/*

 * Copyright (c) 1998, 2008, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.awt;

import java.awt.EventQueue;

import java.awt.Window;

import java.awt.SystemTray;

import java.awt.TrayIcon;

import java.awt.Toolkit;

import java.awt.GraphicsEnvironment;

import java.awt.event.InvocationEvent;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.util.Collections;

import java.util.HashMap;

import java.util.IdentityHashMap;

import java.util.Map;

import java.util.Set;

import java.util.HashSet;

import java.beans.PropertyChangeSupport;

import java.beans.PropertyChangeListener;

import sun.util.logging.PlatformLogger;

import java.util.concurrent.locks.Condition;

import java.util.concurrent.locks.Lock;

import java.util.concurrent.locks.ReentrantLock;

/**

 * The AppContext is a table referenced by ThreadGroup which stores

 * application service instances.  (If you are not writing an application

 * service, or don't know what one is, please do not use this class.)

 * The AppContext allows applet access to what would otherwise be

 * potentially dangerous services, such as the ability to peek at

 * EventQueues or change the look-and-feel of a Swing application.<p>

 *

 * Most application services use a singleton object to provide their

 * services, either as a default (such as getSystemEventQueue or

 * getDefaultToolkit) or as static methods with class data (System).

 * The AppContext works with the former method by extending the concept

 * of "default" to be ThreadGroup-specific.  Application services

 * lookup their singleton in the AppContext.<p>

 *

 * For example, here we have a Foo service, with its pre-AppContext

 * code:<p>

 * <code><pre>

 *    public class Foo {

 *        private static Foo defaultFoo = new Foo();

 *

 *        public static Foo getDefaultFoo() {

 *            return defaultFoo;

 *        }

 *

 *    ... Foo service methods

 *    }</pre></code><p>

 *

 * The problem with the above is that the Foo service is global in scope,

 * so that applets and other untrusted code can execute methods on the

 * single, shared Foo instance.  The Foo service therefore either needs

 * to block its use by untrusted code using a SecurityManager test, or

 * restrict its capabilities so that it doesn't matter if untrusted code

 * executes it.<p>

 *

 * Here's the Foo class written to use the AppContext:<p>

 * <code><pre>

 *    public class Foo {

 *        public static Foo getDefaultFoo() {

 *            Foo foo = (Foo)AppContext.getAppContext().get(Foo.class);

 *            if (foo == null) {

 *                foo = new Foo();

 *                getAppContext().put(Foo.class, foo);

 *            }

 *            return foo;

 *        }

 *

 *    ... Foo service methods

 *    }</pre></code><p>

 *

 * Since a separate AppContext can exist for each ThreadGroup, trusted

 * and untrusted code have access to different Foo instances.  This allows

 * untrusted code access to "system-wide" services -- the service remains

 * within the AppContext "sandbox".  For example, say a malicious applet

 * wants to peek all of the key events on the EventQueue to listen for

 * passwords; if separate EventQueues are used for each ThreadGroup

 * using AppContexts, the only key events that applet will be able to

 * listen to are its own.  A more reasonable applet request would be to

 * change the Swing default look-and-feel; with that default stored in

 * an AppContext, the applet's look-and-feel will change without

 * disrupting other applets or potentially the browser itself.<p>

 *

 * Because the AppContext is a facility for safely extending application

 * service support to applets, none of its methods may be blocked by a

 * a SecurityManager check in a valid Java implementation.  Applets may

 * therefore safely invoke any of its methods without worry of being

 * blocked.

 *

 * Note: If a SecurityManager is installed which derives from

 * sun.awt.AWTSecurityManager, it may override the

 * AWTSecurityManager.getAppContext() method to return the proper

 * AppContext based on the execution context, in the case where

 * the default ThreadGroup-based AppContext indexing would return

 * the main "system" AppContext.  For example, in an applet situation,

 * if a system thread calls into an applet, rather than returning the

 * main "system" AppContext (the one corresponding to the system thread),

 * an installed AWTSecurityManager may return the applet's AppContext

 * based on the execution context.

 *

 * @author  Thomas Ball

 * @author  Fred Ecks

 */

public final class AppContext {

    private static final PlatformLogger log = PlatformLogger.getLogger("sun.awt.AppContext");

    /* Since the contents of an AppContext are unique to each Java

     * session, this class should never be serialized. */

    /*

     * The key to put()/get() the Java EventQueue into/from the AppContext.

     */

    public static final Object EVENT_QUEUE_KEY = new StringBuffer("EventQueue");

    /*

     * The keys to store EventQueue push/pop lock and condition.

     */

    public final static Object EVENT_QUEUE_LOCK_KEY = new StringBuilder("EventQueue.Lock");

    public final static Object EVENT_QUEUE_COND_KEY = new StringBuilder("EventQueue.Condition");

    /* A map of AppContexts, referenced by ThreadGroup.

     */

    private static final Map<ThreadGroup, AppContext> threadGroup2appContext =

            Collections.synchronizedMap(new IdentityHashMap<ThreadGroup, AppContext>());

    /**

     * Returns a set containing all <code>AppContext</code>s.

     */

    public static Set<AppContext> getAppContexts() {

        synchronized (threadGroup2appContext) {

            return new HashSet<AppContext>(threadGroup2appContext.values());

        }

    }

    /* The main "system" AppContext, used by everything not otherwise

       contained in another AppContext.

     */

    private static volatile AppContext mainAppContext = null;

    /*

     * The hash map associated with this AppContext.  A private delegate

     * is used instead of subclassing HashMap so as to avoid all of

     * HashMap's potentially risky methods, such as clear(), elements(),

     * putAll(), etc.

     */

    private final Map<Object, Object> table = new HashMap<>();

    private final ThreadGroup threadGroup;

    /**

     * If any <code>PropertyChangeListeners</code> have been registered,

     * the <code>changeSupport</code> field describes them.

     *

     * @see #addPropertyChangeListener

     * @see #removePropertyChangeListener

     * @see #firePropertyChange

     */

    private PropertyChangeSupport changeSupport = null;

    public static final String DISPOSED_PROPERTY_NAME = "disposed";

    public static final String GUI_DISPOSED = "guidisposed";

    private volatile boolean isDisposed = false; // true if AppContext is disposed

    public boolean isDisposed() {

        return isDisposed;

    }

    static {

        // On the main Thread, we get the ThreadGroup, make a corresponding

        // AppContext, and instantiate the Java EventQueue.  This way, legacy

        // code is unaffected by the move to multiple AppContext ability.

        AccessController.doPrivileged(new PrivilegedAction<Void>() {

            public Void run() {

                ThreadGroup currentThreadGroup =

                        Thread.currentThread().getThreadGroup();

                ThreadGroup parentThreadGroup = currentThreadGroup.getParent();

                while (parentThreadGroup != null) {

                    // Find the root ThreadGroup to construct our main AppContext

                    currentThreadGroup = parentThreadGroup;

                    parentThreadGroup = currentThreadGroup.getParent();

                }

                mainAppContext = new AppContext(currentThreadGroup);

                numAppContexts = 1;

                return null;

            }

        });

    }

    /*

     * The total number of AppContexts, system-wide.  This number is

     * incremented at the beginning of the constructor, and decremented

     * at the end of dispose().  getAppContext() checks to see if this

     * number is 1.  If so, it returns the sole AppContext without

     * checking Thread.currentThread().

     */

    private static volatile int numAppContexts;

    /*

     * The context ClassLoader that was used to create this AppContext.

     */

    private final ClassLoader contextClassLoader;

    /**

     * Constructor for AppContext.  This method is <i>not</i> public,

     * nor should it ever be used as such.  The proper way to construct

     * an AppContext is through the use of SunToolkit.createNewAppContext.

     * A ThreadGroup is created for the new AppContext, a Thread is

     * created within that ThreadGroup, and that Thread calls

     * SunToolkit.createNewAppContext before calling anything else.

     * That creates both the new AppContext and its EventQueue.

     *

     * @param   threadGroup     The ThreadGroup for the new AppContext

     * @see     sun.awt.SunToolkit

     * @since   1.2

     */

    AppContext(ThreadGroup threadGroup) {

        numAppContexts++;

        this.threadGroup = threadGroup;

        threadGroup2appContext.put(threadGroup, this);

        this.contextClassLoader =

             AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {

                    public ClassLoader run() {

                        return Thread.currentThread().getContextClassLoader();

                    }

                });

        // Initialize push/pop lock and its condition to be used by all the

        // EventQueues within this AppContext

        Lock eventQueuePushPopLock = new ReentrantLock();

        put(EVENT_QUEUE_LOCK_KEY, eventQueuePushPopLock);

        Condition eventQueuePushPopCond = eventQueuePushPopLock.newCondition();

        put(EVENT_QUEUE_COND_KEY, eventQueuePushPopCond);

    }

    private static final ThreadLocal<AppContext> threadAppContext =

            new ThreadLocal<AppContext>();

    /**

     * Returns the appropriate AppContext for the caller,

     * as determined by its ThreadGroup.  If the main "system" AppContext

     * would be returned and there's an AWTSecurityManager installed, it

     * is called to get the proper AppContext based on the execution

     * context.

     *

     * @return  the AppContext for the caller.

     * @see     java.lang.ThreadGroup

     * @since   1.2

     */

    public final static AppContext getAppContext() {

        if (numAppContexts == 1)   // If there's only one system-wide,

            return mainAppContext; // return the main system AppContext.

        AppContext appContext = threadAppContext.get();

        if (null == appContext) {

            appContext = AccessController.doPrivileged(new PrivilegedAction<AppContext>()

            {

                public AppContext run() {

                    // Get the current ThreadGroup, and look for it and its

                    // parents in the hash from ThreadGroup to AppContext --

                    // it should be found, because we use createNewContext()

                    // when new AppContext objects are created.

                    ThreadGroup currentThreadGroup = Thread.currentThread().getThreadGroup();

                    ThreadGroup threadGroup = currentThreadGroup;

                    AppContext context = threadGroup2appContext.get(threadGroup);

                    while (context == null) {

                        threadGroup = threadGroup.getParent();

                        if (threadGroup == null) {

                            // If we get here, we're running under a ThreadGroup that

                            // has no AppContext associated with it.  This should never

                            // happen, because createNewContext() should be used by the

                            // toolkit to create the ThreadGroup that everything runs

                            // under.

                            throw new RuntimeException("Invalid ThreadGroup");

                        }

                        context = threadGroup2appContext.get(threadGroup);

                    }

                    // In case we did anything in the above while loop, we add

                    // all the intermediate ThreadGroups to threadGroup2appContext

                    // so we won't spin again.

                    for (ThreadGroup tg = currentThreadGroup; tg != threadGroup; tg = tg.getParent()) {

                        threadGroup2appContext.put(tg, context);

                    }

                    // Now we're done, so we cache the latest key/value pair.

                    // (we do this before checking with any AWTSecurityManager, so if

                    // this Thread equates with the main AppContext in the cache, it

                    // still will)

                    threadAppContext.set(context);

                    return context;

                }

            });

        }

        if (appContext == mainAppContext)  {

            // Before we return the main "system" AppContext, check to

            // see if there's an AWTSecurityManager installed.  If so,

            // allow it to choose the AppContext to return.

            SecurityManager securityManager = System.getSecurityManager();

            if ((securityManager != null) &&

                (securityManager instanceof AWTSecurityManager))

            {

                AWTSecurityManager awtSecMgr = (AWTSecurityManager)securityManager;

                AppContext secAppContext = awtSecMgr.getAppContext();

                if (secAppContext != null)  {

                    appContext = secAppContext; // Return what we're told

                }

            }

        }

        return appContext;

    }

    private long DISPOSAL_TIMEOUT = 5000;  // Default to 5-second timeout

                                           // for disposal of all Frames

                                           // (we wait for this time twice,

                                           // once for dispose(), and once

                                           // to clear the EventQueue).

    private long THREAD_INTERRUPT_TIMEOUT = 1000;

                            // Default to 1-second timeout for all

                            // interrupted Threads to exit, and another

                            // 1 second for all stopped Threads to die.

    /**

     * Disposes of this AppContext, all of its top-level Frames, and

     * all Threads and ThreadGroups contained within it.

     *

     * This method must be called from a Thread which is not contained

     * within this AppContext.

     *

     * @exception  IllegalThreadStateException  if the current thread is

     *                                    contained within this AppContext

     * @since      1.2

     */

    public void dispose() throws IllegalThreadStateException {

        // Check to be sure that the current Thread isn't in this AppContext

        if (this.threadGroup.parentOf(Thread.currentThread().getThreadGroup())) {

            throw new IllegalThreadStateException(

                "Current Thread is contained within AppContext to be disposed."

              );

        }

        synchronized(this) {

            if (this.isDisposed) {

                return; // If already disposed, bail.

            }

            this.isDisposed = true;

        }

        final PropertyChangeSupport changeSupport = this.changeSupport;

        if (changeSupport != null) {

            changeSupport.firePropertyChange(DISPOSED_PROPERTY_NAME, false, true);

        }

        // First, we post an InvocationEvent to be run on the

        // EventDispatchThread which disposes of all top-level Frames and TrayIcons

        final Object notificationLock = new Object();

        Runnable runnable = new Runnable() {

            public void run() {

                Window[] windowsToDispose = Window.getOwnerlessWindows();

                for (Window w : windowsToDispose) {

                    try {

                        w.dispose();

                    } catch (Throwable t) {

                        log.finer("exception occured while disposing app context", t);

                    }

                }

                AccessController.doPrivileged(new PrivilegedAction<Void>() {

                        public Void run() {

                            if (!GraphicsEnvironment.isHeadless() && SystemTray.isSupported())

                            {

                                SystemTray systemTray = SystemTray.getSystemTray();

                                TrayIcon[] trayIconsToDispose = systemTray.getTrayIcons();

                                for (TrayIcon ti : trayIconsToDispose) {

                                    systemTray.remove(ti);

                                }

                            }

                            return null;

                        }

                    });

                // Alert PropertyChangeListeners that the GUI has been disposed.

                if (changeSupport != null) {

                    changeSupport.firePropertyChange(GUI_DISPOSED, false, true);

                }

                synchronized(notificationLock) {

                    notificationLock.notifyAll(); // Notify caller that we're done

                }

            }

        };

        synchronized(notificationLock) {

            SunToolkit.postEvent(this,

                new InvocationEvent(Toolkit.getDefaultToolkit(), runnable));

            try {

                notificationLock.wait(DISPOSAL_TIMEOUT);

            } catch (InterruptedException e) { }

        }

        // Next, we post another InvocationEvent to the end of the

        // EventQueue.  When it's executed, we know we've executed all

        // events in the queue.

        runnable = new Runnable() { public void run() {

            synchronized(notificationLock) {

                notificationLock.notifyAll(); // Notify caller that we're done

            }

        } };

        synchronized(notificationLock) {

            SunToolkit.postEvent(this,

                new InvocationEvent(Toolkit.getDefaultToolkit(), runnable));

            try {

                notificationLock.wait(DISPOSAL_TIMEOUT);

            } catch (InterruptedException e) { }

        }

        // Next, we interrupt all Threads in the ThreadGroup

        this.threadGroup.interrupt();

            // Note, the EventDispatchThread we've interrupted may dump an

            // InterruptedException to the console here.  This needs to be

            // fixed in the EventDispatchThread, not here.

        // Next, we sleep 10ms at a time, waiting for all of the active

        // Threads in the ThreadGroup to exit.

        long startTime = System.currentTimeMillis();

        long endTime = startTime + THREAD_INTERRUPT_TIMEOUT;

        while ((this.threadGroup.activeCount() > 0) &&

               (System.currentTimeMillis() < endTime)) {

            try {

                Thread.sleep(10);

            } catch (InterruptedException e) { }

        }

        // Then, we stop any remaining Threads

        this.threadGroup.stop();

        // Next, we sleep 10ms at a time, waiting for all of the active

        // Threads in the ThreadGroup to die.

        startTime = System.currentTimeMillis();

        endTime = startTime + THREAD_INTERRUPT_TIMEOUT;

        while ((this.threadGroup.activeCount() > 0) &&

               (System.currentTimeMillis() < endTime)) {

            try {

                Thread.sleep(10);

            } catch (InterruptedException e) { }

        }

        // Next, we remove this and all subThreadGroups from threadGroup2appContext

        int numSubGroups = this.threadGroup.activeGroupCount();

        if (numSubGroups > 0) {

            ThreadGroup [] subGroups = new ThreadGroup[numSubGroups];

            numSubGroups = this.threadGroup.enumerate(subGroups);

            for (int subGroup = 0; subGroup < numSubGroups; subGroup++) {

                threadGroup2appContext.remove(subGroups[subGroup]);

            }

        }

        threadGroup2appContext.remove(this.threadGroup);

        threadAppContext.set(null);

        // Finally, we destroy the ThreadGroup entirely.

        try {

            this.threadGroup.destroy();

        } catch (IllegalThreadStateException e) {

            // Fired if not all the Threads died, ignore it and proceed

        }

        synchronized (table) {

            this.table.clear(); // Clear out the Hashtable to ease garbage collection

        }

        numAppContexts--;