/*******************************************************************************
 * Copyright (c) 2005 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.internal.dialogs;

import java.text.BreakIterator;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import org.eclipse.jface.preference.IPreferenceNode;
import org.eclipse.jface.viewers.ITreeContentProvider;
import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.ui.internal.preferences.WorkbenchPreferenceExtensionNode;

/**
 * A class which handles filtering preferences nodes based on a supplied
 * matching string.
 * 
 * @since 3.1
 * 
 */
public class PatternItemFilter extends PatternFilter {

	/**
	 * this cache is needed because
	 * WorkbenchPreferenceExtensionNode.getKeywordLabels() is expensive. When it
	 * tracks keyword changes effectivly than this cache can be removed.
	 */
	private Map keywordCache = new HashMap();

	protected boolean matchItem;

	/**
	 * Create a new instance of a PatternItemFilter
	 * 
	 * @param isMatchItem
	 */
	public PatternItemFilter(boolean isMatchItem) {
		super();
		matchItem = isMatchItem;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.viewers.ViewerFilter#select(org.eclipse.jface.viewers.Viewer,
	 *      java.lang.Object, java.lang.Object)
	 */
	public boolean select(Viewer viewer, Object parentElement, Object element) {

		ITreeContentProvider contentProvider = (ITreeContentProvider) ((TreeViewer) viewer)
				.getContentProvider();

		IPreferenceNode node = (IPreferenceNode) element;
		Object[] children = contentProvider.getChildren(node);
		String text = node.getLabelText();

		if(wordMatches(text))
			return true;
		
		if (matchItem) {

			// Will return true if any subnode of the element matches the search
			if (filter(viewer, element, children).length > 0)
				return true;
		}

		if (node instanceof WorkbenchPreferenceExtensionNode) {
			WorkbenchPreferenceExtensionNode workbenchNode = (WorkbenchPreferenceExtensionNode) node;

			Collection keywordCollection = (Collection) keywordCache.get(node);
			if (keywordCollection == null) {
				keywordCollection = workbenchNode.getKeywordLabels();
				keywordCache.put(node, keywordCollection);
			}
			if (keywordCollection.isEmpty())
				return false;
			Iterator keywords = keywordCollection.iterator();
			while (keywords.hasNext()) {
				if (wordMatches((String) keywords.next()))
					return true;
			}
		}
		return false;

	}

	/**
	 * Return whether or not if any of the words in text satisfy the
	 * match critera.
	 * @param text
	 * @return boolean <code>true</code> if one of the words in text 
	 * satisifes the match criteria.
	 */
	private boolean wordMatches(String text) {
		// Break the text up into words, separating based on whitespace and
		// common punctuation.
		// Previously used String.split(..., "\\W"), where "\W" is a regular
		// expression (see the Javadoc for class Pattern).
		// Need to avoid both String.split and regular expressions, in order to
		// compile against JCL Foundation (bug 80053).
		// Also need to do this in an NL-sensitive way. The use of BreakIterator
		// was suggested in bug 90579.
		BreakIterator iter = BreakIterator.getWordInstance();
		iter.setText(text);
		int i = iter.first();
		while (i != java.text.BreakIterator.DONE && i < text.length()) {
			int j = iter.following(i);
			if (j == java.text.BreakIterator.DONE)
				j = text.length();
			if (Character.isLetterOrDigit(text.charAt(i))) {
				String word = text.substring(i, j);
				if (match(word))
					return true;
			}
			i = j;
		}
		return false;
	}

}
