package goodjava.lucene.logging;

import java.io.IOException;
import java.util.Map;
import org.apache.lucene.search.Query;
import goodjava.lucene.api.GoodIndexWriter;


public class LoggingIndexWriter implements GoodIndexWriter {
	private static final int OP_DELETE_ALL = 1;
	private static final int OP_DELETE_DOCUMENTS = 2;
	private static final int OP_ADD_DOCUMENT = 3;
	private static final int OP_UPDATE_DOCUMENT = 4;

	public final GoodIndexWriter indexWriter;
	private final LogFile logFile;

	public LoggingIndexWriter(GoodIndexWriter indexWriter) throws IOException {
		this.indexWriter = indexWriter;
		logFile = new LogFile("lucene.log","rw");
		logFile.gotoStart();  // for now
	}

	public void close() throws IOException {
		indexWriter.close();
		logFile.commit();
	}

	public void commit() throws IOException {
		indexWriter.commit();
		logFile.commit();
	}

	public void rollback() throws IOException {
		indexWriter.rollback();
		logFile.gotoEnd();
	}

	public void deleteAll() throws IOException {
		indexWriter.deleteAll();
		logFile.writeByte(OP_DELETE_ALL);
	}

	public void deleteDocuments(Query query) throws IOException {
		indexWriter.deleteDocuments(query);
		logFile.writeByte(OP_DELETE_DOCUMENTS);
		logFile.writeQuery(query);
	}

	public void addDocument(Map<String,Object> storedFields) throws IOException {
		indexWriter.addDocument(storedFields);
		logFile.writeByte(OP_ADD_DOCUMENT);
		logFile.writeMap(storedFields);
	}

	public void updateDocument(String keyFieldName,Map<String,Object> storedFields) throws IOException {
		indexWriter.updateDocument(keyFieldName,storedFields);
		logFile.writeByte(OP_UPDATE_DOCUMENT);
		logFile.writeUTF(keyFieldName);
		logFile.writeMap(storedFields);
	}

	public void reindexDocuments(String keyFieldName,Query query) throws IOException {
		indexWriter.reindexDocuments(keyFieldName,query);
	}

	private void playOp() throws IOException {
		int op = logFile.readByte();
		switch(op) {
		case OP_DELETE_ALL:
			indexWriter.deleteAll();
			return;
		case OP_DELETE_DOCUMENTS:
			indexWriter.deleteDocuments( logFile.readQuery() );
			return;
		case OP_ADD_DOCUMENT:
			indexWriter.addDocument( logFile.readMap() );
			return;
		case OP_UPDATE_DOCUMENT:
			indexWriter.updateDocument( logFile.readUTF(), logFile.readMap() );
			return;
		default:
			throw new RuntimeException("invalid op "+op);
		}
	}

	public void playLog() throws IOException {
		logFile.gotoStart();
		while( logFile.hasMore() ) {
			playOp();
		}
		indexWriter.commit();
	}
}