/**
 * Copyright (c) 2011 - 2017, Lunifera GmbH (Gross Enzersdorf), Loetz GmbH&Co.KG (Heidelberg)
 * 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: 
 * 		Loetz GmbH&Co.KG - Initial implementation
 */
package org.eclipse.osbp.display.servlet;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import javax.servlet.ServletException;

import org.eclipse.osbp.display.api.IDisplayUiParticipant;
import org.eclipse.osbp.ecview.jetty.manager.IJettyManager;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.BundleEvent;
import org.osgi.framework.BundleException;
import org.osgi.framework.BundleListener;
import org.osgi.framework.Filter;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceReference;
import org.osgi.service.http.HttpService;
import org.osgi.service.http.NamespaceException;
import org.osgi.util.tracker.ServiceTracker;
import org.osgi.util.tracker.ServiceTrackerCustomizer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Activator implements BundleActivator, BundleListener, ServiceTrackerCustomizer<HttpService, HttpService> {

	private static final Logger LOGGER = LoggerFactory
			.getLogger(Activator.class);

	public static final String BUNDLE_HEADER__MOBILE_RESOURCES = "osbp-display-resources";

	public static final String BUNDLE_ID = "org.eclipse.osbp.display";

	private static BundleContext context;
	private static Activator plugin;

	static BundleContext getContext() {
		return context;
	}

	public static Activator getDefault() {
		return plugin;
	}

	// used to track the HttpService
	private ServiceTracker<HttpService, HttpService> tracker;
	// used to register servlets
	private HttpService httpService;
	private DisplayResourceProvider resourceProvider;
	private ServiceTracker<IDisplayUiParticipant, IDisplayUiParticipant> participantTracker;
	private static final String URI_FRAGMENT = "uriFragment";

	/** The fragment names. */
	private static Set<String> fragmentNames;
	
	/** The fragments. */
	private static Map<String, ServiceReference<IDisplayUiParticipant>> fragments = new HashMap<>();

	@Override
	public void start(BundleContext bundleContext) throws Exception {
		Activator.context = bundleContext;
		plugin = this;
		resourceProvider = new DisplayResourceProvider();
		handleStartedBundles(context);
		bundleContext.addBundleListener(this);

		participantTracker = new ServiceTracker<IDisplayUiParticipant, IDisplayUiParticipant>(
				context, IDisplayUiParticipant.class, null) {
			@Override
			public IDisplayUiParticipant addingService(ServiceReference<IDisplayUiParticipant> reference) {
				Object fragmentName = reference.getProperty(URI_FRAGMENT);
				if	(fragmentName instanceof String) {
					fragments.put(getSimpleName((String)fragmentName), reference);
				}
				return null;
			}
			@Override
			public void modifiedService(ServiceReference<IDisplayUiParticipant> reference,
					IDisplayUiParticipant service) {
				Object fragmentName = reference.getProperty(URI_FRAGMENT);
				if	(fragmentName instanceof String) {
					fragments.put(getSimpleName((String)fragmentName), reference);
				}
			}
			@Override
			public void removedService(ServiceReference<IDisplayUiParticipant> reference,
					IDisplayUiParticipant service) {
				Object fragmentName = reference.getProperty(URI_FRAGMENT);
				if	(fragmentName instanceof String) {
					fragments.remove(getSimpleName((String)fragmentName));
				}
			}		
		};
		participantTracker.open();

		// Start a HttpService-Tracker to get an instance of HttpService
		tracker = new ServiceTracker<>(bundleContext,
				createFilter(bundleContext), this);
		tracker.open();
	}

	protected String getSimpleName(String fragmentName) {
		String[] segments = fragmentName.split("\\.");
		return segments[segments.length-1];
	}

	private static Filter createFilter(BundleContext ctx) {
		// search for http service with the given context path of type
		// application.
		String filter = String.format("(&(%s=%s)(%s=%s))",
				org.osgi.framework.Constants.OBJECTCLASS,
				HttpService.class.getName(), IJettyManager.PROP_SERVICE_TYPE,
				IJettyManager.SERVICE_TYPE__DISPLAY);
		try {
			return ctx.createFilter(filter);
		} catch (InvalidSyntaxException e) {
			LOGGER.error("{}", e);
		}
		return null;
	}

	//
	// Helper methods to get an instance of the http service
	//
	@Override
	public HttpService addingService(ServiceReference<HttpService> reference) {
		httpService = context.getService(reference);

		try {
			// register the servlet at the http service
			httpService.registerServlet("/", new DisplayVaadinServlet(), null,
					resourceProvider);
		} catch (ServletException e) {
			e.printStackTrace();
		} catch (NamespaceException e) {
			e.printStackTrace();
		}

		return httpService;
	}

	@Override
	public void modifiedService(ServiceReference<HttpService> reference,
			HttpService service) {

	}

	@Override
	public void removedService(ServiceReference<HttpService> reference,
			HttpService service) {
		// unregister the servlet from the http service
		httpService.unregister("/");
	}

	/**
	 * Tries to find proper started bundles and adds them to resource provider.
	 * Since bundle changed listener will not find them.
	 * 
	 * @param context
	 */
	protected void handleStartedBundles(BundleContext context) {
		for (Bundle bundle : context.getBundles()) {
			String name = bundle.getSymbolicName();
			if (isValidBundle(bundle)) {
				resourceProvider.add(bundle);
			} else if (bundle.getState() == Bundle.RESOLVED
					&& name.equals("org.eclipse.equinox.http.jetty")) {
				try {
					bundle.start();
				} catch (BundleException e) {
				}
			}
		}
	}

	protected boolean isValidBundle(Bundle bundle) {
		String name = bundle.getSymbolicName();
		if (name.startsWith("com.vaadin")) {
			return true;
		} else if (bundle.getHeaders(BUNDLE_HEADER__MOBILE_RESOURCES) != null) {
			return true;
		}
		return false;
	}

	@Override
	public void bundleChanged(BundleEvent event) {
		// tracks the starting and stopping of vaadin bundles. If a bundle is a
		// vaadin bundle it will be added to the resource provider for lookups.
		String name = event.getBundle().getSymbolicName();
		if (name.startsWith("com.vaadin")) {
			if (event.getType() != BundleEvent.STOPPED) {
				resourceProvider.add(event.getBundle());
			} else if (event.getType() == BundleEvent.STOPPED) {
				resourceProvider.remove(event.getBundle());
			}
		}
	}

	@Override
	public void stop(BundleContext bundleContext) throws Exception {
		Activator.fragmentNames = null;									//NOSONAR
		// close the HttpService-tracker
		tracker.close();
		tracker = null;

		if (participantTracker != null) {
			participantTracker.close();
			participantTracker = null;
		}

		bundleContext.removeBundleListener(this);

		Activator.context = null;
		plugin = null;
	}

	/**
	 * Returns the participant service to create new handles.
	 * 
	 * @return
	 */
	public IDisplayUiParticipant getParticipant() {
		if (participantTracker != null) {
			return participantTracker.getService();
		}
		return null;
	}

	public static ServiceReference<IDisplayUiParticipant> getServiceReference(String name) {
		return Activator.fragments.get(name);
	}

}