ERC1155DelayedReveal

/**
    *  @notice         Returns the metadata URI for an NFT.
    *  @dev            See `BatchMintMetadata` for handling of metadata in this contract.
    *
    *  @param _tokenId The tokenId of an NFT.
    */
function uri(uint256 _tokenId) public view override returns (string memory) {
    (uint256 batchId, ) = _getBatchId(_tokenId);
    string memory batchUri = _getBaseURI(_tokenId);
 
    if (isEncryptedBatch(batchId)) {
        return string(abi.encodePacked(batchUri, "0"));
    } else {
        return string(abi.encodePacked(batchUri, _tokenId.toString()));
    }
}

/**
    *  @notice                  Lets an authorized address lazy mint a given amount of NFTs.
    *
    *  @param _amount           The number of NFTs to lazy mint.
    *  @param _baseURIForTokens The placeholder base URI for the 'n' number of NFTs being lazy minted, where the
    *                           metadata for each of those NFTs is `${baseURIForTokens}/${tokenId}`.
    *  @param _data             The encrypted base URI + provenance hash for the batch of NFTs being lazy minted.
    *  @return batchId          A unique integer identifier for the batch of NFTs lazy minted together.
    */
function lazyMint(
    uint256 _amount,
    string calldata _baseURIForTokens,
    bytes calldata _data
) public virtual override returns (uint256 batchId) {
    if (_data.length > 0) {
        (bytes memory encryptedURI, bytes32 provenanceHash) = abi.decode(_data, (bytes, bytes32));
        if (encryptedURI.length != 0 && provenanceHash != "") {
            _setEncryptedData(nextTokenIdToLazyMint + _amount, _data);
        }
    }
 
    return super.lazyMint(_amount, _baseURIForTokens, _data);
}

/**
    *  @notice       Lets an authorized address reveal a batch of delayed reveal NFTs.
    *
    *  @param _index The ID for the batch of delayed-reveal NFTs to reveal.
    *  @param _key   The key with which the base URI for the relevant batch of NFTs was encrypted.
    */
function reveal(uint256 _index, bytes calldata _key) external virtual override returns (string memory revealedURI) {
    require(_canReveal(), "Not authorized");
 
    uint256 batchId = getBatchIdAtIndex(_index);
    revealedURI = getRevealURI(batchId, _key);
 
    _setEncryptedData(batchId, "");
    _setBaseURI(batchId, revealedURI);
 
    emit TokenURIRevealed(_index, revealedURI);
}
 
/// @dev Checks whether NFTs can be revealed in the given execution context.
function _canReveal() internal view virtual returns (bool) {
    return msg.sender == owner();
}