/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation 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:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.views.navigator;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.runtime.*;
import org.eclipse.jface.viewers.IStructuredContentProvider;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.plugin.AbstractUIPlugin;

/**
 * The FiltersContentProvider provides the elements for use by the list dialog
 * for selecting the patterns to apply.
 */
/* package */ class FiltersContentProvider implements IStructuredContentProvider {

	private static List definedFilters;
	private static List defaultFilters;
	

	private ResourcePatternFilter resourceFilter;
/**
 * Create a FiltersContentProvider using the selections from the suppliec
 * resource filter.
 */
public FiltersContentProvider(ResourcePatternFilter filter) {
	this.resourceFilter = filter;
}
/* (non-Javadoc)
 * Method declared on IContentProvider.
 */
public void dispose() {}
/**
 * Returns the filters which are enabled by default.
 *
 * @return a list of strings
 */
public static List getDefaultFilters() {
	if (defaultFilters == null) {
		readFilters();
	}
	return defaultFilters;
}
/**
 * Returns the filters currently defined for the navigator.
 *
 * @return a list of strings
 */
public static List getDefinedFilters() {
	if (definedFilters == null) {
		readFilters();
	}
	return definedFilters;
}
/* (non-Javadoc)
 * Method declared on IStructuredContentProvider.
 */
public Object[] getElements(Object inputElement) {
	return getDefinedFilters().toArray();
}
/**
 * Return the initially selected elements.
 */
public String[] getInitialSelections() {
	return this.resourceFilter.getPatterns();
}
/* (non-Javadoc)
 * Method declared on IContentProvider.
 */
public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
}
/**
 * Reads the filters currently defined for the workbench. 
 */
private static void readFilters() {
	definedFilters = new ArrayList();
	defaultFilters = new ArrayList();
	AbstractUIPlugin plugin =
		(AbstractUIPlugin) Platform.getPlugin(PlatformUI.PLUGIN_ID);
	if (plugin != null) {
		IExtensionPoint extension = plugin.getDescriptor().getExtensionPoint(ResourcePatternFilter.FILTERS_TAG);
		if (extension != null) {
			IExtension[] extensions =  extension.getExtensions();
			for(int i = 0; i < extensions.length; i++){
				IConfigurationElement [] configElements = extensions[i].getConfigurationElements();
				for(int j = 0; j < configElements.length; j++){
					String pattern = configElements[j].getAttribute("pattern");//$NON-NLS-1$
					if (pattern != null)
						definedFilters.add(pattern);
					String selected = configElements[j].getAttribute("selected");//$NON-NLS-1$
					if (selected != null && selected.equalsIgnoreCase("true"))//$NON-NLS-1$
						defaultFilters.add(pattern);
				}
			}
		}		
	}
}
}