++j) {
                    // Retrieve the item from the transfer.
                    TransferHelperItem calldata item = transferItems[j];

                    if (item.itemType == ConduitItemType.ERC20) {
                        // Ensure that the identifier of an ERC20 token is 0.
                        if (item.identifier != 0) {
                            revert InvalidERC20Identifier();
                        }
                    }

                    // If the item is an ERC721 token and
                    // callERC721Receiver is true...
                    if (item.itemType == ConduitItemType.ERC721) {
                        if (callERC721Receiver) {
                            // Check if the recipient implements
                            // onERC721Received for the given tokenId.
                            _checkERC721Receiver(
                                conduit,
                                transfer.recipient,
                                item.identifier
                            );
                        }
                    }

                    // Create a ConduitTransfer corresponding to each
                    // TransferHelperItem.
                    conduitTransfers[itemIndex] = ConduitTransfer(
                        item.itemType,
                        item.token,
                        msg.sender,
                        transfer.recipient,
                        item.identifier,
                        item.amount
                    );

                    // Increment the index for storing ConduitTransfers.
                    ++itemIndex;
                }
            }
        }

        // Attempt the external call to transfer tokens via the derived conduit.
        try ConduitInterface(conduit).execute(conduitTransfers) returns (
            bytes4 conduitMagicValue
        ) {
            // Check if the value returned from the external call matches
            // the conduit `execute` selector.
            if (conduitMagicValue != ConduitInterface.execute.selector) {
                // If the external call fails, revert with the conduit key
                // and conduit address.
                revert InvalidConduit(conduitKey, conduit);
            }
        } catch Error(string memory reason) {
            // Catch reverts with a provided reason string and
            // revert with the reason, conduit key and conduit address.
            revert ConduitErrorRevertString(reason, conduitKey, conduit);
        } catch (bytes memory data) {
            // Conduits will throw a custom error when attempting to transfer
            // native token item types or an ERC721 item amount other than 1.
            // Bubble up these custom errors when encountered. Note that the
            // conduit itself will bubble up revert reasons from transfers as
            // well, meaning that these errors are not necessarily indicative of
            // an issue with the item type or amount in cases where the same
            // custom error signature is encountered during a conduit transfer.

            // Set initial value of first four bytes of revert data to the mask.
            bytes4 customErrorSelector = bytes4(0xffffffff);

            // Utilize assembly to read first four bytes (if present) directly.
            assembly {
                // Combine original mask with first four bytes of revert data.
                customErrorSelector := and(
                    mload(add(data, 0x20)), // Data begins after length offset.
                    customErrorSelector
                )
            }

            // Pass through the custom error in question if the revert data is
            // the correct length and matches an expected custom error selector.
            if (
                data.length == 4 &&
                (customErrorSelector == InvalidItemType.selector ||
                    customErrorSelector == InvalidERC721TransferAmount.selector)
            ) {
                // "Bubble up" the revert reason.
                assembly {
                    revert(add(data, 0x20), 0x04)
                }
            }

            // Catch all other reverts from the external call to the conduit and
            // include the conduit's raw revert reason as a data argument to a
            // new custom error.
            revert ConduitErrorRevertBytes(data, conduitKey, conduit);
        }
    }

    /**
     * @notice An internal function to check if a recipient address implements
     *         onERC721Received for a given tokenId. Note that this check does
     *         not adhere to the safe transfer specification and is only meant
     *         to provide an additional layer of assurance that the recipient
     *         can receive the tokens — any hooks or post-transfer checks will
     *         fail and the caller will be the transfer helper rather than the
     *         ERC721 contract. Note that the conduit is set as the operator, as
     *         it will be the caller once the transfer is performed.
     *
     * @param conduit   The conduit to provide as the operator when calling
     *                  onERC721Received.
     * @param recipient The ERC721 recipient on which to call onERC721Received.
     * @param tokenId   The ERC721 tokenId of the token being transferred.
     */
    function _checkERC721Receiver(
        address conduit,
        address recipient,
        uint256 tokenId
    ) internal {
        // Check if recipient can receive ERC721 tokens.
        try
            IERC721Receiver(recipient).onERC721Received(
                conduit,
                msg.sender,
                tokenId,
                ""
            )
        returns (bytes4 selector) {
            // Check if onERC721Received selector is valid.
            if (selector != IERC721Receiver.onERC721Received.selector) {
                // Revert if recipient cannot accept
                // ERC721 tokens.
                revert InvalidERC721Recipient(recipient);
            }
        } catch (bytes memory data) {
            // "Bubble up" recipient's revert reason.
            revert ERC721ReceiverErrorRevertBytes(
                data,
                recipient,
                msg.sender,
                tokenId
            );
        } catch Error(string memory reason) {
            // "Bubble up" recipient's revert reason.
            revert ERC721ReceiverErrorRevertString(
                reason,
                recipient,
                msg.sender,
                tokenId
            );
        }
    }

    /**
     * @notice An internal function that reverts if the passed-in recipient
     *         is the zero address.
     *
     * @param recipient The recipient on which to perform the check.
     */
    function _checkRecipientIsNotZeroAddress(address recipient) internal pure {
        // Revert if the recipient is the zero address.
        if (recipient == address(0x0)) {
            revert RecipientCannotBeZeroAddress();
        }
    }
}

// File: contracts/interfaces/IERC721Receiver.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

interface IERC721Receiver {
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}

// File: contracts/helpers/TransferHelperStructs.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

import { ConduitItemType } from "../conduit/lib/ConduitEnums.sol";

/**
 * @dev A TransferHelperItem specifies the itemType (ERC20/ERC721/ERC1155),
 *      token address, token identifier, and amount of the token to be
 *      transferred via the TransferHelper. For ERC20 tokens, identifier
 *      must be 0. For ERC721 tokens, amount must be 1.
 */
struct TransferHelperItem {
    ConduitItemType itemType;
    address token;
    uint256 identifier;
    uint256 amount;
}

/**
 * @dev A TransferHelperItemsWithRecipient specifies the tokens to transfer
 *      via the TransferHelper, their intended recipient, and a boolean flag
 *      indicating whether onERC721Received should be called on a recipient
 *      contract.
 */
struct TransferHelperItemsWithRecipient {
    TransferHelperItem[] items;
    address recipient;
    bool validateERC721Receiver;
}

// File: contracts/interfaces/ConduitInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

import {
    ConduitTransfer,
    ConduitBatch1155Transfer
} from "../conduit/lib/ConduitStructs.sol";

/**
 * @title ConduitInterface
 * @author 0age
 * @notice ConduitInterface contains all external function interfaces, events,
 *         and errors for conduit contracts.
 */
interface ConduitInterface {
    /**
     * @dev Revert with an error when attempting to execute transfers using a
     *      caller that does not have an open channel.
     */
    error ChannelClosed(address channel);

    /**
     * @dev Revert with an error when attempting to update a channel to the
     *      current status of that channel.
     */
    error ChannelStatusAlreadySet(address channel, bool isOpen);

    /**
     * @dev Revert with an error when attempting to execute a transfer for an
     *      item that does not have an ERC20/721/1155 item type.
     */
    error InvalidItemType();

    /**
     * @dev Revert with an error when attempting to update the status of a
     *      channel from a caller that is not the conduit controller.
     */
    error InvalidController();

    /**
     * @dev Emit an event whenever a channel is opened or closed.
     *
     * @param channel The channel that has been updated.
     * @param open    A boolean indicating whether the conduit is open or not.
     */
    event ChannelUpdated(address indexed channel, bool open);

    /**
     * @notice Execute a sequence of ERC20/721/1155 transfers. Only a caller
     *         with an open channel can call this function.
     *
     * @param transfers The ERC20/721/1155 transfers to perform.
     *
     * @return magicValue A magic value indicating that the transfers were
     *                    performed successfully.
     */
    function execute(ConduitTransfer[] calldata transfers)
        external
        returns (bytes4 magicValue);

    /**
     * @notice Execute a sequence of batch 1155 transfers. Only a caller with an
     *         open channel can call this function.
     *
     * @param batch1155Transfers The 1155 batch transfers to perform.
     *
     * @return magicValue A magic value indicating that the transfers were
     *                    performed successfully.
     */
    function executeBatch1155(
        ConduitBatch1155Transfer[] calldata batch1155Transfers
    ) external returns (bytes4 magicValue);

    /**
     * @notice Execute a sequence of transfers, both single and batch 1155. Only
     *         a caller with an open channel can call this function.
     *
     * @param standardTransfers  The ERC20/721/1155 transfers to perform.
     * @param batch1155Transfers The 1155 batch transfers to perform.
     *
     * @return magicValue A magic value indicating that the transfers were
     *                    performed successfully.
     */
    function executeWithBatch1155(
        ConduitTransfer[] calldata standardTransfers,
        ConduitBatch1155Transfer[] calldata batch1155Transfers
    ) external returns (bytes4 magicValue);

    /**
     * @notice Open or close a given channel. Only callable by the controller.
     *
     * @param channel The channel to open or close.
     * @param isOpen  The status of the channel (either open or closed).
     */
    function updateChannel(address channel, bool isOpen) external;
}

// File: contracts/interfaces/ConduitControllerInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

/**
 * @title ConduitControllerInterface
 * @author 0age
 * @notice ConduitControllerInterface contains all external function interfaces,
 *         structs, events, and errors for the conduit controller.
 */
interface ConduitControllerInterface {
    /**
     * @dev Track the conduit key, current owner, new potential owner, and open
     *      channels for each deployed conduit.
     */
    struct ConduitProperties {
        bytes32 key;
        address owner;
        address potentialOwner;
        address[] channels;
        mapping(address => uint256) channelIndexesPlusOne;
    }

    /**
     * @dev Emit an event whenever a new conduit is created.
     *
     * @param conduit    The newly created conduit.
     * @param conduitKey The conduit key used to create the new conduit.
     */
    event NewConduit(address conduit, bytes32 conduitKey);

    /**
     * @dev Emit an event whenever conduit ownership is transferred.
     *
     * @param conduit       The conduit for which ownership has been
     *                      transferred.
     * @param previousOwner The previous owner of the conduit.
     * @param newOwner      The new owner of the conduit.
     */
    event OwnershipTransferred(
        address indexed conduit,
        address indexed previousOwner,
        address indexed newOwner
    );

    /**
     * @dev Emit an event whenever a conduit owner registers a new potential
     *      owner for that conduit.
     *
     * @param newPotentialOwner The new potential owner of the conduit.
     */
    event PotentialOwnerUpdated(address indexed newPotentialOwner);

    /**
     * @dev Revert with an error when attempting to create a new conduit using a
     *      conduit key where the first twenty bytes of the key do not match the
     *      address of the caller.
     */
    error InvalidCreator();

    /**
     * @dev Revert with an error when attempting to create a new conduit when no
     *      initial owner address is supplied.
     */
    error InvalidInitialOwner();

    /**
     * @dev Revert with an error when attempting to set a new potential owner
     *      that is already set.
     */
    error NewPotentialOwnerAlreadySet(
        address conduit,
        address newPotentialOwner
    );

    /**
     * @dev Revert with an error when attempting to cancel ownership transfer
     *      when no new potential owner is currently set.
     */
    error NoPotentialOwnerCurrentlySet(address conduit);

    /**
     * @dev Revert with an error when attempting to interact with a conduit that
     *      does not yet exist.
     */
    error NoConduit();

    /**
     * @dev Revert with an error when attempting to create a conduit that
     *      already exists.
     */
    error ConduitAlreadyExists(address conduit);

    /**
     * @dev Revert with an error when attempting to update channels or transfer
     *      ownership of a conduit when the caller is not the owner of the
     *      conduit in question.
     */
    error CallerIsNotOwner(address conduit);

    /**
     * @dev Revert with an error when attempting to register a new potential
     *      owner and supplying the null address.
     */
    error NewPotentialOwnerIsZeroAddress(address conduit);

    /**
     * @dev Revert with an error when attempting to claim ownership of a conduit
     *      with a caller that is not the current potential owner for the
     *      conduit in question.
     */
    error CallerIsNotNewPotentialOwner(address conduit);

    /**
     * @dev Revert with an error when attempting to retrieve a channel using an
     *      index that is out of range.
     */
    error ChannelOutOfRange(address conduit);

    /**
     * @notice Deploy a new conduit using a supplied conduit key and assigning
     *         an initial owner for the deployed conduit. Note that the first
     *         twenty bytes of the supplied conduit key must match the caller
     *         and that a new conduit cannot be created if one has already been
     *         deployed using the same conduit key.
     *
     * @param conduitKey   The conduit key used to deploy the conduit. Note that
     *                     the first twenty bytes of the conduit key must match
     *                     the caller of this contract.
     * @param initialOwner The initial owner to set for the new conduit.
     *
     * @return conduit The address of the newly deployed conduit.
     */
    function createConduit(bytes32 conduitKey, address initialOwner)
        external
        returns (address conduit);

    /**
     * @notice Open or close a channel on a given conduit, thereby allowing the
     *         specified account to execute transfers against that conduit.
     *         Extreme care must be taken when updating channels, as malicious
     *         or vulnerable channels can transfer any ERC20, ERC721 and ERC1155
     *         tokens where the token holder has granted the conduit approval.
     *         Only the owner of the conduit in question may call this function.
     *
     * @param conduit The conduit for which to open or close the channel.
     * @param channel The channel to open or close on the conduit.
     * @param isOpen  A boolean indicating whether to open or close the channel.
     */
    function updateChannel(
        address conduit,
        address channel,
        bool isOpen
    ) external;

    /**
     * @notice Initiate conduit ownership transfer by assigning a new potential
     *         owner for the given conduit. Once set, the new potential owner
     *         may call `acceptOwnership` to claim ownership of the conduit.
     *         Only the owner of the conduit in question may call this function.
     *
     * @param conduit The conduit for which to initiate ownership transfer.
     * @param newPotentialOwner The new potential owner of the conduit.
     */
    function transferOwnership(address conduit, address newPotentialOwner)
        external;

    /**
     * @notice Clear the currently set potential owner, if any, from a conduit.
     *         Only the owner of the conduit in question may call this function.
     *
     * @param conduit The conduit for which to cancel ownership transfer.
     */
    function cancelOwnershipTransfer(address conduit) external;

    /**
     * @notice Accept ownership of a supplied conduit. Only accounts that the
     *         current owner has set as the new potential owner may call this
     *         function.
     *
     * @param conduit The conduit for which to accept ownership.
     */
    function acceptOwnership(address conduit) external;

    /**
     * @notice Retrieve the current owner of a deployed conduit.
     *
     * @param conduit The conduit for which to retrieve the associated owner.
     *
     * @return owner The owner of the supplied conduit.
     */
    function ownerOf(address conduit) external view returns (address owner);

    /**
     * @notice Retrieve the conduit key for a deployed conduit via reverse
     *         lookup.
     *
     * @param conduit The conduit for which to retrieve the associated conduit
     *                key.
     *
     * @return conduitKey The conduit key used to deploy the supplied conduit.
     */
    function getKey(address conduit) external view returns (bytes32 conduitKey);

    /**
     * @notice Derive the conduit associated with a given conduit key and
     *         determine whether that conduit exists (i.e. whether it has been
     *         deployed).
     *
     * @param conduitKey The conduit key used to derive the conduit.
     *
     * @return conduit The derived address of the conduit.
     * @return exists  A boolean indicating whether the derived conduit has been
     *                 deployed or not.
     */
    function getConduit(bytes32 conduitKey)
        external
        view
        returns (address conduit, bool exists);

    /**
     * @notice Retrieve the potential owner, if any, for a given conduit. The
     *         current owner may set a new potential owner via
     *         `transferOwnership` and that owner may then accept ownership of
     *         the conduit in question via `acceptOwnership`.
     *
     * @param conduit The conduit for which to retrieve the potential owner.
     *
     * @return potentialOwner The potential owner, if any, for the conduit.
     */
    function getPotentialOwner(address conduit)
        external
        view
        returns (address potentialOwner);

    /**
     * @notice Retrieve the status (either open or closed) of a given channel on
     *         a conduit.
     *
     * @param conduit The conduit for which to retrieve the channel status.
     * @param channel The channel for which to retrieve the status.
     *
     * @return isOpen The status of the channel on the given conduit.
     */
    function getChannelStatus(address conduit, address channel)
        external
        view
        returns (bool isOpen);

    /**
     * @notice Retrieve the total number of open channels for a given conduit.
     *
     * @param conduit The conduit for which to retrieve the total channel count.
     *
     * @return totalChannels The total number of open channels for the conduit.
     */
    function getTotalChannels(address conduit)
        external
        view
        returns (uint256 totalChannels);

    /**
     * @notice Retrieve an open channel at a specific index for a given conduit.
     *         Note that the index of a channel can change as a result of other
     *         channels being closed on the conduit.
     *
     * @param conduit      The conduit for which to retrieve the open channel.
     * @param channelIndex The index of the channel in question.
     *
     * @return channel The open channel, if any, at the specified channel index.
     */
    function getChannel(address conduit, uint256 channelIndex)
        external
        view
        returns (address channel);

    /**
     * @notice Retrieve all open channels for a given conduit. Note that calling
     *         this function for a conduit with many channels will revert with
     *         an out-of-gas error.
     *
     * @param conduit The conduit for which to retrieve open channels.
     *
     * @return channels An array of open channels on the given conduit.
     */
    function getChannels(address conduit)
        external
        view
        returns (address[] memory channels);

    /**
     * @dev Retrieve the conduit creation code and runtime code hashes.
     */
    function getConduitCodeHashes()
        external
        view
        returns (bytes32 creationCodeHash, bytes32 runtimeCodeHash);
}

// File: contracts/conduit/Conduit.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

import { ConduitInterface } from "../interfaces/ConduitInterface.sol";

import { ConduitItemType } from "./lib/ConduitEnums.sol";

import { TokenTransferrer } from "../lib/TokenTransferrer.sol";

import {
    ConduitTransfer,
    ConduitBatch1155Transfer
} from "./lib/ConduitStructs.sol";

import "./lib/ConduitConstants.sol";

/**
 * @title Conduit
 * @author 0age
 * @notice This contract serves as an originator for "proxied" transfers. Each
 *         conduit is deployed and controlled by a "conduit controller" that can
 *         add and remove "channels" or contracts that can instruct the conduit
 *         to transfer approved ERC20/721/1155 tokens. *IMPORTANT NOTE: each
 *         conduit has an owner that can arbitrarily add or remove channels, and
 *         a malicious or negligent owner can add a channel that allows for any
 *         approved ERC20/721/1155 tokens to be taken immediately — be extremely
 *         cautious with what conduits you give token approvals to!*
 */
contract Conduit is ConduitInterface, TokenTransferrer {
    // Set deployer as an immutable controller that can update channel statuses.
    address private immutable _controller;

    // Track the status of each channel.
    mapping(address => bool) private _channels;

    /**
     * @notice Ensure that the caller is currently registered as an open channel
     *         on the conduit.
     */
    modifier onlyOpenChannel() {
        // Utilize assembly to access channel storage mapping directly.
        assembly {
            // Write the caller to scratch space.
            mstore(ChannelKey_channel_ptr, caller())

            // Write the storage slot for _channels to scratch space.
            mstore(ChannelKey_slot_ptr, _channels.slot)

            // Derive the position in storage of _channels[msg.sender]
            // and check if the stored value is zero.
            if iszero(
                sload(keccak256(ChannelKey_channel_ptr, ChannelKey_length))
            ) {
                // The caller is not an open channel; revert with
                // ChannelClosed(caller). First, set error signature in memory.
                mstore(ChannelClosed_error_ptr, ChannelClosed_error_signature)

                // Next, set the caller as the argument.
                mstore(ChannelClosed_channel_ptr, caller())

                // Finally, revert, returning full custom error with argument.
                revert(ChannelClosed_error_ptr, ChannelClosed_error_length)
            }
        }

        // Continue with function execution.
        _;
    }

    /**
     * @notice In the constructor, set the deployer as the controller.
     */
    constructor() {
        // Set the deployer as the controller.
        _controller = msg.sender;
    }

    /**
     * @notice Execute a sequence of ERC20/721/1155 transfers. Only a caller
     *         with an open channel can call this function. Note that channels
     *         are expected to implement reentrancy protection if desired, and
     *         that cross-channel reentrancy may be possible if the conduit has
     *         multiple open channels at once. Also note that channels are
     *         expected to implement checks against transferring any zero-amount
     *         items if that constraint is desired.
     *
     * @param transfers The ERC20/721/1155 transfers to perform.
     *
     * @return magicValue A magic value indicating that the transfers were
     *                    performed successfully.
     */
    function execute(ConduitTransfer[] calldata transfers)
        external
        override
        onlyOpenChannel
        returns (bytes4 magicValue)
    {
        // Retrieve the total number of transfers and place on the stack.
        uint256 totalStandardTransfers = transfers.length;

        // Iterate over each transfer.
        for (uint256 i = 0; i < totalStandardTransfers; ) {
            // Retrieve the transfer in question and perform the transfer.
            _transfer(transfers[i]);

            // Skip overflow check as for loop is indexed starting at zero.
            unchecked {
                ++i;
            }
        }

        // Return a magic value indicating that the transfers were performed.
        magicValue = this.execute.selector;
    }

    /**
     * @notice Execute a sequence of batch 1155 item transfers. Only a caller
     *         with an open channel can call this function. Note that channels
     *         are expected to implement reentrancy protection if desired, and
     *         that cross-channel reentrancy may be possible if the conduit has
     *         multiple open channels at once. Also note that channels are
     *         expected to implement checks against transferring any zero-amount
     *         items if that constraint is desired.
     *
     * @param batchTransfers The 1155 batch item transfers to perform.
     *
     * @return magicValue A magic value indicating that the item transfers were
     *                    performed successfully.
     */
    function executeBatch1155(
        ConduitBatch1155Transfer[] calldata batchTransfers
    ) external override onlyOpenChannel returns (bytes4 magicValue) {
        // Perform 1155 batch transfers. Note that memory should be considered
        // entirely corrupted from this point forward.
        _performERC1155BatchTransfers(batchTransfers);

        // Return a magic value indicating that the transfers were performed.
        magicValue = this.executeBatch1155.selector;
    }

    /**
     * @notice Execute a sequence of transfers, both single ERC20/721/1155 item
     *         transfers as well as batch 1155 item transfers. Only a caller
     *         with an open channel can call this function. Note that channels
     *         are expected to implement reentrancy protection if desired, and
     *         that cross-channel reentrancy may be possible if the conduit has
     *         multiple open channels at once. Also note that channels are
     *         expected to implement checks against transferring any zero-amount
     *         items if that constraint is desired.
     *
     * @param standardTransfers The ERC20/721/1155 item transfers to perform.
     * @param batchTransfers    The 1155 batch item transfers to perform.
     *
     * @return magicValue A magic value indicating that the item transfers were
     *                    performed successfully.
     */
    function executeWithBatch1155(
        ConduitTransfer[] calldata standardTransfers,
        ConduitBatch1155Transfer[] calldata batchTransfers
    ) external override onlyOpenChannel returns (bytes4 magicValue) {
        // Retrieve the total number of transfers and place on the stack.
        uint256 totalStandardTransfers = standardTransfers.length;

        // Iterate over each standard transfer.
        for (uint256 i = 0; i < totalStandardTransfers; ) {
            // Retrieve the transfer in question and perform the transfer.
            _transfer(standardTransfers[i]);

            // Skip overflow check as for loop is indexed starting at zero.
            unchecked {
                ++i;
            }
        }

        // Perform 1155 batch transfers. Note that memory should be considered
        // entirely corrupted from this point forward aside from the free memory
        // pointer having the default value.
        _performERC1155BatchTransfers(batchTransfers);

        // Return a magic value indicating that the transfers were performed.
        magicValue = this.executeWithBatch1155.selector;
    }

    /**
     * @notice Open or close a given channel. Only callable by the controller.
     *
     * @param channel The channel to open or close.
     * @param isOpen  The status of the channel (either open or closed).
     */
    function updateChannel(address channel, bool isOpen) external override {
        // Ensure that the caller is the controller of this contract.
        if (msg.sender != _controller) {
            revert InvalidController();
        }

        // Ensure that the channel does not already have the indicated status.
        if (_channels[channel] == isOpen) {
            revert ChannelStatusAlreadySet(channel, isOpen);
        }

        // Update the status of the channel.
        _channels[channel] = isOpen;

        // Emit a corresponding event.
        emit ChannelUpdated(channel, isOpen);
    }

    /**
     * @dev Internal function to transfer a given ERC20/721/1155 item. Note that
     *      channels are expected to implement checks against transferring any
     *      zero-amount items if that constraint is desired.
     *
     * @param item The ERC20/721/1155 item to transfer.
     */
    function _transfer(ConduitTransfer calldata item) internal {
        // Determine the transfer method based on the respective item type.
        if (item.itemType == ConduitItemType.ERC20) {
            // Transfer ERC20 token. Note that item.identifier is ignored and
            // therefore ERC20 transfer items are potentially malleable — this
            // check should be performed by the calling channel if a constraint
            // on item malleability is desired.
            _performERC20Transfer(item.token, item.from, item.to, item.amount);
        } else if (item.itemType == ConduitItemType.ERC721) {
            // Ensure that exactly one 721 item is being transferred.
            if (item.amount != 1) {
                revert InvalidERC721TransferAmount();
            }

            // Transfer ERC721 token.
            _performERC721Transfer(
                item.token,
                item.from,
                item.to,
                item.identifier
            );
        } else if (item.itemType == ConduitItemType.ERC1155) {
            // Transfer ERC1155 token.
            _performERC1155Transfer(
                item.token,
                item.from,
                item.to,
                item.identifier,
                item.amount
            );
        } else {
            // Throw with an error.
            revert InvalidItemType();
        }
    }
}

// File: contracts/conduit/lib/ConduitStructs.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

import { ConduitItemType } from "./ConduitEnums.sol";

struct ConduitTransfer {
    ConduitItemType itemType;
    address token;
    address from;
    address to;
    uint256 identifier;
    uint256 amount;
}

struct ConduitBatch1155Transfer {
    address token;
    address from;
    address to;
    uint256[] ids;
    uint256[] amounts;
}

// File: contracts/interfaces/TransferHelperInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

import {
    TransferHelperItem,
    TransferHelperItemsWithRecipient
} from "../helpers/TransferHelperStructs.sol";

interface TransferHelperInterface {
    /**
     * @notice Transfer multiple items to a single recipient.
     *
     * @param items The items to transfer.
     * @param conduitKey  The key of the conduit performing the bulk transfer.
     */
    function bulkTransfer(
        TransferHelperItemsWithRecipient[] calldata items,
        bytes32 conduitKey
    ) external returns (bytes4);
}

// File: contracts/interfaces/TransferHelperErrors.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

/**
 * @title TransferHelperErrors
 */
interface TransferHelperErrors {
    /**
     * @dev Revert with an error when attempting to execute transfers with a
     *      NATIVE itemType.
     */
    error InvalidItemType();

    /**
     * @dev Revert with an error when an ERC721 transfer with amount other than
     *      one is attempted.
     */
    error InvalidERC721TransferAmount();

    /**
     * @dev Revert with an error when attempting to execute an ERC721 transfer
     *      to an invalid recipient.
     */
    error InvalidERC721Recipient(address recipient);

    /**
     * @dev Revert with an error when a call to a ERC721 receiver reverts with
     *      bytes data.
     */
    error ERC721ReceiverErrorRevertBytes(
        bytes reason,
        address receiver,
        address sender,
        uint256 identifier
    );

    /**
     * @dev Revert with an error when a call to a ERC721 receiver reverts with
     *      string reason.
     */
    error ERC721ReceiverErrorRevertString(
        string reason,
        address receiver,
        address sender,
        uint256 identifier
    );

    /**
     * @dev Revert with an error when an ERC20 token has an invalid identifier.
     */
    error InvalidERC20Identifier();

    /**
     * @dev Revert with an error if the recipient is the zero address.
     */
    error RecipientCannotBeZeroAddress();

    /**
     * @dev Revert with an error when attempting to fill an order referencing an
     *      invalid conduit (i.e. one that has not been deployed).
     */
    error InvalidConduit(bytes32 conduitKey, address conduit);

    /**
     * @dev Revert with an error when a call to a conduit reverts with a
     *      reason string.
     */
    error ConduitErrorRevertString(
        string reason,
        bytes32 conduitKey,
        address conduit
    );

    /**
     * @dev Revert with an error when a call to a conduit reverts with bytes
     *      data.
     */
    error ConduitErrorRevertBytes(
        bytes reason,
        bytes32 conduitKey,
        address conduit
    );
}

// File: contracts/conduit/lib/ConduitEnums.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

enum ConduitItemType {
    NATIVE, // unused
    ERC20,
    ERC721,
    ERC1155
}

// File: contracts/lib/TokenTransferrer.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

import "./TokenTransferrerConstants.sol";

import {
    TokenTransferrerErrors
} from "../interfaces/TokenTransferrerErrors.sol";

import { ConduitBatch1155Transfer } from "../conduit/lib/ConduitStructs.sol";

/**
 * @title TokenTransferrer
 * @author 0age
 * @custom:coauthor d1ll0n
 * @custom:coauthor transmissions11
 * @notice TokenTransferrer is a library for performing optimized ERC20, ERC721,
 *         ERC1155, and batch ERC1155 transfers, used by both Seaport as well as
 *         by conduits deployed by the ConduitController. Use great caution when
 *         considering these functions for use in other codebases, as there are
 *         significant side effects and edge cases that need to be thoroughly
 *         understood and carefully addressed.
 */
contract TokenTransferrer is TokenTransferrerErrors {
    /**
     * @dev Internal function to transfer ERC20 tokens from a given originator
     *      to a given recipient. Sufficient approvals must be set on the
     *      contract performing the transfer.
     *
     * @param token      The ERC20 token to transfer.
     * @param from       The originator of the transfer.
     * @param to         The recipient of the transfer.
     * @param amount     The amount to transfer.
     */
    function _performERC20Transfer(
        address token,
        address from,
        address to,
        uint256 amount
    ) internal {
        // Utilize assembly to perform an optimized ERC20 token transfer.
        assembly {
            // The free memory pointer memory slot will be used when populating
            // call data for the transfer; read the value and restore it later.
            let memPointer := mload(FreeMemoryPointerSlot)

            // Write call data into memory, starting with function selector.
            mstore(ERC20_transferFrom_sig_ptr, ERC20_transferFrom_signature)
            mstore(ERC20_transferFrom_from_ptr, from)
            mstore(ERC20_transferFrom_to_ptr, to)
            mstore(ERC20_transferFrom_amount_ptr, amount)

            // Make call & copy up to 32 bytes of return data to scratch space.
            // Scratch space does not need to be cleared ahead of time, as the
            // subsequent check will ensure that either at least a full word of
            // return data is received (in which case it will be overwritten) or
            // that no data is received (in which case scratch space will be
            // ignored) on a successful call to the given token.
            let callStatus := call(
                gas(),
                token,
                0,
                ERC20_transferFrom_sig_ptr,
                ERC20_transferFrom_length,
                0,
                OneWord
            )

            // Determine whether transfer was successful using status & result.
            let success := and(
                // Set success to whether the call reverted, if not check it
                // either returned exactly 1 (can't just be non-zero data), or
                // had no return data.
                or(
                    and(eq(mload(0), 1), gt(returndatasize(), 31)),
                    iszero(returndatasize())
                ),
                callStatus
            )

            // Handle cases where either the transfer failed or no data was
            // returned. Group these, as most transfers will succeed with data.
            // Equivalent to `or(iszero(success), iszero(returndatasize()))`
            // but after it's inverted for JUMPI this expression is cheaper.
            if iszero(and(success, iszero(iszero(returndatasize())))) {
                // If the token has no code or the transfer failed: Equivalent
                // to `or(iszero(success), iszero(extcodesize(token)))` but
                // after it's inverted for JUMPI this expression is cheaper.
                if iszero(and(iszero(iszero(extcodesize(token))), success)) {
                    // If the transfer failed:
                    if iszero(success) {
                        // If it was due to a revert:
                        if iszero(callStatus) {
                            // If it returned a message, bubble it up as long as
                            // sufficient gas remains to do so:
                            if returndatasize() {
                                // Ensure that sufficient gas is available to
                                // copy returndata while expanding memory where
                                // necessary. Start by computing the word size
                                // of returndata and allocated memory. Round up
                                // to the nearest full word.
                                let returnDataWords := div(
                                    add(returndatasize(), AlmostOneWord),
                                    OneWord
                                )

                                // Note: use the free memory pointer in place of
                                // msize() to work around a Yul warning that
                                // prevents accessing msize directly when the IR
                                // pipeline is activated.
                                let msizeWords := div(memPointer, OneWord)

                                // Next, compute the cost of the returndatacopy.
                                let cost := mul(CostPerWord, returnDataWords)

                                // Then, compute cost of new memory allocation.
                                if gt(returnDataWords, msizeWords) {
                                    cost := add(
                                        cost,
                                        add(
                                            mul(
                                                sub(
                                                    returnDataWords,
                                                    msizeWords
                                                ),
                                                CostPerWord
                                            ),
                                            div(
                                                sub(
                                                    mul(
                                                        returnDataWords,
                                                        returnDataWords
                                                    ),
                                                    mul(msizeWords, msizeWords)
                                                ),
                                                MemoryExpansionCoefficient
                                            )
                                        )
                                    )
                                }

                                // Finally, add a small constant and compare to
                                // gas remaining; bubble up the revert data if
                                // enough gas is still available.
                                if lt(add(cost, ExtraGasBuffer), gas()) {
                                    // Copy returndata to memory; overwrite
                                    // existing memory.
                                    returndatacopy(0, 0, returndatasize())

                                    // Revert, specifying memory region with
                                    // copied returndata.
                                    revert(0, returndatasize())
                                }
                            }

                            // Otherwise revert with a generic error message.
                            mstore(
                                TokenTransferGenericFailure_error_sig_ptr,
                                TokenTransferGenericFailure_error_signature
                            )
                            mstore(
                                TokenTransferGenericFailure_error_token_ptr,
                                token
                            )
                            mstore(
                                TokenTransferGenericFailure_error_from_ptr,
                                from
                            )
                            mstore(TokenTransferGenericFailure_error_to_ptr, to)
                            mstore(TokenTransferGenericFailure_error_id_ptr, 0)
                            mstore(
                                TokenTransferGenericFailure_error_amount_ptr,
                                amount
                            )
                            revert(
                                TokenTransferGenericFailure_error_sig_ptr,
                                TokenTransferGenericFailure_error_length
                            )
                        }

                        // Otherwise revert with a message about the token
                        // returning false or non-compliant return values.
                        mstore(
                            BadReturnValueFromERC20OnTransfer_error_sig_ptr,
                            BadReturnValueFromERC20OnTransfer_error_signature
                        )
                        mstore(
                            BadReturnValueFromERC20OnTransfer_error_token_ptr,
                            token
                        )
                        mstore(
                            BadReturnValueFromERC20OnTransfer_error_from_ptr,
                            from
                        )
                        mstore(
                            BadReturnValueFromERC20OnTransfer_error_to_ptr,
                            to
                        )
                        mstore(
                            BadReturnValueFromERC20OnTransfer_error_amount_ptr,
                            amount
                        )
                        revert(
                            BadReturnValueFromERC20OnTransfer_error_sig_ptr,
                            BadReturnValueFromERC20OnTransfer_error_length
                        )
                    }

                    // Otherwise, revert with error about token not having code:
                    mstore(NoContract_error_sig_ptr, NoContract_error_signature)
                    mstore(NoContract_error_token_ptr, token)
                    revert(NoContract_error_sig_ptr, NoContract_error_length)
                }

                // Otherwise, the token just returned no data despite the call
                // having succeeded; no need to optimize for this as it's not
                // technically ERC20 compliant.
            }

            // Restore the original free memory pointer.
            mstore(FreeMemoryPointerSlot, memPointer)

            // Restore the zero slot to zero.
            mstore(ZeroSlot, 0)
        }
    }

    /**
     * @dev Internal function to transfer an ERC721 token from a given
     *      originator to a given recipient. Sufficient approvals must be set on
     *      the contract performing the transfer. Note that this function does
     *      not check whether the receiver can accept the ERC721 token (i.e. it
     *      does not use `safeTransferFrom`).
     *
     * @param token      The ERC721 token to transfer.
     * @param from       The originator of the transfer.
     * @param to         The recipient of the transfer.
     * @param identifier The tokenId to transfer.
     */
    function _performERC721Transfer(
        address token,
        address from,
        address to,
        uint256 identifier
    ) internal {
        // Utilize assembly to perform an optimized ERC721 token transfer.
        assembly {
            // If the token has no code, revert.
            if iszero(extcodesize(token)) {
                mstore(NoContract_error_sig_ptr, NoContract_error_signature)
                mstore(NoContract_error_token_ptr, token)
                revert(NoContract_error_sig_ptr, NoContract_error_length)
            }

            // The free memory pointer memory slot will be used when populating
            // call data for the transfer; read the value and restore it later.
            let memPointer := mload(FreeMemoryPointerSlot)

            // Write call data to memory starting with function selector.
            mstore(ERC721_transferFrom_sig_ptr, ERC721_transferFrom_signature)
            mstore(ERC721_transferFrom_from_ptr, from)
            mstore(ERC721_transferFrom_to_ptr, to)
            mstore(ERC721_transferFrom_id_ptr, identifier)

            // Perform the call, ignoring return data.
            let success := call(
                gas(),
                token,
                0,
                ERC721_transferFrom_sig_ptr,
                ERC721_transferFrom_length,
                0,
                0
            )

            // If the transfer reverted:
            if iszero(success) {
                // If it returned a message, bubble it up as long as sufficient
                // gas remains to do so:
                if returndatasize() {
                    // Ensure that sufficient gas is available to copy
                    // returndata while expanding memory where necessary. Start
                    // by computing word size of returndata & allocated memory.
                    // Round up to the nearest full word.
                    let returnDataWords := div(
                        add(returndatasize(), AlmostOneWord),
                        OneWord
                    )

                    // Note: use the free memory pointer in place of msize() to
                    // work around a Yul warning that prevents accessing msize
                    // directly when the IR pipeline is activated.
                    let msizeWords := div(memPointer, OneWord)

                    // Next, compute the cost of the returndatacopy.
                    let cost := mul(CostPerWord, returnDataWords)

                    // Then, compute cost of new memory allocation.
                    if gt(returnDataWords, msizeWords) {
                        cost := add(
                            cost,
                            add(
                                mul(
                                    sub(returnDataWords, msizeWords),
                                    CostPerWord
                                ),
                                div(
                                    sub(
                                        mul(returnDataWords, returnDataWords),
                                        mul(msizeWords, msizeWords)
                                    ),
                                    MemoryExpansionCoefficient
                                )
                            )
                        )
                    }

                    // Finally, add a small constant and compare to gas
                    // remaining; bubble up the revert data if enough gas is
                    // still available.
                    if lt(add(cost, ExtraGasBuffer), gas()) {
                        // Copy returndata to memory; overwrite existing memory.
                        returndatacopy(0, 0, returndatasize())

                        // Revert, giving memory region with copied returndata.
                        revert(0, returndatasize())
                    }
                }

                // Otherwise revert with a generic error message.
                mstore(
                    TokenTransferGenericFailure_error_sig_ptr,
                    TokenTransferGenericFailure_error_signature
                )
                mstore(TokenTransferGenericFailure_error_token_ptr, token)
                mstore(TokenTransferGenericFailure_error_from_ptr, from)
                mstore(TokenTransferGenericFailure_error_to_ptr, to)
                mstore(TokenTransferGenericFailure_error_id_ptr, identifier)
                mstore(TokenTransferGenericFailure_error_amount_ptr, 1)
                revert(
                    TokenTransferGenericFailure_error_sig_ptr,
                    TokenTransferGenericFailure_error_length
                )
            }

            // Restore the original free memory pointer.
            mstore(FreeMemoryPointerSlot, memPointer)

            // Restore the zero slot to zero.
            mstore(ZeroSlot, 0)
        }
    }

    /**
     * @dev Internal function to transfer ERC1155 tokens from a given
     *      originator to a given recipient. Sufficient approvals must be set on
     *      the contract performing the transfer and contract recipients must
     *      implement the ERC1155TokenReceiver interface to indicate that they
     *      are willing to accept the transfer.
     *
     * @param token      The ERC1155 token to transfer.
     * @param from       The originator of the transfer.
     * @param to         The recipient of the transfer.
     * @param identifier The id to transfer.
     * @param amount     The amount to transfer.
     */
    function _performERC1155Transfer(
        address token,
        address from,
        address to,
        uint256 identifier,
        uint256 amount
    ) internal {
        // Utilize assembly to perform an optimized ERC1155 token transfer.
        assembly {
            // If the token has no code, revert.
            if iszero(extcodesize(token)) {
                mstore(NoContract_error_sig_ptr, NoContract_error_signature)
                mstore(NoContract_error_token_ptr, token)
                revert(NoContract_error_sig_ptr, NoContract_error_length)
            }

            // The following memory slots will be used when populating call data
            // for the transfer; read the values and restore them later.
            let memPointer := mload(FreeMemoryPointerSlot)
            let slot0x80 := mload(Slot0x80)
            let slot0xA0 := mload(Slot0xA0)
            let slot0xC0 := mload(Slot0xC0)

            // Write call data into memory, beginning with function selector.
            mstore(
                ERC1155_safeTransferFrom_sig_ptr,
                ERC1155_safeTransferFrom_signature
            )
            mstore(ERC1155_safeTransferFrom_from_ptr, from)
            mstore(ERC1155_safeTransferFrom_to_ptr, to)
            mstore(ERC1155_safeTransferFrom_id_ptr, identifier)
            mstore(ERC1155_safeTransferFrom_amount_ptr, amount)
            mstore(
                ERC1155_safeTransferFrom_data_offset_ptr,
                ERC1155_safeTransferFrom_data_length_offset
            )
            mstore(ERC1155_safeTransferFrom_data_length_ptr, 0)

            // Perform the call, ignoring return data.
            let success := call(
                gas(),
                token,
                0,
                ERC1155_safeTransferFrom_sig_ptr,
                ERC1155_safeTransferFrom_length,
                0,
                0
            )

            // If the transfer reverted:
            if iszero(success) {
                // If it returned a message, bubble it up as long as sufficient
                // gas remains to do so:
                if returndatasize() {
                    // Ensure that sufficient gas is available to copy
                    // returndata while expanding memory where necessary. Start
                    // by computing word size of returndata & allocated memory.
                    // Round up to the nearest full word.
                    let returnDataWords := div(
                        add(returndatasize(), AlmostOneWord),
                        OneWord
                    )

                    // Note: use the free memory pointer in place of msize() to
                    // work around a Yul warning that prevents accessing msize
                    // directly when the IR pipeline is activated.
                    let msizeWords := div(memPointer, OneWord)

                    // Next, compute the cost of the returndatacopy.
                    let cost := mul(CostPerWord, returnDataWords)

                    // Then, compute cost of new memory allocation.
                    if gt(returnDataWords, msizeWords) {
                        cost := add(
                            cost,
                            add(
                                mul(
                                    sub(returnDataWords, msizeWords),
                                    CostPerWord
                                ),
                                div(
                                    sub(
                                        mul(returnDataWords, returnDataWords),
                                        mul(msizeWords, msizeWords)
                                    ),
                                    MemoryExpansionCoefficient
                                )
                            )
                        )
                    }

                    // Finally, add a small constant and compare to gas
                    // remaining; bubble up the revert data if enough gas is
                    // still available.
                    if lt(add(cost, ExtraGasBuffer), gas()) {
                        // Copy returndata to memory; overwrite existing memory.
                        returndatacopy(0, 0, returndatasize())

                        // Revert, giving memory region with copied returndata.
                        revert(0, returndatasize())
                    }
                }

                // Otherwise revert with a generic error message.
                mstore(
                    TokenTransferGenericFailure_error_sig_ptr,
                    TokenTransferGenericFailure_error_signature
                )
                mstore(TokenTransferGenericFailure_error_token_ptr, token)
                mstore(TokenTransferGenericFailure_error_from_ptr, from)
                mstore(TokenTransferGenericFailure_error_to_ptr, to)
                mstore(TokenTransferGenericFailure_error_id_ptr, identifier)
                mstore(TokenTransferGenericFailure_error_amount_ptr, amount)
                revert(
                    TokenTransferGenericFailure_error_sig_ptr,
                    TokenTransferGenericFailure_error_length
                )
            }

            mstore(Slot0x80, slot0x80) // Restore slot 0x80.
            mstore(Slot0xA0, slot0xA0) // Restore slot 0xA0.
            mstore(Slot0xC0, slot0xC0) // Restore slot 0xC0.

            // Restore the original free memory pointer.
            mstore(FreeMemoryPointerSlot, memPointer)

            // Restore the zero slot to zero.
            mstore(ZeroSlot, 0)
        }
    }

    /**
     * @dev Internal function to transfer ERC1155 tokens from a given
     *      originator to a given recipient. Sufficient approvals must be set on
     *      the contract performing the transfer and contract recipients must
     *      implement the ERC1155TokenReceiver interface to indicate that they
     *      are willing to accept the transfer. NOTE: this function is not
     *      memory-safe; it will overwrite existing memory, restore the free
     *      memory pointer to the default value, and overwrite the zero slot.
     *      This function should only be called once memory is no longer
     *      required and when uninitialized arrays are not utilized, and memory
     *      should be considered fully corrupted (aside from the existence of a
     *      default-value free memory pointer) after calling this function.
     *
     * @param batchTransfers The group of 1155 batch transfers to perform.
     */
    function _performERC1155BatchTransfers(
        ConduitBatch1155Transfer[] calldata batchTransfers
    ) internal {
        // Utilize assembly to perform optimized batch 1155 transfers.
        assembly {
            let len := batchTransfers.length
            // Pointer to first head in the array, which is offset to the struct
            // at each index. This gets incremented after each loop to avoid
            // multiplying by 32 to get the offset for each element.
            let nextElementHeadPtr := batchTransfers.offset

            // Pointer to beginning of the head of the array. This is the
            // reference position each offset references. It's held static to
            // let each loop calculate the data position for an element.
            let arrayHeadPtr := nextElementHeadPtr

            // Write the function selector, which will be reused for each call:
            // safeBatchTransferFrom(address,address,uint256[],uint256[],bytes)
            mstore(
                ConduitBatch1155Transfer_from_offset,
                ERC1155_safeBatchTransferFrom_signature
            )

            // Iterate over each batch transfer.
            for {
                let i := 0
            } lt(i, len) {
                i := add(i, 1)
            } {
                // Read the offset to the beginning of the element and add
                // it to pointer to the beginning of the array head to get
                // the absolute position of the element in calldata.
                let elementPtr := add(
                    arrayHeadPtr,
                    calldataload(nextElementHeadPtr)
                )

                // Retrieve the token from calldata.
                let token := calldataload(elementPtr)

                // If the token has no code, revert.
                if iszero(extcodesize(token)) {
                    mstore(NoContract_error_sig_ptr, NoContract_error_signature)
                    mstore(NoContract_error_token_ptr, token)
                    revert(NoContract_error_sig_ptr, NoContract_error_length)
                }

                // Get the total number of supplied ids.
                let idsLength := calldataload(
                    add(elementPtr, ConduitBatch1155Transfer_ids_length_offset)
                )

                // Determine the expected offset for the amounts array.
                let expectedAmountsOffset := add(
                    ConduitBatch1155Transfer_amounts_length_baseOffset,
                    mul(idsLength, OneWord)
                )

                // Validate struct encoding.
                let invalidEncoding := iszero(
                    and(
                        // ids.length == amounts.length
                        eq(
                            idsLength,
                            calldataload(add(elementPtr, expectedAmountsOffset))
                        ),
                        and(
                            // ids_offset == 0xa0
                            eq(
                                calldataload(
                                    add(
                                        elementPtr,
                                        ConduitBatch1155Transfer_ids_head_offset
                                    )
                                ),
                                ConduitBatch1155Transfer_ids_length_offset
                            ),
                            // amounts_offset == 0xc0 + ids.length*32
                            eq(
                                calldataload(
                                    add(
                                        elementPtr,
                                        ConduitBatchTransfer_amounts_head_offset
                                    )
                                ),
                                expectedAmountsOffset
                            )
                        )
                    )
                )

                // Revert with an error if the encoding is not valid.
                if invalidEncoding {
                    mstore(
                        Invalid1155BatchTransferEncoding_ptr,
                        Invalid1155BatchTransferEncoding_selector
                    )
                    revert(
                        Invalid1155BatchTransferEncoding_ptr,
                        Invalid1155BatchTransferEncoding_length
                    )
                }

                // Update the offset position for the next loop
                nextElementHeadPtr := add(nextElementHeadPtr, OneWord)

                // Copy the first section of calldata (before dynamic values).
                calldatacopy(
                    BatchTransfer1155Params_ptr,
                    add(elementPtr, ConduitBatch1155Transfer_from_offset),
                    ConduitBatch1155Transfer_usable_head_size
                )

                // Determine size of calldata required for ids and amounts. Note
                // that the size includes both lengths as well as the data.
                let idsAndAmountsSize := add(TwoWords, mul(idsLength, TwoWords))

                // Update the offset for the data array in memory.
                mstore(
                    BatchTransfer1155Params_data_head_ptr,
                    add(
                        BatchTransfer1155Params_ids_length_offset,
                        idsAndAmountsSize
                    )
                )

                // Set the length of the data array in memory to zero.
                mstore(
                    add(
                        BatchTransfer1155Params_data_length_basePtr,
                        idsAndAmountsSize
                    ),
                    0
                )

                // Determine the total calldata size for the call to transfer.
                let transferDataSize := add(
                    BatchTransfer1155Params_calldata_baseSize,
                    idsAndAmountsSize
                )

                // Copy second section of calldata (including dynamic values).
                calldatacopy(
                    BatchTransfer1155Params_ids_length_ptr,
                    add(elementPtr, ConduitBatch1155Transfer_ids_length_offset),
                    idsAndAmountsSize
                )

                // Perform the call to transfer 1155 tokens.
                let success := call(
                    gas(),
                    token,
                    0,
                    ConduitBatch1155Transfer_from_offset, // Data portion start.
                    transferDataSize, // Location of the length of callData.
                    0,
                    0
                )

                // If the transfer reverted:
                if iszero(success) {
                    // If it returned a message, bubble it up as long as
                    // sufficient gas remains to do so:
                    if returndatasize() {
                        // Ensure that sufficient gas is available to copy
                        // returndata while expanding memory where necessary.
                        // Start by computing word size of returndata and
                        // allocated memory. Round up to the nearest full word.
                        let returnDataWords := div(
                            add(returndatasize(), AlmostOneWord),
                            OneWord
                        )

                        // Note: use transferDataSize in place of msize() to
                        // work around a Yul warning that prevents accessing
                        // msize directly when the IR pipeline is activated.
                        // The free memory pointer is not used here because
                        // this function does almost all memory management
                        // manually and does not update it, and transferDataSize
                        // should be the largest memory value used (unless a
                        // previous batch was larger).
                        let msizeWords := div(transferDataSize, OneWord)

                        // Next, compute the cost of the returndatacopy.
                        let cost := mul(CostPerWord, returnDataWords)

                        // Then, compute cost of new memory allocation.
                        if gt(returnDataWords, msizeWords) {
                            cost := add(
                                cost,
                                add(
                                    mul(
                                        sub(returnDataWords, msizeWords),
                                        CostPerWord
                                    ),
                                    div(
                                        sub(
                                            mul(
                                                returnDataWords,
                                                returnDataWords
                                            ),
                                            mul(msizeWords, msizeWords)
                                        ),
                                        MemoryExpansionCoefficient
                                    )
                                )
                            )
                        }

                        // Finally, add a small constant and compare to gas
                        // remaining; bubble up the revert data if enough gas is
                        // still available.
                        if lt(add(cost, ExtraGasBuffer), gas()) {
                            // Copy returndata to memory; overwrite existing.
                            returndatacopy(0, 0, returndatasize())

                            // Revert with memory region containing returndata.
                            revert(0, returndatasize())
                        }
                    }

                    // Set the error signature.
                    mstore(
                        0,
                        ERC1155BatchTransferGenericFailure_error_signature
                    )

                    // Write the token.
                    mstore(ERC1155BatchTransferGenericFailure_token_ptr, token)

                    // Increase the offset to ids by 32.
                    mstore(
                        BatchTransfer1155Params_ids_head_ptr,
                        ERC1155BatchTransferGenericFailure_ids_offset
                    )

                    // Increase the offset to amounts by 32.
                    mstore(
                        BatchTransfer1155Params_amounts_head_ptr,
                        add(
                            OneWord,
                            mload(BatchTransfer1155Params_amounts_head_ptr)
                        )
                    )

                    // Return modified region. The total size stays the same as
                    // `token` uses the same number of bytes as `data.length`.
                    revert(0, transferDataSize)
                }
            }

            // Reset the free memory pointer to the default value; memory must
            // be assumed to be dirtied and not reused from this point forward.
            // Also note that the zero slot is not reset to zero, meaning empty
            // arrays cannot be safely created or utilized until it is restored.
            mstore(FreeMemoryPointerSlot, DefaultFreeMemoryPointer)
        }
    }
}

// File: contracts/conduit/lib/ConduitConstants.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

// error ChannelClosed(address channel)
uint256 constant ChannelClosed_error_signature = (
    0x93daadf200000000000000000000000000000000000000000000000000000000
);
uint256 constant ChannelClosed_error_ptr = 0x00;
uint256 constant ChannelClosed_channel_ptr = 0x4;
uint256 constant ChannelClosed_error_length = 0x24;

// For the mapping:
// mapping(address => bool) channels
// The position in storage for a particular account is:
// keccak256(abi.encode(account, channels.slot))
uint256 constant ChannelKey_channel_ptr = 0x00;
uint256 constant ChannelKey_slot_ptr = 0x20;
uint256 constant ChannelKey_length = 0x40;

// File: contracts/lib/TokenTransferrerConstants.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

/*
 * -------------------------- Disambiguation & Other Notes ---------------------
 *    - The term "head" is used as it is in the documentation for ABI encoding,
 *      but only in reference to dynamic types, i.e. it always refers to the
 *      offset or pointer to the body of a dynamic type. In calldata, the head
 *      is always an offset (relative to the parent object), while in memory,
 *      the head is always the pointer to the body. More information found here:
 *      https://docs.soliditylang.org/en/v0.8.14/abi-spec.html#argument-encoding
 *        - Note that the length of an array is separate from and precedes the
 *          head of the array.
 *
 *    - The term "body" is used in place of the term "head" used in the ABI
 *      documentation. It refers to the start of the data for a dynamic type,
 *      e.g. the first word of a struct or the first word of the first element
 *      in an array.
 *
 *    - The term "pointer" is used to describe the absolute position of a value
 *      and never an offset relative to another value.
 *        - The suffix "_ptr" refers to a memory pointer.
 *        - The suffix "_cdPtr" refers to a calldata pointer.
 *
 *    - The term "offset" is used to describe the position of a value relative
 *      to some parent value. For example, OrderParameters_conduit_offset is the
 *      offset to the "conduit" value in the OrderParameters struct relative to
 *      the start of the body.
 *        - Note: Offsets are used to derive pointers.
 *
 *    - Some structs have pointers defined for all of their fields in this file.
 *      Lines which are commented out are fields that are not used in the
 *      codebase but have been left in for readability.
 */

uint256 constant AlmostOneWord = 0x1f;
uint256 constant OneWord = 0x20;
uint256 constant TwoWords = 0x40;
uint256 constant ThreeWords = 0x60;

uint256 constant FreeMemoryPointerSlot = 0x40;
uint256 constant ZeroSlot = 0x60;
uint256 constant DefaultFreeMemoryPointer = 0x80;

uint256 constant Slot0x80 = 0x80;
uint256 constant Slot0xA0 = 0xa0;
uint256 constant Slot0xC0 = 0xc0;

// abi.encodeWithSignature("transferFrom(address,address,uint256)")
uint256 constant ERC20_transferFrom_signature = (
    0x23b872dd00000000000000000000000000000000000000000000000000000000
);
uint256 constant ERC20_transferFrom_sig_ptr = 0x0;
uint256 constant ERC20_transferFrom_from_ptr = 0x04;
uint256 constant ERC20_transferFrom_to_ptr = 0x24;
uint256 constant ERC20_transferFrom_amount_ptr = 0x44;
uint256 constant ERC20_transferFrom_length = 0x64; // 4 + 32 * 3 == 100

// abi.encodeWithSignature(
//     "safeTransferFrom(address,address,uint256,uint256,bytes)"
// )
uint256 constant ERC1155_safeTransferFrom_signature = (
    0xf242432a00000000000000000000000000000000000000000000000000000000
);
uint256 constant ERC1155_safeTransferFrom_sig_ptr = 0x0;
uint256 constant ERC1155_safeTransferFrom_from_ptr = 0x04;
uint256 constant ERC1155_safeTransferFrom_to_ptr = 0x24;
uint256 constant ERC1155_safeTransferFrom_id_ptr = 0x44;
uint256 constant ERC1155_safeTransferFrom_amount_ptr = 0x64;
uint256 constant ERC1155_safeTransferFrom_data_offset_ptr = 0x84;
uint256 constant ERC1155_safeTransferFrom_data_length_ptr = 0xa4;
uint256 constant ERC1155_safeTransferFrom_length = 0xc4; // 4 + 32 * 6 == 196
uint256 constant ERC1155_safeTransferFrom_data_length_offset = 0xa0;

// abi.encodeWithSignature(
//     "safeBatchTransferFrom(address,address,uint256[],uint256[],bytes)"
// )
uint256 constant ERC1155_safeBatchTransferFrom_signature = (
    0x2eb2c2d600000000000000000000000000000000000000000000000000000000
);

bytes4 constant ERC1155_safeBatchTransferFrom_selector = bytes4(
    bytes32(ERC1155_safeBatchTransferFrom_signature)
);

uint256 constant ERC721_transferFrom_signature = ERC20_transferFrom_signature;
uint256 constant ERC721_transferFrom_sig_ptr = 0x0;
uint256 constant ERC721_transferFrom_from_ptr = 0x04;
uint256 constant ERC721_transferFrom_to_ptr = 0x24;
uint256 constant ERC721_transferFrom_id_ptr = 0x44;
uint256 constant ERC721_transferFrom_length = 0x64; // 4 + 32 * 3 == 100

// abi.encodeWithSignature("NoContract(address)")
uint256 constant NoContract_error_signature = (
    0x5f15d67200000000000000000000000000000000000000000000000000000000
);
uint256 constant NoContract_error_sig_ptr = 0x0;
uint256 constant NoContract_error_token_ptr = 0x4;
uint256 constant NoContract_error_length = 0x24; // 4 + 32 == 36

// abi.encodeWithSignature(
//     "TokenTransferGenericFailure(address,address,address,uint256,uint256)"
// )
uint256 constant TokenTransferGenericFailure_error_signature = (
    0xf486bc8700000000000000000000000000000000000000000000000000000000
);
uint256 constant TokenTransferGenericFailure_error_sig_ptr = 0x0;
uint256 constant TokenTransferGenericFailure_error_token_ptr = 0x4;
uint256 constant TokenTransferGenericFailure_error_from_ptr = 0x24;
uint256 constant TokenTransferGenericFailure_error_to_ptr = 0x44;
uint256 constant TokenTransferGenericFailure_error_id_ptr = 0x64;
uint256 constant TokenTransferGenericFailure_error_amount_ptr = 0x84;

// 4 + 32 * 5 == 164
uint256 constant TokenTransferGenericFailure_error_length = 0xa4;

// abi.encodeWithSignature(
//     "BadReturnValueFromERC20OnTransfer(address,address,address,uint256)"
// )
uint256 constant BadReturnValueFromERC20OnTransfer_error_signature = (
    0x9889192300000000000000000000000000000000000000000000000000000000
);
uint256 constant BadReturnValueFromERC20OnTransfer_error_sig_ptr = 0x0;
uint256 constant BadReturnValueFromERC20OnTransfer_error_token_ptr = 0x4;
uint256 constant BadReturnValueFromERC20OnTransfer_error_from_ptr = 0x24;
uint256 constant BadReturnValueFromERC20OnTransfer_error_to_ptr = 0x44;
uint256 constant BadReturnValueFromERC20OnTransfer_error_amount_ptr = 0x64;

// 4 + 32 * 4 == 132
uint256 constant BadReturnValueFromERC20OnTransfer_error_length = 0x84;

uint256 constant ExtraGasBuffer = 0x20;
uint256 constant CostPerWord = 3;
uint256 constant MemoryExpansionCoefficient = 0x200;

// Values are offset by 32 bytes in order to write the token to the beginning
// in the event of a revert
uint256 constant BatchTransfer1155Params_ptr = 0x24;
uint256 constant BatchTransfer1155Params_ids_head_ptr = 0x64;
uint256 constant BatchTransfer1155Params_amounts_head_ptr = 0x84;
uint256 constant BatchTransfer1155Params_data_head_ptr = 0xa4;
uint256 constant BatchTransfer1155Params_data_length_basePtr = 0xc4;
uint256 constant BatchTransfer1155Params_calldata_baseSize = 0xc4;

uint256 constant BatchTransfer1155Params_ids_length_ptr = 0xc4;

uint256 constant BatchTransfer1155Params_ids_length_offset = 0xa0;
uint256 constant BatchTransfer1155Params_amounts_length_baseOffset = 0xc0;
uint256 constant BatchTransfer1155Params_data_length_baseOffset = 0xe0;

uint256 constant ConduitBatch1155Transfer_usable_head_size = 0x80;

uint256 constant ConduitBatch1155Transfer_from_offset = 0x20;
uint256 constant ConduitBatch1155Transfer_ids_head_offset = 0x60;
uint256 constant ConduitBatch1155Transfer_amounts_head_offset = 0x80;
uint256 constant ConduitBatch1155Transfer_ids_length_offset = 0xa0;
uint256 constant ConduitBatch1155Transfer_amounts_length_baseOffset = 0xc0;
uint256 constant ConduitBatch1155Transfer_calldata_baseSize = 0xc0;

// Note: abbreviated version of above constant to adhere to line length limit.
uint256 constant ConduitBatchTransfer_amounts_head_offset = 0x80;

uint256 constant Invalid1155BatchTransferEncoding_ptr = 0x00;
uint256 constant Invalid1155BatchTransferEncoding_length = 0x04;
uint256 constant Invalid1155BatchTransferEncoding_selector = (
    0xeba2084c00000000000000000000000000000000000000000000000000000000
);

uint256 constant ERC1155BatchTransferGenericFailure_error_signature = (
    0xafc445e200000000000000000000000000000000000000000000000000000000
);
uint256 constant ERC1155BatchTransferGenericFailure_token_ptr = 0x04;
uint256 constant ERC1155BatchTransferGenericFailure_ids_offset = 0xc0;

// File: contracts/interfaces/TokenTransferrerErrors.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

/**
 * @title TokenTransferrerErrors
 */
interface TokenTransferrerErrors {
    /**
     * @dev Revert with an error when an ERC721 transfer with amount other than
     *      one is attempted.
     */
    error InvalidERC721TransferAmount();

    /**
     * @dev Revert with an error when attempting to fulfill an order where an
     *      item has an amount of zero.
     */
    error MissingItemAmount();

    /**
     * @dev Revert with an error when attempting to fulfill an order where an
     *      item has unused parameters. This includes both the token and the
     *      identifier parameters for native transfers as well as the identifier
     *      parameter for ERC20 transfers. Note that the conduit does not
     *      perform this check, leaving it up to the calling channel to enforce
     *      when desired.
     */
    error UnusedItemParameters();

    /**
     * @dev Revert with an error when an ERC20, ERC721, or ERC1155 token
     *      transfer reverts.
     *
     * @param token      The token for which the transfer was attempted.
     * @param from       The source of the attempted transfer.
     * @param to         The recipient of the attempted transfer.
     * @param identifier The identifier for the attempted transfer.
     * @param amount     The amount for the attempted transfer.
     */
    error TokenTransferGenericFailure(
        address token,
        address from,
        address to,
        uint256 identifier,
        uint256 amount
    );

    /**
     * @dev Revert with an error when a batch ERC1155 token transfer reverts.
     *
     * @param token       The token for which the transfer was attempted.
     * @param from        The source of the attempted transfer.
     * @param to          The recipient of the attempted transfer.
     * @param identifiers The identifiers for the attempted transfer.
     * @param amounts     The amounts for the attempted transfer.
     */
    error ERC1155BatchTransferGenericFailure(
        address token,
        address from,
        address to,
        uint256[] identifiers,
        uint256[] amounts
    );

    /**
     * @dev Revert with an error when an ERC20 token transfer returns a falsey
     *      value.
     *
     * @param token      The token for which the ERC20 transfer was attempted.
     * @param from       The source of the attempted ERC20 transfer.
     * @param to         The recipient of the attempted ERC20 transfer.
     * @param amount     The amount for the attempted ERC20 transfer.
     */
    error BadReturnValueFromERC20OnTransfer(
        address token,
        address from,
        address to,
        uint256 amount
    );

    /**
     * @dev Revert with an error when an account being called as an assumed
     *      contract does not have code and returns no data.
     *
     * @param account The account that should contain code.
     */
    error NoContract(address account);

    /**
     * @dev Revert with an error when attempting to execute an 1155 batch
     *      transfer using calldata not produced by default ABI encoding or with
     *      different lengths for ids and amounts arrays.
     */
    error Invalid1155BatchTransferEncoding();
}