package it.cavallium.strangedb.database.references;

import it.cavallium.strangedb.database.IReferencesIO;
import it.cavallium.strangedb.database.blocks.DatabaseBlocksIO;

import java.io.IOException;
import java.nio.ByteBuffer;

import static it.cavallium.strangedb.database.IBlocksMetadata.EMPTY_BLOCK_ID;

public class DatabaseReferencesIO implements IReferencesIO {

	private final DatabaseBlocksIO blocksIO;
	private final DatabaseReferencesMetadata referencesMetadata;

	public DatabaseReferencesIO(DatabaseBlocksIO blocksIO, DatabaseReferencesMetadata referencesMetadata) {
		this.blocksIO = blocksIO;
		this.referencesMetadata = referencesMetadata;
	}

	@Override
	public long allocateReference() throws IOException {
		return referencesMetadata.newReference(EMPTY_BLOCK_ID);
	}

	@Override
	public long allocateReference(int size, ByteBuffer data) throws IOException {
		long blockId = (size == 0) ? EMPTY_BLOCK_ID : blocksIO.newBlock(size, data);
		return referencesMetadata.newReference(blockId);
	}

	@Override
	public void writeToReference(long reference, int size, ByteBuffer data) throws IOException {
		long blockId = (size == 0) ? EMPTY_BLOCK_ID : blocksIO.newBlock(size, data);
		referencesMetadata.editReference(reference, blockId);
	}

	@Override
	public ByteBuffer readFromReference(long reference) throws IOException {
		long blockId = referencesMetadata.getReference(reference);
		return blocksIO.readBlock(blockId);
	}
}