/*******************************************************************************
 * Breakout Cave Survey Visualizer
 *
 * Copyright (C) 2014 James Edwards
 *
 * jedwards8 at fastmail dot fm
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *******************************************************************************/
package org.andork.util;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.LinkedList;

import org.andork.event.HierarchicalBasicPropertyChangeListener;
import org.andork.event.SourcePath;
import org.andork.func.Bimapper;
import org.andork.func.BimapperStreamBimapper;
import org.andork.func.StreamBimapper;

public abstract class AbstractFilePersister<M> implements HierarchicalBasicPropertyChangeListener {
	protected StreamBimapper<M> bimapper;
	protected Batcher<M> batcher;
	protected File file;

	public AbstractFilePersister(File file, Bimapper<M, String> format) {
		this(file, new BimapperStreamBimapper<M>(format));
	}

	public AbstractFilePersister(File file, StreamBimapper<M> bimapper) {
		this.file = file;
		this.bimapper = bimapper;

		batcher = new Batcher<M>() {
			@Override
			protected void handleLater(final LinkedList<M> batch) {
				saveInBackground(batch);
			}
		};
	}

	@Override
	public void childrenChanged(Object source, ChangeType changeType, Object... children) {
		batcher.add(getRootModel(source));
	}

	private M getRootModel(Object source) {
		if (source instanceof SourcePath) {
			return getRootModel(((SourcePath) source).parent);
		}
		return (M) source;
	}

	public M load() throws Exception {
		if (!file.exists()) {
			return null;
		}
		return bimapper.read(new FileInputStream(file));
	}

	@Override
	public void propertyChange(Object source, Object property, Object oldValue, Object newValue, int index) {
		batcher.add(getRootModel(source));
	}

	protected void save(M model) {
		try {
			if (!file.getParentFile().exists()) {
				file.getParentFile().mkdirs();
			}
			bimapper.write(model, new FileOutputStream(file));
		} catch (Throwable t) {
			t.printStackTrace();
		}
	}

	protected abstract void saveInBackground(final LinkedList<M> batch);

	public void saveLater(M model) {
		batcher.add(model);
	}

}