package com.luceneserver.core;

import java.io.File;
import java.io.IOException;
import java.util.concurrent.Callable;

import org.apache.lucene.document.Document;
import org.apache.lucene.document.TextField;
import org.apache.lucene.document.Field.Store;
import org.apache.lucene.index.IndexDeletionPolicy;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.KeepOnlyLastCommitDeletionPolicy;
import org.apache.lucene.index.SnapshotDeletionPolicy;
import org.apache.lucene.replicator.IndexReplicationHandler;
import org.apache.lucene.replicator.IndexRevision;
import org.apache.lucene.replicator.LocalReplicator;
import org.apache.lucene.replicator.PerSessionDirectoryFactory;
import org.apache.lucene.replicator.ReplicationClient;
import org.apache.lucene.replicator.ReplicationClient.ReplicationHandler;
import org.apache.lucene.replicator.ReplicationClient.SourceDirectoryFactory;
import org.apache.lucene.replicator.Replicator;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.store.RAMDirectory;

import com.luceneserver.constants.LuceneConstants;

public class DemoReplicator implements LuceneConstants {

	IndexWriter indexWriter;
	Replicator replicator;
	Directory workingDir;
	Directory backupDir;
	ReplicationClient client;

	protected void initializeReplicator() {
		replicator = new LocalReplicator();
	}

	protected void initializeDirAndIndices() throws IOException {
		workingDir = FSDirectory.open(new File(LUCENE_INDEX_HOME+File.separator+INDEX_NAME).toPath());
		IndexWriterConfig indexWriterConfig = new IndexWriterConfig();
		IndexDeletionPolicy deletionPolicy = new SnapshotDeletionPolicy(new KeepOnlyLastCommitDeletionPolicy());
		indexWriterConfig.setIndexDeletionPolicy(deletionPolicy);
		indexWriter = new IndexWriter(workingDir, indexWriterConfig);
	}

	protected void addDocuments() throws IOException {
		for (int i = 0; i < 1000000; i++) {
			Document document = new Document();
			document.add(new TextField("content", String.valueOf(Math.random()), Store.YES));
			indexWriter.addDocument(document);
		}
		indexWriter.commit();
		replicator.publish(new IndexRevision(indexWriter));
	}

	protected void initializeReplication() throws IOException {

		Callable<Boolean> callback = null;
		File backupFolder = new File(LUCENE_INDEX_BACKUP_HOME + File.separator + BACKUP_INDEX_NAME);
		backupDir = FSDirectory.open(backupFolder.toPath());
		ReplicationHandler handler = new IndexReplicationHandler(backupDir, callback);


		SourceDirectoryFactory factory = new PerSessionDirectoryFactory(backupFolder.toPath());
		client = new ReplicationClient(replicator, handler, factory);
	}

	protected void doBackup() throws IOException {
		System.out.println("Doing a backup");
		client.updateNow();
	}

	public static void main(String args[]) throws IOException {
		DemoReplicator demo = new DemoReplicator();
		demo.initializeDirAndIndices();
		demo.initializeReplicator();
		demo.initializeReplication();
		demo.addDocuments();
		demo.doBackup();
	}

}