//License: GPL. Copyright 2007 by Immanuel Scholz and others
package org.openstreetmap.josm.actions;

import static org.openstreetmap.josm.tools.I18n.tr;

import java.awt.event.ActionEvent;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

import javax.swing.JFileChooser;
import javax.swing.JOptionPane;
import javax.swing.filechooser.FileFilter;

import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.data.osm.OsmPrimitive;
import org.openstreetmap.josm.gui.layer.OsmDataLayer;
import org.openstreetmap.josm.io.OsmWriter;

public abstract class SaveActionBase extends DiskAccessAction {

	private OsmDataLayer layer;

	public SaveActionBase(String name, String iconName, String tooltip, int shortCut, int modifiers, OsmDataLayer layer) {
		super(name, iconName, tooltip, shortCut, modifiers);
		this.layer = layer;
	}

	public void actionPerformed(ActionEvent e) {
		OsmDataLayer layer = this.layer;
		if (layer == null && Main.map != null && Main.map.mapView.getActiveLayer() instanceof OsmDataLayer)
			layer = (OsmDataLayer)Main.map.mapView.getActiveLayer();
		if (layer == null)
			layer = Main.main.editLayer();

		if (!checkSaveConditions(layer))
			return;


		File file = getFile(layer);
		if (file == null)
			return;

		save(file, layer);

		layer.name = file.getName();
		layer.associatedFile = file;
		Main.parent.repaint();
	}

	protected abstract File getFile(OsmDataLayer layer);

	/**
	 * Checks whether it is ok to launch a save (whether we have data,
	 * there is no conflict etc...)
	 * @return <code>true</code>, if it is save to save.
	 */
	public boolean checkSaveConditions(OsmDataLayer layer) {
		if (Main.map == null) {
			JOptionPane.showMessageDialog(Main.parent, tr("No document open so nothing to save."));
			return false;
		}
		if (isDataSetEmpty(layer) && JOptionPane.NO_OPTION == JOptionPane.showConfirmDialog(Main.parent,tr("The document contains no data. Save anyway?"), tr("Empty document"), JOptionPane.YES_NO_OPTION))
			return false;
		if (!Main.map.conflictDialog.conflicts.isEmpty()) {
			int answer = JOptionPane.showConfirmDialog(Main.parent, 
					tr("There are unresolved conflicts. Conflicts will not be saved and handled as if you rejected all. Continue?"),tr("Conflicts"), JOptionPane.YES_NO_OPTION);
			if (answer != JOptionPane.YES_OPTION)
				return false;
		}
		return true;
	}

	public static File openFileDialog() {
		JFileChooser fc = createAndOpenFileChooser(false, false);
		if (fc == null)
			return null;

		File file = fc.getSelectedFile();

		String fn = file.getPath();
		if (fn.indexOf('.') == -1) {
			FileFilter ff = fc.getFileFilter();
			if (ff instanceof ExtensionFileFilter)
				fn = "." + ((ExtensionFileFilter)ff).defaultExtension;
			else
				fn += ".osm";
			file = new File(fn);
		}
		return file;
	}

	private static void copy(File src, File dst) throws IOException {
		FileInputStream srcStream;
		FileOutputStream dstStream;
		try {
			srcStream = new FileInputStream(src);
			dstStream = new FileOutputStream(dst);
		} catch (FileNotFoundException e) {
			JOptionPane.showMessageDialog(Main.parent, tr("Could not back up file.")+"\n"+e.getMessage());
			return;
		}
		byte buf[] = new byte[1<<16];
		int len;
		while ((len = srcStream.read(buf)) != -1) {
			dstStream.write(buf, 0, len);
		}
		srcStream.close();
		dstStream.close();
	}

	public static void save(File file, OsmDataLayer layer) {
		File tmpFile = null;
		try {
			if (ExtensionFileFilter.filters[ExtensionFileFilter.GPX].acceptName(file.getPath())) {
				GpxExportAction.exportGpx(file, layer);
			} else if (ExtensionFileFilter.filters[ExtensionFileFilter.OSM].acceptName(file.getPath())) {
				// use a tmp file because if something errors out in the
				// process of writing the file, we might just end up with
				// a truncated file.  That can destroy lots of work.
				if (file.exists()) {
					tmpFile = new File(file.getPath() + "~");
					copy(file, tmpFile);
				}
				OsmWriter.output(new FileOutputStream(file), new OsmWriter.All(layer.data, false));
				if (!Main.pref.getBoolean("save.keepbackup"))
					tmpFile.delete();
			} else if (ExtensionFileFilter.filters[ExtensionFileFilter.CSV].acceptName(file.getPath())) {
				JOptionPane.showMessageDialog(Main.parent, tr("CSV output not supported yet."));
				return;
			} else {
				JOptionPane.showMessageDialog(Main.parent, tr("Unknown file extension."));
				return;
			}
			layer.cleanData(null, false);
		} catch (IOException e) {
			e.printStackTrace();
			JOptionPane.showMessageDialog(Main.parent, tr("An error occurred while saving.")+"\n"+e.getMessage());
		}
		try {
			// if the file save failed, then the tempfile will not
			// be deleted.  So, restore the backup if we made one.
			if (tmpFile != null && tmpFile.exists()) {
				copy(tmpFile, file);
			}
		} catch (IOException e) {
			e.printStackTrace();
			JOptionPane.showMessageDialog(Main.parent, tr("An error occurred while restoring backup file.")+"\n"+e.getMessage());
		}
	}

	/**
	 * Check the data set if it would be empty on save. It is empty, if it contains
	 * no objects (after all objects that are created and deleted without beeing 
	 * transfered to the server have been removed).
	 *  
	 * @return <code>true</code>, if a save result in an empty data set.
	 */
	private boolean isDataSetEmpty(OsmDataLayer layer) {
		for (OsmPrimitive osm : layer.data.allNonDeletedPrimitives())
			if (!osm.deleted || osm.id > 0)
				return false;
		return true;
	}
}
