// SPDX-License-Identifier: MIT

pragma solidity >=0.7.6 <0.8.0;

/**
 * @title ERC721 Non-Fungible Token Standard, Tokens Receiver.
 * Interface for any contract that wants to support safeTransfers from ERC721 asset contracts.
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 * @dev Note: The ERC-165 identifier for this interface is 0x150b7a02.
 */
interface IERC721Receiver {
    /**
     * Handles the receipt of an NFT.
     * @dev The ERC721 smart contract calls this function on the recipient
     *  after a {IERC721-safeTransferFrom}. This function MUST return the function selector,
     *  otherwise the caller will revert the transaction. The selector to be
     *  returned can be obtained as `this.onERC721Received.selector`. This
     *  function MAY throw to revert and reject the transfer.
     * @dev Note: the ERC721 contract address is always the message sender.
     * @param operator The address which called `safeTransferFrom` function
     * @param from The address which previously owned the token
     * @param tokenId The NFT identifier which is being transferred
     * @param data Additional data with no specified format
     * @return bytes4 `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}