/*
 * Copyright (c) 2003-2004 Christopher Lenz and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     Christopher Lenz - initial API and implementation
 * 
 * $Id: ShowSelectedElementOnlyAction.java,v 1.1 2004-09-02 18:11:50 jsurfer Exp $
 */

package net.sourceforge.phpeclipse.css.ui.internal.editor;

import net.sourceforge.phpeclipse.css.ui.CssUI;
import net.sourceforge.phpeclipse.css.ui.internal.CssUIMessages;
import net.sourceforge.phpeclipse.css.ui.internal.CssUIPreferences;

import org.eclipse.jface.preference.IPreferenceStore;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;
import org.eclipse.ui.texteditor.ITextEditor;
import org.eclipse.ui.texteditor.TextEditorAction;

/**
 * A toolbar action which toggles the presentation model of the connected text 
 * editor. The editor shows either the highlight range only or always the whole 
 * document.
 * 
 * <p>
 *  This class is an implementation for the retargetable action 
 *  <code>TOGGLE_SHOW_SELECTED_ELEMENT_ONLY</code> provided by the platform.
 * </p>
 * 
 * @see org.eclipse.ui.texteditor.ITextEditorActionDefinitionIds#TOGGLE_SHOW_SELECTED_ELEMENT_ONLY
 */
public class ShowSelectedElementOnlyAction extends TextEditorAction
	implements IPropertyChangeListener {

	// Instance Variables ------------------------------------------------------

	private IPreferenceStore store;

	// Constructors ------------------------------------------------------------

	/**
	 * Constructor.
	 */
	public ShowSelectedElementOnlyAction() {
		super(CssUIMessages.getResourceBundle(),
			"CssEditor.showSelectedElementOnly.", null); //$NON-NLS-1$
		store = CssUI.getDefault().getPreferenceStore();
		update();
	}

	// TextEditor Implementation -----------------------------------------------

	/*
	 * @see org.eclipse.jface.action.IAction#run()
	 */
	public void run() {
		ITextEditor editor = getTextEditor();
		if (editor != null) {
			IRegion highlightRange = editor.getHighlightRange();
			editor.resetHighlightRange();
			boolean show = !editor.showsHighlightRangeOnly();
			setChecked(show);
			editor.showHighlightRangeOnly(show);
			if (highlightRange != null) {
				editor.setHighlightRange(highlightRange.getOffset(),
					highlightRange.getLength(), true);
			}
			store.removePropertyChangeListener(this);
			store.setValue(
				CssUIPreferences.EDITOR_SHOW_SELECTED_ELEMENT_ONLY, show);
			store.addPropertyChangeListener(this);
		}
	}

	/*
	 * @see TextEditorAction#setEditor(ITextEditor)
	 */
	public void setEditor(ITextEditor editor) {
		super.setEditor(editor);
		if (editor != null) {
			if (store == null) {
				store = CssUI.getDefault().getPreferenceStore();
				store.addPropertyChangeListener(this);
			}
			synchronizeWithPreference(editor);
		} else if (store != null) {
			store.removePropertyChangeListener(this);
			store = null;
		}
		update();
	}
	
	/*
	 * @see org.eclipse.ui.texteditor.IUpdate#update()
	 */
	public void update() {
		ITextEditor editor = getTextEditor();
		if (editor != null) {
			setChecked(getTextEditor().showsHighlightRangeOnly());
			setEnabled(true);
		} else {
			setEnabled(false);
		}
	}

	// IPropertyChangeListener Implementation ----------------------------------

	/*
	 * @see IPropertyChangeListener#propertyChange(PropertyChangeEvent)
	 */
	public void propertyChange(PropertyChangeEvent event) {
		String p = event.getProperty();
		if (CssUIPreferences.EDITOR_SHOW_SELECTED_ELEMENT_ONLY.equals(p)) {
			synchronizeWithPreference(getTextEditor());
		}
	}

	// Private Methods ---------------------------------------------------------

	/**
	 * Synchronizes the appearance of the editor with what the preference store
	 * contains.
	 * 
	 * @param editor the editor to synchronize
	 */
	private void synchronizeWithPreference(ITextEditor editor) {
		if (editor != null) {
			boolean show = this.store.getBoolean(
				CssUIPreferences.EDITOR_SHOW_SELECTED_ELEMENT_ONLY);
			setChecked(show);
			if (show != editor.showsHighlightRangeOnly()) {
				IRegion highlightRange = editor.getHighlightRange();
				editor.resetHighlightRange();
				editor.showHighlightRangeOnly(show);
				if (highlightRange != null) {
					editor.setHighlightRange(highlightRange.getOffset(),
						highlightRange.getLength(), true);
				}
			}
		}
	}

}