/*******************************************************************************
 * Copyright (C) 2007,2010 Robin Rosenberg <robin.rosenberg@dewire.com>
 * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
 * Copyright (C) 2010, Mathias Kinzler <mathias.kinzler@sap.com>
 * Copyright (C) 2012, Matthias Sohn <matthias.sohn@sap.com>
 *
 * 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
 *******************************************************************************/
package org.eclipse.egit.ui;

import java.io.IOException;
import java.net.Authenticator;
import java.net.ProxySelector;
import java.util.ArrayList;
import java.util.Dictionary;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import java.util.concurrent.atomic.AtomicBoolean;

import org.eclipse.core.net.proxy.IProxyService;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.resources.WorkspaceJob;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.SubProgressMonitor;
import org.eclipse.core.runtime.jobs.ISchedulingRule;
import org.eclipse.egit.core.RepositoryUtil;
import org.eclipse.egit.core.project.RepositoryMapping;
import org.eclipse.egit.ui.internal.ConfigurationChecker;
import org.eclipse.egit.ui.internal.UIText;
import org.eclipse.egit.ui.internal.credentials.EGitCredentialsProvider;
import org.eclipse.egit.ui.internal.trace.GitTraceLocation;
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;
import org.eclipse.jgit.events.IndexChangedEvent;
import org.eclipse.jgit.events.IndexChangedListener;
import org.eclipse.jgit.events.ListenerHandle;
import org.eclipse.jgit.events.RepositoryEvent;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.transport.CredentialsProvider;
import org.eclipse.jgit.transport.SshSessionFactory;
import org.eclipse.jsch.core.IJSchService;
import org.eclipse.osgi.service.debug.DebugOptions;
import org.eclipse.osgi.service.debug.DebugOptionsListener;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.widgets.Display;
import org.eclipse.ui.IWindowListener;
import org.eclipse.ui.IWorkbenchWindow;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.plugin.AbstractUIPlugin;
import org.eclipse.ui.statushandlers.StatusManager;
import org.eclipse.ui.themes.ITheme;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;

/**
 * This is a plugin singleton mostly controlling logging.
 */
public class Activator extends AbstractUIPlugin implements DebugOptionsListener {

	/**
	 *  The one and only instance
	 */
	private static Activator plugin;

	/**
	 * Property listeners for plugin specific events
	 */
	private static List<IPropertyChangeListener> propertyChangeListeners =
		new ArrayList<IPropertyChangeListener>(5);

	/**
	 * Property constant indicating the decorator configuration has changed.
	 */
	public static final String DECORATORS_CHANGED = "org.eclipse.egit.ui.DECORATORS_CHANGED"; //$NON-NLS-1$

	/**
	 * @return the {@link Activator} singleton.
	 */
	public static Activator getDefault() {
		return plugin;
	}

	/**
	 * @return the id of the egit ui plugin
	 */
	public static String getPluginId() {
		return getDefault().getBundle().getSymbolicName();
	}

	/**
	 * Handle an error. The error is logged. If <code>show</code> is
	 * <code>true</code> the error is shown to the user.
	 *
	 * @param message 		a localized message
	 * @param throwable
	 * @param show
	 */
	public static void handleError(String message, Throwable throwable,
			boolean show) {
		handleIssue(IStatus.ERROR, message, throwable, show);
	}

	/**
	 * Handle an issue. The issue is logged. If <code>show</code> is
	 * <code>true</code> the issue is shown to the user.
	 *
	 * @param severity
	 *            status severity, use constants defined in {@link IStatus}
	 * @param message
	 *            a localized message
	 * @param throwable
	 * @param show
	 * @since 2.2
	 */
	public static void handleIssue(int severity, String message, Throwable throwable,
			boolean show) {
		IStatus status = new Status(severity, getPluginId(), message,
				throwable);
		int style = StatusManager.LOG;
		if (show)
			style |= StatusManager.SHOW;
		StatusManager.getManager().handle(status, style);
	}

	/**
	 * Shows an error. The error is NOT logged.
	 *
	 * @param message
	 *            a localized message
	 * @param throwable
	 */
	public static void showError(String message, Throwable throwable) {
		IStatus status = new Status(IStatus.ERROR, getPluginId(), message,
				throwable);
		StatusManager.getManager().handle(status, StatusManager.SHOW);
	}

	/**
	 * Shows an error. The error is NOT logged.
	 *
	 * @param message
	 *            a localized message
	 * @param status
	 */
	public static void showErrorStatus(String message, IStatus status) {
		StatusManager.getManager().handle(status, StatusManager.SHOW);
	}

	/**
	 * Get the theme used by this plugin.
	 *
	 * @return our theme.
	 */
	public static ITheme getTheme() {
		return plugin.getWorkbench().getThemeManager().getCurrentTheme();
	}

	/**
	 * Get a font known to this plugin.
	 *
	 * @param id
	 *            one of our THEME_* font preference ids (see
	 *            {@link UIPreferences});
	 * @return the configured font, borrowed from the registry.
	 */
	public static Font getFont(final String id) {
		return getTheme().getFontRegistry().get(id);
	}

	/**
	 * Get a font known to this plugin, but with bold style applied over top.
	 *
	 * @param id
	 *            one of our THEME_* font preference ids (see
	 *            {@link UIPreferences});
	 * @return the configured font, borrowed from the registry.
	 */
	public static Font getBoldFont(final String id) {
		return getTheme().getFontRegistry().getBold(id);
	}

	private RepositoryChangeScanner rcs;
	private ResourceRefreshJob refreshJob;
	private ListenerHandle refreshHandle;
	private DebugOptions debugOptions;

	private IWindowListener focusListener;

	/**
	 * Construct the {@link Activator} egit ui plugin singleton instance
	 */
	public Activator() {
		Activator.setActivator(this);
	}

	private static void setActivator(Activator a) {
		plugin = a;
	}


	public void start(final BundleContext context) throws Exception {
		super.start(context);

		// we want to be notified about debug options changes
		Dictionary<String, String> props = new Hashtable<String, String>(4);
		props.put(DebugOptions.LISTENER_SYMBOLICNAME, context.getBundle()
				.getSymbolicName());
		context.registerService(DebugOptionsListener.class.getName(), this,
				props);

		setupSSH(context);
		setupProxy(context);
		setupRepoChangeScanner();
		setupRepoIndexRefresh();
		setupFocusHandling();
		setupCredentialsProvider();
		ConfigurationChecker.checkConfiguration();
	}

	private void setupCredentialsProvider() {
		CredentialsProvider.setDefault(new EGitCredentialsProvider());
	}

	static boolean isActive() {
		final AtomicBoolean ret = new AtomicBoolean();
		final Display display = PlatformUI.getWorkbench().getDisplay();
		if (display.isDisposed())
			return false;
		display.syncExec(new Runnable() {
			public void run() {
				ret.set(display.getActiveShell() != null);
			}
		});
		return ret.get();
	}

	private void setupFocusHandling() {
		focusListener = new IWindowListener() {

			public void windowOpened(IWorkbenchWindow window) {
				// nothing
			}

			public void windowDeactivated(IWorkbenchWindow window) {
				// nothing
			}

			public void windowClosed(IWorkbenchWindow window) {
				// nothing
			}

			public void windowActivated(IWorkbenchWindow window) {
				if (rcs.doReschedule)
					rcs.schedule();
				refreshJob.triggerRefresh();
			}
		};
		PlatformUI.getWorkbench().addWindowListener(focusListener);
	}

	public void optionsChanged(DebugOptions options) {
		// initialize the trace stuff
		debugOptions = options;
		GitTraceLocation.initializeFromOptions(options, isDebugging());
	}

	/**
	 * @return the {@link DebugOptions}
	 */
	public DebugOptions getDebugOptions() {
		return debugOptions;
	}

	private void setupRepoIndexRefresh() {
		refreshJob = new ResourceRefreshJob();
		refreshHandle = Repository.getGlobalListenerList()
				.addIndexChangedListener(refreshJob);
	}

	/**
	 * Register for changes made to Team properties.
	 *
	 * @param listener
	 *            The listener to register
	 */
	public static synchronized void addPropertyChangeListener(
			IPropertyChangeListener listener) {
		propertyChangeListeners.add(listener);
	}

	/**
	 * Remove a Team property changes.
	 *
	 * @param listener
	 *            The listener to remove
	 */
	public static synchronized void removePropertyChangeListener(
			IPropertyChangeListener listener) {
		propertyChangeListeners.remove(listener);
	}

	/**
	 * Broadcast a Team property change.
	 *
	 * @param event
	 *            The event to broadcast
	 */
	public static synchronized void broadcastPropertyChange(PropertyChangeEvent event) {
		for (IPropertyChangeListener listener : propertyChangeListeners)
			listener.propertyChange(event);
	}

	/**
	 * Refresh projects in repositories that we suspect may have resource
	 * changes.
	 */
	static class ResourceRefreshJob extends WorkspaceJob implements
			IndexChangedListener {

		ResourceRefreshJob() {
			super(UIText.Activator_refreshJobName);
		}

		private Set<IProject> projectsToScan = new LinkedHashSet<IProject>();
		private Set<Repository> repositoriesChanged = new HashSet<Repository>();

		@Override
		public IStatus runInWorkspace(IProgressMonitor monitor) {
			IProject[] projects = ResourcesPlugin.getWorkspace().getRoot().getProjects();
			monitor.beginTask(UIText.Activator_refreshingProjects, projects.length);

			while (projectsToScan.size() > 0) {
				IProject p;
				synchronized (projectsToScan) {
					if (projectsToScan.size() == 0)
						break;
					Iterator<IProject> i = projectsToScan.iterator();
					p = i.next();
					i.remove();
				}
				ISchedulingRule rule = p.getWorkspace().getRuleFactory().refreshRule(p);
				try {
					getJobManager().beginRule(rule, monitor);
					if(p.exists()) // handle missing projects after branch switch
						p.refreshLocal(IResource.DEPTH_INFINITE, new SubProgressMonitor(monitor, 1));
				} catch (CoreException e) {
					handleError(UIText.Activator_refreshFailed, e, false);
					return new Status(IStatus.ERROR, getPluginId(), e.getMessage());
				} finally {
					getJobManager().endRule(rule);
				}
			}
			monitor.done();
			return Status.OK_STATUS;
		}

		public void onIndexChanged(IndexChangedEvent e) {
			if (Activator.getDefault().getPreferenceStore()
					.getBoolean(UIPreferences.REFESH_ON_INDEX_CHANGE))
				mayTriggerRefresh(e);
		}

		/**
		 * Record which projects have changes. Initiate a resource refresh job
		 * if the user settings allow it.
		 *
		 * @param e
		 *            The {@link RepositoryEvent} that triggered this refresh
		 */
		private void mayTriggerRefresh(RepositoryEvent e) {
			repositoriesChanged.add(e.getRepository());
			if (!Activator.getDefault().getPreferenceStore()
					.getBoolean(UIPreferences.REFESH_ONLY_WHEN_ACTIVE)
					|| isActive())
				triggerRefresh();
		}

		/**
		 * Figure which projects belong to a repository, add them to a set of
		 * project to refresh and schedule the refresh as a job.
		 */
		void triggerRefresh() {
			if (GitTraceLocation.REPOSITORYCHANGESCANNER.isActive())
				GitTraceLocation.getTrace().trace(
						GitTraceLocation.REPOSITORYCHANGESCANNER.getLocation(),
						"Triggered refresh"); //$NON-NLS-1$
			IProject[] projects = ResourcesPlugin.getWorkspace().getRoot()
					.getProjects();
			Set<IProject> toRefresh = new HashSet<IProject>();
			synchronized (repositoriesChanged) {
				for (IProject p : projects) {
					RepositoryMapping mapping = RepositoryMapping.getMapping(p);
					if (mapping != null
							&& repositoriesChanged.contains(mapping
									.getRepository())) {
						toRefresh.add(p);
					}
				}
				repositoriesChanged.clear();
			}
			synchronized (projectsToScan) {
				projectsToScan.addAll(toRefresh);
			}
			if (projectsToScan.size() > 0)
				schedule();
		}
	}

	/**
	 * A Job that looks at the repository meta data and triggers a refresh of
	 * the resources in the affected projects.
	 */
	static class RepositoryChangeScanner extends WorkspaceJob {
		RepositoryChangeScanner() {
			super(UIText.Activator_repoScanJobName);
		}

		// FIXME, need to be more intelligent about this to avoid too much work
		private static final long REPO_SCAN_INTERVAL = 10000L;
		// volatile in order to ensure thread synchronization
		private volatile boolean doReschedule = true;

		void setReschedule(boolean reschedule){
			doReschedule = reschedule;
		}

		@Override
		public IStatus runInWorkspace(IProgressMonitor monitor) {
			Repository[] repos = org.eclipse.egit.core.Activator.getDefault()
					.getRepositoryCache().getAllRepositories();
			if (repos.length == 0)
				return Status.OK_STATUS;

			// When people use Git from the command line a lot of changes
			// may happen. Don't scan when inactive depending on the user's
			// choice.

			if (Activator.getDefault().getPreferenceStore()
					.getBoolean(UIPreferences.REFESH_ONLY_WHEN_ACTIVE)) {
				if (!isActive()) {
					monitor.done();
					if (doReschedule)
						schedule(REPO_SCAN_INTERVAL);
					return Status.OK_STATUS;
				}
			}

			monitor.beginTask(UIText.Activator_scanningRepositories,
					repos.length);
			try {
				for (Repository repo : repos) {
					if (monitor.isCanceled())
						break;
					if (GitTraceLocation.REPOSITORYCHANGESCANNER.isActive())
						GitTraceLocation.getTrace().trace(
								GitTraceLocation.REPOSITORYCHANGESCANNER
										.getLocation(),
								"Scanning " + repo + " for changes"); //$NON-NLS-1$ //$NON-NLS-2$

					repo.scanForRepoChanges();
					monitor.worked(1);
				}
			} catch (IOException e) {
				if (GitTraceLocation.REPOSITORYCHANGESCANNER.isActive())
					GitTraceLocation.getTrace().trace(
							GitTraceLocation.REPOSITORYCHANGESCANNER
									.getLocation(),
							"Stopped rescheduling " + getName() + "job"); //$NON-NLS-1$ //$NON-NLS-2$
				return createErrorStatus(UIText.Activator_scanError, e);
			} finally {
				monitor.done();
			}
			if (GitTraceLocation.REPOSITORYCHANGESCANNER.isActive())
				GitTraceLocation.getTrace().trace(
						GitTraceLocation.REPOSITORYCHANGESCANNER.getLocation(),
						"Rescheduling " + getName() + " job"); //$NON-NLS-1$ //$NON-NLS-2$
			if (doReschedule)
				schedule(REPO_SCAN_INTERVAL);
			return Status.OK_STATUS;
		}
	}

	private void setupRepoChangeScanner() {
		rcs = new RepositoryChangeScanner();
		rcs.setSystem(true);
		rcs.schedule(RepositoryChangeScanner.REPO_SCAN_INTERVAL);
	}

	private void setupSSH(final BundleContext context) {
		final ServiceReference ssh;

		ssh = context.getServiceReference(IJSchService.class.getName());
		if (ssh != null) {
			SshSessionFactory.setInstance(new EclipseSshSessionFactory(
					(IJSchService) context.getService(ssh)));
		}
	}

	private void setupProxy(final BundleContext context) {
		final ServiceReference proxy;

		proxy = context.getServiceReference(IProxyService.class.getName());
		if (proxy != null) {
			ProxySelector.setDefault(new EclipseProxySelector(
					(IProxyService) context.getService(proxy)));
			Authenticator.setDefault(new EclipseAuthenticator(
					(IProxyService) context.getService(proxy)));
		}
	}

	public void stop(final BundleContext context) throws Exception {
		if (refreshHandle != null) {
			refreshHandle.remove();
			refreshHandle = null;
		}

		if (focusListener != null) {
			PlatformUI.getWorkbench().removeWindowListener(focusListener);
			focusListener = null;
		}

		if (GitTraceLocation.REPOSITORYCHANGESCANNER.isActive())
			GitTraceLocation.getTrace().trace(
					GitTraceLocation.REPOSITORYCHANGESCANNER.getLocation(),
					"Trying to cancel " + rcs.getName() + " job"); //$NON-NLS-1$ //$NON-NLS-2$

		rcs.setReschedule(false);

		rcs.cancel();
		if (GitTraceLocation.REPOSITORYCHANGESCANNER.isActive())
			GitTraceLocation.getTrace().trace(
					GitTraceLocation.REPOSITORYCHANGESCANNER.getLocation(),
					"Trying to cancel " + refreshJob.getName() + " job"); //$NON-NLS-1$ //$NON-NLS-2$
		refreshJob.cancel();

		rcs.join();
		refreshJob.join();

		if (GitTraceLocation.REPOSITORYCHANGESCANNER.isActive())
			GitTraceLocation.getTrace().trace(
					GitTraceLocation.REPOSITORYCHANGESCANNER.getLocation(),
					"Jobs terminated"); //$NON-NLS-1$

		super.stop(context);
		plugin = null;
	}

	/**
	 * @param message
	 * @param e
	 */
	public static void logError(String message, Throwable e) {
		handleError(message, e, false);
	}

	/**
	 * @param message
	 * @param e
	 */
	public static void error(String message, Throwable e) {
		handleError(message, e, false);
	}

	/**
	 * Creates an error status
	 *
	 * @param message
	 *            a localized message
	 * @param throwable
	 * @return a new Status object
	 */
	public static IStatus createErrorStatus(String message, Throwable throwable) {
		return new Status(IStatus.ERROR, getPluginId(), message, throwable);
	}

	/**
	 * Creates an error status
	 *
	 * @param message
	 *            a localized message
	 * @return a new Status object
	 */
	public static IStatus createErrorStatus(String message) {
		return new Status(IStatus.ERROR, getPluginId(), message);
	}

	/**
	 * @return the {@link RepositoryUtil} instance
	 */
	public RepositoryUtil getRepositoryUtil() {
		return org.eclipse.egit.core.Activator.getDefault().getRepositoryUtil();
	}

}
