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

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;

import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.gui.MapFrame;
import org.openstreetmap.josm.gui.download.DownloadSelection;
import org.openstreetmap.josm.gui.preferences.PreferenceSetting;

/**
 * All plugins *must* have an standard constructor taking no arguments.
 *
 * This constructor is called at JOSM startup, after all Main-objects have been initialized.
 * For all purposes of loading dynamic resources, the Plugin's class loader should be used
 * (or else, the plugin jar will not be within the class path).
 *
 * A plugin may subclass this abstract base class (but it is optional).
 *
 * The actual implementation of this class is optional, as all functions will be called
 * via reflection. This is to be able to change this interface without the need of
 * recompiling or even breaking the plugins. If your class does not provide a
 * function here (or does provide a function with a mismatching signature), it will not
 * be called. That simple.
 *
 * Or in other words: See this base class as an documentation of what automatic callbacks
 * are provided (you can register yourself to more callbacks in your plugin class
 * constructor).
 *
 * Subclassing Plugin and overriding some functions makes it easy for you to keep sync
 * with the correct actual plugin architecture of JOSM.
 *
 * @author Immanuel.Scholz
 */
public abstract class Plugin {

    /**
     * This is the info available for this plugin. You can access this from your
     * constructor.
     *
     * (The actual implementation to request the info from a static variable
     * is a bit hacky, but it works).
     */
    public final PluginInformation info = PluginInformation.currentPluginInitialization;

    /**
     * @return The directory for the plugin to store all kind of stuff.
     */
    public final String getPluginDir() {
        return new File(Main.pref.getPluginsDirFile(), info.name).getPath();
    }

    /**
     * Called after Main.mapFrame is initalized. (After the first data is loaded).
     * You can use this callback to tweak the newFrame to your needs, as example install
     * an alternative Painter.
     */
    public void mapFrameInitialized(MapFrame oldFrame, MapFrame newFrame) {}

    /**
     * Called in the preferences dialog to create a preferences page for the plugin,
     * if any available.
     */
    public PreferenceSetting getPreferenceSetting() { return null; }

    /**
     * Called in the download dialog to give the plugin a chance to modify the list
     * of bounding box selectors.
     */
    public void addDownloadSelection(List<DownloadSelection> list) {}

    /**
     * Copies the ressource 'from' to the file in the plugin directory named 'to'.
     */
    public void copy(String from, String to) throws FileNotFoundException, IOException {
        String pluginDirName = Main.pref.getPreferencesDir()+"plugins/"+info.name+"/";
        File pluginDir = new File(pluginDirName);
        if (!pluginDir.exists())
            pluginDir.mkdirs();
        FileOutputStream out = new FileOutputStream(pluginDirName+to);
        InputStream in = getClass().getResourceAsStream(from);
        byte[] buffer = new byte[8192];
        for(int len = in.read(buffer); len > 0; len = in.read(buffer))
            out.write(buffer, 0, len);
        in.close();
        out.close();
    }
}