/*

 * Copyright 1997-2008 Sun Microsystems, Inc.  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.  Sun designates this

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

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.awt.im;

import java.awt.AWTEvent;

import java.awt.AWTKeyStroke;

import java.awt.Component;

import java.awt.EventQueue;

import java.awt.Frame;

import java.awt.Rectangle;

import java.awt.Toolkit;

import java.awt.Window;

import java.awt.event.ComponentEvent;

import java.awt.event.ComponentListener;

import java.awt.event.FocusEvent;

import java.awt.event.InputEvent;

import java.awt.event.InputMethodEvent;

import java.awt.event.KeyEvent;

import java.awt.event.WindowEvent;

import java.awt.event.WindowListener;

import java.awt.im.InputMethodRequests;

import java.awt.im.spi.InputMethod;

import java.lang.Character.Subset;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.text.MessageFormat;

import java.util.HashMap;

import java.util.Iterator;

import java.util.Locale;

import java.util.prefs.BackingStoreException;

import java.util.prefs.Preferences;

import sun.awt.SunToolkit;

/**

 * This InputContext class contains parts of the implementation of

 * java.text.im.InputContext. These parts have been moved

 * here to avoid exposing protected members that are needed by the

 * subclass InputMethodContext.

 *

 * @see java.awt.im.InputContext

 * @author JavaSoft Asia/Pacific

 */

public class InputContext extends java.awt.im.InputContext

                          implements ComponentListener, WindowListener {

    // The current input method is represented by two objects:

    // a locator is used to keep information about the selected

    // input method and locale until we actually need a real input

    // method; only then the input method itself is created.

    // Once there is an input method, the input method's locale

    // takes precedence over locale information in the locator.

    private InputMethodLocator inputMethodLocator;

    private InputMethod inputMethod;

    private boolean inputMethodCreationFailed;

    // holding bin for previously used input method instances, but not the current one

    private HashMap usedInputMethods;

    // the current client component is kept until the user focusses on a different

    // client component served by the same input context. When that happens, we call

    // endComposition so that text doesn't jump from one component to another.

    private Component currentClientComponent;

    private Component awtFocussedComponent;

    private boolean   isInputMethodActive;

    private Subset[]  characterSubsets = null;

    // true if composition area has been set to invisible when focus was lost

    private boolean compositionAreaHidden = false;

    // The input context for whose input method we may have to call hideWindows

    private static InputContext inputMethodWindowContext;

    // Previously active input method to decide whether we need to call

    // InputMethodAdapter.stopListening() on activateInputMethod()

    private static InputMethod previousInputMethod = null;

    // true if the current input method requires client window change notification

    private boolean clientWindowNotificationEnabled = false;

    // client window to which this input context is listening

    private Window clientWindowListened;

    // cache location notification

    private Rectangle clientWindowLocation = null;

    // holding the state of clientWindowNotificationEnabled of only non-current input methods

    private HashMap perInputMethodState;

    // Input Method selection hot key stuff

    private static AWTKeyStroke inputMethodSelectionKey;

    private static boolean inputMethodSelectionKeyInitialized = false;

    private static final String inputMethodSelectionKeyPath = "/java/awt/im/selectionKey";

    private static final String inputMethodSelectionKeyCodeName = "keyCode";

    private static final String inputMethodSelectionKeyModifiersName = "modifiers";

    /**

     * Constructs an InputContext.

     */

    protected InputContext() {

        InputMethodManager imm = InputMethodManager.getInstance();

        synchronized (InputContext.class) {

            if (!inputMethodSelectionKeyInitialized) {

                inputMethodSelectionKeyInitialized = true;

                if (imm.hasMultipleInputMethods()) {

                    initializeInputMethodSelectionKey();

                }

            }

        }

        selectInputMethod(imm.getDefaultKeyboardLocale());

    }

    /**

     * @see java.awt.im.InputContext#selectInputMethod

     * @exception NullPointerException when the locale is null.

     */

    public synchronized boolean selectInputMethod(Locale locale) {

        if (locale == null) {

            throw new NullPointerException();

        }

        // see whether the current input method supports the locale

        if (inputMethod != null) {

            if (inputMethod.setLocale(locale)) {

                return true;

            }

        } else if (inputMethodLocator != null) {

            // This is not 100% correct, since the input method

            // may support the locale without advertising it.

            // But before we try instantiations and setLocale,

            // we look for an input method that's more confident.

            if (inputMethodLocator.isLocaleAvailable(locale)) {

                inputMethodLocator = inputMethodLocator.deriveLocator(locale);

                return true;

            }

        }

        // see whether there's some other input method that supports the locale

        InputMethodLocator newLocator = InputMethodManager.getInstance().findInputMethod(locale);

        if (newLocator != null) {

            changeInputMethod(newLocator);

            return true;

        }

        // make one last desperate effort with the current input method

        // ??? is this good? This is pretty high cost for something that's likely to fail.

        if (inputMethod == null && inputMethodLocator != null) {

            inputMethod = getInputMethod();

            if (inputMethod != null) {

                return inputMethod.setLocale(locale);

            }

        }

        return false;

    }

    /**

     * @see java.awt.im.InputContext#getLocale

     */

    public Locale getLocale() {

        if (inputMethod != null) {

            return inputMethod.getLocale();

        } else if (inputMethodLocator != null) {

            return inputMethodLocator.getLocale();

        } else {

            return null;

        }

    }

    /**

     * @see java.awt.im.InputContext#setCharacterSubsets

     */

    public void setCharacterSubsets(Subset[] subsets) {

        if (subsets == null) {

            characterSubsets = null;

        } else {

            characterSubsets = new Subset[subsets.length];

            System.arraycopy(subsets, 0,

                             characterSubsets, 0, characterSubsets.length);

        }

        if (inputMethod != null) {

            inputMethod.setCharacterSubsets(subsets);

        }

    }

    /**

     * @see java.awt.im.InputContext#reconvert

     * @since 1.3

     * @exception UnsupportedOperationException when input method is null

     */

    public synchronized void reconvert() {

        InputMethod inputMethod = getInputMethod();

        if (inputMethod == null) {

            throw new UnsupportedOperationException();

        }

        inputMethod.reconvert();

    }

    /**

     * @see java.awt.im.InputContext#dispatchEvent

     */

    public void dispatchEvent(AWTEvent event) {

        if (event instanceof InputMethodEvent) {

            return;

        }

        // Ignore focus events that relate to the InputMethodWindow of this context.

        // This is a workaround.  Should be removed after 4452384 is fixed.

        if (event instanceof FocusEvent) {

            Component opposite = ((FocusEvent)event).getOppositeComponent();

            if ((opposite != null) &&

                (getComponentWindow(opposite) instanceof InputMethodWindow) &&

                (opposite.getInputContext() == this)) {

                return;

            }

        }

        InputMethod inputMethod = getInputMethod();

        int id = event.getID();

        switch (id) {

        case FocusEvent.FOCUS_GAINED:

            focusGained((Component) event.getSource());

            break;

        case FocusEvent.FOCUS_LOST:

            focusLost((Component) event.getSource(), ((FocusEvent) event).isTemporary());

            break;

        case KeyEvent.KEY_PRESSED:

            if (checkInputMethodSelectionKey((KeyEvent)event)) {

                // pop up the input method selection menu

                InputMethodManager.getInstance().notifyChangeRequestByHotKey((Component)event.getSource());

                break;

            }

            // fall through

        default:

            if ((inputMethod != null) && (event instanceof InputEvent)) {

                inputMethod.dispatchEvent(event);

            }

        }

    }

    /**

     * Handles focus gained events for any component that's using

     * this input context.

     * These events are generated by AWT when the keyboard focus

     * moves to a component.

     * Besides actual client components, the source components

     * may also be the composition area or any component in an

     * input method window.

     * <p>

     * When handling the focus event for a client component, this

     * method checks whether the input context was previously

     * active for a different client component, and if so, calls

     * endComposition for the previous client component.

     *

     * @param source the component gaining the focus

     */

    private void focusGained(Component source) {

        /*

         * NOTE: When a Container is removing its Component which

         * invokes this.removeNotify(), the Container has the global

         * Component lock. It is possible to happen that an

         * application thread is calling this.removeNotify() while an

         * AWT event queue thread is dispatching a focus event via

         * this.dispatchEvent(). If an input method uses AWT

         * components (e.g., IIIMP status window), it causes deadlock,

         * for example, Component.show()/hide() in this situation

         * because hide/show tried to obtain the lock.  Therefore,

         * it's necessary to obtain the global Component lock before

         * activating or deactivating an input method.

         */

        synchronized (source.getTreeLock()) {

            synchronized (this) {

                if ("sun.awt.im.CompositionArea".equals(source.getClass().getName())) {

                    // no special handling for this one

                } else if (getComponentWindow(source) instanceof InputMethodWindow) {

                    // no special handling for this one either

                } else {

                    if (!source.isDisplayable()) {

                        // Component is being disposed

                        return;

                    }

                    // Focus went to a real client component.

                    // Check whether we're switching between client components

                    // that share an input context. We can't do that earlier

                    // than here because we don't want to end composition

                    // until we really know we're switching to a different component

                    if (inputMethod != null) {

                        if (currentClientComponent != null && currentClientComponent != source) {

                            if (!isInputMethodActive) {

                                activateInputMethod(false);

                            }

                            endComposition();

                            deactivateInputMethod(false);

                        }

                    }

                    currentClientComponent = source;

                }

                awtFocussedComponent = source;

                if (inputMethod instanceof InputMethodAdapter) {

                    ((InputMethodAdapter) inputMethod).setAWTFocussedComponent(source);

                }

                // it's possible that the input method is still active because

                // we suppressed a deactivate cause by an input method window

                // coming up

                if (!isInputMethodActive) {

                    activateInputMethod(true);

                }

                // If the client component is an active client with the below-the-spot

                // input style, then make the composition window undecorated without a title bar.

                InputMethodContext inputContext = ((InputMethodContext)this);

                if (!inputContext.isCompositionAreaVisible()) {

                      InputMethodRequests req = source.getInputMethodRequests();

                      if (req != null && inputContext.useBelowTheSpotInput()) {

                          inputContext.setCompositionAreaUndecorated(true);

                      } else {

                          inputContext.setCompositionAreaUndecorated(false);

                      }

                }

                // restores the composition area if it was set to invisible

                // when focus got lost

                if (compositionAreaHidden == true) {

                    ((InputMethodContext)this).setCompositionAreaVisible(true);

                    compositionAreaHidden = false;

                }

            }

        }

    }

    /**

     * Activates the current input method of this input context, and grabs

     * the composition area for use by this input context.

     * If updateCompositionArea is true, the text in the composition area

     * is updated (set to false if the text is going to change immediately

     * to avoid screen flicker).

     */

    private void activateInputMethod(boolean updateCompositionArea) {

        // call hideWindows() if this input context uses a different

        // input method than the previously activated one

        if (inputMethodWindowContext != null && inputMethodWindowContext != this &&

                inputMethodWindowContext.inputMethodLocator != null &&

                !inputMethodWindowContext.inputMethodLocator.sameInputMethod(inputMethodLocator) &&

                inputMethodWindowContext.inputMethod != null) {

            inputMethodWindowContext.inputMethod.hideWindows();

        }

        inputMethodWindowContext = this;

        if (inputMethod != null) {

            if (previousInputMethod != inputMethod &&

                    previousInputMethod instanceof InputMethodAdapter) {

                // let the host adapter pass through the input events for the

                // new input method

                ((InputMethodAdapter) previousInputMethod).stopListening();

            }

            previousInputMethod = null;

            if (inputMethod instanceof InputMethodAdapter) {

                ((InputMethodAdapter) inputMethod).setClientComponent(currentClientComponent);

            }

            inputMethod.activate();

            isInputMethodActive = true;

            if (perInputMethodState != null) {

                Boolean state = (Boolean) perInputMethodState.remove(inputMethod);

                if (state != null) {

                    clientWindowNotificationEnabled = state.booleanValue();

                }

            }

            if (clientWindowNotificationEnabled) {

                if (!addedClientWindowListeners()) {

                    addClientWindowListeners();

                }

                synchronized(this) {

                    if (clientWindowListened != null) {

                        notifyClientWindowChange(clientWindowListened);

                    }

                }

            } else {

                if (addedClientWindowListeners()) {

                    removeClientWindowListeners();

                }

            }

        }

        InputMethodManager.getInstance().setInputContext(this);

        ((InputMethodContext) this).grabCompositionArea(updateCompositionArea);

    }

    static Window getComponentWindow(Component component) {

        while (true) {

            if (component == null) {

                return null;

            } else if (component instanceof Window) {

                return (Window) component;

            } else {

                component = component.getParent();

            }

        }

    }

    /**

     * Handles focus lost events for any component that's using

     * this input context.

     * These events are generated by AWT when the keyboard focus

     * moves away from a component.

     * Besides actual client components, the source components

     * may also be the composition area or any component in an

     * input method window.

     *

     * @param source the component losing the focus

     * @isTemporary whether the focus change is temporary

     */

    private void focusLost(Component source, boolean isTemporary) {

        // see the note on synchronization in focusGained

        synchronized (source.getTreeLock()) {

            synchronized (this) {

                // We need to suppress deactivation if removeNotify has been called earlier.

                // This is indicated by isInputMethodActive == false.

                if (isInputMethodActive) {

                    deactivateInputMethod(isTemporary);

                }

                awtFocussedComponent = null;

                if (inputMethod instanceof InputMethodAdapter) {

                    ((InputMethodAdapter) inputMethod).setAWTFocussedComponent(null);

                }

                // hides the composition area if currently it is visible

                InputMethodContext inputContext = ((InputMethodContext)this);

                if (inputContext.isCompositionAreaVisible()) {

                    inputContext.setCompositionAreaVisible(false);

                    compositionAreaHidden = true;

                }

            }

        }

    }

    /**

     * Checks the key event is the input method selection key or not.

     */

    private boolean checkInputMethodSelectionKey(KeyEvent event) {

        if (inputMethodSelectionKey != null) {

            AWTKeyStroke aKeyStroke = AWTKeyStroke.getAWTKeyStrokeForEvent(event);

            return inputMethodSelectionKey.equals(aKeyStroke);

        } else {

            return false;

        }

    }

    private void deactivateInputMethod(boolean isTemporary) {

        InputMethodManager.getInstance().setInputContext(null);

        if (inputMethod != null) {

            isInputMethodActive = false;

            inputMethod.deactivate(isTemporary);

            previousInputMethod = inputMethod;

        }

    }

    /**

     * Switches from the current input method to the one described by newLocator.

     * The current input method, if any, is asked to end composition, deactivated,

     * and saved for future use. The newLocator is made the current locator. If

     * the input context is active, an input method instance for the new locator

     * is obtained; otherwise this is deferred until required.

     */

    synchronized void changeInputMethod(InputMethodLocator newLocator) {

        // If we don't have a locator yet, this must be a new input context.

        // If we created a new input method here, we might get into an

        // infinite loop: create input method -> create some input method window ->

        // create new input context -> add input context to input method manager's context list ->

        // call changeInputMethod on it.

        // So, just record the locator. dispatchEvent will create the input method when needed.

        if (inputMethodLocator == null) {

            inputMethodLocator = newLocator;

            inputMethodCreationFailed = false;

            return;

        }

        // If the same input method is specified, just keep it.

        // Adjust the locale if necessary.

        if (inputMethodLocator.sameInputMethod(newLocator)) {

            Locale newLocale = newLocator.getLocale();

            if (newLocale != null && inputMethodLocator.getLocale() != newLocale) {

                if (inputMethod != null) {

                    inputMethod.setLocale(newLocale);

                }

                inputMethodLocator = newLocator;

            }

            return;

        }

        // Switch out the old input method