/**
 *#########################################################################
 *
 * A component of the Gatherer application, part of the Greenstone digital
 * library suite from the New Zealand Digital Library Project at the
 * University of Waikato, New Zealand.
 *
 * Author: John Thompson, Greenstone Digital Library, University of Waikato
 *
 * Copyright (C) 1999 New Zealand Digital Library Project
 *
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *########################################################################
 */
package org.greenstone.gatherer.cdm;

/**************************************************************************************
 * Written:      08/05/02
 * Revised:      17/11/02 - Commented
 *               07/07/03 - DOM support
 **************************************************************************************/
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
import javax.swing.event.*;
import org.greenstone.gatherer.Configuration;
import org.greenstone.gatherer.DebugStream;
import org.greenstone.gatherer.Dictionary;
import org.greenstone.gatherer.Gatherer;
import org.greenstone.gatherer.gui.GLIButton;
import org.greenstone.gatherer.util.Utility;
import org.w3c.dom.*;

/** This class manages the language commands, remembering both a list of languages to build indexes in, plus the default language.
 * @author John Thompson, Greenstone Digital Library, University of Waikato
 * @version 2.3
 */
public class LanguageManager
    extends DOMProxyListModel {

    static public Document LANGUAGES_DOCUMENT = Utility.parse("xml/languages.xml", true);

    static final private Dimension COMPONENT_SIZE = new Dimension(125,25);

    /** The visual controls for this manager. */
    private Control controls = null;
    /** A reference to this class as a model, for the inner controls class. */
    private DOMProxyListModel model = null;
    /** A hashtable of code->name mappings of known languages. */
    private LinkedHashMap known_languages = null;
    /** The default language object. */
    private Language default_language = null;
 
   /** Constructor. */
    public LanguageManager(Element languages_element) {
	super(languages_element, CollectionConfiguration.LANGUAGE_ELEMENT, new Language());
	
	DebugStream.println("LanguageManager: " + getSize() + " languages parsed.");

	this.model = this;
	// Retrieve the default language
	NodeList default_language_elements = CollectionDesignManager.collect_config.getDocumentElement().getElementsByTagName(CollectionConfiguration.LANGUAGE_DEFAULT_ELEMENT);
	if(default_language_elements.getLength() > 0) {
	    default_language = new Language((Element)default_language_elements.item(0));
	}
	// Load a series of code->language mappings into known_languages, by reading from the 'languages.xml' file, which is essentially a subset of the ISO 639 Standard.
	known_languages = new LinkedHashMap();
	/*
	  try {
	    File in_file = new File("languages.dat");
	    FileReader in_reader = new FileReader(in_file);
	    BufferedReader in = new BufferedReader(in_reader);
	    String entry = null;
	    while((entry = in.readLine()) != null) {
		if(!entry.startsWith("#")) {
		    StringTokenizer tokenizer = new StringTokenizer(entry);
		    if(tokenizer.countTokens() >= 2) {
			String name = tokenizer.nextToken();
			String code = tokenizer.nextToken().toLowerCase();
			known_languages.put(code, name);
		    }
		}
	    }
	    in.close();
	    in_reader.close();
	    in = null;
	    in_reader = null;
	    in_file = null;
	}
	catch (Exception error) {
	    error.printStackTrace();
	}
	*/
	NodeList language_elements = LANGUAGES_DOCUMENT.getDocumentElement().getElementsByTagName(CollectionConfiguration.LANGUAGE_ELEMENT);
	for(int i = 0; i < language_elements.getLength(); i++) {
	    Element language_element = (Element) language_elements.item(i);
	    String code = language_element.getAttribute(CollectionConfiguration.CODE_ATTRIBUTE);
	    String name = language_element.getAttribute(CollectionConfiguration.NAME_ATTRIBUTE);
	    known_languages.put(code.toLowerCase(), name);
	    name = null;
	    code = null;
	    language_element = null;
	}
    }

    /** Method to add a new language.
     * @param language The <strong>Language</strong> to add.
     * @see org.greenstone.gatherer.Gatherer
     * @see org.greenstone.gatherer.collection.CollectionManager
     */
    private void addLanguage(Language language) {
	if(!contains(language)) {
	    Element element = language.getElement();
	    append(language);
	    Gatherer.c_man.configurationChanged();
	}
    }

    public void destroy() {
	if(controls != null) {
	    controls.destroy();
	    controls = null;
	}
	known_languages.clear();
	known_languages = null;
    }

    /** Method to retrieve the control for this manager.
     * @return the Control for editing the language partitions
     */
    public Control getControls() {
	if(controls == null) {
	    // Build controls
	    controls = new LanguageControl();
	}
	return controls;
    }

    /** Method to retrieve the default language code.
     * @return A <strong>Language</strong> containing a two letter code.
     */
    /* private Language getDefaultLanguage() {
	// If no default is set...
	if(default_language != null && default_language.isAssigned()) {
	    return default_language;
	}
	return null;
	} */

    /** Method to retrieve a certain language object by its code.
     * @param code The two letter code of a language, as a <strong>String</strong>.
     * @return The <strong>Language</strong> that matches the given code, or <i>null</i> if no such language exists.
     */
    public Language getLanguage(String code) {
	int size = getSize();
	for(int i = 0; i < size; i++) {
	    Language language = (Language) getElementAt(i);
	    if(language.getCode().equals(code)) {
		return language;
	    }
	}
	return null;
    }

    public ArrayList getLanguages() {
	return children();
    }

    /** Method to return a list of the known language codes.
     * @return an ArrayList containing the series of known language codes as per the languages.dat file
     */
    public ArrayList getLanguageCodes() {
	return new ArrayList(known_languages.keySet());
    }

    public String getLanguageName(String code) {
	return (String) known_languages.get(code);
    }

    /** Method to remove a certain language.
     * @param language The <strong>Language</strong> to remove.
     * @see org.greenstone.gatherer.Gatherer
     * @see org.greenstone.gatherer.collection.CollectionManager
     */
    private void removeLanguage(Language language) {
	remove(language);
	if(default_language != null && default_language.equals(language)) {
	    default_language = null;
	    ((LanguageControl)controls).clearDefaultLanguage();
	}
	Gatherer.c_man.configurationChanged();
    }

    /** Method to set the default language.
     * @param language The <strong>Language</strong> to use as a default, or <i>null</i> for no default.
     * @see org.greenstone.gatherer.Gatherer
     * @see org.greenstone.gatherer.collection.CollectionManager
     */
    public void setDefault(Language language) {
	if(language != null) {
	    if(default_language == null) {
		// Create the default index element, and place immediately after indexes element.
		Element default_language_element = root.getOwnerDocument().createElement(CollectionConfiguration.LANGUAGE_DEFAULT_ELEMENT);
		default_language = new Language(default_language_element);
		Node target_node = CollectionConfiguration.findInsertionPoint(default_language_element);
		if(target_node != null) {
		    root.getOwnerDocument().getDocumentElement().insertBefore(default_language_element, target_node);
		}
		else {
		    root.getOwnerDocument().getDocumentElement().appendChild(default_language_element);
		}
	    }
	    default_language.setAssigned(true);
	    default_language.setCode(language.getCode());
	}
	else {
	    if(default_language != null) {
		default_language.setAssigned(false);
	    }
	}
	Gatherer.c_man.configurationChanged();
    }


    /** This class represents the visual component of the Language Manager. */
    private class LanguageControl
	extends JPanel 
	implements Control {
	/** The button to add a new language support. */
	private JButton add_button = null;
	/** The button to clear the current default language. */
	private JButton clear_button = null;
	/** The button to remove a supported language. */
	private JButton remove_button = null;
	/** The button to set the current language as the default one. */
	private JButton set_button = null;
	/** A combobox listing the available supported languages. */
	private JComboBox selector_combobox = null;
	/** A list of currently supported languages. */
	private JList language_list = null;
	/** A description of the language currently selected. */
	private JTextArea description_textarea = null;
	/** The text field showing the currently name of the default language. Non-editable. */
	private JTextField default_language_field = null;
	/** Constructor.
	 * @see org.greenstone.gatherer.cdm.LanguageManager.LanguageControl.AddListener
	 * @see org.greenstone.gatherer.cdm.LanguageManager.LanguageControl.ClearDefaultListener
	 * @see org.greenstone.gatherer.cdm.LanguageManager.LanguageControl.ListListener
	 * @see org.greenstone.gatherer.cdm.LanguageManager.LanguageControl.RemoveListener
	 * @see org.greenstone.gatherer.cdm.LanguageManager.LanguageControl.SelectorListener
	 * @see org.greenstone.gatherer.cdm.LanguageManager.LanguageControl.SetDefaultListener
	 */
	public LanguageControl() {
	    super();
	    // Creation.
	    JPanel center_panel = new JPanel();

	    JLabel language_list_label = new JLabel();
	    Dictionary.registerText(language_list_label, "CDM.LanguageManager.Assigned_Languages");
	    language_list = new JList(model);

	    JPanel details_panel = new JPanel();

	    JPanel default_panel = new JPanel();

	    JLabel default_label = new JLabel();
	    default_label.setBorder(BorderFactory.createEmptyBorder(0,0,0,5));
	    Dictionary.registerText(default_label, "CDM.LanguageManager.Default_Language");

	    if(default_language == null) {
		default_language_field = new JTextField();
	    }
	    else {
		default_language_field = new JTextField(default_language.toString());
	    }
	    default_language_field.setPreferredSize(COMPONENT_SIZE);
	    default_language_field.setBackground(Configuration.getColor("coloring.collection_tree_background", false));
	    default_language_field.setEditable(false);
	    JPanel control_panel = new JPanel();

	    JLabel selector_label = new JLabel();
	    Dictionary.registerText(selector_label, "CDM.LanguageManager.Selector");

	    selector_combobox = new JComboBox(getLanguageCodes().toArray());
	    selector_combobox.setPreferredSize(COMPONENT_SIZE);
	    selector_combobox.setBackground(Configuration.getColor("coloring.collection_tree_background", false));
	    selector_combobox.setRenderer(new LanguageListCellRenderer());
	    Dictionary.registerTooltip(selector_combobox, "CDM.LanguageManager.Selector_Tooltip");

	    JPanel button_panel = new JPanel();

	    add_button = new GLIButton();
	    add_button.setMnemonic(KeyEvent.VK_A);
	    Dictionary.registerBoth(add_button, "CDM.LanguageManager.Add", "CDM.LanguageManager.Add_Tooltip");

	    remove_button = new GLIButton();
	    remove_button.setMnemonic(KeyEvent.VK_R);
	    remove_button.setEnabled(false);
	    Dictionary.registerBoth(remove_button, "CDM.LanguageManager.Remove", "CDM.LanguageManager.Remove_Tooltip");

	    clear_button = new GLIButton();
	    clear_button.setMnemonic(KeyEvent.VK_C);
	    // If there is a default language, then this is enabled
	    clear_button.setEnabled(default_language != null && default_language.isAssigned());
	    Dictionary.registerBoth(clear_button, "CDM.LanguageManager.Clear_Default", "CDM.LanguageManager.Clear_Default_Tooltip");

	    set_button = new GLIButton();
	    set_button.setMnemonic(KeyEvent.VK_S);
	    set_button.setEnabled(false);
	    Dictionary.registerBoth(set_button, "CDM.LanguageManager.Set_Default", "CDM.LanguageManager.Set_Default_Tooltip");

	    // Set up and connect listeners.
	    add_button.addActionListener(new AddListener());
	    clear_button.addActionListener(new ClearDefaultListener());
	    remove_button.addActionListener(new RemoveListener());
	    selector_combobox.addActionListener(new SelectorListener());
	    set_button.addActionListener(new SetDefaultListener());
	    language_list.addListSelectionListener(new ListListener());

	    // Layout components
	    default_panel.setBorder(BorderFactory.createCompoundBorder(BorderFactory.createRaisedBevelBorder(), BorderFactory.createEmptyBorder(2,0,2,2)));
	    default_panel.setLayout(new BorderLayout());
	    default_panel.add(default_label, BorderLayout.WEST);
	    default_panel.add(default_language_field, BorderLayout.CENTER);

	    control_panel.setBorder(BorderFactory.createEmptyBorder(5,0,0,0));
	    control_panel.setLayout(new BorderLayout());
	    control_panel.add(selector_label, BorderLayout.WEST);
	    control_panel.add(selector_combobox, BorderLayout.CENTER);

	    details_panel.setBorder(BorderFactory.createEmptyBorder(5,0,5,0));
	    details_panel.setLayout(new BorderLayout());
	    details_panel.add(default_panel, BorderLayout.CENTER);
	    details_panel.add(control_panel, BorderLayout.SOUTH);

	    center_panel.setLayout(new BorderLayout());
	    center_panel.add(language_list_label, BorderLayout.NORTH);
	    center_panel.add(new JScrollPane(language_list), BorderLayout.CENTER);
	    center_panel.add(details_panel, BorderLayout.SOUTH);

	    button_panel.setLayout(new GridLayout(2,2));
	    button_panel.add(add_button);
	    button_panel.add(remove_button);
	    button_panel.add(set_button);
	    button_panel.add(clear_button);

	    setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
	    setLayout(new BorderLayout());
	    add(center_panel, BorderLayout.CENTER);
	    add(button_panel, BorderLayout.SOUTH);
	}
	
	public void clearDefaultLanguage() {
	    clear_button.doClick();
	}

	/** Destructor.	*/
	public void destroy() {
	}

	public void gainFocus() {
	}

	public void loseFocus() {
	}

	/** Listens for actions apon the 'add' button in the LanguageManager controls, and if detected calls the add method of the manager with a newly created language. */
	private class AddListener
	    implements ActionListener {
	    /** Add a new language support.
	     * @param event an ActionEvent
	     * @see org.greenstone.gatherer.cdm.Language
	     */
	    public void actionPerformed(ActionEvent event) {
		String language_code = (String) selector_combobox.getSelectedItem();
		if(language_code != null) {
		    addLanguage(new Language(language_code));
		}
		add_button.setEnabled(false);
	    }
	}

	/** Listens for actions apon the 'clear default' button in the LanguageManager controls, and if detected calls the setDefault method of the manager with <i>null</i>. */
	private class ClearDefaultListener
	    implements ActionListener {
	    /** Clear the default index.
	     * @param event An <strong>ActionEvent</strong>.
	     */
	    public void actionPerformed(ActionEvent event) {
		setDefault(null);
		clear_button.setEnabled(false);
		default_language_field.setText("");
	    }
	}

	/** Listens for actions apon the 'remove' button in the LanguageManager controls, and if detected calls the remove method of the manager with the language selected for removal. */
	private class RemoveListener
	    implements ActionListener {
	    /** Remove the currently selected language, if any.
	     * @param event An <strong>ActionEvent</strong>.
	     * @see org.greenstone.gatherer.cdm.Language
	     */
	    public void actionPerformed(ActionEvent event) {
		Language delete_me = (Language)language_list.getSelectedValue();
		if(delete_me != null) {
		    removeLanguage(delete_me);
		    if(default_language != null && default_language.equals(delete_me)) {
			setDefault(null);
			clear_button.setEnabled(false);
			default_language_field.setText("");
		    }
		}
		remove_button.setEnabled(false);
	    }
	}

	/** Listens for selections within the combobox on the LanguageManager controls, and if a change is detected enables, or disables, controls appropriately. */
	private class SelectorListener
	    implements ActionListener {
	    /** Enable or disable controls depeding on selection.
	     * @param event An <strong>ActionEvent</strong>.
	     */
	    public void actionPerformed(ActionEvent event) {
		if(selector_combobox.getSelectedItem() != null) {
		    add_button.setEnabled(true);
		}
		else {
		    add_button.setEnabled(false);
		}
	    }
	}

	/** Listens for actions apon the 'set default' button in the LanguageManager controls, and if detected calls the <i>setDefault()</i> method of the manager with the language selected for default. */
	private class SetDefaultListener
	    implements ActionListener {
	    /** Set the default index to the one currently selected, if any.
	     * @param event An <strong>ActionEvent</strong>.
	     * @see org.greenstone.gatherer.cdm.Language
	     */
	    public void actionPerformed(ActionEvent event) {
		if(!language_list.isSelectionEmpty()) {
		    setDefault((Language)language_list.getSelectedValue());
		    clear_button.setEnabled(true);
		    default_language_field.setText(default_language.toString());
		}
	    }
	}

	/** Listens for selections within the list on the LanguageManager controls, and if a change is detected enables, or disables, controls appropriately. */
	private class ListListener
	    implements ListSelectionListener {
	    /** Enable or disable controls depending on the current list selection.
	     * @param event A <strong>ListSelectionEvent</strong>.
	     */
	    public void valueChanged(ListSelectionEvent event) {
		if(language_list.isSelectionEmpty()) {
		    remove_button.setEnabled(false);
		    set_button.setEnabled(false);
		}
		else {
		    remove_button.setEnabled(true);
		    set_button.setEnabled(true);
		}
	    }
	}
    }
}