/**
	 * Sets the update site list. Both enabled and disabled update sites can be added and the method also provides a flag that if set removes all previous
	 * update sites.
	 * 
	 * @param enabledUpdateSites
	 * @param disabledUpdateSites
	 * @param clearExistingUpdateSites If set, all currently existing update sites are removed.
	 */
	public static void setUpdateSites( Collection<URI> enabledUpdateSites, List<URI> disabledUpdateSites, boolean clearExistingUpdateSites )
	{
		List<MetadataRepositoryElement> repositoryElements = new ArrayList<MetadataRepositoryElement>();
//		AviXPlugin.getLog4J().debug( "setUpdateSitesClear BEGIN" ); //$NON-NLS-1$

//		AviXPlugin.getLog4J().info( MessageFormat.format( "Clear existing update sites = {0}", clearExistingUpdateSites ) ); //$NON-NLS-1$
		ProvisioningUI provisioningUI = ProvisioningUI.getDefaultUI();
		if ( !clearExistingUpdateSites ) {
			// Add already known update sites
			IMetadataRepositoryManager metaManager = ProvUI.getMetadataRepositoryManager(provisioningUI.getSession());
			int visibilityFlags = provisioningUI.getRepositoryTracker().getMetadataRepositoryFlags();
			URI[] currentlyEnabled = metaManager.getKnownRepositories(visibilityFlags);
			URI[] currentlyDisabled = metaManager.getKnownRepositories(IRepositoryManager.REPOSITORIES_DISABLED | visibilityFlags);
//			AviXPlugin.getLog4J().info( "Adding existing enabled update sites..." ); //$NON-NLS-1$
			for ( URI uri : currentlyEnabled ) {
				MetadataRepositoryElement metadataRepositoryElement = new MetadataRepositoryElement( null, uri, true );
//				AviXPlugin.getLog4J().info( MessageFormat.format( "enabled: {0}", uri ) ); //$NON-NLS-1$
				repositoryElements.add( metadataRepositoryElement );
			}
//			AviXPlugin.getLog4J().info( "Adding existing disabled update sites..." ); //$NON-NLS-1$
			for ( URI uri : currentlyDisabled ) {
				MetadataRepositoryElement metadataRepositoryElement = new MetadataRepositoryElement( null, uri, false );
//				AviXPlugin.getLog4J().info( MessageFormat.format( "disabled: {0}", uri ) ); //$NON-NLS-1$
				repositoryElements.add( metadataRepositoryElement );
			}
		}

//		AviXPlugin.getLog4J().info( "Adding enabled update sites..." ); //$NON-NLS-1$
		if ( enabledUpdateSites != null ) {
			for ( URI uri : enabledUpdateSites ) {
				MetadataRepositoryElement metadataRepositoryElement = new MetadataRepositoryElement( null, uri, true );
//				AviXPlugin.getLog4J().info( MessageFormat.format( "enabled: {0}", uri ) ); //$NON-NLS-1$
				repositoryElements.add( metadataRepositoryElement );
			}
		}
//		AviXPlugin.getLog4J().info( "Adding disabled update sites..." ); //$NON-NLS-1$
		if ( disabledUpdateSites != null ) {
			for ( URI uri : disabledUpdateSites ) {
				MetadataRepositoryElement metadataRepositoryElement = new MetadataRepositoryElement( null, uri, false );
//				AviXPlugin.getLog4J().info( MessageFormat.format( "disabled: {0}", uri ) ); //$NON-NLS-1$
				repositoryElements.add( metadataRepositoryElement );
			}
		}

		// Set the update site list.
		MetadataRepositoryElement[] elements = repositoryElements.toArray( new MetadataRepositoryElement[repositoryElements.size()] );
		ElementUtils.updateRepositoryUsingElements( provisioningUI, elements, null );

//		AviXPlugin.getLog4J().debug( "setUpdateSitesClear END" ); //$NON-NLS-1$
	}

	/**
	 * Tries to dig out all installable IU groups from the currently enabled update sites.<br>
	 * <br>
	 * Note: The IUs are not currently tested for dependencies so they may not be able to be installed. 
	 * @param agent
	 * @param monitor
	 * @return All {@link IInstallableUnit}s that are found in the enabled update sites that are of type "IUGroup" and are not already installed.
	 */
	public static List<IInstallableUnit> getNonInstalledInstallableUnits( IProvisioningAgent agent, IProgressMonitor monitor )
	{
		List<IInstallableUnit> result = Collections.emptyList();
		
		ProvisioningUI provisioningUI = ProvisioningUI.getDefaultUI();
		IMetadataRepositoryManager metaManager = ProvUI.getMetadataRepositoryManager(provisioningUI.getSession());
//		IQueryResult<IInstallableUnit> queryResultAll = metaManager.query( QueryUtil.createIUAnyQuery(), monitor );
//		Set<IInstallableUnit> allInstallableUnits = queryResultAll.toUnmodifiableSet();
//		int size = allInstallableUnits.size();
		IQueryResult<IInstallableUnit> queryResult = metaManager.query( QueryUtil.createIUGroupQuery(), monitor );
		Set<IInstallableUnit> installableUnits = queryResult.toUnmodifiableSet();
		List<IInstallableUnit> notInstalledInstallableUnits = new ArrayList<IInstallableUnit>();
		for ( IInstallableUnit installableUnit : installableUnits ) {
			if (isInstalled( agent, monitor, installableUnit ) ) {
				continue;
			}
			notInstalledInstallableUnits.add( installableUnit );
		}
		
		// Filter out only last version of the installable units
		Map<String, IInstallableUnit> installableUnitMap = new HashMap<String, IInstallableUnit>();
		for ( IInstallableUnit installableUnit : notInstalledInstallableUnits ) {
			String id = installableUnit.getId();
			Version iuVersion = installableUnit.getVersion();
			
			IInstallableUnit mapInstallableUnit = installableUnitMap.get( id );
			if ( mapInstallableUnit != null ) {
				Version mapIUVersion = mapInstallableUnit.getVersion();
				if ( mapIUVersion.compareTo( iuVersion ) < 0 ) {
					installableUnitMap.put( id, installableUnit );
				}
			}
			else {
				installableUnitMap.put( id, installableUnit );
			}
		}
		
		// TODO: Filter out IUs that cannot be installed due to dependencies
		
		if ( !installableUnitMap.isEmpty() ) {
			result = new ArrayList<IInstallableUnit>( installableUnitMap.values() );
		}
		
		return result;
	}

	/**
	 * Installs installable units in a synchronous manner. It is up to the caller to run this in a job if a background job is desired.
	 * @param agent
	 * @param monitor
	 * @param installableUnits
	 * @return
	 * @throws OperationCanceledException
	 */
	public static IStatus installInstallableUnits(IProvisioningAgent agent, IProgressMonitor monitor, List<IInstallableUnit> installableUnits ) throws OperationCanceledException
	{
		ProvisioningSession session = new ProvisioningSession( agent );
		InstallOperation operation = new InstallOperation( session, installableUnits );
		SubMonitor sub = SubMonitor.convert( monitor, "Installing new software...", 200 );
		IStatus status = operation.resolveModal( sub.newChild( 100 ) );
		if ( status.getCode() == UpdateOperation.STATUS_NOTHING_TO_UPDATE ) {
			return status;
		}
		if ( status.getSeverity() == IStatus.CANCEL )
			throw new OperationCanceledException();

		if ( status.getSeverity() != IStatus.ERROR ) {
			// More complex status handling might include showing the user what updates
			// are available if there are multiples, differentiating patches vs. updates, etc.
			// In this example, we simply update as suggested by the operation.
			ProvisioningJob job = operation.getProvisioningJob( null );
			status = job.runModal( sub.newChild( 100 ) );
			if ( status.getSeverity() == IStatus.CANCEL )
				throw new OperationCanceledException();
		}
		
		return status;
	}

	/**
	 * Checks for updates and performs updates synchronously. It is up to the caller to run this in a job if a background job is desired.<br>
	 * <br>
	 * Code stolen from the example RCPMail application with prestartupdate in P2.
	 * 
	 * @param agent
	 * @param monitor
	 * @return
	 * @throws OperationCanceledException
	 */
	public static IStatus checkForUpdates(IProvisioningAgent agent, IProgressMonitor monitor) throws OperationCanceledException
	{
		ProvisioningSession session = new ProvisioningSession( agent );
		// the default update operation looks for updates to the currently
		// running profile, using the default profile root marker. To change
		// which installable units are being updated, use the more detailed
		// constructors.
		UpdateOperation operation = new UpdateOperation( session );
		SubMonitor sub = SubMonitor.convert( monitor, "Checking for updates...", 200 );
		IStatus status = operation.resolveModal( sub.newChild( 100 ) );
		if ( status.getCode() == UpdateOperation.STATUS_NOTHING_TO_UPDATE ) {
			return status;
		}
		if ( status.getSeverity() == IStatus.CANCEL )
			throw new OperationCanceledException();

		if ( status.getSeverity() != IStatus.ERROR ) {
			// More complex status handling might include showing the user what updates
			// are available if there are multiples, differentiating patches vs. updates, etc.
			// In this example, we simply update as suggested by the operation.
			ProvisioningJob job = operation.getProvisioningJob( null );
			status = job.runModal( sub.newChild( 100 ) );
			if ( status.getSeverity() == IStatus.CANCEL )
				throw new OperationCanceledException();
		}
		return status;
	}

	public void preStartup()
	{
		// Perform update related stuff on application startup.
		// - Add update sites from preferences
		// - If enabled, perform auto update
		
		// Initialize the update sites. This can add update sites specified in the preferences.
		UpdateManager.initializeUpdateSites();
		
		if ( UpdateManager.isInstallOnStartup() || UpdateManager.isUpdateOnStartup() ) {
			// The AviXPlugin.bundleContext used below is a public variable in the product plugin activator. It is initialized in AviXPlugin.start( BundleContext context ). Just make it available in your own activator and fix the code.
			final IProvisioningAgent agent = (IProvisioningAgent)ServiceHelper.getService( AviXPlugin.bundleContext, IProvisioningAgent.SERVICE_NAME );
			if (agent == null) {
//				AviXPlugin.getLog4J().warn("No provisioning agent found. Application is not setup to handle automatic installations." ); //$NON-NLS-1$
			}
			else if ( !UpdateManager.isJustUpdated() ) {

				final IRunnableWithProgress runnable = new IRunnableWithProgress() {
					public void run( IProgressMonitor monitor ) throws InvocationTargetException, InterruptedException
					{
						// Check for new things to install.
						boolean restart = false;
						if ( UpdateManager.isInstallOnStartup() ) {
//							AviXPlugin.getLog4J().info("Checking for installable IUs..." ); //$NON-NLS-1$
							List<IInstallableUnit> installableUnits = UpdateManager.getNonInstalledInstallableUnits( agent, monitor );
							if ( !installableUnits.isEmpty() ) {
								IStatus installStatus = UpdateManager.installInstallableUnits( agent, monitor, installableUnits );
								if ( installStatus.getCode() == UpdateOperation.STATUS_NOTHING_TO_UPDATE ) {
									PlatformUI.getWorkbench().getDisplay().asyncExec( new Runnable() {
										public void run()
										{
//											AviXPlugin.getLog4J().info("No new IUs to install were found." ); //$NON-NLS-1$
//											MessageDialog.openInformation( null, "Updates", "No updates were found" );
										}
									} );
								}
								else if ( installStatus.getSeverity() != IStatus.ERROR ) {
//									AviXPlugin.getLog4J().info("New IUs installed. Restarting workbench." ); //$NON-NLS-1$
									UpdateManager.setJustUpdated( true );
									restart = true;
								}
								else {
//									AviXPlugin.getLog4J().info("Error occured during install operation: " + installStatus.getMessage() ); //$NON-NLS-1$
//									AviXPlugin.getLog4J().info( installStatus );
								}
							}
						}
						if ( UpdateManager.isUpdateOnStartup() ) {
//							AviXPlugin.getLog4J().info("Checking for updates..." ); //$NON-NLS-1$
							IStatus updateStatus = UpdateManager.checkForUpdates( agent, monitor );
							if ( updateStatus.getCode() == UpdateOperation.STATUS_NOTHING_TO_UPDATE ) {
								PlatformUI.getWorkbench().getDisplay().asyncExec( new Runnable() {
									public void run()
									{
//										AviXPlugin.getLog4J().info("No new IUs to install were found." ); //$NON-NLS-1$
//										MessageDialog.openInformation( null, "Updates", "No updates were found" );
									}
								} );
							}
							else if ( updateStatus.getSeverity() != IStatus.ERROR ) {
//								AviXPlugin.getLog4J().info("Updates installed. Restarting workbench." ); //$NON-NLS-1$
								UpdateManager.setJustUpdated( true );
								restart = true;
							}
							else {
//								AviXPlugin.getLog4J().info("Error occured during update operation: " + updateStatus.getMessage() ); //$NON-NLS-1$
//								AviXPlugin.getLog4J().info( updateStatus );
							}
						}
						
						if ( restart ) {
							// Make sure the restart call is made by the UI thread.
							PlatformUI.getWorkbench().getDisplay().asyncExec( new Runnable() {
								@Override
								public void run()
								{
//									AviXPlugin.getLog4J().info("Waiting for user input to restart..." ); //$NON-NLS-1$
									MessageDialog.openInformation( null, "Updates", "Application will now restart to complete the installation of updates." );
//									AviXPlugin.getLog4J().info("Performing restart of workbench." ); //$NON-NLS-1$
									PlatformUI.getWorkbench().restart();
								}
							} );
						}
					}
				};

				// Execute in UI thread
				Display.getCurrent().asyncExec( new Runnable() {
					@Override
					public void run()
					{
						try {
//							AviXPlugin.getLog4J().info("Showing progress bar for update check." ); //$NON-NLS-1$
							// Gives thread access errors
							new ProgressMonitorDialog(null).run(true, true, runnable);
						} catch (InvocationTargetException e) {
							e.printStackTrace();
						} catch (InterruptedException e) {
						}
					}
				} );
			}
			else {
				UpdateManager.setJustUpdated( false );
//				AviXPlugin.getLog4J().info("Do not check for installable IUs or updates this time as application was just restarted after updates/installations were made. Application will check for updates again next time it is started." ); //$NON-NLS-1$
			}
		}
	}