/*******************************************************************************
 * Copyright (c) 2007, 2011 Association for Decentralized Information Management in
 * Industry THTH ry.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *******************************************************************************/
package org.simantics.history.impl;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.logging.Logger;

import org.simantics.databoard.Bindings;
import org.simantics.databoard.accessor.StreamAccessor;
import org.simantics.databoard.accessor.error.AccessorException;
import org.simantics.databoard.accessor.impl.AccessorParams;
import org.simantics.databoard.accessor.java.JavaArray;
import org.simantics.databoard.binding.Binding;
import org.simantics.databoard.binding.error.BindingException;
import org.simantics.databoard.binding.impl.ArrayListBinding;
import org.simantics.databoard.type.Datatype;
import org.simantics.databoard.util.Bean;
import org.simantics.history.HistoryException;
import org.simantics.history.HistoryManager;

public class MemoryHistory implements HistoryManager {

	Map<String, Item> items = new HashMap<String, Item>();
	
	/** Logger */
	static Logger logger = Logger.getLogger( MemoryHistory.class.getName() );
	
	@Override
	public void create(Bean... descs) throws HistoryException {
		for (Bean desc : descs) {
			try {
				String id = (String) desc.getField("id");
				Datatype format = (Datatype) desc.getField("format");
				
				Binding sampleBinding = Bindings.getBinding( format );
				ArrayListBinding arrayBinding = new ArrayListBinding( sampleBinding );
				ArrayList<?> array = new ArrayList<Object>();
				JavaArray sa = new JavaArray(null, arrayBinding, array, AccessorParams.DEFAULT );
				Item item = new Item();
				item.stream = sa;
				item.desc = desc.clone();
				item.format = format;
				items.put(id, item);				
			} catch (BindingException e) {
				throw new HistoryException("Invalid history item description", e);
			}
		}
	}

	@Override
	public void delete(String... itemIds) throws HistoryException {
		for (String itemId : itemIds) {
			try {
				Item i = items.remove( itemId );
				if (i==null) throw new HistoryException("Null item");
				i.stream.close();
			} catch (AccessorException e) {
				throw new HistoryException();
			}
		}
	}

	@Override
	public void modify(Bean... descs) throws HistoryException {
		for (Bean desc : descs) {
			try {
				String id = (String) desc.getField("id");
				Item i = items.get( id );
				if ( i == null ) {
					create(desc);
				} else {
					
					if (desc.equalContents(i.desc)) continue;
					Datatype format = (Datatype) desc.getField("format");
					if (!i.format.equals(format)) {
						throw new HistoryException("Format conversion is not supported");
					}
					// Write new metadata bean 
					//i.desc = desc.clone();
					// Workaround clone -- we cannot clone referable records ( as there is no adaptation context )
					try {
						byte[] data = desc.serialize();
						i.desc = desc.getClass().newInstance();
						i.desc.deserialize(data);
					} catch (IOException e) {
						throw new HistoryException(e);
					} catch (InstantiationException e) {
						throw new HistoryException(e);
					} catch (IllegalAccessException e) {
						throw new HistoryException(e);
					}
				}
			} catch (BindingException e) {
				throw new HistoryException(e);
			}
		}
	}

	@Override
	public Bean getItem(String itemId) throws HistoryException {
		Item i = items.get( itemId );
		if ( i==null ) throw new HistoryException(itemId+" does not exist");
		return i.desc;
	}

	@Override
	public Bean[] getItems() throws HistoryException {
		Bean[] result = new Bean[ items.size() ];
		int ix=0; 
		for (Item i : items.values()) result[ix++] = i.desc;
		return result;
	}

	@Override
	public void close() {		
	}

	@Override
	public StreamAccessor openStream(String itemId, String mode) throws HistoryException {
		Item i = items.get(itemId);
		if ( i == null ) {
			throw new HistoryException(itemId+" does not exist");
		}
		return i.stream;
	}

	@Override
	public synchronized boolean exists(String itemId) throws HistoryException {
		return items.containsKey(itemId);
	}
	
	static class Item {
		JavaArray stream;
		Bean desc;
		Datatype format;
	}

}