/*
    *  Gettext Commons
    *
    *  Copyright (C) 2005  Felix Berger
    *  Copyright (C) 2005  Steffen Pingel
    *
    *  This library is free software; you can redistribute it and/or
    *  modify it under the terms of the GNU Lesser General Public
    *  License as published by the Free Software Foundation; either
   *  version 2.1 of the License, or (at your option) any later version.
   *
   *  This library 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
   *  Lesser General Public License for more details.
   *
   *  You should have received a copy of the GNU Lesser General Public
   *  License along with this library; if not, write to the Free Software
   *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  package org.xnap.commons.i18n;
  
  import java.lang.ref.WeakReference;
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Locale;
  
  /**
   * Manager class that maintains a set of {@link org.xnap.commons.i18n.I18n}
   * objects and {@link org.xnap.commons.i18n.LocaleChangeListener} objects.
   * <p>
   * The locale of all managed <code>I18n</code> objects can be changed by
   * invoking {@link org.xnap.commons.i18n.I18nManager#setDefaultLocale(Locale)}.
   * 
   * @author Felix Berger
   * @author Steffen Pingel
   * @since 0.9
   */
  public class I18nManager {
  
  	private static I18nManager instance = new I18nManager();
  
  	/** List of managed {@link I18n} objects. */
  	List i18ns = new ArrayList();
  
  	/** List of managed {@link LocaleChangeListener} objects. */
  	List localeChangeListeners = new ArrayList();
  
  	private I18nManager()
  	{
  	}
  
  	/**
  	 * Returns the global <code>I18Manger</code> singleton.
  	 * 
  	 * @return the <code>I18Manger</code> instance
  	 * @since 0.9
  	 */
  	public static I18nManager getInstance()
  	{
  		return instance;
  	}
  
  	/**
  	 * Adds <code>i18n</code> to the list of managed <code>I18n</code>
  	 * objects.
  	 * 
  	 * @param i18n
  	 *            the <code>I18n</code> instance
  	 * @see #setDefaultLocale(Locale)
  	 * @see #remove(I18n)
  	 * @since 0.9
  	 */
  	public void add(I18n i18n)
  	{
  		i18ns.add(i18n);
  	}
  
  	/**
  	 * Sets the locale for all I18n instances that were instantiated through the
  	 * factory.
  	 * <p>
  	 * Use this method to globally change the locale for all I18n based
  	 * translations.
  	 * <p>
  	 * NOTE: This only works if the objects that display messages do not cache
  	 * translated messages.
  	 * <p>
  	 * 
  	 * @param locale
  	 *            the new default locale
  	 * @see I18n#setLocale(Locale)
  	 * @since 0.9
  	 */
  	public void setDefaultLocale(Locale locale)
  	{
  		for (Iterator it = i18ns.iterator(); it.hasNext();) {
  			I18n i18n = (I18n)it.next();
 			i18n.setLocale(locale);
 		}
 
 		fireLocaleChangedEvent(locale);
 	}
 
 	/**
 	 * Adds a listener that is notified when the default locale has been
 	 * changed.
 	 * 
 	 * @param listener
 	 *            the listener
 	 * @see #setDefaultLocale(Locale)
 	 * @since 0.9
 	 */
 	public void addLocaleChangeListener(LocaleChangeListener listener)
 	{
 		synchronized (localeChangeListeners) {
 			localeChangeListeners.add(listener);
 		}
 	}
 
 	/**
 	 * Adds a listener that is notified when the default locale has been changed
 	 * using a {@link WeakReference}. The listener is removed when it has been
 	 * cleaned up by the garbage collection.
 	 * <p>
 	 * This is useful for temporary objects that may have an indeterminate
 	 * lifetime such as dialogs.
 	 * 
 	 * @param listener
 	 *            the listener
 	 * @see #setDefaultLocale(Locale)
 	 * @since 0.9
 	 */
 	public void addWeakLocaleChangeListener(LocaleChangeListener listener)
 	{
 		synchronized (localeChangeListeners) {
 			localeChangeListeners.add(new WeakLocaleChangeListener(listener));
 		}
 	}
 
 	/**
 	 * Removes <code>i18n</code> from the list of managed <code>I18n</code>
 	 * objects.
 	 * 
 	 * @param i18n
 	 *            the <code>I18n</code> instance
 	 * @see #add(I18n)
 	 * @since 0.9
 	 */
 	public void remove(I18n i18n)
 	{
 		i18ns.remove(i18n);
 	}
 
 	/**
 	 * Removes <code>listener</code> from the list of objects that are
 	 * notified when the locale has changed.
 	 * 
 	 * @param listener
 	 *            the listener
 	 * @since 0.9
 	 */
 	public void removeLocaleChangeListener(LocaleChangeListener listener)
 	{
 		synchronized (localeChangeListeners) {
 			localeChangeListeners.remove(listener);
 		}
 	}
 
 	/**
 	 * Notifies listeners of a locale change.
 	 * 
 	 * @param newLocale
 	 *            new locale
 	 * @since 0.9
 	 */
 	protected void fireLocaleChangedEvent(Locale newLocale)
 	{
 		LocaleChangeListener[] listeners;
 		synchronized (localeChangeListeners) {
 			listeners = (LocaleChangeListener[])localeChangeListeners.toArray(new LocaleChangeListener[0]);
 		}
 		if (listeners.length > 0) {
 			LocaleChangeEvent event = new LocaleChangeEvent(I18nFactory.class, newLocale);
 			for (int i = listeners.length - 1; i >= 0; i--) {
 				listeners[i].localeChanged(event);
 			}
 		}
 	}
 
 	private static class WeakLocaleChangeListener implements LocaleChangeListener {
 
 		private WeakReference reference;
 
 		public WeakLocaleChangeListener(LocaleChangeListener listener)
 		{
 			reference = new WeakReference(listener);
 		}
 
 		public void localeChanged(LocaleChangeEvent event)
 		{
 			Object listener = reference.get();
 			if (listener != null) {
 				((LocaleChangeListener)listener).localeChanged(event);
 			}
 			else {
 				I18nManager.getInstance().removeLocaleChangeListener(this);
 			}
 		}
 
 	}
 
 }