package org.simantics.db.service;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;

import org.simantics.databoard.Bindings;
import org.simantics.databoard.Files;
import org.simantics.databoard.binding.Binding;
import org.simantics.databoard.parser.repository.DataValueRepository;
import org.simantics.db.exception.RuntimeDatabaseException;

public class ClusterSets {

	//    final private static boolean DEBUG = false;

	private File writeDirectory;
	final private String databaseId;
	final private HashMap<Long, Long> clusterSets; // Maps cluster set resource id to last user cluster id in the cluster set.
	final private HashMap<Long, Long> reverseMap;
	private int refCount; // Reference counter for user of this class.
	private boolean modified; // True if modified since last save.

	public void setWriteDirectory(File writeDirectory) {
		this.writeDirectory = writeDirectory;
	}
	
	private File getFile1(File directory) {
		return new File(directory, "clusterSets." + this.databaseId + ".dat");
	}

	private File getFile2(File directory) {
		return new File(directory, "clusterSets." + this.databaseId + ".dat.reverse");
	}

	public ClusterSets(File readDirectory, File writeDirectory, String databaseId) {

		try {

			this.databaseId = databaseId;
			this.writeDirectory = writeDirectory;

			readDirectory.mkdirs();

			File file1 = getFile1(readDirectory);
			File file2 = getFile2(readDirectory);

			this.refCount = 1;
			PersistentData pd, pd2;
			try {
				pd = (PersistentData)Files.readFile(file1, PersistentData.BINDING);
			} catch (IOException e) {
				// New file
				pd = new PersistentData();
				pd.values = new HashMap<Long, Long>();
				Files.writeFile(file1, PersistentData.BINDING, pd);
			}
			try {
				pd2 = (PersistentData)Files.readFile(file2, PersistentData.BINDING);
			} catch (IOException e) {
				// New file
				pd2 = new PersistentData();
				pd2.values = new HashMap<Long, Long>();
				Files.writeFile(file2, PersistentData.BINDING, pd2);
			}
			this.clusterSets = pd.values;
			this.reverseMap = pd2.values;
			this.modified = false;
		} catch (Exception e) {
			e.printStackTrace();
			throw new RuntimeDatabaseException("Failed to create ClusterSets.");
		}
	}
	public synchronized int inc() {
		return ++refCount;
	}
	public synchronized int dec() {
		return --refCount;
	}
	// Save is thread safe.
	public void dispose() {
		try {
			// We still save changes even if transaction is not finished.
			// This is because we have no cancel mechanism for cluster (sets).
			save();
		} catch (IOException e) {
			e.printStackTrace();
			throw new RuntimeDatabaseException("Failed to save ClusterSets.");
		} 
	}
	// clusterSets is not thread safe.
	public synchronized boolean containsKey(long resourceId) {
		return clusterSets.containsKey(resourceId);
	}
	public synchronized Long get(Long resourceId) {
		return clusterSets.get(resourceId);
	}
	public synchronized void put(long resourceId, long clusterId) {
		clusterSets.put(resourceId, clusterId);
		reverseMap.put(clusterId, resourceId);
		modified = true;
	}
	public synchronized Long getClusterSet(Long clusterId) {
		return reverseMap.get(clusterId);
	}
	public void clear() {
		
		for(Long key : clusterSets.keySet())
			clusterSets.put(key, -1L);
		
		touch();
		
	}
	public synchronized void touch() {
		modified = true;
	}
	public synchronized void save() throws IOException {

		if (!modified)
			return;
		
		writeDirectory.mkdirs();
		File file1 = getFile1(writeDirectory);
		File file2 = getFile2(writeDirectory);
		PersistentData pd = new PersistentData();
		pd.values = clusterSets;
		Files.writeFile(file1, PersistentData.BINDING, pd);
		pd = new PersistentData();
		pd.values = reverseMap;
		Files.writeFile(file2, PersistentData.BINDING, pd);
		modified = false;

	}
	static public class PersistentData {
		final public static Binding BINDING = Bindings.getBindingUnchecked(PersistentData.class);
		//        public TreeMap<Long, Long> values;
		public HashMap<Long, Long> values;
		public static void main(String[] args) throws Exception {
			System.err.println("" + BINDING.type().toSingleLineString());
			PersistentData pd = new PersistentData();
			//         pd.values = new TreeMap<Long, Long>();
			pd.values = new HashMap<Long, Long>();
			for (long i=0; i<10; ++i)
				pd.values.put(i, i);
			BINDING.printValue(pd, System.err, new DataValueRepository(), true);
		}
	}
	
}