/*
 * 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: CssMergeViewer.java,v 1.1 2004-09-02 18:11:49 jsurfer Exp $
 */

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

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

import org.eclipse.compare.CompareConfiguration;
import org.eclipse.compare.contentmergeviewer.TextMergeViewer;
import org.eclipse.jface.preference.IPreferenceStore;
import org.eclipse.jface.preference.PreferenceConverter;
import org.eclipse.jface.text.IDocumentPartitioner;
import org.eclipse.jface.text.TextViewer;
import org.eclipse.jface.text.source.SourceViewer;
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.swt.widgets.Composite;

/**
 * Merge viewer for CSS files.
 */
public class CssMergeViewer extends TextMergeViewer {

	// Constants ---------------------------------------------------------------

	/**
	 * Alias for the preference constant <code>EDITOR_BACKGROUND_COLOR</code>.
	 */
	private static final String PREFERENCE_BACKGROUND_COLOR =
		CssUIPreferences.EDITOR_BACKGROUND_COLOR;

	/**
	 * Alias for the preference constant
	 * <code>EDITOR_BACKGROUND_DEFAULT_COLOR</code>.
	 */
	private static final String PREFERENCE_BACKGROUND_DEFAULT_COLOR =
		CssUIPreferences.EDITOR_BACKGROUND_DEFAULT_COLOR;

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

	/**
	 * The preference store.
	 */
	private IPreferenceStore preferenceStore;

	/**
	 * The listener for changes to the preference store. 
	 */
	private IPropertyChangeListener propertyChangeListener;

	/**
	 * The CSS text tools.
	 */
	private CssTextTools textTools;

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

	/**
	 * Constructor.
	 * 
	 * @param parent the parent control
	 * @param style SWT style bits for top level composite of this viewer
	 * @param configuration the configuration object
	 */
	public CssMergeViewer(Composite parent, int style,
		CompareConfiguration configuration) {
		super(parent, style, configuration);
	}

	// TextMergeViewer Implementation ------------------------------------------

	/*
	 * @see TextMergeViewer#configureTextViewer()
	 */
	protected void configureTextViewer(TextViewer textViewer) {

		CssUI plugin = CssUI.getDefault();

		this.preferenceStore = plugin.getPreferenceStore();
		if (preferenceStore != null) {
			 propertyChangeListener = new IPropertyChangeListener() {
				public void propertyChange(PropertyChangeEvent event) {
					handlePreferenceStoreChanged(event);
				}
			};
			preferenceStore.addPropertyChangeListener(propertyChangeListener);
		}

		textTools = plugin.getTextTools();
		if (textViewer instanceof SourceViewer) {
			SourceViewer sourceViewer = (SourceViewer) textViewer;
			sourceViewer.configure(new CssSourceViewerConfiguration(
				textTools, preferenceStore));
		}

		updateBackgroundColor();
	}

	/*
	 * @see TextMergeViewer#getDocumentPartitioner()
	 */
	protected IDocumentPartitioner getDocumentPartitioner() {
		return textTools.createDocumentPartitioner();
	}

	/*
	 * @see org.eclipse.compare.contentmergeviewer.ContentMergeViewer#getTitle()
	 */
	public String getTitle() {
		return CssUIMessages.getString(
			"CssMergeViewer.title"); //$NON-NLS-1$
	}

	/*
	 * @see org.eclipse.jface.viewers.ContentViewer#handleDispose(org.eclipse.swt.events.DisposeEvent)
	 */
	protected void handleDispose(DisposeEvent event) {
		if (propertyChangeListener != null) {
			if (preferenceStore != null) {
				preferenceStore.removePropertyChangeListener(
					propertyChangeListener);
			}
			propertyChangeListener = null;
		}
		super.handleDispose(event);
	}

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

	/**
	 * Called when the preference store notifies us about a change.
	 * 
	 * @param event the change event
	 */
	protected void handlePreferenceStoreChanged(PropertyChangeEvent event) {
		String p = event.getProperty();
		if (PREFERENCE_BACKGROUND_COLOR.equals(p)
		 || PREFERENCE_BACKGROUND_DEFAULT_COLOR.equals(p)) {
			updateBackgroundColor();
		} else if (textTools.affectsPresentation(event)) {
			invalidateTextPresentation();
		}
	}

	/**
	 * Updates the background color of the merge viewer to the value set in the
	 * preferences.
	 */
	private void updateBackgroundColor() {
		boolean defaultBackgroundColor = preferenceStore.getBoolean(
			PREFERENCE_BACKGROUND_DEFAULT_COLOR);
		if (defaultBackgroundColor) {
			setBackgroundColor(null);
		} else {
			RGB backgroundColor = PreferenceConverter.getColor(
				preferenceStore, CssUIPreferences.EDITOR_BACKGROUND_COLOR);
			setBackgroundColor(backgroundColor);
		}
	}

}