/*******************************************************************************
 * Copyright (c) 2005, 2006 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.gecko.runtime.application.internal;

import java.security.Guard;
import java.security.GuardedObject;
import java.util.HashMap;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;

import org.osgi.framework.BundleContext;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceRegistration;
import org.osgi.service.application.ApplicationDescriptor;
import org.osgi.service.application.ScheduledApplication;
import org.osgi.service.event.Event;
import org.osgi.service.event.EventHandler;
import org.osgi.service.event.TopicPermission;

public class GeckoScheduledApplication implements ScheduledApplication, EventHandler {
	
	private static Logger logger = Logger.getLogger("org.gecko.scheduledApplication");
	private static final String FILTER_PREFIX = "(&(objectclass=" + ApplicationDescriptor.class.getName() + ")(" + ApplicationDescriptor.APPLICATION_PID + "="; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
	private static final String FILTER_POSTFIX = "))"; //$NON-NLS-1$

	private boolean recurring;
	private String topic;
	private String eventFilter;
	@SuppressWarnings("rawtypes")
	private Map args;
	private String applicationPid;
	private String id;
	private ServiceRegistration<?> registration;
	private SecureServiceTracker<ApplicationDescriptor, ApplicationDescriptor> appDescTracker;
	private volatile boolean removed = false;

	@SuppressWarnings("rawtypes")
	GeckoScheduledApplication(BundleContext context, String id, String appPid, Map args, String topic, String eventFilter, boolean recurring) throws InvalidSyntaxException {
		this.id = id;
		this.applicationPid = appPid;
		this.args = args;
		this.topic = topic == null || topic.trim().equals("") || topic.trim().equals("*") ? null : topic; //$NON-NLS-1$ //$NON-NLS-2$
		this.eventFilter = eventFilter;
		this.recurring = recurring;
		appDescTracker = new SecureServiceTracker<>(context, context.createFilter(FILTER_PREFIX + appPid + FILTER_POSTFIX));
		appDescTracker.open(false);
	}

	/* 
	 * (non-Javadoc)
	 * @see org.osgi.service.application.ScheduledApplication#getScheduleId()
	 */
	public String getScheduleId() {
		return id;
	}

	/* 
	 * (non-Javadoc)
	 * @see org.osgi.service.application.ScheduledApplication#getTopic()
	 */
	public synchronized String getTopic() {
		if (removed)
			throw new IllegalStateException("Application has been unregistered");
		return topic;
	}

	/* 
	 * (non-Javadoc)
	 * @see org.osgi.service.application.ScheduledApplication#getEventFilter()
	 */
	public synchronized String getEventFilter() {
		if (removed)
			throw new IllegalStateException("Application has been unregistered");
		return eventFilter;
	}

	/* 
	 * (non-Javadoc)
	 * @see org.osgi.service.application.ScheduledApplication#isRecurring()
	 */
	public synchronized boolean isRecurring() {
		if (removed)
			throw new IllegalStateException("Application has been unregistered");
		return recurring;
	}

	/* 
	 * (non-Javadoc)
	 * @see org.osgi.service.application.ScheduledApplication#getApplicationDescriptor()
	 */
	public synchronized ApplicationDescriptor getApplicationDescriptor() {
		if (removed)
			throw new IllegalStateException("Application has been unregistered");
		return appDescTracker.getService();
	}

	/* 
	 * (non-Javadoc)
	 * @see org.osgi.service.application.ScheduledApplication#getArguments()
	 */
	@SuppressWarnings({ "rawtypes", "unchecked" })
	public synchronized Map getArguments() {
		if (removed)
			throw new IllegalStateException("Application has been unregistered");
		return args == null ? null : new HashMap(args);
	}

	/* 
	 * (non-Javadoc)
	 * @see org.osgi.service.application.ScheduledApplication#remove()
	 */
	public synchronized void remove() {
		if (removed) {
			return;
		}
		removed = true;
//		AppPersistence.removeScheduledApp(this);
		if (registration != null)
			registration.unregister();
		registration = null;
		appDescTracker.close();
	}

	/* 
	 * (non-Javadoc)
	 * @see org.osgi.service.event.EventHandler#handleEvent(org.osgi.service.event.Event)
	 */
	public synchronized void handleEvent(Event event) {
		try {
			if (removed) {
				return;
			}
			ApplicationDescriptor desc = getApplicationDescriptor();
			if (desc == null)
				// in this case the application descriptor was removed;
				// we must return and keep the scheduled application in case the application comes back
				return;
			desc.launch(getArguments(event));
		} catch (Exception e) {
			logger.log(Level.WARNING, "Failed to launch the scheduled application: " + getApplicationDescriptor().getApplicationId());
			// return here to avoid removing non-recurring applications when an error occurs
			return; 
		}
		if (!isRecurring())
			remove();
	}

	/**
	 * Returns the application id
	 * @return the application id
	 */
	public Object getApplicationPid() {
		return applicationPid;
	}

	/**
	 * Sets the service registration for the {@link ScheduledApplication}
	 * @param registration the service registration
	 */
	synchronized void setServiceRegistration(ServiceRegistration<?> registration) {
		this.registration = registration;
		// just in case we were removed before the registration was set
		if (removed) {
			registration.unregister();
		}
	}

	/**
	 * Returns the arguments for a trigger event 
	 * @param trigger the trigger event
	 * @return the arguments map
	 */
	@SuppressWarnings({ "rawtypes", "unchecked" })
	private Map getArguments(Event trigger) {
		Map result = args == null ? new HashMap() : getArguments();
		result.put(TRIGGERING_EVENT, new GuardedObject(trigger, new TriggerGuard(trigger.getTopic())));
		return result;
	}

	/*
	 * This is used to guard the event topic argument which is passed to an application
	 * when we are launching it from a scheduling. 
	 */
	public class TriggerGuard implements Guard {
		String eventTopic;

		public TriggerGuard(String topic) {
			this.eventTopic = topic;
		}

		/*
		 * does the proper TopicPermission check for the event topic
		 */
		public void checkGuard(Object object) throws SecurityException {
			SecurityManager sm = System.getSecurityManager();
			if (sm != null)
				sm.checkPermission(new TopicPermission(eventTopic, TopicPermission.SUBSCRIBE));
		}

	}
}