L1ERC721Bridge.sol 4.15 KB
// SPDX-License-Identifier: MIT
pragma solidity 0.8.15;

import { ERC721Bridge } from "../universal/ERC721Bridge.sol";
import { IERC721 } from "@openzeppelin/contracts/token/ERC721/IERC721.sol";
import { L2ERC721Bridge } from "../L2/L2ERC721Bridge.sol";
import { Semver } from "../universal/Semver.sol";

/**
 * @title L1ERC721Bridge
 * @notice The L1 ERC721 bridge is a contract which works together with the L2 ERC721 bridge to
 *         make it possible to transfer ERC721 tokens from Ethereum to Optimism. This contract
 *         acts as an escrow for ERC721 tokens deposited into L2.
 */
contract L1ERC721Bridge is ERC721Bridge, Semver {
    /**
     * @notice Mapping of L1 token to L2 token to ID to boolean, indicating if the given L1 token
     *         by ID was deposited for a given L2 token.
     */
    mapping(address => mapping(address => mapping(uint256 => bool))) public deposits;

    /**
     * @custom:semver 1.1.1
     *
     * @param _messenger   Address of the CrossDomainMessenger on this network.
     * @param _otherBridge Address of the ERC721 bridge on the other network.
     */
    constructor(address _messenger, address _otherBridge)
        Semver(1, 1, 1)
        ERC721Bridge(_messenger, _otherBridge)
    {}

    /**
     * @notice Completes an ERC721 bridge from the other domain and sends the ERC721 token to the
     *         recipient on this domain.
     *
     * @param _localToken  Address of the ERC721 token on this domain.
     * @param _remoteToken Address of the ERC721 token on the other domain.
     * @param _from        Address that triggered the bridge on the other domain.
     * @param _to          Address to receive the token on this domain.
     * @param _tokenId     ID of the token being deposited.
     * @param _extraData   Optional data to forward to L2. Data supplied here will not be used to
     *                     execute any code on L2 and is only emitted as extra data for the
     *                     convenience of off-chain tooling.
     */
    function finalizeBridgeERC721(
        address _localToken,
        address _remoteToken,
        address _from,
        address _to,
        uint256 _tokenId,
        bytes calldata _extraData
    ) external onlyOtherBridge {
        require(_localToken != address(this), "L1ERC721Bridge: local token cannot be self");

        // Checks that the L1/L2 NFT pair has a token ID that is escrowed in the L1 Bridge.
        require(
            deposits[_localToken][_remoteToken][_tokenId] == true,
            "L1ERC721Bridge: Token ID is not escrowed in the L1 Bridge"
        );

        // Mark that the token ID for this L1/L2 token pair is no longer escrowed in the L1
        // Bridge.
        deposits[_localToken][_remoteToken][_tokenId] = false;

        // When a withdrawal is finalized on L1, the L1 Bridge transfers the NFT to the
        // withdrawer.
        IERC721(_localToken).safeTransferFrom(address(this), _to, _tokenId);

        // slither-disable-next-line reentrancy-events
        emit ERC721BridgeFinalized(_localToken, _remoteToken, _from, _to, _tokenId, _extraData);
    }

    /**
     * @inheritdoc ERC721Bridge
     */
    function _initiateBridgeERC721(
        address _localToken,
        address _remoteToken,
        address _from,
        address _to,
        uint256 _tokenId,
        uint32 _minGasLimit,
        bytes calldata _extraData
    ) internal override {
        require(_remoteToken != address(0), "L1ERC721Bridge: remote token cannot be address(0)");

        // Construct calldata for _l2Token.finalizeBridgeERC721(_to, _tokenId)
        bytes memory message = abi.encodeWithSelector(
            L2ERC721Bridge.finalizeBridgeERC721.selector,
            _remoteToken,
            _localToken,
            _from,
            _to,
            _tokenId,
            _extraData
        );

        // Lock token into bridge
        deposits[_localToken][_remoteToken][_tokenId] = true;
        IERC721(_localToken).transferFrom(_from, address(this), _tokenId);

        // Send calldata into L2
        MESSENGER.sendMessage(OTHER_BRIDGE, message, _minGasLimit);
        emit ERC721BridgeInitiated(_localToken, _remoteToken, _from, _to, _tokenId, _extraData);
    }
}