// File: HR.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.18;

import "@openzeppelin/contracts/token/ERC721/IERC721.sol";

// ERC-721 functions necessary for our interaction
interface IBlackHole is IERC721 {
    function lastBurner() external view returns (address);
    function withdraw() external;
    function minted() external view returns (uint256);
    function burnt() external view returns (uint256);
    function burn(uint256 tokenId) external;
}

contract HawkingRadiation {
    IBlackHole public blackHoleContract;
    mapping(address => uint256) public burntViaHawking;
    uint256 public collectedEth;
    uint256 public totalBurntViaHawking;

    bool public hasCollected = false;

    constructor(address _blackHoleAddress) {
        blackHoleContract = IBlackHole(_blackHoleAddress);
    }

    function transferAndBurnViaHawking(uint256 tokenId) external {
        require(!hasCollected, "ETH has been collected, cannot burn anymore");

        // Transfer the NFT to this contract
        blackHoleContract.transferFrom(msg.sender, address(this), tokenId);
        
        // Check that this contract is now the owner
        require(blackHoleContract.ownerOf(tokenId) == address(this), "Failed to transfer NFT to HawkingRadiation contract");
        
        // Burn the NFT
        blackHoleContract.burn(tokenId);
        
        burntViaHawking[msg.sender] += 1;
        totalBurntViaHawking += 1;
    }

    function collectBlackHoleETH() external {
        require(!hasCollected, "ETH already collected");

        address lastBurner = blackHoleContract.lastBurner();
        require(lastBurner == address(this), "HawkingRadiation was not the last to burn an NFT");

        uint256 blackHoleBalance = address(blackHoleContract).balance;

        blackHoleContract.withdraw();

        require(address(this).balance == blackHoleBalance, "ETH transfer from Black Hole failed");
        collectedEth = blackHoleBalance;
        hasCollected = true;
    }

    function claimETH() external {
        require(hasCollected, "ETH hasn't been collected yet");
    
        uint256 userBurntCount = burntViaHawking[msg.sender];
        require(userBurntCount > 0, "You haven't burnt any NFT via HawkingRadiation");

        uint256 ethShare = (collectedEth * userBurntCount) / totalBurntViaHawking;

        require(ethShare > 0, "No ETH to claim");

        // Reduce the user's count and the contract's ETH balance
        burntViaHawking[msg.sender] = 0; // Resetting the user's burnt count after claiming
        collectedEth -= ethShare;

        payable(msg.sender).transfer(ethShare);
    }
}

// File: @openzeppelin/contracts/token/ERC721/IERC721.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;

import "../../utils/introspection/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`.
     *
     * 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;

    /**
     * @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 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: Note that the caller is responsible to confirm that the recipient is capable of receiving ERC721
     * or else they may be permanently lost. Usage of {safeTransferFrom} prevents loss, though the caller must
     * understand this adds an external call which potentially creates a reentrancy vulnerability.
     *
     * 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 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 the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @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);
}

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

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);
}