/*
    * This file is a part of CAST project.
    * (c) Copyright 2007, AGH University of Science & Technology
    * https://caribou.iisg.agh.edu.pl/trac/cast
    *
    * Licensed under the Eclipse Public License, Version 1.0 (the "License").
    * You may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    * http://www.eclipse.org/legal/epl-v10.html
   */
  /*
   * File: AbstractConfigurableView.java
   * Created: 2007-00-00
   * Author: awos, entrop
   * $Id: UserPreferences.java 3266 2009-08-27 15:28:45Z tmilos $
   */
  
  package pl.edu.agh.cast.project;
  
  import java.util.LinkedList;
  import java.util.List;
  
  import org.apache.log4j.Logger;
  import org.eclipse.core.resources.IProject;
  import org.eclipse.core.runtime.preferences.IEclipsePreferences;
  import org.eclipse.core.runtime.preferences.InstanceScope;
  import org.osgi.service.prefs.BackingStoreException;
  import org.osgi.service.prefs.Preferences;
  
  import pl.edu.agh.cast.Activator;
  import pl.edu.agh.cast.CastApplication;
  
  /**
   * Contains global user preferences.
   *
   * @author AGH CAST Team
   */
  public class UserPreferences {
  
  	/**
  	 * Enumeration of user preferences.
  	 *
  	 * @author AGH CAST Team
  	 */
  	public static enum Pref {
  
  		/**
  		 * User preference: <em>Show project startup dialog</em>.
  		 */
  		SHOW_PROJECT_STARTUP_DIALOG("showProjectStartupDialog"); //$NON-NLS-1$
  
  		private String value;
  
  		public String getValue() {
  			return value;
  		}
  
  		private Pref(String value) {
  			this.value = value;
  		}
  
  	}
  
  	private static final String KEY_CONFIGURATION_ID_NAME = "KEY_CONFIGURATION_ID"; //$NON-NLS-1$
  
  	private static final String ORG_ECLIPSE_UI_NODE_NAME = "org.eclipse.ui"; //$NON-NLS-1$
  
  	private static final String MRU_ORDER_NODE_NAME = "order"; //$NON-NLS-1$
  
  	private static final String MRU_PROJECT_NAME_PREFIX = "#"; //$NON-NLS-1$
  
  	private static final String MRU_NODE_NAME = "MRU"; //$NON-NLS-1$
  
  	private static final Logger LOG = Activator.getLogger();
  
  	private static UserPreferences instance;
  
  	/**
  	 * Returns single, shared instance of {@link UserPreferences}.
  	 *
  	 * @return single, shared instance of {@link UserPreferences}
  	 */
  	public static UserPreferences getInstance() {
  		if (instance == null) {
  			instance = new UserPreferences();
  		}
  		return instance;
  	}
  
  	/**
  	 * Removes project from Most Recently Used (MRU) list.
  	 *
  	 * @param name
  	 *            name of the project
  	 */
  	public void removeMRUProject(String name) {
  		try {
  			Preferences pluginNode = getPluginNode().node(MRU_NODE_NAME);
  
 			Preferences orderNode = pluginNode.node(MRU_ORDER_NODE_NAME);
 			List<String> order = readNode(orderNode);
 			order.remove(name);
 			writeNode(orderNode, order);
 
 			Preferences projectNode = pluginNode.node(MRU_PROJECT_NAME_PREFIX + name);
 			projectNode.removeNode();
 
 			pluginNode.flush();
 		} catch (BackingStoreException e) {
 			LOG.error("Failed to remove project from MRU list", e); //$NON-NLS-1$
 		}
 
 	}
 
 	/**
 	 * Returns a list of MRU projects.
 	 *
 	 * @return a list of MRU projects
 	 */
 	public List<MostRecentlyUsedProject> getMostRecentlyUsedProjects() {
 		List<MostRecentlyUsedProject> projects = new LinkedList<MostRecentlyUsedProject>();
 		Preferences mruNode = getPluginNode().node(MRU_NODE_NAME);
 		List<String> order = readNode(mruNode.node(MRU_ORDER_NODE_NAME));
 		for (String projName : order) {
 			List<String> locations = readNode(mruNode.node(MRU_PROJECT_NAME_PREFIX + projName));
 			projects.add(new MostRecentlyUsedProject(projName, locations));
 		}
 		return projects;
 	}
 
 	/**
 	 * Changes MRU project name. If project is bound to only one location then replaces old project with new one. If
 	 * project is bound to more locations -> removes actual project location from 'old name project' bound, and adds new
 	 * project name with actual location.
 	 *
 	 *
 	 * @param project
 	 *            Project with old name.
 	 * @param newName
 	 *            Future new name of project.
 	 */
 	public void changeMostRecentlyProjectName(IProject project, String newName) {
 		String oldName = ProjectUtil.getInstance().getDisplayName(project);
 		if (oldName.equals(newName)) {
 			return;
 		}
 
 		try {
 			Preferences mruNode = getPluginNode().node(MRU_NODE_NAME);
 			Preferences orderNode = mruNode.node(MRU_ORDER_NODE_NAME);
 			List<String> order = readNode(orderNode);
 
 			Preferences oldProjectNode = mruNode.node(MRU_PROJECT_NAME_PREFIX + oldName);
 			List<String> projDirs = readNode(oldProjectNode);
 
 			String projectDir = project.getLocation().toPortableString();
 			if (projDirs.size() == 1) {
 				// replace old name with new name in 'order' node
 				setMostRecent(orderNode, oldName);
 				order.set(0, newName);
 				writeNode(orderNode, order);
 
 				// if old project registered in only one location then remove
 				// old project node
 				oldProjectNode.removeNode();
 			} else {
 				// if old project registered in many locations then remove
 				// active location from old project
 				setMostRecent(orderNode, newName);
 				setMostRecent(oldProjectNode, projectDir);
 				oldProjectNode = mruNode.node(MRU_PROJECT_NAME_PREFIX + oldName);
 				projDirs.remove(0);
 				writeNode(oldProjectNode, projDirs);
 			}
 
 			Preferences newProjectNode = mruNode.node(MRU_PROJECT_NAME_PREFIX + newName);
 
 			// add project location to new project node
 			setMostRecent(newProjectNode, projectDir);
 
 			mruNode.flush();
 
 		} catch (BackingStoreException ex) {
 			LOG.error("Failed to change name for MRU project", ex); //$NON-NLS-1$
 		}
 	}
 
 	/**
 	 * MRU projects are kept in the preferences in the following form
 	 *
 	 * <pre>
 	 * MRU
 	 * |_ order
 	 *    |_ 0 = project_name0
 	 *    |_ 1 = project_name1
 	 *    ...
 	 *    |_ n = project_namen
 	 * |_ #project_name0
 	 *    |_ 0 = most_recent_location
 	 *    |_ 1 = older_location
 	 *    ...
 	 *    |_ n = oldest_location
 	 * |_ #project_name1
 	 *    ...
 	 * ...
 	 * </pre>
 	 *
 	 * @param p
 	 *            project to set as most recently used
 	 */
 	public void registerMostRecentlyUsedProject(IProject p) {
 		try {
 			String projectName = ProjectUtil.getInstance().getDisplayName(p);
 			String projectLoc = p.getLocation().toPortableString();
 
 			Preferences mruNode = getPluginNode().node(MRU_NODE_NAME);
 			Preferences orderNode = mruNode.node(MRU_ORDER_NODE_NAME);
 			Preferences projectNode = mruNode.node(MRU_PROJECT_NAME_PREFIX + projectName);
 
 			setMostRecent(orderNode, projectName);
 			setMostRecent(projectNode, projectLoc);
 
 			mruNode.flush();
 		} catch (BackingStoreException e) {
 			LOG.error("Failed to save MRU project", e); //$NON-NLS-1$
 		}
 
 	}
 
 	private void setMostRecent(Preferences node, String entry) throws BackingStoreException {
 		List<String> entries = readNode(node);
 		entries.remove(entry);
 		entries.add(0, entry);
 		writeNode(node, entries);
 	}
 
 	private List<String> readNode(Preferences node) {
 		List<String> entries = new LinkedList<String>();
 		Integer i = 0;
 		String entry;
 		while ((entry = node.get(i.toString(), null)) != null) {
 			entries.add(entry);
 			i++;
 		}
 		return entries;
 	}
 
 	private void writeNode(Preferences projectNode, List<String> locations) throws BackingStoreException {
 		projectNode.clear();
 		Integer i = 0;
 		for (String loc : locations) {
 			projectNode.put(i.toString(), loc);
 			i++;
 		}
 	}
 
 	/**
 	 * Sets the value of given preference.
 	 *
 	 * @param pref
 	 *            preference
 	 * @param val
 	 *            the value
 	 */
 	public void setPreference(Pref pref, String val) {
 		Preferences node = getPluginNode();
 		node.put(pref.getValue(), val);
 		try {
 			node.flush();
 		} catch (BackingStoreException e) {
 			Activator.getLogger().error("Failed to save preference " + pref, e); //$NON-NLS-1$
 		}
 	}
 
 	/**
 	 * Returns the value of given preference.
 	 *
 	 * @param pref
 	 *            preference
 	 * @return the value
 	 */
 	public String getPreference(Pref pref) {
 		Preferences node = getPluginNode();
 		return node.get(pref.getValue(), null);
 	}
 
 	/**
 	 * Initializes default preference values.
 	 */
 	public void initializeDefaults() {
 		InstanceScope is = new InstanceScope();
 		IEclipsePreferences uiNode = is.getNode(ORG_ECLIPSE_UI_NODE_NAME);
 		if (uiNode.get(KEY_CONFIGURATION_ID_NAME, null) == null) {
 			uiNode.put(KEY_CONFIGURATION_ID_NAME, CastApplication.KEY_SCHEME_ID);
 		}
 		try {
 			uiNode.flush();
 		} catch (BackingStoreException e) {
 			Activator.getLogger().error("Failed to save default prefs", e); //$NON-NLS-1$
 		}
 	}
 
 	private static Preferences getPluginNode() {
 		InstanceScope is = new InstanceScope();
 		return is.getNode(Activator.PLUGIN_ID);
 	}
 
 }