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/*
 * Copyright (c) 1996, 2011, 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
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package java.awt;

import java.awt.event.InputEvent;
import java.awt.event.MouseEvent;
import java.awt.event.ActionEvent;
import java.awt.event.WindowEvent;
import java.lang.reflect.Method;
import java.security.AccessController;
import sun.security.action.GetPropertyAction;
import sun.awt.AWTAutoShutdown;
import sun.awt.SunToolkit;

import java.util.Vector;
import java.util.logging.*;

import sun.awt.dnd.SunDragSourceContextPeer;


EventDispatchThread is a package-private AWT class which takes
events off the EventQueue and dispatches them to the appropriate
AWT components.
The Thread starts a "permanent" event pump with a call to
pumpEvents(Conditional) in its run() method. Event handlers can choose to
block this event pump at any time, but should start a new pump (not
a new EventDispatchThread) by again calling pumpEvents(Conditional). This
secondary event pump will exit automatically as soon as the Condtional
evaluate()s to false and an additional Event is pumped and dispatched.

Author:Tom Ball, Amy Fowler, Fred Ecks, David Mendenhall
Since:1.1
/**
 * EventDispatchThread is a package-private AWT class which takes
 * events off the EventQueue and dispatches them to the appropriate
 * AWT components.
 *
 * The Thread starts a "permanent" event pump with a call to
 * pumpEvents(Conditional) in its run() method. Event handlers can choose to
 * block this event pump at any time, but should start a new pump (<b>not</b>
 * a new EventDispatchThread) by again calling pumpEvents(Conditional). This
 * secondary event pump will exit automatically as soon as the Condtional
 * evaluate()s to false and an additional Event is pumped and dispatched.
 *
 * @author Tom Ball
 * @author Amy Fowler
 * @author Fred Ecks
 * @author David Mendenhall
 *
 * @since 1.1
 */
class EventDispatchThread extends Thread {
    private static final Logger eventLog = Logger.getLogger("java.awt.event.EventDispatchThread");

    private EventQueue theQueue;
    private boolean doDispatch = true;
    private static final int ANY_EVENT = -1;

    private Vector<EventFilter> eventFilters = new Vector<EventFilter>();
    // used in handleException
    private int modalFiltersCount = 0;

    EventDispatchThread(ThreadGroup group, String name, EventQueue queue) {
        super(group, name);
        theQueue = queue;
    }

    void stopDispatchingImpl(boolean wait) {
        // Note: We stop dispatching via a flag rather than using
        // Thread.interrupt() because we can't guarantee that the wait()
        // we interrupt will be EventQueue.getNextEvent()'s.  -fredx 8-11-98

        StopDispatchEvent stopEvent = new StopDispatchEvent();

        // wait for the dispatcher to complete
        if (Thread.currentThread() != this) {

            // fix 4122683, 4128923
            // Post an empty event to ensure getNextEvent is unblocked
            //
            // We have to use postEventPrivate instead of postEvent because
            // EventQueue.pop calls EventDispatchThread.stopDispatching.
            // Calling SunToolkit.flushPendingEvents in this case could
            // lead to deadlock.
            theQueue.postEventPrivate(stopEvent);

            if (wait) {
                try {
                    join();
                } catch(InterruptedException e) {
                }
            }
        } else {
            stopEvent.dispatch();
        }
        synchronized (theQueue) {
            if (theQueue.getDispatchThread() == this) {
                theQueue.detachDispatchThread();
            }
        }
    }

    public void stopDispatching() {
        stopDispatchingImpl(true);
    }

    public void stopDispatchingLater() {
        stopDispatchingImpl(false);
    }

    class StopDispatchEvent extends AWTEvent implements ActiveEvent {
        /*
         * serialVersionUID
         */
        static final long serialVersionUID = -3692158172100730735L;

        public StopDispatchEvent() {
            super(EventDispatchThread.this,0);
        }

        public void dispatch() {
            doDispatch = false;
        }
    }

    public void run() {
        try {
            pumpEvents(new Conditional() {
                public boolean evaluate() {
                    return true;
                }
            });
        } finally {
            /*
             * This synchronized block is to secure that the event dispatch
             * thread won't die in the middle of posting a new event to the
             * associated event queue. It is important because we notify
             * that the event dispatch thread is busy after posting a new event
             * to its queue, so the EventQueue.dispatchThread reference must
             * be valid at that point.
             */
            synchronized (theQueue) {
                if (theQueue.getDispatchThread() == this) {
                    theQueue.detachDispatchThread();
                }
                /*
                 * Event dispatch thread dies in case of an uncaught exception.
                 * A new event dispatch thread for this queue will be started
                 * only if a new event is posted to it. In case if no more
                 * events are posted after this thread died all events that
                 * currently are in the queue will never be dispatched.
                 */
                /*
                 * Fix for 4648733. Check both the associated java event
                 * queue and the PostEventQueue.
                 */
                if (theQueue.peekEvent() != null ||
                    !SunToolkit.isPostEventQueueEmpty()) {
                    theQueue.initDispatchThread();
                }
                AWTAutoShutdown.getInstance().notifyThreadFree(this);
            }
        }
    }

    void pumpEvents(Conditional cond) {
        pumpEvents(ANY_EVENT, cond);
    }

    void pumpEventsForHierarchy(Conditional cond, Component modalComponent) {
        pumpEventsForHierarchy(ANY_EVENT, cond, modalComponent);
    }

    void pumpEvents(int id, Conditional cond) {
        pumpEventsForHierarchy(id, cond, null);
    }

    void pumpEventsForHierarchy(int id, Conditional cond, Component modalComponent)
    {
        pumpEventsForFilter(id, cond, new HierarchyEventFilter(modalComponent));
    }

    void pumpEventsForFilter(Conditional cond, EventFilter filter) {
        pumpEventsForFilter(ANY_EVENT, cond, filter);
    }

    void pumpEventsForFilter(int id, Conditional cond, EventFilter filter) {
        addEventFilter(filter);
        while (doDispatch && cond.evaluate()) {
            if (isInterrupted() || !pumpOneEventForFilters(id)) {
                doDispatch = false;
            }
        }
        removeEventFilter(filter);
    }

    void addEventFilter(EventFilter filter) {
        if (eventLog.isLoggable(Level.FINEST)) {
            eventLog.finest("adding the event filter: " + filter);
        }
        synchronized (eventFilters) {
            if (!eventFilters.contains(filter)) {
                if (filter instanceof ModalEventFilter) {
                    ModalEventFilter newFilter = (ModalEventFilter)filter;
                    int k = 0;
                    for (k = 0; k < eventFilters.size(); k++) {
                        EventFilter f = eventFilters.get(k);
                        if (f instanceof ModalEventFilter) {
                            ModalEventFilter cf = (ModalEventFilter)f;
                            if (cf.compareTo(newFilter) > 0) {
                                break;
                            }
                        }
                    }
                    eventFilters.add(k, filter);
                    modalFiltersCount++;
                } else {
                    eventFilters.add(filter);
                }
            }
        }
    }

    void removeEventFilter(EventFilter filter) {
        if (eventLog.isLoggable(Level.FINEST)) {
            eventLog.finest("removing the event filter: " + filter);
        }
        synchronized (eventFilters) {
            if (eventFilters.contains(filter)) {
                if (filter instanceof ModalEventFilter) {
                    modalFiltersCount--;
                }
                eventFilters.remove(filter);
            }
        }
    }

    boolean pumpOneEventForFilters(int id) {
        try {
            AWTEvent event;
            boolean eventOK;
            do {
                event = (id == ANY_EVENT)
                    ? theQueue.getNextEvent()
                    : theQueue.getNextEvent(id);

                eventOK = true;
                synchronized (eventFilters) {
                    for (int i = eventFilters.size() - 1; i >= 0; i--) {
                        EventFilter f = eventFilters.get(i);
                        EventFilter.FilterAction accept = f.acceptEvent(event);
                        if (accept == EventFilter.FilterAction.REJECT) {
                            eventOK = false;
                            break;
                        } else if (accept == EventFilter.FilterAction.ACCEPT_IMMEDIATELY) {
                            break;
                        }
                    }
                }
                eventOK = eventOK && SunDragSourceContextPeer.checkEvent(event);
                if (!eventOK) {
                    event.consume();
                }
            }
            while (eventOK == false);

            if (eventLog.isLoggable(Level.FINEST)) {
                eventLog.log(Level.FINEST, "Dispatching: " + event);
            }

            theQueue.dispatchEvent(event);
            return true;
        }
        catch (ThreadDeath death) {
            return false;

        }
        catch (InterruptedException interruptedException) {
            return false; // AppContext.dispose() interrupts all
                          // Threads in the AppContext

        }
        catch (Throwable e) {
            processException(e, modalFiltersCount > 0);
        }
        return true;
    }

    private void processException(Throwable e, boolean isModal) {
        if (eventLog.isLoggable(Level.FINE)) {
            eventLog.log(Level.FINE, "Processing exception: " + e +
                                     ", isModal = " + isModal);
        }
        if (!handleException(e)) {
            // See bug ID 4499199.
            // If we are in a modal dialog, we cannot throw
            // an exception for the ThreadGroup to handle (as added
            // in RFE 4063022).  If we did, the message pump of
            // the modal dialog would be interrupted.
            // We instead choose to handle the exception ourselves.
            // It may be useful to add either a runtime flag or API
            // later if someone would like to instead dispose the
            // dialog and allow the thread group to handle it.
            if (isModal) {
                System.err.println(
                    "Exception occurred during event dispatching:");
                e.printStackTrace();
            } else if (e instanceof RuntimeException) {
                throw (RuntimeException)e;
            } else if (e instanceof Error) {
                throw (Error)e;
            }
        }
    }

    private static final String handlerPropName = "sun.awt.exception.handler";
    private static String handlerClassName = null;
    private static String NO_HANDLER = new String();

    
Handles an exception thrown in the event-dispatch thread.

 If the system property "sun.awt.exception.handler" is defined, then
when this method is invoked it will attempt to do the following:

    

  1.  Load the class named by the value of that property, using the
     current thread's context class loader,

  2.  Instantiate that class using its zero-argument constructor,

  3.  Find the resulting handler object's public void handle
     method, which should take a single argument of type
     Throwable, and

  4.  Invoke the handler's handle method, passing it the
     thrown argument that was passed to this method.


If any of the first three steps fail then this method will return
false and all following invocations of this method will return
false immediately.  An exception thrown by the handler object's
handle will be caught, and will cause this method to return
false.  If the handler's handle method is successfully
invoked, then this method will return true.  This method will
never throw any sort of exception.

 Note: This method is a temporary hack to work around the
absence of a real API that provides the ability to replace the
event-dispatch thread.  The magic "sun.awt.exception.handler" property
will be removed in a future release.

Params:
  • thrown –  The Throwable that was thrown in the event-dispatch
                thread
Returns: false if any of the above steps failed, otherwise
         true
/**
     * Handles an exception thrown in the event-dispatch thread.
     *
     * <p> If the system property "sun.awt.exception.handler" is defined, then
     * when this method is invoked it will attempt to do the following:
     *
     * <ol>
     * <li> Load the class named by the value of that property, using the
     *      current thread's context class loader,
     * <li> Instantiate that class using its zero-argument constructor,
     * <li> Find the resulting handler object's <tt>public void handle</tt>
     *      method, which should take a single argument of type
     *      <tt>Throwable</tt>, and
     * <li> Invoke the handler's <tt>handle</tt> method, passing it the
     *      <tt>thrown</tt> argument that was passed to this method.
     * </ol>
     *
     * If any of the first three steps fail then this method will return
     * <tt>false</tt> and all following invocations of this method will return
     * <tt>false</tt> immediately.  An exception thrown by the handler object's
     * <tt>handle</tt> will be caught, and will cause this method to return
     * <tt>false</tt>.  If the handler's <tt>handle</tt> method is successfully
     * invoked, then this method will return <tt>true</tt>.  This method will
     * never throw any sort of exception.
     *
     * <p> <i>Note:</i> This method is a temporary hack to work around the
     * absence of a real API that provides the ability to replace the
     * event-dispatch thread.  The magic "sun.awt.exception.handler" property
     * <i>will be removed</i> in a future release.
     *
     * @param  thrown  The Throwable that was thrown in the event-dispatch
     *                 thread
     *
     * @return  <tt>false</tt> if any of the above steps failed, otherwise
     *          <tt>true</tt>
     */
    private boolean handleException(Throwable thrown) {

        try {

            if (handlerClassName == NO_HANDLER) {
                return false;   /* Already tried, and failed */
            }

            /* Look up the class name */
            if (handlerClassName == null) {
                handlerClassName = ((String) AccessController.doPrivileged(
                    new GetPropertyAction(handlerPropName)));
                if (handlerClassName == null) {
                    handlerClassName = NO_HANDLER; /* Do not try this again */
                    return false;
                }
            }

            /* Load the class, instantiate it, and find its handle method */
            Method m;
            Object h;
            try {
                ClassLoader cl = Thread.currentThread().getContextClassLoader();
                Class c = Class.forName(handlerClassName, true, cl);
                m = c.getMethod("handle", new Class[] { Throwable.class });
                h = c.newInstance();
            } catch (Throwable x) {
                handlerClassName = NO_HANDLER; /* Do not try this again */
                return false;
            }

            /* Finally, invoke the handler */
            m.invoke(h, new Object[] { thrown });

        } catch (Throwable x) {
            return false;
        }

        return true;
    }

    boolean isDispatching(EventQueue eq) {
        return theQueue.equals(eq);
    }

    EventQueue getEventQueue() { return theQueue; }

    private static class HierarchyEventFilter implements EventFilter {
        private Component modalComponent;
        public HierarchyEventFilter(Component modalComponent) {
            this.modalComponent = modalComponent;
        }
        public FilterAction acceptEvent(AWTEvent event) {
            if (modalComponent != null) {
                int eventID = event.getID();
                boolean mouseEvent = (eventID >= MouseEvent.MOUSE_FIRST) &&
                                     (eventID <= MouseEvent.MOUSE_LAST);
                boolean actionEvent = (eventID >= ActionEvent.ACTION_FIRST) &&
                                      (eventID <= ActionEvent.ACTION_LAST);
                boolean windowClosingEvent = (eventID == WindowEvent.WINDOW_CLOSING);
                /*
                 * filter out MouseEvent and ActionEvent that's outside
                 * the modalComponent hierarchy.
                 * KeyEvent is handled by using enqueueKeyEvent
                 * in Dialog.show
                 */
                if (Component.isInstanceOf(modalComponent, "javax.swing.JInternalFrame")) {
                    /*
                     * Modal internal frames are handled separately. If event is
                     * for some component from another heavyweight than modalComp,
                     * it is accepted. If heavyweight is the same - we still accept
                     * event and perform further filtering in LightweightDispatcher
                     */
                    return windowClosingEvent ? FilterAction.REJECT : FilterAction.ACCEPT;
                }
                if (mouseEvent || actionEvent || windowClosingEvent) {
                    Object o = event.getSource();
                    if (o instanceof sun.awt.ModalExclude) {
                        // Exclude this object from modality and
                        // continue to pump it's events.
                        return FilterAction.ACCEPT;
                    } else if (o instanceof Component) {
                        Component c = (Component) o;
                        // 5.0u3 modal exclusion
                        boolean modalExcluded = false;
                        if (modalComponent instanceof Container) {
                            while (c != modalComponent && c != null) {
                                if ((c instanceof Window) &&
                                    (sun.awt.SunToolkit.isModalExcluded((Window)c))) {
                                    // Exclude this window and all its children from
                                    //  modality and continue to pump it's events.
                                    modalExcluded = true;
                                    break;
                                }
                                c = c.getParent();
                            }
                        }
                        if (!modalExcluded && (c != modalComponent)) {
                            return FilterAction.REJECT;
                        }
                    }
                }
            }
            return FilterAction.ACCEPT;
        }
    }
}