Copyright (c) 2005, 2018 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2005, 2018 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.equinox.internal.app;

import java.security.Guard;
import java.security.GuardedObject;
import java.util.HashMap;
import java.util.Map;
import org.eclipse.osgi.framework.log.FrameworkLogEntry;
import org.eclipse.osgi.util.NLS;
import org.osgi.framework.*;
import org.osgi.service.application.ApplicationDescriptor;
import org.osgi.service.application.ScheduledApplication;
import org.osgi.service.event.*;
import org.osgi.util.tracker.ServiceTracker;

public class EclipseScheduledApplication implements ScheduledApplication, EventHandler {
	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;
	private Map<String, Object> args;
	private String appPid;
	private String id;
	private ServiceRegistration sr;
	private ServiceTracker appTracker;
	private boolean removed = false;

	EclipseScheduledApplication(BundleContext context, String id, String appPid, Map<String, Object> args, String topic, String eventFilter, boolean recurring) throws InvalidSyntaxException {
		this.id = id;
		this.appPid = 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;
		appTracker = new ServiceTracker(context, context.createFilter(FILTER_PREFIX + appPid + FILTER_POSTFIX), null);
		Activator.openTracker(appTracker, false);
	}

	@Override
	public String getScheduleId() {
		return id;
	}

	String getAppPid() {
		return appPid;
	}

	@Override
	public synchronized String getTopic() {
		if (removed)
			throw new IllegalStateException(Messages.scheduled_app_removed);
		return topic;
	}

	@Override
	public synchronized String getEventFilter() {
		if (removed)
			throw new IllegalStateException(Messages.scheduled_app_removed);
		return eventFilter;
	}

	@Override
	public synchronized boolean isRecurring() {
		if (removed)
			throw new IllegalStateException(Messages.scheduled_app_removed);
		return recurring;
	}

	@Override
	public synchronized ApplicationDescriptor getApplicationDescriptor() {
		if (removed)
			throw new IllegalStateException(Messages.scheduled_app_removed);
		return (ApplicationDescriptor) Activator.getService(appTracker);
	}

	@Override
	public synchronized Map<String, Object> getArguments() {
		if (removed)
			throw new IllegalStateException(Messages.scheduled_app_removed);
		return args == null ? null : new HashMap<>(args);
	}

	private Map<String, Object> getArguments(Event trigger) {
		Map<String, Object> result = args == null ? new HashMap<String, Object>() : getArguments();
		result.put(TRIGGERING_EVENT, new GuardedObject(trigger, new TriggerGuard(trigger.getTopic())));
		return result;
	}

	@Override
	public synchronized void remove() {
		if (removed)
			return;
		removed = true;
		AppPersistence.removeScheduledApp(this);
		if (sr != null)
			sr.unregister();
		sr = null;
		appTracker.close();
	}

	@Override
	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 app incase the application comes back
				return;
			desc.launch(getArguments(event));
		} catch (Exception e) {
			String message = NLS.bind(Messages.scheduled_app_launch_error, sr);
			Activator.log(new FrameworkLogEntry(Activator.PI_APP, FrameworkLogEntry.WARNING, 0, message, 0, e, null));
			return; // return here to avoid removing non-recurring apps when an error occurs
		}
		if (!isRecurring())
			remove();
	}

	synchronized void setServiceRegistration(ServiceRegistration sr) {
		this.sr = sr;
		if (removed) // just incase we were removed before the sr was set
			sr.unregister();
	}

	/*
	 * 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
		 */
		@Override
		public void checkGuard(Object object) throws SecurityException {
			SecurityManager sm = System.getSecurityManager();
			if (sm != null)
				sm.checkPermission(new TopicPermission(eventTopic, TopicPermission.SUBSCRIBE));
		}

	}
}