// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
// Description: Class used to track new UI appearing and make sure any events
// are propogated to that new UI.
 
using System;
using System.Windows.Automation;
using System.Diagnostics;
using MS.Win32;
 
namespace MS.Internal.Automation
{
    // WindowShowOrOpenTracker - Class used to track new UI appearing and make sure any events
    // are propogated to that new UI.
    internal delegate void WindowShowOrOpenHandler( IntPtr hwnd, AutomationElement rawEl );
 
    // Class used to track new UI appearing and make sure any events
    // are propogated to that new UI.
    internal class WindowShowOrOpenTracker : WinEventWrap
    {
        //------------------------------------------------------
        //
        //  Constructors
        //
        //------------------------------------------------------
 
        #region Constructors
 
        internal WindowShowOrOpenTracker(WindowShowOrOpenHandler newUIHandler)
            : base(new int[]
            {NativeMethods.EventObjectUIFragmentCreate, NativeMethods.EVENT_OBJECT_CREATE, NativeMethods.EVENT_OBJECT_SHOW}) 
        {
            AddCallback(newUIHandler);
        }
 
        #endregion Constructors
 
 
        //------------------------------------------------------
        //
        //  Internal Methods
        //
        //------------------------------------------------------
 
        #region Internal Methods
 
        internal override void WinEventProc(int eventId, IntPtr hwnd, int idObject, int idChild, uint eventTime)
        {
            // ignore any event not pertaining directly to the window
            if (idObject != UnsafeNativeMethods.OBJID_WINDOW)
                return;
 
            // Ignore if this is a bogus hwnd (shouldn't happen)
            if (hwnd == IntPtr.Zero)
                return;
 
            NativeMethods.HWND nativeHwnd = NativeMethods.HWND.Cast( hwnd );
 
            // Ignore windows that have been destroyed
            if (! SafeNativeMethods.IsWindow( nativeHwnd ))
                return;
 
            // Ignore invisible windows (IsWindowVisible takes the hwnd ancestor 
            // visibility into account)
            if (! SafeNativeMethods.IsWindowVisible( nativeHwnd ))
                return; 
 
            if (eventId == NativeMethods.EVENT_OBJECT_CREATE)
            {
                // Ignore WCP hwnd creates; we get eventId EventObjectUIFragmentCreate for those
                // Are these all the WCP classnames?  Is there a better way to ignore WCP windows?
                string str = ProxyManager.GetClassName(nativeHwnd);
                if (string.Compare(str, 0, _wcpClassName, 0, _wcpClassName.Length, StringComparison.OrdinalIgnoreCase) == 0)
                    return;
            }
 
            AutomationElement rawEl = AutomationElement.FromHandle( hwnd );
 
            // Do the notify.  Note that this handler is used to notify client-side UIAutomation providers of windows
            // being destroyed or hidden.  The delegate called here is itself protected by a lock.  This delegate may
            // call out to proxies but also calls ClientEventManager.RaiseEventInThisClientOnly which properly
            // queues the actual callout to client code.
            object [] handlers = GetHandlers();
            Debug.Assert(handlers.Length <= 1, "handlers.Length");
            if (handlers.Length > 0)
                ((WindowShowOrOpenHandler)handlers[0])( hwnd, rawEl );
        }
 
        #endregion Internal Methods
 
 
        //------------------------------------------------------
        //
        //  Private Fields
        //
        //------------------------------------------------------
 
        #region Private Fields
 
        private static readonly string _wcpClassName = "HwndWrapper";
 
        #endregion Private Fields
    }
}