/*******************************************************************************
 * Copyright (c) 2000, 2008 IBM Corporation and others.
 * 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
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 * Port to the D programming language:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module dwt.accessibility.Accessible;

import dwt.accessibility.AccessibleListener;
import dwt.accessibility.AccessibleTextListener;
import dwt.accessibility.AccessibleControlListener;
import dwt.accessibility.AccessibleControlListener;
import dwt.accessibility.AccessibleFactory;
import dwt.accessibility.AccessibleObject;
import tango.core.Thread;
import dwt.DWT;
//import dwt.events.*;
import dwt.internal.gtk.OS;
import dwt.widgets.Control;
import tango.core.Array;
import dwt.events.DisposeListener;
import dwt.events.DisposeEvent;

/**
 * Instances of this class provide a bridge between application
 * code and assistive technology clients. Many platforms provide
 * default accessible behavior for most widgets, and this class
 * allows that default behavior to be overridden. Applications
 * can get the default Accessible object for a control by sending
 * it <code>getAccessible</code>, and then add an accessible listener
 * to override simple items like the name and help string, or they
 * can add an accessible control listener to override complex items.
 * As a rule of thumb, an application would only want to use the
 * accessible control listener to implement accessibility for a
 * custom control.
 *
 * @see Control#getAccessible
 * @see AccessibleListener
 * @see AccessibleEvent
 * @see AccessibleControlListener
 * @see AccessibleControlEvent
 * @see <a href="http://www.eclipse.org/swt/snippets/#accessibility">Accessibility snippets</a>
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 *
 * @since 2.0
 */
public class Accessible {
    AccessibleListener[] accessibleListeners;
    AccessibleControlListener[] controlListeners;
    AccessibleTextListener[] textListeners;
    AccessibleObject accessibleObject;
    Control control;

    this (Control control) {
        this.control = control;
        AccessibleFactory.registerAccessible (this);
        control.addDisposeListener (new class () DisposeListener {
            public void widgetDisposed (DisposeEvent e) {
                release ();
            }
        });
    }

    /**
     * Adds the listener to the collection of listeners who will
     * be notified when an accessible client asks for certain strings,
     * such as name, description, help, or keyboard shortcut. The
     * listener is notified by sending it one of the messages defined
     * in the <code>AccessibleListener</code> interface.
     *
     * @param listener the listener that should be notified when the receiver
     * is asked for a name, description, help, or keyboard shortcut string
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
     * </ul>
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @see AccessibleListener
     * @see #removeAccessibleListener
     */
    public void addAccessibleListener (AccessibleListener listener) {
        checkWidget ();
        if (listener is null) DWT.error (DWT.ERROR_NULL_ARGUMENT);
        accessibleListeners ~= listener;
    }

    /**
     * Adds the listener to the collection of listeners who will
     * be notified when an accessible client asks for custom control
     * specific information. The listener is notified by sending it
     * one of the messages defined in the <code>AccessibleControlListener</code>
     * interface.
     *
     * @param listener the listener that should be notified when the receiver
     * is asked for custom control specific information
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
     * </ul>
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @see AccessibleControlListener
     * @see #removeAccessibleControlListener
     */
    public void addAccessibleControlListener (AccessibleControlListener listener) {
        checkWidget ();
        if (listener is null) DWT.error (DWT.ERROR_NULL_ARGUMENT);
        controlListeners ~= listener;
    }

    /**
     * Adds the listener to the collection of listeners who will
     * be notified when an accessible client asks for custom text control
     * specific information. The listener is notified by sending it
     * one of the messages defined in the <code>AccessibleTextListener</code>
     * interface.
     *
     * @param listener the listener that should be notified when the receiver
     * is asked for custom text control specific information
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
     * </ul>
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @see AccessibleTextListener
     * @see #removeAccessibleTextListener
     *
     * @since 3.0
     */
    public void addAccessibleTextListener (AccessibleTextListener listener) {
        checkWidget ();
        if (listener is null) DWT.error (DWT.ERROR_NULL_ARGUMENT);
        textListeners ~= listener;
    }

    /**
     * Returns the control for this Accessible object.
     *
     * @return the receiver's control
     * @since 3.0
     */
    public Control getControl() {
        return control;
    }

    /* checkWidget was copied from Widget, and rewritten to work in this package */
    void checkWidget () {
        if (!isValidThread ()) DWT.error (DWT.ERROR_THREAD_INVALID_ACCESS);
        if (control.isDisposed ()) DWT.error (DWT.ERROR_WIDGET_DISPOSED);
    }

    AccessibleListener[] getAccessibleListeners () {
        if (accessibleListeners.length is 0 ) return null;
        return accessibleListeners.dup;
    }

    GtkWidget* getControlHandle () {
        return control.handle;
    }

    AccessibleControlListener[] getControlListeners () {
        if (controlListeners.length is 0) return null;
        return controlListeners.dup;
    }

    AccessibleTextListener[] getTextListeners () {
        if (textListeners.length is 0) return null;
        return textListeners.dup;
    }

    /**
     * Invokes platform specific functionality to allocate a new accessible object.
     * <p>
     * <b>IMPORTANT:</b> This method is <em>not</em> part of the public
     * API for <code>Accessible</code>. It is marked public only so that it
     * can be shared within the packages provided by DWT. It is not
     * available on all platforms, and should never be called from
     * application code.
     * </p>
     *
     * @param control the control to get the accessible object for
     * @return the platform specific accessible object
     */
    public static Accessible internal_new_Accessible (Control control) {
        return new Accessible (control);
    }

    /* isValidThread was copied from Widget, and rewritten to work in this package */
    bool isValidThread () {
        return control.getDisplay ().getThread () is Thread.getThis ();
    }

    void release () {
        AccessibleFactory.unregisterAccessible (/*Accessible.*/this);
        if (accessibleObject !is null) {
            accessibleObject.release ();
            accessibleObject = null;
        }
        accessibleListeners = null;
        controlListeners = null;
        textListeners = null;
    }
    /**
     * Removes the listener from the collection of listeners who will
     * be notified when an accessible client asks for custom control
     * specific information.
     *
     * @param listener the listener that should no longer be notified when the receiver
     * is asked for custom control specific information
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
     * </ul>
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @see AccessibleControlListener
     * @see #addAccessibleControlListener
     */
    public void removeAccessibleControlListener (AccessibleControlListener listener) {
        checkWidget ();
        if (listener is null) DWT.error (DWT.ERROR_NULL_ARGUMENT);
        controlListeners.length = remove( controlListeners, listener, delegate bool(AccessibleControlListener a1, AccessibleControlListener a2 ){ return a1 is a2; });
    }

    /**
     * Removes the listener from the collection of listeners who will
     * be notified when an accessible client asks for certain strings,
     * such as name, description, help, or keyboard shortcut.
     *
     * @param listener the listener that should no longer be notified when the receiver
     * is asked for a name, description, help, or keyboard shortcut string
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
     * </ul>
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @see AccessibleListener
     * @see #addAccessibleListener
     */
    public void removeAccessibleListener (AccessibleListener listener) {
        checkWidget ();
        if (listener is null) DWT.error (DWT.ERROR_NULL_ARGUMENT);
        accessibleListeners.length = remove( accessibleListeners, listener, delegate bool( AccessibleListener a1, AccessibleListener a2 ){ return a1 is a2; });
    }

    /**
     * Removes the listener from the collection of listeners who will
     * be notified when an accessible client asks for custom text control
     * specific information.
     *
     * @param listener the listener that should no longer be notified when the receiver
     * is asked for custom text control specific information
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
     * </ul>
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @see AccessibleTextListener
     * @see #addAccessibleTextListener
     *
     * @since 3.0
     */
    public void removeAccessibleTextListener (AccessibleTextListener listener) {
        checkWidget ();
        if (listener is null) DWT.error (DWT.ERROR_NULL_ARGUMENT);
        textListeners.length = remove( textListeners, listener, delegate bool(AccessibleTextListener a1, AccessibleTextListener a2 ){ return a1 is a2; });
    }

    /**
     * Sends a message to accessible clients that the child selection
     * within a custom container control has changed.
     *
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @since 3.0
     */
    public void selectionChanged () {
        checkWidget ();
        if (accessibleObject !is null) {
            accessibleObject.selectionChanged ();
        }
    }

    /**
     * Sends a message to accessible clients indicating that the focus
     * has changed within a custom control.
     *
     * @param childID an identifier specifying a child of the control
     *
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     */
    public void setFocus (int childID) {
        checkWidget ();
        if (accessibleObject !is null) {
            accessibleObject.setFocus (childID);
        }
    }

    /**
     * Sends a message to accessible clients that the text
     * caret has moved within a custom control.
     *
     * @param index the new caret index within the control
     *
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @since 3.0
     */
    public void textCaretMoved (int index) {
        checkWidget ();
        if (accessibleObject !is null) {
            accessibleObject.textCaretMoved (index);
        }
    }

    /**
     * Sends a message to accessible clients that the text
     * within a custom control has changed.
     *
     * @param type the type of change, one of <code>ACC.NOTIFY_TEXT_INSERT</code>
     * or <code>ACC.NOTIFY_TEXT_DELETE</code>
     * @param startIndex the text index within the control where the insertion or deletion begins
     * @param length the non-negative length in characters of the insertion or deletion
     *
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @see ACC#TEXT_INSERT
     * @see ACC#TEXT_DELETE
     *
     * @since 3.0
     */
    public void textChanged (int type, int startIndex, int length) {
        checkWidget ();
        if (accessibleObject !is null) {
            accessibleObject.textChanged (type, startIndex, length);
        }
    }

    /**
     * Sends a message to accessible clients that the text
     * selection has changed within a custom control.
     *
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @since 3.0
     */
    public void textSelectionChanged () {
        checkWidget ();
        if (accessibleObject !is null) {
            accessibleObject.textSelectionChanged ();
        }
    }
}