// File: contracts/examples/erc1155-transfer/FxERC1155ChildTunnel.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {IFxERC1155} from "../../tokens/IFxERC1155.sol";
import {ERC1155Holder} from "../../lib/ERC1155Holder.sol";
import {Create2} from "../..//lib/Create2.sol";
import {FxBaseChildTunnel} from "../../tunnel/FxBaseChildTunnel.sol";

contract FxERC1155ChildTunnel is FxBaseChildTunnel, Create2, ERC1155Holder {
    bytes32 public constant DEPOSIT = keccak256("DEPOSIT");
    bytes32 public constant DEPOSIT_BATCH = keccak256("DEPOSIT_BATCH");
    bytes32 public constant WITHDRAW = keccak256("WITHDRAW");
    bytes32 public constant WITHDRAW_BATCH = keccak256("WITHDRAW_BATCH");
    bytes32 public constant MAP_TOKEN = keccak256("MAP_TOKEN");
    //string public constant URI = "FXERC1155URI" ;

    event TokenMapped(address indexed rootToken, address indexed childToken);
    // root to child token
    mapping(address => address) public rootToChildToken;
    address public tokenTemplate;

    constructor(address _fxChild, address _tokenTemplate) FxBaseChildTunnel(_fxChild) {
        tokenTemplate = _tokenTemplate;
        require(_isContract(_tokenTemplate), "Token template is not contract");
    }

    function withdraw(
        address childToken,
        uint256 id,
        uint256 amount,
        bytes memory data
    ) public {
        _withdraw(childToken, msg.sender, id, amount, data);
    }

    function withdrawTo(
        address childToken,
        address receiver,
        uint256 id,
        uint256 amount,
        bytes memory data
    ) public {
        _withdraw(childToken, receiver, id, amount, data);
    }

    function withdrawBatch(
        address childToken,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) public {
        _withdrawBatch(childToken, msg.sender, ids, amounts, data);
    }

    function withdrawToBatch(
        address childToken,
        address receiver,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) public {
        _withdrawBatch(childToken, receiver, ids, amounts, data);
    }

    function _processMessageFromRoot(
        uint256, /* stateId */
        address sender,
        bytes memory data
    ) internal override validateSender(sender) {
        (bytes32 syncType, bytes memory syncData) = abi.decode(data, (bytes32, bytes));

        if (syncType == MAP_TOKEN) {
            _mapToken(syncData);
        } else if (syncType == DEPOSIT) {
            _syncDeposit(syncData);
        } else if (syncType == DEPOSIT_BATCH) {
            _syncDepositBatch(syncData);
        } else {
            revert("FxERC1155ChildTunnel: INVALID_SYNC_TYPE");
        }
    }

    function _mapToken(bytes memory syncData) internal returns (address) {
        (address rootToken, string memory uri) = abi.decode(syncData, (address, string));

        address childToken = rootToChildToken[rootToken];
        require(childToken == address(0x0), "FxERC1155ChildTunnel: ALREADY_MAPPED");

        bytes32 salt = keccak256(abi.encodePacked(rootToken));
        childToken = createClone(salt, tokenTemplate);
        IFxERC1155(childToken).initialize(address(this), rootToken, string(abi.encodePacked(uri)));

        rootToChildToken[rootToken] = childToken;
        emit TokenMapped(rootToken, childToken);

        return childToken;
    }

    function _syncDeposit(bytes memory syncData) internal {
        (address rootToken, address depositor, address user, uint256 id, uint256 amount, bytes memory data) = abi
            .decode(syncData, (address, address, address, uint256, uint256, bytes));

        address childToken = rootToChildToken[rootToken];
        IFxERC1155 childTokenContract = IFxERC1155(childToken);

        childTokenContract.mint(user, id, amount, data);
    }

    function _syncDepositBatch(bytes memory syncData) internal {
        (
            address rootToken,
            address depositor,
            address user,
            uint256[] memory ids,
            uint256[] memory amounts,
            bytes memory data
        ) = abi.decode(syncData, (address, address, address, uint256[], uint256[], bytes));

        address childToken = rootToChildToken[rootToken];
        IFxERC1155 childTokenContract = IFxERC1155(childToken);

        childTokenContract.mintBatch(user, ids, amounts, data);
    }

    function _withdraw(
        address childToken,
        address receiver,
        uint256 id,
        uint256 amount,
        bytes memory data
    ) internal {
        IFxERC1155 childTokenContract = IFxERC1155(childToken);
        address rootToken = childTokenContract.connectedToken();

        require(
            childToken != address(0x0) && rootToken != address(0x0) && childToken == rootToChildToken[rootToken],
            "FxERC1155ChildTunnel: NO_MAPPED_TOKEN"
        );

        childTokenContract.burn(msg.sender, id, amount);

        bytes memory message = abi.encode(WITHDRAW, abi.encode(rootToken, childToken, receiver, id, amount, data));
        _sendMessageToRoot(message);
    }

    function _withdrawBatch(
        address childToken,
        address receiver,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) internal {
        IFxERC1155 childTokenContract = IFxERC1155(childToken);
        address rootToken = childTokenContract.connectedToken();

        require(
            childToken != address(0x0) && rootToken != address(0x0) && childToken == rootToChildToken[rootToken],
            "FxERC1155ChildTunnel: NO_MAPPED_TOKEN"
        );

        childTokenContract.burnBatch(msg.sender, ids, amounts);

        bytes memory message = abi.encode(
            WITHDRAW_BATCH,
            abi.encode(rootToken, childToken, receiver, ids, amounts, data)
        );
        _sendMessageToRoot(message);
    }

    function _isContract(address _addr) private view returns (bool) {
        uint32 size;
        assembly {
            size := extcodesize(_addr)
        }
        return (size > 0);
    }
}

// File: contracts/tokens/IFxERC1155.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {IERC1155} from "../lib/IERC1155.sol";

interface IFxERC1155 is IERC1155 {
    function fxManager() external returns (address);

    function initialize(
        address fxManager_,
        address connectedToken_,
        string memory uri_
    ) external;

    function connectedToken() external returns (address);

    function mint(
        address user,
        uint256 id,
        uint256 amount,
        bytes memory data
    ) external;

    function mintBatch(
        address user,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) external;

    function burn(
        address user,
        uint256 id,
        uint256 amount
    ) external;

    function burnBatch(
        address user,
        uint256[] memory ids,
        uint256[] memory amounts
    ) external;
}

// File: contracts/lib/ERC1155Holder.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./ERC1155Receiver.sol";

/**
 * @dev _Available since v3.1._
 */
contract ERC1155Holder is ERC1155Receiver {
    function onERC1155Received(
        address,
        address,
        uint256,
        uint256,
        bytes memory
    ) public virtual override returns (bytes4) {
        return this.onERC1155Received.selector;
    }

    function onERC1155BatchReceived(
        address,
        address,
        uint256[] memory,
        uint256[] memory,
        bytes memory
    ) public virtual override returns (bytes4) {
        return this.onERC1155BatchReceived.selector;
    }
}

// File: contracts/lib/Create2.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

// Create2 adds common methods for minimal proxy with create2
abstract contract Create2 {
    // creates clone using minimal proxy
    function createClone(bytes32 _salt, address _target) internal returns (address _result) {
        bytes20 _targetBytes = bytes20(_target);

        assembly {
            let clone := mload(0x40)
            mstore(clone, 0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000000000000000000000)
            mstore(add(clone, 0x14), _targetBytes)
            mstore(add(clone, 0x28), 0x5af43d82803e903d91602b57fd5bf30000000000000000000000000000000000)
            _result := create2(0, clone, 0x37, _salt)
        }

        require(_result != address(0), "Create2: Failed on minimal deploy");
    }

    // get minimal proxy creation code
    function minimalProxyCreationCode(address logic) internal pure returns (bytes memory) {
        bytes10 creation = 0x3d602d80600a3d3981f3;
        bytes10 prefix = 0x363d3d373d3d3d363d73;
        bytes20 targetBytes = bytes20(logic);
        bytes15 suffix = 0x5af43d82803e903d91602b57fd5bf3;
        return abi.encodePacked(creation, prefix, targetBytes, suffix);
    }

    // get computed create2 address
    function computedCreate2Address(
        bytes32 salt,
        bytes32 bytecodeHash,
        address deployer
    ) public pure returns (address) {
        bytes32 _data = keccak256(abi.encodePacked(bytes1(0xff), deployer, salt, bytecodeHash));
        return address(uint160(uint256(_data)));
    }
}

// File: contracts/tunnel/FxBaseChildTunnel.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

// IFxMessageProcessor represents interface to process message
interface IFxMessageProcessor {
    function processMessageFromRoot(
        uint256 stateId,
        address rootMessageSender,
        bytes calldata data
    ) external;
}

/**
 * @notice Mock child tunnel contract to receive and send message from L2
 */
abstract contract FxBaseChildTunnel is IFxMessageProcessor {
    // MessageTunnel on L1 will get data from this event
    event MessageSent(bytes message);

    // fx child
    address public fxChild;

    // fx root tunnel
    address public fxRootTunnel;

    constructor(address _fxChild) {
        fxChild = _fxChild;
    }

    // Sender must be fxRootTunnel in case of ERC20 tunnel
    modifier validateSender(address sender) {
        require(sender == fxRootTunnel, "FxBaseChildTunnel: INVALID_SENDER_FROM_ROOT");
        _;
    }

    // set fxRootTunnel if not set already
    function setFxRootTunnel(address _fxRootTunnel) external virtual {
        require(fxRootTunnel == address(0x0), "FxBaseChildTunnel: ROOT_TUNNEL_ALREADY_SET");
        fxRootTunnel = _fxRootTunnel;
    }

    function processMessageFromRoot(
        uint256 stateId,
        address rootMessageSender,
        bytes calldata data
    ) external override {
        require(msg.sender == fxChild, "FxBaseChildTunnel: INVALID_SENDER");
        _processMessageFromRoot(stateId, rootMessageSender, data);
    }

    /**
     * @notice Emit message that can be received on Root Tunnel
     * @dev Call the internal function when need to emit message
     * @param message bytes message that will be sent to Root Tunnel
     * some message examples -
     *   abi.encode(tokenId);
     *   abi.encode(tokenId, tokenMetadata);
     *   abi.encode(messageType, messageData);
     */
    function _sendMessageToRoot(bytes memory message) internal {
        emit MessageSent(message);
    }

    /**
     * @notice Process message received from Root Tunnel
     * @dev function needs to be implemented to handle message as per requirement
     * This is called by onStateReceive function.
     * Since it is called via a system call, any event will not be emitted during its execution.
     * @param stateId unique state id
     * @param sender root message sender
     * @param message bytes message that was sent from Root Tunnel
     */
    function _processMessageFromRoot(
        uint256 stateId,
        address sender,
        bytes memory message
    ) internal virtual;
}

// File: contracts/lib/IERC1155.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Required interface of an ERC1155 compliant contract, as defined in the
 * https://eips.ethereum.org/EIPS/eip-1155[EIP].
 *
 * _Available since v3.1._
 */
interface IERC1155 is IERC165 {
    /**
     * @dev Emitted when `value` tokens of token type `id` are transferred from `from` to `to` by `operator`.
     */
    event TransferSingle(address indexed operator, address indexed from, address indexed to, uint256 id, uint256 value);

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

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

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

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

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

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

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

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

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

// File: contracts/lib/IERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: contracts/lib/ERC1155Receiver.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC1155Receiver.sol";
import "./ERC165.sol";

/**
 * @dev _Available since v3.1._
 */
abstract contract ERC1155Receiver is ERC165, IERC1155Receiver {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
        return interfaceId == type(IERC1155Receiver).interfaceId || super.supportsInterface(interfaceId);
    }
}

// File: contracts/lib/IERC1155Receiver.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * _Available since v3.1._
 */
interface IERC1155Receiver is IERC165 {
    /**
        @dev Handles the receipt of a single ERC1155 token type. This function is
        called at the end of a `safeTransferFrom` after the balance has been updated.
        To accept the transfer, this must return
        `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
        (i.e. 0xf23a6e61, or its own function selector).
        @param operator The address which initiated the transfer (i.e. msg.sender)
        @param from The address which previously owned the token
        @param id The ID of the token being transferred
        @param value The amount of tokens being transferred
        @param data Additional data with no specified format
        @return `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))` if transfer is allowed
    */
    function onERC1155Received(
        address operator,
        address from,
        uint256 id,
        uint256 value,
        bytes calldata data
    ) external returns (bytes4);

    /**
        @dev Handles the receipt of a multiple ERC1155 token types. This function
        is called at the end of a `safeBatchTransferFrom` after the balances have
        been updated. To accept the transfer(s), this must return
        `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
        (i.e. 0xbc197c81, or its own function selector).
        @param operator The address which initiated the batch transfer (i.e. msg.sender)
        @param from The address which previously owned the token
        @param ids An array containing ids of each token being transferred (order and length must match values array)
        @param values An array containing amounts of each token being transferred (order and length must match ids array)
        @param data Additional data with no specified format
        @return `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))` if transfer is allowed
    */
    function onERC1155BatchReceived(
        address operator,
        address from,
        uint256[] calldata ids,
        uint256[] calldata values,
        bytes calldata data
    ) external returns (bytes4);
}

// File: contracts/lib/ERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// File: contracts/examples/state-transfer/FxStateChildTunnel.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {FxBaseChildTunnel} from "../../tunnel/FxBaseChildTunnel.sol";

/**
 * @title FxStateChildTunnel
 */
contract FxStateChildTunnel is FxBaseChildTunnel {
    uint256 public latestStateId;
    address public latestRootMessageSender;
    bytes public latestData;

    constructor(address _fxChild) FxBaseChildTunnel(_fxChild) {}

    function _processMessageFromRoot(
        uint256 stateId,
        address sender,
        bytes memory data
    ) internal override validateSender(sender) {
        latestStateId = stateId;
        latestRootMessageSender = sender;
        latestData = data;
    }

    function sendMessageToRoot(bytes memory message) public {
        _sendMessageToRoot(message);
    }
}

// File: contracts/examples/mintable-erc20-transfer/FxMintableERC20ChildTunnel.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {FxBaseChildTunnel} from "../../tunnel/FxBaseChildTunnel.sol";
import {Create2} from "../../lib/Create2.sol";
import {Ownable} from "../../lib/Ownable.sol";
import {FxERC20} from "../../tokens/FxERC20.sol";

/**
 * @title FxMintableERC20ChildTunnel
 */
contract FxMintableERC20ChildTunnel is Ownable, FxBaseChildTunnel, Create2 {
    bytes32 public constant DEPOSIT = keccak256("DEPOSIT");
    //bytes32 public constant MAP_TOKEN = keccak256("MAP_TOKEN");

    // event for token maping
    event TokenMapped(address indexed rootToken, address indexed childToken);
    // root to child token
    mapping(address => address) public rootToChildToken;
    // child token template
    address public childTokenTemplate;
    // root token tempalte code hash
    bytes32 public rootTokenTemplateCodeHash;

    constructor(
        address _fxChild,
        address _childTokenTemplate,
        address _rootTokenTemplate
    ) FxBaseChildTunnel(_fxChild) {
        childTokenTemplate = _childTokenTemplate;
        require(_isContract(_childTokenTemplate), "Token template is not contract");
        // compute root token template code hash
        rootTokenTemplateCodeHash = keccak256(minimalProxyCreationCode(_rootTokenTemplate));
    }

    // deploy child token with unique id
    function deployChildToken(
        uint256 uniqueId,
        string memory name,
        string memory symbol,
        uint8 decimals
    ) public onlyOwner returns (address) {
        // deploy new child token using unique id
        bytes32 childSalt = keccak256(abi.encodePacked(uniqueId));
        address childToken = createClone(childSalt, childTokenTemplate);

        // compute root token address before deployment using create2
        bytes32 rootSalt = keccak256(abi.encodePacked(childToken));
        address rootToken = computedCreate2Address(rootSalt, rootTokenTemplateCodeHash, fxRootTunnel);

        // check if mapping is already there
        require(rootToChildToken[rootToken] == address(0x0), "FxMintableERC20ChildTunnel: ALREADY_MAPPED");
        rootToChildToken[rootToken] = childToken;
        emit TokenMapped(rootToken, childToken);

        // initialize child token with all parameters
        FxERC20(childToken).initialize(address(this), rootToken, name, symbol, decimals);
    }

    //To mint tokens on child chain
    function mintToken(address childToken, uint256 amount) public onlyOwner {
        FxERC20 childTokenContract = FxERC20(childToken);
        // child token contract will have root token
        address rootToken = childTokenContract.connectedToken();

        // validate root and child token mapping
        require(
            childToken != address(0x0) && rootToken != address(0x0) && childToken == rootToChildToken[rootToken],
            "FxERC20ChildTunnel: NO_MAPPED_TOKEN"
        );

        //mint token
        childTokenContract.mint(msg.sender, amount);
    }

    function withdraw(address childToken, uint256 amount) public {
        FxERC20 childTokenContract = FxERC20(childToken);
        // child token contract will have root token
        address rootToken = childTokenContract.connectedToken();

        // validate root and child token mapping
        require(
            childToken != address(0x0) && rootToken != address(0x0) && childToken == rootToChildToken[rootToken],
            "FxERC20ChildTunnel: NO_MAPPED_TOKEN"
        );

        // withdraw tokens
        childTokenContract.burn(msg.sender, amount);

        // name, symbol and decimals
        FxERC20 rootTokenContract = FxERC20(childToken);
        string memory name = rootTokenContract.name();
        string memory symbol = rootTokenContract.symbol();
        uint8 decimals = rootTokenContract.decimals();
        bytes memory metaData = abi.encode(name, symbol, decimals);

        // send message to root regarding token burn
        _sendMessageToRoot(abi.encode(rootToken, childToken, msg.sender, amount, metaData));
    }

    //
    // Internal functions
    //

    function _processMessageFromRoot(
        uint256, /* stateId */
        address sender,
        bytes memory data
    ) internal override validateSender(sender) {
        // decode incoming data
        (bytes32 syncType, bytes memory syncData) = abi.decode(data, (bytes32, bytes));

        if (syncType == DEPOSIT) {
            _syncDeposit(syncData);
        } else {
            revert("FxERC20ChildTunnel: INVALID_SYNC_TYPE");
        }
    }

    function _syncDeposit(bytes memory syncData) internal {
        (address rootToken, address depositor, address to, uint256 amount, bytes memory depositData) = abi.decode(
            syncData,
            (address, address, address, uint256, bytes)
        );
        address childToken = rootToChildToken[rootToken];

        // deposit tokens
        FxERC20 childTokenContract = FxERC20(childToken);
        childTokenContract.mint(to, amount);

        // call `onTokenTranfer` on `to` with limit and ignore error
        if (_isContract(to)) {
            uint256 txGas = 2000000;
            bool success = false;
            bytes memory data = abi.encodeWithSignature(
                "onTokenTransfer(address,address,address,address,uint256,bytes)",
                rootToken,
                childToken,
                depositor,
                to,
                amount,
                depositData
            );
            // solium-disable-next-line security/no-inline-assembly
            assembly {
                success := call(txGas, to, 0, add(data, 0x20), mload(data), 0, 0)
            }
        }
    }

    // check if address is contract
    function _isContract(address _addr) private view returns (bool) {
        uint32 size;
        assembly {
            size := extcodesize(_addr)
        }
        return (size > 0);
    }
}

// File: contracts/lib/Ownable.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

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

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        address msgSender = msg.sender;
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

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

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

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

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

// File: contracts/tokens/FxERC20.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {ERC20} from "../lib/ERC20.sol";
import {IFxERC20} from "./IFxERC20.sol";

/**
 * @title FxERC20 represents fx erc20
 */
contract FxERC20 is IFxERC20, ERC20 {
    address internal _fxManager;
    address internal _connectedToken;

    function initialize(
        address fxManager_,
        address connectedToken_,
        string memory name_,
        string memory symbol_,
        uint8 decimals_
    ) public override {
        require(_fxManager == address(0x0) && _connectedToken == address(0x0), "Token is already initialized");
        _fxManager = fxManager_;
        _connectedToken = connectedToken_;

        // setup meta data
        setupMetaData(name_, symbol_, decimals_);
    }

    // fxManager rturns fx manager
    function fxManager() public view override returns (address) {
        return _fxManager;
    }

    // connectedToken returns root token
    function connectedToken() public view override returns (address) {
        return _connectedToken;
    }

    // setup name, symbol and decimals
    function setupMetaData(
        string memory _name,
        string memory _symbol,
        uint8 _decimals
    ) public {
        require(msg.sender == _fxManager, "Invalid sender");
        _setupMetaData(_name, _symbol, _decimals);
    }

    function mint(address user, uint256 amount) public override {
        require(msg.sender == _fxManager, "Invalid sender");
        _mint(user, amount);
    }

    function burn(address user, uint256 amount) public override {
        require(msg.sender == _fxManager, "Invalid sender");
        _burn(user, amount);
    }
}

// File: contracts/lib/ERC20.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {IERC20} from "./IERC20.sol";
import {SafeMath} from "./SafeMath.sol";

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is IERC20 {
    using SafeMath for uint256;

    mapping(address => uint256) private _balances;

    mapping(address => mapping(address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Returns the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
     * called.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(msg.sender, recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(msg.sender, spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * Requirements:
     *
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(
            sender,
            msg.sender,
            _allowances[sender][msg.sender].sub(amount, "ERC20: transfer amount exceeds allowance")
        );
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(msg.sender, spender, _allowances[msg.sender][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(
            msg.sender,
            spender,
            _allowances[msg.sender][spender].sub(subtractedValue, "ERC20: decreased allowance below zero")
        );
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(
        address sender,
        address recipient,
        uint256 amount
    ) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    function _setupMetaData(
        string memory name_,
        string memory symbol_,
        uint8 decimals_
    ) internal virtual {
        _name = name_;
        _symbol = symbol_;
        _decimals = decimals_;
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be to transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}

// File: contracts/tokens/IFxERC20.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {IERC20} from "../lib/IERC20.sol";

interface IFxERC20 is IERC20 {
    function fxManager() external returns (address);

    function connectedToken() external returns (address);

    function initialize(
        address _fxManager,
        address _connectedToken,
        string memory _name,
        string memory _symbol,
        uint8 _decimals
    ) external;

    function mint(address user, uint256 amount) external;

    function burn(address user, uint256 amount) external;
}

// File: contracts/lib/IERC20.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

// File: contracts/lib/SafeMath.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

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

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

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

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

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

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: contracts/examples/mintable-erc20-transfer/FxMintableERC20RootTunnel.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {Create2} from "../../lib/Create2.sol";
import {SafeMath} from "../../lib/SafeMath.sol";
import {FxERC20} from "../../tokens/FxERC20.sol";
import {FxBaseRootTunnel} from "../../tunnel/FxBaseRootTunnel.sol";
import {SafeERC20, IERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

/**
 * @title FxMintableERC20RootTunnel
 */
contract FxMintableERC20RootTunnel is FxBaseRootTunnel, Create2 {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    // maybe DEPOSIT and MAP_TOKEN can be reduced to bytes4
    bytes32 public constant DEPOSIT = keccak256("DEPOSIT");
    //bytes32 public constant MAP_TOKEN = keccak256("MAP_TOKEN");

    mapping(address => address) public rootToChildTokens;
    address public rootTokenTemplate;
    bytes32 public childTokenTemplateCodeHash;

    constructor(
        address _checkpointManager,
        address _fxRoot,
        address _rootTokenTemplate
    ) FxBaseRootTunnel(_checkpointManager, _fxRoot) {
        rootTokenTemplate = _rootTokenTemplate;
    }

    function deposit(
        address rootToken,
        address user,
        uint256 amount,
        bytes memory data
    ) public {
        // map token if not mapped
        require(rootToChildTokens[rootToken] != address(0x0), "FxMintableERC20RootTunnel: NO_MAPPING_FOUND");

        // transfer from depositor to this contract
        IERC20(rootToken).safeTransferFrom(
            msg.sender, // depositor
            address(this), // manager contract
            amount
        );

        // DEPOSIT, encode(rootToken, depositor, user, amount, extra data)
        bytes memory message = abi.encode(DEPOSIT, abi.encode(rootToken, msg.sender, user, amount, data));
        _sendMessageToChild(message);
    }

    // exit processor
    function _processMessageFromChild(bytes memory data) internal override {
        (address rootToken, address childToken, address to, uint256 amount, bytes memory metaData) = abi.decode(
            data,
            (address, address, address, uint256, bytes)
        );

        // if root token is not available, create it
        if (!_isContract(rootToken) && rootToChildTokens[rootToken] == address(0x0)) {
            (string memory name, string memory symbol, uint8 decimals) = abi.decode(metaData, (string, string, uint8));

            address _createdToken = _deployRootToken(childToken, name, symbol, decimals);
            require(_createdToken == rootToken, "FxMintableERC20RootTunnel: ROOT_TOKEN_CREATION_MISMATCH");
        }

        // validate mapping for root to child
        require(rootToChildTokens[rootToken] == childToken, "FxERC20RootTunnel: INVALID_MAPPING_ON_EXIT");

        // check if current balance for token is less than amount,
        // mint remaining amount for this address
        FxERC20 tokenObj = FxERC20(rootToken);
        uint256 balanceOf = tokenObj.balanceOf(address(this));
        if (balanceOf < amount) {
            tokenObj.mint(address(this), amount.sub(balanceOf));
        }

        //approve token transfer
        tokenObj.approve(address(this), amount);

        // transfer from tokens
        IERC20(rootToken).safeTransferFrom(address(this), to, amount);
    }

    function _deployRootToken(
        address childToken,
        string memory name,
        string memory symbol,
        uint8 decimals
    ) internal returns (address) {
        // deploy new root token
        bytes32 salt = keccak256(abi.encodePacked(childToken));
        address rootToken = createClone(salt, rootTokenTemplate);
        FxERC20(rootToken).initialize(address(this), rootToken, name, symbol, decimals);

        // add into mapped tokens
        rootToChildTokens[rootToken] = childToken;

        return rootToken;
    }

    // check if address is contract
    function _isContract(address _addr) private view returns (bool) {
        uint32 size;
        assembly {
            size := extcodesize(_addr)
        }
        return (size > 0);
    }
}

// File: contracts/tunnel/FxBaseRootTunnel.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {RLPReader} from "../lib/RLPReader.sol";
import {MerklePatriciaProof} from "../lib/MerklePatriciaProof.sol";
import {Merkle} from "../lib/Merkle.sol";
import "../lib/ExitPayloadReader.sol";

interface IFxStateSender {
    function sendMessageToChild(address _receiver, bytes calldata _data) external;
}

contract ICheckpointManager {
    struct HeaderBlock {
        bytes32 root;
        uint256 start;
        uint256 end;
        uint256 createdAt;
        address proposer;
    }

    /**
     * @notice mapping of checkpoint header numbers to block details
     * @dev These checkpoints are submited by plasma contracts
     */
    mapping(uint256 => HeaderBlock) public headerBlocks;
}

abstract contract FxBaseRootTunnel {
    using RLPReader for RLPReader.RLPItem;
    using Merkle for bytes32;
    using ExitPayloadReader for bytes;
    using ExitPayloadReader for ExitPayloadReader.ExitPayload;
    using ExitPayloadReader for ExitPayloadReader.Log;
    using ExitPayloadReader for ExitPayloadReader.LogTopics;
    using ExitPayloadReader for ExitPayloadReader.Receipt;

    // keccak256(MessageSent(bytes))
    bytes32 public constant SEND_MESSAGE_EVENT_SIG = 0x8c5261668696ce22758910d05bab8f186d6eb247ceac2af2e82c7dc17669b036;

    // state sender contract
    IFxStateSender public fxRoot;
    // root chain manager
    ICheckpointManager public checkpointManager;
    // child tunnel contract which receives and sends messages
    address public fxChildTunnel;

    // storage to avoid duplicate exits
    mapping(bytes32 => bool) public processedExits;

    constructor(address _checkpointManager, address _fxRoot) {
        checkpointManager = ICheckpointManager(_checkpointManager);
        fxRoot = IFxStateSender(_fxRoot);
    }

    // set fxChildTunnel if not set already
    function setFxChildTunnel(address _fxChildTunnel) public virtual {
        require(fxChildTunnel == address(0x0), "FxBaseRootTunnel: CHILD_TUNNEL_ALREADY_SET");
        fxChildTunnel = _fxChildTunnel;
    }

    /**
     * @notice Send bytes message to Child Tunnel
     * @param message bytes message that will be sent to Child Tunnel
     * some message examples -
     *   abi.encode(tokenId);
     *   abi.encode(tokenId, tokenMetadata);
     *   abi.encode(messageType, messageData);
     */
    function _sendMessageToChild(bytes memory message) internal {
        fxRoot.sendMessageToChild(fxChildTunnel, message);
    }

    function _validateAndExtractMessage(bytes memory inputData) internal returns (bytes memory) {
        ExitPayloadReader.ExitPayload memory payload = inputData.toExitPayload();

        bytes memory branchMaskBytes = payload.getBranchMaskAsBytes();
        uint256 blockNumber = payload.getBlockNumber();
        // checking if exit has already been processed
        // unique exit is identified using hash of (blockNumber, branchMask, receiptLogIndex)
        bytes32 exitHash = keccak256(
            abi.encodePacked(
                blockNumber,
                // first 2 nibbles are dropped while generating nibble array
                // this allows branch masks that are valid but bypass exitHash check (changing first 2 nibbles only)
                // so converting to nibble array and then hashing it
                MerklePatriciaProof._getNibbleArray(branchMaskBytes),
                payload.getReceiptLogIndex()
            )
        );
        require(processedExits[exitHash] == false, "FxRootTunnel: EXIT_ALREADY_PROCESSED");
        processedExits[exitHash] = true;

        ExitPayloadReader.Receipt memory receipt = payload.getReceipt();
        ExitPayloadReader.Log memory log = receipt.getLog();

        // check child tunnel
        require(fxChildTunnel == log.getEmitter(), "FxRootTunnel: INVALID_FX_CHILD_TUNNEL");

        bytes32 receiptRoot = payload.getReceiptRoot();
        // verify receipt inclusion
        require(
            MerklePatriciaProof.verify(receipt.toBytes(), branchMaskBytes, payload.getReceiptProof(), receiptRoot),
            "FxRootTunnel: INVALID_RECEIPT_PROOF"
        );

        // verify checkpoint inclusion
        _checkBlockMembershipInCheckpoint(
            blockNumber,
            payload.getBlockTime(),
            payload.getTxRoot(),
            receiptRoot,
            payload.getHeaderNumber(),
            payload.getBlockProof()
        );

        ExitPayloadReader.LogTopics memory topics = log.getTopics();

        require(
            bytes32(topics.getField(0).toUint()) == SEND_MESSAGE_EVENT_SIG, // topic0 is event sig
            "FxRootTunnel: INVALID_SIGNATURE"
        );

        // received message data
        bytes memory message = abi.decode(log.getData(), (bytes)); // event decodes params again, so decoding bytes to get message
        return message;
    }

    function _checkBlockMembershipInCheckpoint(
        uint256 blockNumber,
        uint256 blockTime,
        bytes32 txRoot,
        bytes32 receiptRoot,
        uint256 headerNumber,
        bytes memory blockProof
    ) private view returns (uint256) {
        (bytes32 headerRoot, uint256 startBlock, , uint256 createdAt, ) = checkpointManager.headerBlocks(headerNumber);

        require(
            keccak256(abi.encodePacked(blockNumber, blockTime, txRoot, receiptRoot)).checkMembership(
                blockNumber - startBlock,
                headerRoot,
                blockProof
            ),
            "FxRootTunnel: INVALID_HEADER"
        );
        return createdAt;
    }

    /**
     * @notice receive message from  L2 to L1, validated by proof
     * @dev This function verifies if the transaction actually happened on child chain
     *
     * @param inputData RLP encoded data of the reference tx containing following list of fields
     *  0 - headerNumber - Checkpoint header block number containing the reference tx
     *  1 - blockProof - Proof that the block header (in the child chain) is a leaf in the submitted merkle root
     *  2 - blockNumber - Block number containing the reference tx on child chain
     *  3 - blockTime - Reference tx block time
     *  4 - txRoot - Transactions root of block
     *  5 - receiptRoot - Receipts root of block
     *  6 - receipt - Receipt of the reference transaction
     *  7 - receiptProof - Merkle proof of the reference receipt
     *  8 - branchMask - 32 bits denoting the path of receipt in merkle tree
     *  9 - receiptLogIndex - Log Index to read from the receipt
     */
    function receiveMessage(bytes memory inputData) public virtual {
        bytes memory message = _validateAndExtractMessage(inputData);
        _processMessageFromChild(message);
    }

    /**
     * @notice Process message received from Child Tunnel
     * @dev function needs to be implemented to handle message as per requirement
     * This is called by onStateReceive function.
     * Since it is called via a system call, any event will not be emitted during its execution.
     * @param message bytes message that was sent from Child Tunnel
     */
    function _processMessageFromChild(bytes memory message) internal virtual;
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// File: contracts/lib/RLPReader.sol



/*
 * @author Hamdi Allam hamdi.allam97@gmail.com
 * Please reach out with any questions or concerns
 */
pragma solidity ^0.8.0;

library RLPReader {
    uint8 constant STRING_SHORT_START = 0x80;
    uint8 constant STRING_LONG_START = 0xb8;
    uint8 constant LIST_SHORT_START = 0xc0;
    uint8 constant LIST_LONG_START = 0xf8;
    uint8 constant WORD_SIZE = 32;

    struct RLPItem {
        uint256 len;
        uint256 memPtr;
    }

    struct Iterator {
        RLPItem item; // Item that's being iterated over.
        uint256 nextPtr; // Position of the next item in the list.
    }

    /*
     * @dev Returns the next element in the iteration. Reverts if it has not next element.
     * @param self The iterator.
     * @return The next element in the iteration.
     */
    function next(Iterator memory self) internal pure returns (RLPItem memory) {
        require(hasNext(self));

        uint256 ptr = self.nextPtr;
        uint256 itemLength = _itemLength(ptr);
        self.nextPtr = ptr + itemLength;

        return RLPItem(itemLength, ptr);
    }

    /*
     * @dev Returns true if the iteration has more elements.
     * @param self The iterator.
     * @return true if the iteration has more elements.
     */
    function hasNext(Iterator memory self) internal pure returns (bool) {
        RLPItem memory item = self.item;
        return self.nextPtr < item.memPtr + item.len;
    }

    /*
     * @param item RLP encoded bytes
     */
    function toRlpItem(bytes memory item) internal pure returns (RLPItem memory) {
        uint256 memPtr;
        assembly {
            memPtr := add(item, 0x20)
        }

        return RLPItem(item.length, memPtr);
    }

    /*
     * @dev Create an iterator. Reverts if item is not a list.
     * @param self The RLP item.
     * @return An 'Iterator' over the item.
     */
    function iterator(RLPItem memory self) internal pure returns (Iterator memory) {
        require(isList(self));

        uint256 ptr = self.memPtr + _payloadOffset(self.memPtr);
        return Iterator(self, ptr);
    }

    /*
     * @param item RLP encoded bytes
     */
    function rlpLen(RLPItem memory item) internal pure returns (uint256) {
        return item.len;
    }

    /*
     * @param item RLP encoded bytes
     */
    function payloadLen(RLPItem memory item) internal pure returns (uint256) {
        return item.len - _payloadOffset(item.memPtr);
    }

    /*
     * @param item RLP encoded list in bytes
     */
    function toList(RLPItem memory item) internal pure returns (RLPItem[] memory) {
        require(isList(item));

        uint256 items = numItems(item);
        RLPItem[] memory result = new RLPItem[](items);

        uint256 memPtr = item.memPtr + _payloadOffset(item.memPtr);
        uint256 dataLen;
        for (uint256 i = 0; i < items; i++) {
            dataLen = _itemLength(memPtr);
            result[i] = RLPItem(dataLen, memPtr);
            memPtr = memPtr + dataLen;
        }

        return result;
    }

    // @return indicator whether encoded payload is a list. negate this function call for isData.
    function isList(RLPItem memory item) internal pure returns (bool) {
        if (item.len == 0) return false;

        uint8 byte0;
        uint256 memPtr = item.memPtr;
        assembly {
            byte0 := byte(0, mload(memPtr))
        }

        if (byte0 < LIST_SHORT_START) return false;
        return true;
    }

    /*
     * @dev A cheaper version of keccak256(toRlpBytes(item)) that avoids copying memory.
     * @return keccak256 hash of RLP encoded bytes.
     */
    function rlpBytesKeccak256(RLPItem memory item) internal pure returns (bytes32) {
        uint256 ptr = item.memPtr;
        uint256 len = item.len;
        bytes32 result;
        assembly {
            result := keccak256(ptr, len)
        }
        return result;
    }

    function payloadLocation(RLPItem memory item) internal pure returns (uint256, uint256) {
        uint256 offset = _payloadOffset(item.memPtr);
        uint256 memPtr = item.memPtr + offset;
        uint256 len = item.len - offset; // data length
        return (memPtr, len);
    }

    /*
     * @dev A cheaper version of keccak256(toBytes(item)) that avoids copying memory.
     * @return keccak256 hash of the item payload.
     */
    function payloadKeccak256(RLPItem memory item) internal pure returns (bytes32) {
        (uint256 memPtr, uint256 len) = payloadLocation(item);
        bytes32 result;
        assembly {
            result := keccak256(memPtr, len)
        }
        return result;
    }

    /** RLPItem conversions into data types **/

    // @returns raw rlp encoding in bytes
    function toRlpBytes(RLPItem memory item) internal pure returns (bytes memory) {
        bytes memory result = new bytes(item.len);
        if (result.length == 0) return result;

        uint256 ptr;
        assembly {
            ptr := add(0x20, result)
        }

        copy(item.memPtr, ptr, item.len);
        return result;
    }

    // any non-zero byte is considered true
    function toBoolean(RLPItem memory item) internal pure returns (bool) {
        require(item.len == 1);
        uint256 result;
        uint256 memPtr = item.memPtr;
        assembly {
            result := byte(0, mload(memPtr))
        }

        return result == 0 ? false : true;
    }

    function toAddress(RLPItem memory item) internal pure returns (address) {
        // 1 byte for the length prefix
        require(item.len == 21);

        return address(uint160(toUint(item)));
    }

    function toUint(RLPItem memory item) internal pure returns (uint256) {
        require(item.len > 0 && item.len <= 33);

        uint256 offset = _payloadOffset(item.memPtr);
        uint256 len = item.len - offset;

        uint256 result;
        uint256 memPtr = item.memPtr + offset;
        assembly {
            result := mload(memPtr)

            // shfit to the correct location if neccesary
            if lt(len, 32) {
                result := div(result, exp(256, sub(32, len)))
            }
        }

        return result;
    }

    // enforces 32 byte length
    function toUintStrict(RLPItem memory item) internal pure returns (uint256) {
        // one byte prefix
        require(item.len == 33);

        uint256 result;
        uint256 memPtr = item.memPtr + 1;
        assembly {
            result := mload(memPtr)
        }

        return result;
    }

    function toBytes(RLPItem memory item) internal pure returns (bytes memory) {
        require(item.len > 0);

        uint256 offset = _payloadOffset(item.memPtr);
        uint256 len = item.len - offset; // data length
        bytes memory result = new bytes(len);

        uint256 destPtr;
        assembly {
            destPtr := add(0x20, result)
        }

        copy(item.memPtr + offset, destPtr, len);
        return result;
    }

    /*
     * Private Helpers
     */

    // @return number of payload items inside an encoded list.
    function numItems(RLPItem memory item) private pure returns (uint256) {
        if (item.len == 0) return 0;

        uint256 count = 0;
        uint256 currPtr = item.memPtr + _payloadOffset(item.memPtr);
        uint256 endPtr = item.memPtr + item.len;
        while (currPtr < endPtr) {
            currPtr = currPtr + _itemLength(currPtr); // skip over an item
            count++;
        }

        return count;
    }

    // @return entire rlp item byte length
    function _itemLength(uint256 memPtr) private pure returns (uint256) {
        uint256 itemLen;
        uint256 byte0;
        assembly {
            byte0 := byte(0, mload(memPtr))
        }

        if (byte0 < STRING_SHORT_START) itemLen = 1;
        else if (byte0 < STRING_LONG_START) itemLen = byte0 - STRING_SHORT_START + 1;
        else if (byte0 < LIST_SHORT_START) {
            assembly {
                let byteLen := sub(byte0, 0xb7) // # of bytes the actual length is
                memPtr := add(memPtr, 1) // skip over the first byte
                /* 32 byte word size */
                let dataLen := div(mload(memPtr), exp(256, sub(32, byteLen))) // right shifting to get the len
                itemLen := add(dataLen, add(byteLen, 1))
            }
        } else if (byte0 < LIST_LONG_START) {
            itemLen = byte0 - LIST_SHORT_START + 1;
        } else {
            assembly {
                let byteLen := sub(byte0, 0xf7)
                memPtr := add(memPtr, 1)

                let dataLen := div(mload(memPtr), exp(256, sub(32, byteLen))) // right shifting to the correct length
                itemLen := add(dataLen, add(byteLen, 1))
            }
        }

        return itemLen;
    }

    // @return number of bytes until the data
    function _payloadOffset(uint256 memPtr) private pure returns (uint256) {
        uint256 byte0;
        assembly {
            byte0 := byte(0, mload(memPtr))
        }

        if (byte0 < STRING_SHORT_START) return 0;
        else if (byte0 < STRING_LONG_START || (byte0 >= LIST_SHORT_START && byte0 < LIST_LONG_START)) return 1;
        else if (byte0 < LIST_SHORT_START)
            // being explicit
            return byte0 - (STRING_LONG_START - 1) + 1;
        else return byte0 - (LIST_LONG_START - 1) + 1;
    }

    /*
     * @param src Pointer to source
     * @param dest Pointer to destination
     * @param len Amount of memory to copy from the source
     */
    function copy(
        uint256 src,
        uint256 dest,
        uint256 len
    ) private pure {
        if (len == 0) return;

        // copy as many word sizes as possible
        for (; len >= WORD_SIZE; len -= WORD_SIZE) {
            assembly {
                mstore(dest, mload(src))
            }

            src += WORD_SIZE;
            dest += WORD_SIZE;
        }

        if (len == 0) return;

        // left over bytes. Mask is used to remove unwanted bytes from the word
        uint256 mask = 256**(WORD_SIZE - len) - 1;

        assembly {
            let srcpart := and(mload(src), not(mask)) // zero out src
            let destpart := and(mload(dest), mask) // retrieve the bytes
            mstore(dest, or(destpart, srcpart))
        }
    }
}

// File: contracts/lib/MerklePatriciaProof.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {RLPReader} from "./RLPReader.sol";

library MerklePatriciaProof {
    /*
     * @dev Verifies a merkle patricia proof.
     * @param value The terminating value in the trie.
     * @param encodedPath The path in the trie leading to value.
     * @param rlpParentNodes The rlp encoded stack of nodes.
     * @param root The root hash of the trie.
     * @return The boolean validity of the proof.
     */
    function verify(
        bytes memory value,
        bytes memory encodedPath,
        bytes memory rlpParentNodes,
        bytes32 root
    ) internal pure returns (bool) {
        RLPReader.RLPItem memory item = RLPReader.toRlpItem(rlpParentNodes);
        RLPReader.RLPItem[] memory parentNodes = RLPReader.toList(item);

        bytes memory currentNode;
        RLPReader.RLPItem[] memory currentNodeList;

        bytes32 nodeKey = root;
        uint256 pathPtr = 0;

        bytes memory path = _getNibbleArray(encodedPath);
        if (path.length == 0) {
            return false;
        }

        for (uint256 i = 0; i < parentNodes.length; i++) {
            if (pathPtr > path.length) {
                return false;
            }

            currentNode = RLPReader.toRlpBytes(parentNodes[i]);
            if (nodeKey != keccak256(currentNode)) {
                return false;
            }
            currentNodeList = RLPReader.toList(parentNodes[i]);

            if (currentNodeList.length == 17) {
                if (pathPtr == path.length) {
                    if (keccak256(RLPReader.toBytes(currentNodeList[16])) == keccak256(value)) {
                        return true;
                    } else {
                        return false;
                    }
                }

                uint8 nextPathNibble = uint8(path[pathPtr]);
                if (nextPathNibble > 16) {
                    return false;
                }
                nodeKey = bytes32(RLPReader.toUintStrict(currentNodeList[nextPathNibble]));
                pathPtr += 1;
            } else if (currentNodeList.length == 2) {
                uint256 traversed = _nibblesToTraverse(RLPReader.toBytes(currentNodeList[0]), path, pathPtr);
                if (pathPtr + traversed == path.length) {
                    //leaf node
                    if (keccak256(RLPReader.toBytes(currentNodeList[1])) == keccak256(value)) {
                        return true;
                    } else {
                        return false;
                    }
                }

                //extension node
                if (traversed == 0) {
                    return false;
                }

                pathPtr += traversed;
                nodeKey = bytes32(RLPReader.toUintStrict(currentNodeList[1]));
            } else {
                return false;
            }
        }
    }

    function _nibblesToTraverse(
        bytes memory encodedPartialPath,
        bytes memory path,
        uint256 pathPtr
    ) private pure returns (uint256) {
        uint256 len = 0;
        // encodedPartialPath has elements that are each two hex characters (1 byte), but partialPath
        // and slicedPath have elements that are each one hex character (1 nibble)
        bytes memory partialPath = _getNibbleArray(encodedPartialPath);
        bytes memory slicedPath = new bytes(partialPath.length);

        // pathPtr counts nibbles in path
        // partialPath.length is a number of nibbles
        for (uint256 i = pathPtr; i < pathPtr + partialPath.length; i++) {
            bytes1 pathNibble = path[i];
            slicedPath[i - pathPtr] = pathNibble;
        }

        if (keccak256(partialPath) == keccak256(slicedPath)) {
            len = partialPath.length;
        } else {
            len = 0;
        }
        return len;
    }

    // bytes b must be hp encoded
    function _getNibbleArray(bytes memory b) internal pure returns (bytes memory) {
        bytes memory nibbles = "";
        if (b.length > 0) {
            uint8 offset;
            uint8 hpNibble = uint8(_getNthNibbleOfBytes(0, b));
            if (hpNibble == 1 || hpNibble == 3) {
                nibbles = new bytes(b.length * 2 - 1);
                bytes1 oddNibble = _getNthNibbleOfBytes(1, b);
                nibbles[0] = oddNibble;
                offset = 1;
            } else {
                nibbles = new bytes(b.length * 2 - 2);
                offset = 0;
            }

            for (uint256 i = offset; i < nibbles.length; i++) {
                nibbles[i] = _getNthNibbleOfBytes(i - offset + 2, b);
            }
        }
        return nibbles;
    }

    function _getNthNibbleOfBytes(uint256 n, bytes memory str) private pure returns (bytes1) {
        return bytes1(n % 2 == 0 ? uint8(str[n / 2]) / 0x10 : uint8(str[n / 2]) % 0x10);
    }
}

// File: contracts/lib/Merkle.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

library Merkle {
    function checkMembership(
        bytes32 leaf,
        uint256 index,
        bytes32 rootHash,
        bytes memory proof
    ) internal pure returns (bool) {
        require(proof.length % 32 == 0, "Invalid proof length");
        uint256 proofHeight = proof.length / 32;
        // Proof of size n means, height of the tree is n+1.
        // In a tree of height n+1, max #leafs possible is 2 ^ n
        require(index < 2**proofHeight, "Leaf index is too big");

        bytes32 proofElement;
        bytes32 computedHash = leaf;
        for (uint256 i = 32; i <= proof.length; i += 32) {
            assembly {
                proofElement := mload(add(proof, i))
            }

            if (index % 2 == 0) {
                computedHash = keccak256(abi.encodePacked(computedHash, proofElement));
            } else {
                computedHash = keccak256(abi.encodePacked(proofElement, computedHash));
            }

            index = index / 2;
        }
        return computedHash == rootHash;
    }
}

// File: contracts/lib/ExitPayloadReader.sol



pragma solidity ^0.8.0;

import {RLPReader} from "./RLPReader.sol";

library ExitPayloadReader {
    using RLPReader for bytes;
    using RLPReader for RLPReader.RLPItem;

    uint8 constant WORD_SIZE = 32;

    struct ExitPayload {
        RLPReader.RLPItem[] data;
    }

    struct Receipt {
        RLPReader.RLPItem[] data;
        bytes raw;
        uint256 logIndex;
    }

    struct Log {
        RLPReader.RLPItem data;
        RLPReader.RLPItem[] list;
    }

    struct LogTopics {
        RLPReader.RLPItem[] data;
    }

    // copy paste of private copy() from RLPReader to avoid changing of existing contracts
    function copy(
        uint256 src,
        uint256 dest,
        uint256 len
    ) private pure {
        if (len == 0) return;

        // copy as many word sizes as possible
        for (; len >= WORD_SIZE; len -= WORD_SIZE) {
            assembly {
                mstore(dest, mload(src))
            }

            src += WORD_SIZE;
            dest += WORD_SIZE;
        }

        // left over bytes. Mask is used to remove unwanted bytes from the word
        uint256 mask = 256**(WORD_SIZE - len) - 1;
        assembly {
            let srcpart := and(mload(src), not(mask)) // zero out src
            let destpart := and(mload(dest), mask) // retrieve the bytes
            mstore(dest, or(destpart, srcpart))
        }
    }

    function toExitPayload(bytes memory data) internal pure returns (ExitPayload memory) {
        RLPReader.RLPItem[] memory payloadData = data.toRlpItem().toList();

        return ExitPayload(payloadData);
    }

    function getHeaderNumber(ExitPayload memory payload) internal pure returns (uint256) {
        return payload.data[0].toUint();
    }

    function getBlockProof(ExitPayload memory payload) internal pure returns (bytes memory) {
        return payload.data[1].toBytes();
    }

    function getBlockNumber(ExitPayload memory payload) internal pure returns (uint256) {
        return payload.data[2].toUint();
    }

    function getBlockTime(ExitPayload memory payload) internal pure returns (uint256) {
        return payload.data[3].toUint();
    }

    function getTxRoot(ExitPayload memory payload) internal pure returns (bytes32) {
        return bytes32(payload.data[4].toUint());
    }

    function getReceiptRoot(ExitPayload memory payload) internal pure returns (bytes32) {
        return bytes32(payload.data[5].toUint());
    }

    function getReceipt(ExitPayload memory payload) internal pure returns (Receipt memory receipt) {
        receipt.raw = payload.data[6].toBytes();
        RLPReader.RLPItem memory receiptItem = receipt.raw.toRlpItem();

        if (receiptItem.isList()) {
            // legacy tx
            receipt.data = receiptItem.toList();
        } else {
            // pop first byte before parsting receipt
            bytes memory typedBytes = receipt.raw;
            bytes memory result = new bytes(typedBytes.length - 1);
            uint256 srcPtr;
            uint256 destPtr;
            assembly {
                srcPtr := add(33, typedBytes)
                destPtr := add(0x20, result)
            }

            copy(srcPtr, destPtr, result.length);
            receipt.data = result.toRlpItem().toList();
        }

        receipt.logIndex = getReceiptLogIndex(payload);
        return receipt;
    }

    function getReceiptProof(ExitPayload memory payload) internal pure returns (bytes memory) {
        return payload.data[7].toBytes();
    }

    function getBranchMaskAsBytes(ExitPayload memory payload) internal pure returns (bytes memory) {
        return payload.data[8].toBytes();
    }

    function getBranchMaskAsUint(ExitPayload memory payload) internal pure returns (uint256) {
        return payload.data[8].toUint();
    }

    function getReceiptLogIndex(ExitPayload memory payload) internal pure returns (uint256) {
        return payload.data[9].toUint();
    }

    // Receipt methods
    function toBytes(Receipt memory receipt) internal pure returns (bytes memory) {
        return receipt.raw;
    }

    function getLog(Receipt memory receipt) internal pure returns (Log memory) {
        RLPReader.RLPItem memory logData = receipt.data[3].toList()[receipt.logIndex];
        return Log(logData, logData.toList());
    }

    // Log methods
    function getEmitter(Log memory log) internal pure returns (address) {
        return RLPReader.toAddress(log.list[0]);
    }

    function getTopics(Log memory log) internal pure returns (LogTopics memory) {
        return LogTopics(log.list[1].toList());
    }

    function getData(Log memory log) internal pure returns (bytes memory) {
        return log.list[2].toBytes();
    }

    function toRlpBytes(Log memory log) internal pure returns (bytes memory) {
        return log.data.toRlpBytes();
    }

    // LogTopics methods
    function getField(LogTopics memory topics, uint256 index) internal pure returns (RLPReader.RLPItem memory) {
        return topics.data[index];
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

// File: contracts/examples/erc20-transfer/FxERC20RootTunnel.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {ERC20} from "../../lib/ERC20.sol";
import {Create2} from "../../lib/Create2.sol";
import {IRootChainManager} from "../../lib/IRootChainManager.sol";
import {FxBaseRootTunnel} from "../../tunnel/FxBaseRootTunnel.sol";
import {SafeERC20, IERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

/**
 * @title FxERC20RootTunnel
 */
contract FxERC20RootTunnel is FxBaseRootTunnel, Create2 {
    using SafeERC20 for IERC20;
    // maybe DEPOSIT and MAP_TOKEN can be reduced to bytes4
    bytes32 public constant DEPOSIT = keccak256("DEPOSIT");
    bytes32 public constant MAP_TOKEN = keccak256("MAP_TOKEN");
    bytes32 public immutable childTokenTemplateCodeHash;
    IRootChainManager public immutable rootChainManager;

    event TokenMappedERC20(address indexed rootToken, address indexed childToken);
    event FxWithdrawERC20(
        address indexed rootToken,
        address indexed childToken,
        address indexed userAddress,
        uint256 amount
    );
    event FxDepositERC20(
        address indexed rootToken,
        address indexed depositor,
        address indexed userAddress,
        uint256 amount
    );

    mapping(address => address) public rootToChildTokens;

    constructor(
        address _checkpointManager,
        address _fxRoot,
        address _fxERC20Token,
        IRootChainManager _rootChainManager
    ) FxBaseRootTunnel(_checkpointManager, _fxRoot) {
        rootChainManager = _rootChainManager;
        // compute child token template code hash
        childTokenTemplateCodeHash = keccak256(minimalProxyCreationCode(_fxERC20Token));
    }

    /**
     * @notice Map a token to enable its movement via the PoS Portal, callable only by mappers
     * @param rootToken address of token on root chain
     */
    function mapToken(address rootToken) public {
        // check if token is already mapped
        require(rootToChildTokens[rootToken] == address(0x0), "FxERC20RootTunnel: ALREADY_MAPPED");
        require(rootChainManager.rootToChildToken(rootToken) == address(0x0), "FxERC20RootTunnel: MAPPED_ON_POS");

        // name, symbol and decimals
        ERC20 rootTokenContract = ERC20(rootToken);
        string memory name = rootTokenContract.name();
        string memory symbol = rootTokenContract.symbol();
        uint8 decimals = rootTokenContract.decimals();

        // MAP_TOKEN, encode(rootToken, name, symbol, decimals)
        bytes memory message = abi.encode(MAP_TOKEN, abi.encode(rootToken, name, symbol, decimals));
        _sendMessageToChild(message);

        // compute child token address before deployment using create2
        bytes32 salt = keccak256(abi.encodePacked(rootToken));
        address childToken = computedCreate2Address(salt, childTokenTemplateCodeHash, fxChildTunnel);

        // add into mapped tokens
        rootToChildTokens[rootToken] = childToken;
        emit TokenMappedERC20(rootToken, childToken);
    }

    function deposit(
        address rootToken,
        address user,
        uint256 amount,
        bytes memory data
    ) public {
        // map token if not mapped
        if (rootToChildTokens[rootToken] == address(0x0)) {
            mapToken(rootToken);
        }

        // transfer from depositor to this contract
        IERC20(rootToken).safeTransferFrom(
            msg.sender, // depositor
            address(this), // manager contract
            amount
        );

        // DEPOSIT, encode(rootToken, depositor, user, amount, extra data)
        bytes memory message = abi.encode(DEPOSIT, abi.encode(rootToken, msg.sender, user, amount, data));
        _sendMessageToChild(message);
        emit FxDepositERC20(rootToken, msg.sender, user, amount);
    }

    // exit processor
    function _processMessageFromChild(bytes memory data) internal override {
        (address rootToken, address childToken, address to, uint256 amount) = abi.decode(
            data,
            (address, address, address, uint256)
        );
        // validate mapping for root to child
        require(rootToChildTokens[rootToken] == childToken, "FxERC20RootTunnel: INVALID_MAPPING_ON_EXIT");

        // transfer from tokens to
        IERC20(rootToken).safeTransfer(to, amount);
        emit FxWithdrawERC20(rootToken, childToken, to, amount);
    }
}

// File: contracts/lib/IRootChainManager.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

/*
 * @dev Interace to provide a function from Polygon Root Chain Manager
 */
interface IRootChainManager {
    function rootToChildToken(address _rootToken) external returns (address);
}

// File: contracts/examples/state-transfer/FxStateRootTunnel.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {FxBaseRootTunnel} from "../../tunnel/FxBaseRootTunnel.sol";

/**
 * @title FxStateRootTunnel
 */
contract FxStateRootTunnel is FxBaseRootTunnel {
    bytes public latestData;

    constructor(address _checkpointManager, address _fxRoot) FxBaseRootTunnel(_checkpointManager, _fxRoot) {}

    function _processMessageFromChild(bytes memory data) internal override {
        latestData = data;
    }

    function sendMessageToChild(bytes memory message) public {
        _sendMessageToChild(message);
    }
}

// File: contracts/examples/erc721-transfer/FxERC721RootTunnel.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {ERC721} from "../../lib/ERC721.sol";
import {Create2} from "../../lib/Create2.sol";
import {FxBaseRootTunnel} from "../../tunnel/FxBaseRootTunnel.sol";
import {IERC721Receiver} from "../../lib/IERC721Receiver.sol";

/**
 * @title FxERC721RootTunnel
 */
contract FxERC721RootTunnel is FxBaseRootTunnel, Create2, IERC721Receiver {
    // maybe DEPOSIT and MAP_TOKEN can be reduced to bytes4
    bytes32 public constant DEPOSIT = keccak256("DEPOSIT");
    bytes32 public constant MAP_TOKEN = keccak256("MAP_TOKEN");

    event TokenMappedERC721(address indexed rootToken, address indexed childToken);
    event FxWithdrawERC721(
        address indexed rootToken,
        address indexed childToken,
        address indexed userAddress,
        uint256 id
    );
    event FxDepositERC721(
        address indexed rootToken,
        address indexed depositor,
        address indexed userAddress,
        uint256 id
    );

    mapping(address => address) public rootToChildTokens;
    bytes32 public childTokenTemplateCodeHash;

    constructor(
        address _checkpointManager,
        address _fxRoot,
        address _fxERC721Token
    ) FxBaseRootTunnel(_checkpointManager, _fxRoot) {
        // compute child token template code hash
        childTokenTemplateCodeHash = keccak256(minimalProxyCreationCode(_fxERC721Token));
    }

    function onERC721Received(
        address, /* operator */
        address, /* from */
        uint256, /* tokenId */
        bytes calldata /* data */
    ) external pure override returns (bytes4) {
        return this.onERC721Received.selector;
    }

    /**
     * @notice Map a token to enable its movement via the PoS Portal, callable only by mappers
     * @param rootToken address of token on root chain
     */
    function mapToken(address rootToken) public {
        // check if token is already mapped
        require(rootToChildTokens[rootToken] == address(0x0), "FxERC721RootTunnel: ALREADY_MAPPED");

        // name, symbol
        ERC721 rootTokenContract = ERC721(rootToken);
        string memory name = rootTokenContract.name();
        string memory symbol = rootTokenContract.symbol();

        // MAP_TOKEN, encode(rootToken, name, symbol)
        bytes memory message = abi.encode(MAP_TOKEN, abi.encode(rootToken, name, symbol));
        _sendMessageToChild(message);

        // compute child token address before deployment using create2
        bytes32 salt = keccak256(abi.encodePacked(rootToken));
        address childToken = computedCreate2Address(salt, childTokenTemplateCodeHash, fxChildTunnel);

        // add into mapped tokens
        rootToChildTokens[rootToken] = childToken;
        emit TokenMappedERC721(rootToken, childToken);
    }

    function deposit(
        address rootToken,
        address user,
        uint256 tokenId,
        bytes memory data
    ) public {
        // map token if not mapped
        if (rootToChildTokens[rootToken] == address(0x0)) {
            mapToken(rootToken);
        }

        // transfer from depositor to this contract
        ERC721(rootToken).safeTransferFrom(
            msg.sender, // depositor
            address(this), // manager contract
            tokenId,
            data
        );

        // DEPOSIT, encode(rootToken, depositor, user, tokenId, extra data)
        bytes memory message = abi.encode(DEPOSIT, abi.encode(rootToken, msg.sender, user, tokenId, data));
        _sendMessageToChild(message);
        emit FxDepositERC721(rootToken, msg.sender, user, tokenId);
    }

    // exit processor
    function _processMessageFromChild(bytes memory data) internal override {
        (address rootToken, address childToken, address to, uint256 tokenId, bytes memory syncData) = abi.decode(
            data,
            (address, address, address, uint256, bytes)
        );
        // validate mapping for root to child
        require(rootToChildTokens[rootToken] == childToken, "FxERC721RootTunnel: INVALID_MAPPING_ON_EXIT");

        // transfer from tokens to
        ERC721(rootToken).safeTransferFrom(address(this), to, tokenId, syncData);
        emit FxWithdrawERC721(rootToken, childToken, to, tokenId);
    }
}

// File: contracts/lib/ERC721.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC721.sol";
import "./IERC721Receiver.sol";
import "./IERC721Metadata.sol";
import "./Address.sol";
import "./Context.sol";
import "./Strings.sol";
import "./ERC165.sol";

/**
 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
 * the Metadata extension, but not including the Enumerable extension, which is available separately as
 * {ERC721Enumerable}.
 */
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
    using Address for address;
    using Strings for uint256;

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    // Mapping from token ID to owner address
    mapping(uint256 => address) private _owners;

    // Mapping owner address to token count
    mapping(address => uint256) private _balances;

    // Mapping from token ID to approved address
    mapping(uint256 => address) private _tokenApprovals;

    // Mapping from owner to operator approvals
    mapping(address => mapping(address => bool)) private _operatorApprovals;

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
        return
            interfaceId == type(IERC721).interfaceId ||
            interfaceId == type(IERC721Metadata).interfaceId ||
            super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC721-balanceOf}.
     */
    function balanceOf(address owner) public view virtual override returns (uint256) {
        require(owner != address(0), "ERC721: balance query for the zero address");
        return _balances[owner];
    }

    /**
     * @dev See {IERC721-ownerOf}.
     */
    function ownerOf(uint256 tokenId) public view virtual override returns (address) {
        address owner = _owners[tokenId];
        require(owner != address(0), "ERC721: owner query for nonexistent token");
        return owner;
    }

    /**
     * @dev See {IERC721Metadata-name}.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev See {IERC721Metadata-symbol}.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev See {IERC721Metadata-tokenURI}.
     */
    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");

        string memory baseURI = _baseURI();
        return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
    }

    /**
     * @dev Base URI for computing {tokenURI}. Empty by default, can be overriden
     * in child contracts.
     */
    function _baseURI() internal view virtual returns (string memory) {
        return "";
    }

    /**
     * @dev See {IERC721-approve}.
     */
    function approve(address to, uint256 tokenId) public virtual override {
        address owner = ERC721.ownerOf(tokenId);
        require(to != owner, "ERC721: approval to current owner");

        require(
            _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
            "ERC721: approve caller is not owner nor approved for all"
        );

        _approve(to, tokenId);
        emit Approval(owner, to, tokenId);
    }

    /**
     * @dev See {IERC721-getApproved}.
     */
    function getApproved(uint256 tokenId) public view virtual override returns (address) {
        require(_exists(tokenId), "ERC721: approved query for nonexistent token");

        return _tokenApprovals[tokenId];
    }

    /**
     * @dev See {IERC721-setApprovalForAll}.
     */
    function setApprovalForAll(address operator, bool approved) public virtual override {
        require(operator != _msgSender(), "ERC721: approve to caller");

        _operatorApprovals[_msgSender()][operator] = approved;
        emit ApprovalForAll(_msgSender(), operator, approved);
    }

    /**
     * @dev See {IERC721-isApprovedForAll}.
     */
    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
        return _operatorApprovals[owner][operator];
    }

    /**
     * @dev See {IERC721-transferFrom}.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");

        _transfer(from, to, tokenId);
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        safeTransferFrom(from, to, tokenId, "");
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
        _safeTransfer(from, to, tokenId, _data);
    }

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * `_data` is additional data, it has no specified format and it is sent in call to `to`.
     *
     * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
     * implement alternative mechanisms to perform token transfer, such as signature-based.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeTransfer(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) internal virtual {
        _transfer(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Returns whether `tokenId` exists.
     *
     * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
     *
     * Tokens start existing when they are minted (`_mint`),
     * and stop existing when they are burned (`_burn`).
     */
    function _exists(uint256 tokenId) internal view virtual returns (bool) {
        return _owners[tokenId] != address(0);
    }

    /**
     * @dev Returns whether `spender` is allowed to manage `tokenId`.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
        require(_exists(tokenId), "ERC721: operator query for nonexistent token");
        address owner = ERC721.ownerOf(tokenId);
        return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
    }

    /**
     * @dev Safely mints `tokenId` and transfers it to `to`.
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeMint(address to, uint256 tokenId) internal virtual {
        _safeMint(to, tokenId, "");
    }

    /**
     * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
     * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
     */
    function _safeMint(
        address to,
        uint256 tokenId,
        bytes memory _data
    ) internal virtual {
        _mint(to, tokenId);
        require(
            _checkOnERC721Received(address(0), to, tokenId, _data),
            "ERC721: transfer to non ERC721Receiver implementer"
        );
    }

    /**
     * @dev Mints `tokenId` and transfers it to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - `to` cannot be the zero address.
     *
     * Emits a {Transfer} event.
     */
    function _mint(address to, uint256 tokenId) internal virtual {
        require(to != address(0), "ERC721: mint to the zero address");
        require(!_exists(tokenId), "ERC721: token already minted");

        _beforeTokenTransfer(address(0), to, tokenId);

        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(address(0), to, tokenId);
    }

    /**
     * @dev Destroys `tokenId`.
     * The approval is cleared when the token is burned.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     *
     * Emits a {Transfer} event.
     */
    function _burn(uint256 tokenId) internal virtual {
        address owner = ERC721.ownerOf(tokenId);

        _beforeTokenTransfer(owner, address(0), tokenId);

        // Clear approvals
        _approve(address(0), tokenId);

        _balances[owner] -= 1;
        delete _owners[tokenId];

        emit Transfer(owner, address(0), tokenId);
    }

    /**
     * @dev Transfers `tokenId` from `from` to `to`.
     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     *
     * Emits a {Transfer} event.
     */
    function _transfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {
        require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer of token that is not own");
        require(to != address(0), "ERC721: transfer to the zero address");

        _beforeTokenTransfer(from, to, tokenId);

        // Clear approvals from the previous owner
        _approve(address(0), tokenId);
        emit Approval(ERC721.ownerOf(tokenId), address(0), tokenId);

        _balances[from] -= 1;
        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(from, to, tokenId);
    }

    /**
     * @dev Approve `to` to operate on `tokenId`
     *
     */
    function _approve(address to, uint256 tokenId) internal virtual {
        _tokenApprovals[tokenId] = to;
    }

    function _setupMetaData(string memory name_, string memory symbol_) internal virtual {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
     * The call is not executed if the target address is not a contract.
     *
     * @param from address representing the previous owner of the given token ID
     * @param to target address that will receive the tokens
     * @param tokenId uint256 ID of the token to be transferred
     * @param _data bytes optional data to send along with the call
     * @return bool whether the call correctly returned the expected magic value
     */
    function _checkOnERC721Received(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) private returns (bool) {
        if (to.isContract()) {
            try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
                return retval == IERC721Receiver(to).onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert("ERC721: transfer to non ERC721Receiver implementer");
                } else {
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        } else {
            return true;
        }
    }

    /**
     * @dev Hook that is called before any token transfer. This includes minting
     * and burning.
     *
     * Calling conditions:
     *
     * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
     * transferred to `to`.
     * - When `from` is zero, `tokenId` will be minted for `to`.
     * - When `to` is zero, ``from``'s `tokenId` will be burned.
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {}
}

// File: contracts/lib/IERC721Receiver.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
    /**
     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
     *
     * The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}

// File: contracts/lib/IERC721.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

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

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

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

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

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

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

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

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

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

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

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

// File: contracts/lib/IERC721Metadata.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC721.sol";

/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Metadata is IERC721 {
    /**
     * @dev Returns the token collection name.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the token collection symbol.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
     */
    function tokenURI(uint256 tokenId) external view returns (string memory);
}

// File: contracts/lib/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

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

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

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

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

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

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

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

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

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

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

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

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

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) private pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: contracts/lib/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

// File: contracts/lib/Strings.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant alphabet = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = alphabet[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }
}

// File: contracts/tokens/FxERC721.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {ERC721} from "../lib/ERC721.sol";
import {IFxERC721} from "./IFxERC721.sol";

/**
 * @title FxERC20 represents fx erc20
 */
contract FxERC721 is IFxERC721, ERC721 {
    address internal _fxManager;
    address internal _connectedToken;

    function initialize(
        address fxManager_,
        address connectedToken_,
        string memory name_,
        string memory symbol_
    ) public override {
        require(_fxManager == address(0x0) && _connectedToken == address(0x0), "Token is already initialized");
        _fxManager = fxManager_;
        _connectedToken = connectedToken_;

        // setup meta data
        setupMetaData(name_, symbol_);
    }

    // fxManager returns fx manager
    function fxManager() public view override returns (address) {
        return _fxManager;
    }

    // connectedToken returns root token
    function connectedToken() public view override returns (address) {
        return _connectedToken;
    }

    // setup name, symbol and decimals
    function setupMetaData(string memory _name, string memory _symbol) public {
        require(msg.sender == _fxManager, "Invalid sender");
        _setupMetaData(_name, _symbol);
    }

    function mint(
        address user,
        uint256 tokenId,
        bytes memory _data
    ) public override {
        require(msg.sender == _fxManager, "Invalid sender");
        _safeMint(user, tokenId, _data);
    }

    function burn(uint256 tokenId) public override {
        require(msg.sender == _fxManager, "Invalid sender");
        _burn(tokenId);
    }
}

// File: contracts/tokens/IFxERC721.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {IERC721} from "../lib/IERC721.sol";

interface IFxERC721 is IERC721 {
    function fxManager() external returns (address);

    function connectedToken() external returns (address);

    function initialize(
        address _fxManager,
        address _connectedToken,
        string memory _name,
        string memory _symbol
    ) external;

    function mint(
        address user,
        uint256 tokenId,
        bytes memory _data
    ) external;

    function burn(uint256 tokenId) external;
}

// File: contracts/lib/ERC1155.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC1155.sol";
import "./IERC1155Receiver.sol";
import "./IERC1155MetadataURI.sol";
import "./Address.sol";
import "./Context.sol";
import "./ERC165.sol";

/**
 *
 * @dev Implementation of the basic standard multi-token.
 * See https://eips.ethereum.org/EIPS/eip-1155
 * Originally based on code by Enjin: https://github.com/enjin/erc-1155
 *
 * _Available since v3.1._
 */
contract ERC1155 is Context, ERC165, IERC1155, IERC1155MetadataURI {
    using Address for address;

    // Mapping from token ID to account balances
    mapping(uint256 => mapping(address => uint256)) private _balances;

    // Mapping from account to operator approvals
    mapping(address => mapping(address => bool)) private _operatorApprovals;

    // Used as the URI for all token types by relying on ID substitution, e.g. https://token-cdn-domain/{id}.json
    string private _uri;

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
        return
            interfaceId == type(IERC1155).interfaceId ||
            interfaceId == type(IERC1155MetadataURI).interfaceId ||
            super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC1155MetadataURI-uri}.
     *
     * This implementation returns the same URI for *all* token types. It relies
     * on the token type ID substitution mechanism
     * https://eips.ethereum.org/EIPS/eip-1155#metadata[defined in the EIP].
     *
     * Clients calling this function must replace the `\{id\}` substring with the
     * actual token type ID.
     */
    function uri(uint256) public view virtual override returns (string memory) {
        return _uri;
    }

    /**
     * @dev See {IERC1155-balanceOf}.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function balanceOf(address account, uint256 id) public view virtual override returns (uint256) {
        require(account != address(0), "ERC1155: balance query for the zero address");
        return _balances[id][account];
    }

    /**
     * @dev See {IERC1155-balanceOfBatch}.
     *
     * Requirements:
     *
     * - `accounts` and `ids` must have the same length.
     */
    function balanceOfBatch(address[] memory accounts, uint256[] memory ids)
        public
        view
        virtual
        override
        returns (uint256[] memory)
    {
        require(accounts.length == ids.length, "ERC1155: accounts and ids length mismatch");

        uint256[] memory batchBalances = new uint256[](accounts.length);

        for (uint256 i = 0; i < accounts.length; ++i) {
            batchBalances[i] = balanceOf(accounts[i], ids[i]);
        }

        return batchBalances;
    }

    /**
     * @dev See {IERC1155-setApprovalForAll}.
     */
    function setApprovalForAll(address operator, bool approved) public virtual override {
        require(_msgSender() != operator, "ERC1155: setting approval status for self");

        _operatorApprovals[_msgSender()][operator] = approved;
        emit ApprovalForAll(_msgSender(), operator, approved);
    }

    /**
     * @dev See {IERC1155-isApprovedForAll}.
     */
    function isApprovedForAll(address account, address operator) public view virtual override returns (bool) {
        return _operatorApprovals[account][operator];
    }

    /**
     * @dev See {IERC1155-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 id,
        uint256 amount,
        bytes memory data
    ) public virtual override {
        require(to != address(0), "ERC1155: transfer to the zero address");
        require(
            from == _msgSender() || isApprovedForAll(from, _msgSender()),
            "ERC1155: caller is not owner nor approved"
        );

        address operator = _msgSender();

        _beforeTokenTransfer(operator, from, to, _asSingletonArray(id), _asSingletonArray(amount), data);

        uint256 fromBalance = _balances[id][from];
        require(fromBalance >= amount, "ERC1155: insufficient balance for transfer");
        _balances[id][from] = fromBalance - amount;
        _balances[id][to] += amount;

        emit TransferSingle(operator, from, to, id, amount);

        _doSafeTransferAcceptanceCheck(operator, from, to, id, amount, data);
    }

    /**
     * @dev See {IERC1155-safeBatchTransferFrom}.
     */
    function safeBatchTransferFrom(
        address from,
        address to,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) public virtual override {
        require(ids.length == amounts.length, "ERC1155: ids and amounts length mismatch");
        require(to != address(0), "ERC1155: transfer to the zero address");
        require(
            from == _msgSender() || isApprovedForAll(from, _msgSender()),
            "ERC1155: transfer caller is not owner nor approved"
        );

        address operator = _msgSender();

        _beforeTokenTransfer(operator, from, to, ids, amounts, data);

        for (uint256 i = 0; i < ids.length; ++i) {
            uint256 id = ids[i];
            uint256 amount = amounts[i];

            uint256 fromBalance = _balances[id][from];
            require(fromBalance >= amount, "ERC1155: insufficient balance for transfer");
            _balances[id][from] = fromBalance - amount;
            _balances[id][to] += amount;
        }

        emit TransferBatch(operator, from, to, ids, amounts);

        _doSafeBatchTransferAcceptanceCheck(operator, from, to, ids, amounts, data);
    }

    /**
     * @dev Sets a new URI for all token types, by relying on the token type ID
     * substitution mechanism
     * https://eips.ethereum.org/EIPS/eip-1155#metadata[defined in the EIP].
     *
     * By this mechanism, any occurrence of the `\{id\}` substring in either the
     * URI or any of the amounts in the JSON file at said URI will be replaced by
     * clients with the token type ID.
     *
     * For example, the `https://token-cdn-domain/\{id\}.json` URI would be
     * interpreted by clients as
     * `https://token-cdn-domain/000000000000000000000000000000000000000000000000000000000004cce0.json`
     * for token type ID 0x4cce0.
     *
     * See {uri}.
     *
     * Because these URIs cannot be meaningfully represented by the {URI} event,
     * this function emits no events.
     */
    function _setURI(string memory newuri) internal virtual {
        _uri = newuri;
    }

    /**
     * @dev Creates `amount` tokens of token type `id`, and assigns them to `account`.
     *
     * Emits a {TransferSingle} event.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - If `account` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
     * acceptance magic value.
     */
    function _mint(
        address account,
        uint256 id,
        uint256 amount,
        bytes memory data
    ) internal virtual {
        require(account != address(0), "ERC1155: mint to the zero address");

        address operator = _msgSender();

        _beforeTokenTransfer(operator, address(0), account, _asSingletonArray(id), _asSingletonArray(amount), data);

        _balances[id][account] += amount;
        emit TransferSingle(operator, address(0), account, id, amount);

        _doSafeTransferAcceptanceCheck(operator, address(0), account, id, amount, data);
    }

    /**
     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {_mint}.
     *
     * Requirements:
     *
     * - `ids` and `amounts` must have the same length.
     * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155BatchReceived} and return the
     * acceptance magic value.
     */
    function _mintBatch(
        address to,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) internal virtual {
        require(to != address(0), "ERC1155: mint to the zero address");
        require(ids.length == amounts.length, "ERC1155: ids and amounts length mismatch");

        address operator = _msgSender();

        _beforeTokenTransfer(operator, address(0), to, ids, amounts, data);

        for (uint256 i = 0; i < ids.length; i++) {
            _balances[ids[i]][to] += amounts[i];
        }

        emit TransferBatch(operator, address(0), to, ids, amounts);

        _doSafeBatchTransferAcceptanceCheck(operator, address(0), to, ids, amounts, data);
    }

    /**
     * @dev Destroys `amount` tokens of token type `id` from `account`
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens of token type `id`.
     */
    function _burn(
        address account,
        uint256 id,
        uint256 amount
    ) internal virtual {
        require(account != address(0), "ERC1155: burn from the zero address");

        address operator = _msgSender();

        _beforeTokenTransfer(operator, account, address(0), _asSingletonArray(id), _asSingletonArray(amount), "");

        uint256 accountBalance = _balances[id][account];
        require(accountBalance >= amount, "ERC1155: burn amount exceeds balance");
        _balances[id][account] = accountBalance - amount;

        emit TransferSingle(operator, account, address(0), id, amount);
    }

    /**
     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {_burn}.
     *
     * Requirements:
     *
     * - `ids` and `amounts` must have the same length.
     */
    function _burnBatch(
        address account,
        uint256[] memory ids,
        uint256[] memory amounts
    ) internal virtual {
        require(account != address(0), "ERC1155: burn from the zero address");
        require(ids.length == amounts.length, "ERC1155: ids and amounts length mismatch");

        address operator = _msgSender();

        _beforeTokenTransfer(operator, account, address(0), ids, amounts, "");

        for (uint256 i = 0; i < ids.length; i++) {
            uint256 id = ids[i];
            uint256 amount = amounts[i];

            uint256 accountBalance = _balances[id][account];
            require(accountBalance >= amount, "ERC1155: burn amount exceeds balance");
            _balances[id][account] = accountBalance - amount;
        }

        emit TransferBatch(operator, account, address(0), ids, amounts);
    }

    function _setupMetaData(string memory uri_) internal virtual {
        _setURI(uri_);
    }

    /**
     * @dev Hook that is called before any token transfer. This includes minting
     * and burning, as well as batched variants.
     *
     * The same hook is called on both single and batched variants. For single
     * transfers, the length of the `id` and `amount` arrays will be 1.
     *
     * Calling conditions (for each `id` and `amount` pair):
     *
     * - When `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * of token type `id` will be  transferred to `to`.
     * - When `from` is zero, `amount` tokens of token type `id` will be minted
     * for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens of token type `id`
     * will be burned.
     * - `from` and `to` are never both zero.
     * - `ids` and `amounts` have the same, non-zero length.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address operator,
        address from,
        address to,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) internal virtual {}

    function _doSafeTransferAcceptanceCheck(
        address operator,
        address from,
        address to,
        uint256 id,
        uint256 amount,
        bytes memory data
    ) private {
        if (to.isContract()) {
            try IERC1155Receiver(to).onERC1155Received(operator, from, id, amount, data) returns (bytes4 response) {
                if (response != IERC1155Receiver(to).onERC1155Received.selector) {
                    revert("ERC1155: ERC1155Receiver rejected tokens");
                }
            } catch Error(string memory reason) {
                revert(reason);
            } catch {
                revert("ERC1155: transfer to non ERC1155Receiver implementer");
            }
        }
    }

    function _doSafeBatchTransferAcceptanceCheck(
        address operator,
        address from,
        address to,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) private {
        if (to.isContract()) {
            try IERC1155Receiver(to).onERC1155BatchReceived(operator, from, ids, amounts, data) returns (
                bytes4 response
            ) {
                if (response != IERC1155Receiver(to).onERC1155BatchReceived.selector) {
                    revert("ERC1155: ERC1155Receiver rejected tokens");
                }
            } catch Error(string memory reason) {
                revert(reason);
            } catch {
                revert("ERC1155: transfer to non ERC1155Receiver implementer");
            }
        }
    }

    function _asSingletonArray(uint256 element) private pure returns (uint256[] memory) {
        uint256[] memory array = new uint256[](1);
        array[0] = element;

        return array;
    }
}

// File: contracts/lib/IERC1155MetadataURI.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC1155.sol";

/**
 * @dev Interface of the optional ERC1155MetadataExtension interface, as defined
 * in the https://eips.ethereum.org/EIPS/eip-1155#metadata-extensions[EIP].
 *
 * _Available since v3.1._
 */
interface IERC1155MetadataURI is IERC1155 {
    /**
     * @dev Returns the URI for token type `id`.
     *
     * If the `\{id\}` substring is present in the URI, it must be replaced by
     * clients with the actual token type ID.
     */
    function uri(uint256 id) external view returns (string memory);
}

// File: contracts/tokens/FxERC1155.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import {ERC1155} from "../lib/ERC1155.sol";
import {IFxERC1155} from "./IFxERC1155.sol";

contract FxERC1155 is ERC1155, IFxERC1155 {
    address internal _fxManager;
    address internal _connectedToken;

    function initialize(
        address fxManager_,
        address connectedToken_,
        string memory uri_
    ) public override {
        require(_fxManager == address(0x0) && _connectedToken == address(0x0), "Token is already initialized");
        _fxManager = fxManager_;
        _connectedToken = connectedToken_;

        setupMetaData(uri_);
    }

    function fxManager() public view override returns (address) {
        return _fxManager;
    }

    function connectedToken() public view override returns (address) {
        return _connectedToken;
    }

    function setupMetaData(string memory _uri) public {
        require(msg.sender == _fxManager, "Invalid sender");
        _setupMetaData(_uri);
    }

    function mint(
        address user,
        uint256 id,
        uint256 amount,
        bytes memory data
    ) public override {
        require(msg.sender == _fxManager, "Invalid sender");
        _mint(user, id, amount, data);
    }

    function mintBatch(
        address user,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) public override {
        require(msg.sender == _fxManager, "Invalid sender");
        _mintBatch(user, ids, amounts, data);
    }

    function burn(
        address user,
        uint256 id,
        uint256 amount
    ) public override {
        require(msg.sender == _fxManager, "Invalid sender");
        _burn(user, id, amount);
    }

    function burnBatch(
        address user,
        uint256[] memory ids,
        uint256[] memory amounts
    ) public override {
        require(msg.sender == _fxManager, "Invalid sender");
        _burnBatch(user, ids, amounts);
    }
}

// File: contracts/examples/erc1155-transfer/FxERC1155RootTunnel.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {ERC1155} from "../../lib/ERC1155.sol";
import {ERC1155Holder} from "../../lib/ERC1155Holder.sol";
import {Create2} from "../../lib/Create2.sol";
import {FxBaseRootTunnel} from "../../tunnel/FxBaseRootTunnel.sol";

contract FxERC1155RootTunnel is FxBaseRootTunnel, Create2, ERC1155Holder {
    bytes32 public constant DEPOSIT = keccak256("DEPOSIT");
    bytes32 public constant DEPOSIT_BATCH = keccak256("DEPOSIT_BATCH");
    bytes32 public constant WITHDRAW = keccak256("WITHDRAW");
    bytes32 public constant WITHDRAW_BATCH = keccak256("WITHDRAW_BATCH");
    bytes32 public constant MAP_TOKEN = keccak256("MAP_TOKEN");

    event TokenMappedERC1155(address indexed rootToken, address indexed childToken);
    event FxWithdrawERC1155(
        address indexed rootToken,
        address indexed childToken,
        address indexed userAddress,
        uint256 id,
        uint256 amount
    );
    event FxDepositERC1155(
        address indexed rootToken,
        address indexed depositor,
        address indexed userAddress,
        uint256 id,
        uint256 amount
    );
    event FxWithdrawBatchERC1155(
        address indexed rootToken,
        address indexed childToken,
        address indexed userAddress,
        uint256[] ids,
        uint256[] amounts
    );
    event FxDepositBatchERC1155(
        address indexed rootToken,
        address indexed userAddress,
        uint256[] ids,
        uint256[] amounts
    );

    mapping(address => address) public rootToChildTokens;
    bytes32 public childTokenTemplateCodeHash;

    constructor(
        address _checkpointManager,
        address _fxRoot,
        address _fxERC1155Token
    ) FxBaseRootTunnel(_checkpointManager, _fxRoot) {
        childTokenTemplateCodeHash = keccak256(minimalProxyCreationCode(_fxERC1155Token));
    }

    function mapToken(address rootToken) public {
        require(rootToChildTokens[rootToken] == address(0x0), "FxERC1155RootTunnel: ALREADY_MAPPED");

        ERC1155 rootTokenContract = ERC1155(rootToken);
        string memory uri = rootTokenContract.uri(0); //token Id?

        // MAP_TOKEN, encode(rootToken,uri)
        bytes memory message = abi.encode(MAP_TOKEN, abi.encode(rootToken, uri));
        _sendMessageToChild(message);

        // compute child token address before deployment using create2
        bytes32 salt = keccak256(abi.encodePacked(rootToken));
        address childToken = computedCreate2Address(salt, childTokenTemplateCodeHash, fxChildTunnel);

        // add into mapped tokens
        rootToChildTokens[rootToken] = childToken;
        emit TokenMappedERC1155(rootToken, childToken);
    }

    function deposit(
        address rootToken,
        address user,
        uint256 id,
        uint256 amount,
        bytes memory data
    ) public {
        // map token if not mapped
        if (rootToChildTokens[rootToken] == address(0x0)) {
            mapToken(rootToken);
        }

        // transfer from depositor to this contract
        ERC1155(rootToken).safeTransferFrom(
            msg.sender, // depositor
            address(this), // manager contract
            id,
            amount,
            data
        );

        // DEPOSIT, encode(rootToken, depositor, user, id, amount, extra data)
        bytes memory message = abi.encode(DEPOSIT, abi.encode(rootToken, msg.sender, user, id, amount, data));
        _sendMessageToChild(message);
        emit FxDepositERC1155(rootToken, msg.sender, user, id, amount);
    }

    function depositBatch(
        address rootToken,
        address user,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) public {
        // map token if not mapped
        if (rootToChildTokens[rootToken] == address(0x0)) {
            mapToken(rootToken);
        }

        // transfer from depositor to this contract
        ERC1155(rootToken).safeBatchTransferFrom(
            msg.sender, // depositor
            address(this), // manager contract
            ids,
            amounts,
            data
        );

        // DEPOSIT_BATCH, encode(rootToken, depositor, user, id, amount, extra data)
        bytes memory message = abi.encode(DEPOSIT_BATCH, abi.encode(rootToken, msg.sender, user, ids, amounts, data));
        _sendMessageToChild(message);
        emit FxDepositBatchERC1155(rootToken, user, ids, amounts);
    }

    function _processMessageFromChild(bytes memory data) internal override {
        (bytes32 syncType, bytes memory syncData) = abi.decode(data, (bytes32, bytes));

        if (syncType == WITHDRAW) {
            _syncWithdraw(syncData);
        } else if (syncType == WITHDRAW_BATCH) {
            _syncBatchWithdraw(syncData);
        } else {
            revert("FxERC1155RootTunnel: INVALID_SYNC_TYPE");
        }
    }

    function _syncWithdraw(bytes memory syncData) internal {
        (address rootToken, address childToken, address user, uint256 id, uint256 amount, bytes memory data) = abi
            .decode(syncData, (address, address, address, uint256, uint256, bytes));
        require(rootToChildTokens[rootToken] == childToken, "FxERC1155RootTunnel: INVALID_MAPPING_ON_EXIT");
        ERC1155(rootToken).safeTransferFrom(address(this), user, id, amount, data);
        emit FxWithdrawERC1155(rootToken, childToken, user, id, amount);
    }

    function _syncBatchWithdraw(bytes memory syncData) internal {
        (
            address rootToken,
            address childToken,
            address user,
            uint256[] memory ids,
            uint256[] memory amounts,
            bytes memory data
        ) = abi.decode(syncData, (address, address, address, uint256[], uint256[], bytes));
        require(rootToChildTokens[rootToken] == childToken, "FxERC1155RootTunnel: INVALID_MAPPING_ON_EXIT");
        ERC1155(rootToken).safeBatchTransferFrom(address(this), user, ids, amounts, data);
        emit FxWithdrawBatchERC1155(rootToken, childToken, user, ids, amounts);
    }
}

// File: contracts/examples/erc721-transfer/FxERC721ChildTunnel.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {FxBaseChildTunnel} from "../../tunnel/FxBaseChildTunnel.sol";
import {Create2} from "../../lib/Create2.sol";
import {IFxERC721} from "../../tokens/IFxERC721.sol";
import {IERC721Receiver} from "../../lib/IERC721Receiver.sol";

/**
 * @title FxERC721ChildTunnel
 */
contract FxERC721ChildTunnel is FxBaseChildTunnel, Create2, IERC721Receiver {
    bytes32 public constant DEPOSIT = keccak256("DEPOSIT");
    bytes32 public constant MAP_TOKEN = keccak256("MAP_TOKEN");
    string public constant SUFFIX_NAME = " (FXERC721)";
    string public constant PREFIX_SYMBOL = "fx";

    // event for token maping
    event TokenMapped(address indexed rootToken, address indexed childToken);
    // root to child token
    mapping(address => address) public rootToChildToken;
    // token template
    address public tokenTemplate;

    constructor(address _fxChild, address _tokenTemplate) FxBaseChildTunnel(_fxChild) {
        tokenTemplate = _tokenTemplate;
        require(_isContract(_tokenTemplate), "Token template is not contract");
    }

    function onERC721Received(
        address, /* operator */
        address, /* from */
        uint256, /* tokenId */
        bytes calldata /* data */
    ) external pure override returns (bytes4) {
        return this.onERC721Received.selector;
    }

    function withdraw(
        address childToken,
        uint256 tokenId,
        bytes memory data
    ) external {
        _withdraw(childToken, msg.sender, tokenId, data);
    }

    function withdrawTo(
        address childToken,
        address receiver,
        uint256 tokenId,
        bytes memory data
    ) external {
        _withdraw(childToken, receiver, tokenId, data);
    }

    //
    // Internal methods
    //

    function _processMessageFromRoot(
        uint256, /* stateId */
        address sender,
        bytes memory data
    ) internal override validateSender(sender) {
        // decode incoming data
        (bytes32 syncType, bytes memory syncData) = abi.decode(data, (bytes32, bytes));

        if (syncType == DEPOSIT) {
            _syncDeposit(syncData);
        } else if (syncType == MAP_TOKEN) {
            _mapToken(syncData);
        } else {
            revert("FxERC721ChildTunnel: INVALID_SYNC_TYPE");
        }
    }

    function _mapToken(bytes memory syncData) internal returns (address) {
        (address rootToken, string memory name, string memory symbol) = abi.decode(syncData, (address, string, string));

        // get root to child token
        address childToken = rootToChildToken[rootToken];

        // check if it's already mapped
        require(childToken == address(0x0), "FxERC721ChildTunnel: ALREADY_MAPPED");

        // deploy new child token
        bytes32 salt = keccak256(abi.encodePacked(rootToken));
        childToken = createClone(salt, tokenTemplate);
        IFxERC721(childToken).initialize(
            address(this),
            rootToken,
            string(abi.encodePacked(name, SUFFIX_NAME)),
            string(abi.encodePacked(PREFIX_SYMBOL, symbol))
        );

        // map the token
        rootToChildToken[rootToken] = childToken;
        emit TokenMapped(rootToken, childToken);

        // return new child token
        return childToken;
    }

    function _syncDeposit(bytes memory syncData) internal {
        (address rootToken, address depositor, address to, uint256 tokenId, bytes memory depositData) = abi.decode(
            syncData,
            (address, address, address, uint256, bytes)
        );
        address childToken = rootToChildToken[rootToken];

        // deposit tokens
        IFxERC721 childTokenContract = IFxERC721(childToken);
        childTokenContract.mint(to, tokenId, depositData);
    }

    function _withdraw(
        address childToken,
        address receiver,
        uint256 tokenId,
        bytes memory data
    ) internal {
        IFxERC721 childTokenContract = IFxERC721(childToken);
        // child token contract will have root token
        address rootToken = childTokenContract.connectedToken();

        // validate root and child token mapping
        require(
            childToken != address(0x0) && rootToken != address(0x0) && childToken == rootToChildToken[rootToken],
            "FxERC721ChildTunnel: NO_MAPPED_TOKEN"
        );

        require(msg.sender == childTokenContract.ownerOf(tokenId));

        // withdraw tokens
        childTokenContract.burn(tokenId);

        // send message to root regarding token burn
        _sendMessageToRoot(abi.encode(rootToken, childToken, receiver, tokenId, data));
    }

    // check if address is contract
    function _isContract(address _addr) private view returns (bool) {
        uint32 size;
        assembly {
            size := extcodesize(_addr)
        }
        return (size > 0);
    }
}

// File: contracts/examples/erc20-transfer/FxERC20ChildTunnel.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {FxBaseChildTunnel} from "../../tunnel/FxBaseChildTunnel.sol";
import {Create2} from "../../lib/Create2.sol";
import {IFxERC20} from "../../tokens/IFxERC20.sol";

/**
 * @title FxERC20ChildTunnel
 */
contract FxERC20ChildTunnel is FxBaseChildTunnel, Create2 {
    bytes32 public constant DEPOSIT = keccak256("DEPOSIT");
    bytes32 public constant MAP_TOKEN = keccak256("MAP_TOKEN");
    string public constant SUFFIX_NAME = " (FXERC20)";
    string public constant PREFIX_SYMBOL = "fx";

    // event for token maping
    event TokenMapped(address indexed rootToken, address indexed childToken);
    // root to child token
    mapping(address => address) public rootToChildToken;
    // token template
    address public tokenTemplate;

    constructor(address _fxChild, address _tokenTemplate) FxBaseChildTunnel(_fxChild) {
        tokenTemplate = _tokenTemplate;
        require(_isContract(_tokenTemplate), "Token template is not contract");
    }

    function withdraw(address childToken, uint256 amount) public {
        _withdraw(childToken, msg.sender, amount);
    }

    function withdrawTo(
        address childToken,
        address receiver,
        uint256 amount
    ) public {
        _withdraw(childToken, receiver, amount);
    }

    //
    // Internal methods
    //

    function _processMessageFromRoot(
        uint256, /* stateId */
        address sender,
        bytes memory data
    ) internal override validateSender(sender) {
        // decode incoming data
        (bytes32 syncType, bytes memory syncData) = abi.decode(data, (bytes32, bytes));

        if (syncType == DEPOSIT) {
            _syncDeposit(syncData);
        } else if (syncType == MAP_TOKEN) {
            _mapToken(syncData);
        } else {
            revert("FxERC20ChildTunnel: INVALID_SYNC_TYPE");
        }
    }

    function _mapToken(bytes memory syncData) internal returns (address) {
        (address rootToken, string memory name, string memory symbol, uint8 decimals) = abi.decode(
            syncData,
            (address, string, string, uint8)
        );

        // get root to child token
        address childToken = rootToChildToken[rootToken];

        // check if it's already mapped
        require(childToken == address(0x0), "FxERC20ChildTunnel: ALREADY_MAPPED");

        // deploy new child token
        bytes32 salt = keccak256(abi.encodePacked(rootToken));
        childToken = createClone(salt, tokenTemplate);
        IFxERC20(childToken).initialize(
            address(this),
            rootToken,
            string(abi.encodePacked(name, SUFFIX_NAME)),
            string(abi.encodePacked(PREFIX_SYMBOL, symbol)),
            decimals
        );

        // map the token
        rootToChildToken[rootToken] = childToken;
        emit TokenMapped(rootToken, childToken);

        // return new child token
        return childToken;
    }

    function _syncDeposit(bytes memory syncData) internal {
        (address rootToken, address depositor, address to, uint256 amount, bytes memory depositData) = abi.decode(
            syncData,
            (address, address, address, uint256, bytes)
        );
        address childToken = rootToChildToken[rootToken];

        // deposit tokens
        IFxERC20 childTokenContract = IFxERC20(childToken);
        childTokenContract.mint(to, amount);

        // call `onTokenTranfer` on `to` with limit and ignore error
        if (_isContract(to)) {
            uint256 txGas = 2000000;
            bool success = false;
            bytes memory data = abi.encodeWithSignature(
                "onTokenTransfer(address,address,address,address,uint256,bytes)",
                rootToken,
                childToken,
                depositor,
                to,
                amount,
                depositData
            );
            // solium-disable-next-line security/no-inline-assembly
            assembly {
                success := call(txGas, to, 0, add(data, 0x20), mload(data), 0, 0)
            }
        }
    }

    function _withdraw(
        address childToken,
        address receiver,
        uint256 amount
    ) internal {
        IFxERC20 childTokenContract = IFxERC20(childToken);
        // child token contract will have root token
        address rootToken = childTokenContract.connectedToken();

        // validate root and child token mapping
        require(
            childToken != address(0x0) && rootToken != address(0x0) && childToken == rootToChildToken[rootToken],
            "FxERC20ChildTunnel: NO_MAPPED_TOKEN"
        );

        // withdraw tokens
        childTokenContract.burn(msg.sender, amount);

        // send message to root regarding token burn
        _sendMessageToRoot(abi.encode(rootToken, childToken, receiver, amount));
    }

    // check if address is contract
    function _isContract(address _addr) private view returns (bool) {
        uint32 size;
        assembly {
            size := extcodesize(_addr)
        }
        return (size > 0);
    }
}