/*******************************************************************************
 * Copyright (c) 2005 Oracle Corporation.
 * 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:
 *    Ian Trimble - initial API and implementation
 *******************************************************************************/ 
package org.eclipse.jst.jsf.core.jsfappconfig;

import java.io.IOException;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.jdt.core.ElementChangedEvent;
import org.eclipse.jdt.core.IElementChangedListener;
import org.eclipse.jdt.core.IJavaElementDelta;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jst.jsf.core.internal.JSFCorePlugin;

/**
 * RuntimeClasspathJSFAppConfigLocater attempts to locate application
 * configuration files in JAR files on the runtime classpath. The runtime
 * classpath includes the server runtime classpath and the JAR files that will
 * be deployed to the web application's /WEB-INF/lib folder.
 * 
 * <p><b>Provisional API - subject to change</b></p>
 * 
 * @author Ian Trimble - Oracle
 */
public class RuntimeClasspathJSFAppConfigLocater extends AbstractJSFAppConfigLocater
	implements IElementChangedListener {

	/*
	 * (non-Javadoc)
	 * @see org.eclipse.jst.jsf.core.jsfappconfig.AbstractJSFAppConfigLocater#startLocating()
	 */
	public void startLocating() {
		locateProviders();
		JavaCore.addElementChangedListener(this);
	}

	/*
	 * (non-Javadoc)
	 * @see org.eclipse.jst.jsf.core.jsfappconfig.AbstractJSFAppConfigLocater#stopLocating()
	 */
	public void stopLocating() {
		JavaCore.removeElementChangedListener(this);
	}

	/**
	 * Locates application configuration resources specified in JAR files on
	 * the runtime classpath, and updates the set of
	 * {@link IJSFAppConfigProvider} instances accordingly.
	 */
	public void locateProviders() {
		try {
			List JARs = JSFAppConfigUtils.getConfigFileJARsFromClasspath(manager.getProject());
			Iterator itJARs = JARs.iterator();
			Set newConfigProviders = new LinkedHashSet();
			while (itJARs.hasNext()) {
				String JARFilename = (String)itJARs.next();
				JARFileJSFAppConfigProvider configProvider = new JARFileJSFAppConfigProvider(JARFilename);
				newConfigProviders.add(configProvider);
			}
			updateConfigProviders(newConfigProviders);
		} catch(CoreException ce) {
			//log error
			JSFCorePlugin.log(IStatus.ERROR, ce.getLocalizedMessage(), ce);
		} catch(IOException ioe) {
			//log error
			JSFCorePlugin.log(IStatus.ERROR, ioe.getLocalizedMessage(), ioe);
		}
	}

	/**
	 * Called when a Java element has changed.
	 * 
	 * @param event ElementChangedEvent instance describing the change.
	 */
	public void elementChanged(ElementChangedEvent event) {
		if (classpathChanged(event.getDelta())) {
			locateProviders();
		}
	}

	/**
	 * Recursively tests if the passed IJavaElementDelta instance or any of its
	 * descendents indicate a classpath change has occurred.
	 * 
	 * @param delta IJavaElement instance to be tested.
	 * @return true if a claspath change has occurred, else false.
	 */
	protected boolean classpathChanged(IJavaElementDelta delta) {
		int deltaFlags = delta.getFlags();
		if (((deltaFlags & IJavaElementDelta.F_ADDED_TO_CLASSPATH) == IJavaElementDelta.F_ADDED_TO_CLASSPATH) ||
				((deltaFlags & IJavaElementDelta.F_ARCHIVE_CONTENT_CHANGED) == IJavaElementDelta.F_ARCHIVE_CONTENT_CHANGED) ||
				((deltaFlags & IJavaElementDelta.F_REMOVED_FROM_CLASSPATH) == IJavaElementDelta.F_REMOVED_FROM_CLASSPATH)) {
			return true;
		}  
		boolean changed = false;
		IJavaElementDelta[] childDeltas = delta.getAffectedChildren();
		if (childDeltas != null) {
			for (int i = 0; i < childDeltas.length; i++) {
				if (classpathChanged(childDeltas[i])) {
					changed = true;
					break;
				}
			}
		}
		return changed;
	}
}