hyperlane-monorepo/solidity/contracts/token/HypERC721Collateral.sol

// SPDX-License-Identifier: Apache-2.0
pragma solidity >=0.8.0;

import {TokenRouter} from "./libs/TokenRouter.sol";
import {TokenMessage} from "./libs/TokenMessage.sol";

import {IERC721} from "@openzeppelin/contracts/token/ERC721/IERC721.sol";

/**
 * @title Hyperlane ERC721 Token Collateral that wraps an existing ERC721 with remote transfer functionality.
 * @author Abacus Works
 */
contract HypERC721Collateral is TokenRouter {
    IERC721 public immutable wrappedToken;

    /**
     * @notice Constructor
     * @param erc721 Address of the token to keep as collateral
     */
    constructor(address erc721, address _mailbox) TokenRouter(_mailbox) {
        wrappedToken = IERC721(erc721);
    }

    function ownerOf(uint256 _tokenId) external view returns (address) {
        return IERC721(wrappedToken).ownerOf(_tokenId);
    }

    /**
     * @dev Returns the balance of `_account` for `wrappedToken`.
     * @inheritdoc TokenRouter
     */
    function balanceOf(address _account)
        external
        view
        override
        returns (uint256)
    {
        return IERC721(wrappedToken).balanceOf(_account);
    }

    /**
     * @dev Transfers `_tokenId` of `wrappedToken` from `msg.sender` to this contract.
     * @inheritdoc TokenRouter
     */
    function _transferFromSender(uint256 _tokenId)
        internal
        virtual
        override
        returns (bytes memory)
    {
        // safeTransferFrom not used here because recipient is this contract
        wrappedToken.transferFrom(msg.sender, address(this), _tokenId);
        return bytes(""); // no metadata
    }

    /**
     * @dev Transfers `_tokenId` of `wrappedToken` from this contract to `_recipient`.
     * @inheritdoc TokenRouter
     */
    function _transferTo(
        address _recipient,
        uint256 _tokenId,
        bytes calldata // no metadata
    ) internal override {
        wrappedToken.safeTransferFrom(address(this), _recipient, _tokenId);
    }
}