BatchMintMetadata (ERC1155 & ERC721)

function getBaseURICount() public view returns (uint256);

• Returns the total number of batches of NFTs, where each batch has a single base URI and metadata for NFTs in the batch is stored as baseURI/tokenId.
• This value is updated when the metadata of a new set of NFTs is 'batch minted' using the _batchMintMetadata function.

function getBatchIdAtIndex(uint256 _index) public view returns (uint256);

• The extension smart contract stores an array of 'batch IDs' i.e. IDs for different batches of NFTs minted on the contract. This function returns the batch ID at a given index in this ordered array of batch IDs.

function _getBatchId(uint256 tokenId) internal view returns (uint256 batchId, uint256 index);

• Returns the batch ID for the batch of NFTs the given tokenId belongs to.
• Parameter tokenId: the tokenId for which to retrieve the associated batch ID.

function _getBaseURI(uint256 _tokenId) internal view returns (string memory);

• Returns the base metadata URI for the given tokenId.
• Parameter tokenId: the tokenId for which to retrieve the associated base metadata URI.

function _setBaseURI(uint256 batchId, string memory baseURI) internal;

• Update the base metadata URI for a given batch of NFTs.
• Parameter batchID: the batch ID of the batch of NFTs whose metadata URI is to be updated.
• Parameter baseURI: the value to set as the new base URI for the relevant batch of NFTs.

function _batchMintMetadata(
    uint256 _startId,
    uint256 _amountToMint,
    string memory _baseURIForTokens
) internal returns (uint256 nextTokenIdToMint, uint256 batchId);

• Mints a batch of tokenIds and associates a common baseURI to all those Ids.
• Parameter _startId: The lowest tokenId from the batch of NFTs to mint. It is assumed that token Ids are assigned to NFTs in a serial order, when batch minting e.g. [startId, startId + 1, ... n-1, n]
• Parameter _amountToMint: The number of NFTs to mint at once.
• Parameter _baseURIForTokens: The common base URI for the batch of NFTs being minted, where for a batch of NFTs with token IDs [startId, startId + 1, ... n-1, n], each NFT's associated metadata URI is [baseURI/startId, baseURI/startId+1, ... baseURI/n-1, baseURI/n]