using mshtml;

using SHDocVw;

using System;

using System.Runtime.InteropServices;

using System.Windows;

using System.Windows.Interop;

using static Microsoft.Uii.Csr.Win32API;


namespace WebIntegration {
	public class WebDriverHelper {

		#region "Interfaces' GUIDs"

		public static readonly Guid IID_IWebBrowserApp = new Guid("{0002DF05-0000-0000-C000-000000000046}");
		public static readonly Guid IID_IUnknown = new Guid("{00000000-0000-0000-C000-000000000046}");
		public static readonly Guid IID_IWebBrowser2 = new Guid("D30C1661-CDAF-11d0-8A3E-00C04FC9E26E");

		#endregion


		#region "IServiceProvide interface"

		[ComImport,
		ComVisible(true),
		Guid("6D5140C1-7436-11CE-8034-00AA006009FA"),
		InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
		public interface IServiceProvider {
			[return: MarshalAs(UnmanagedType.I4)]
			[PreserveSig]
			int QueryService(ref Guid guidService, ref Guid riid, [MarshalAs(UnmanagedType.Interface)] out object ppvObject);
		}

		#endregion


		private const string WindowMessage = "WM_HTML_GETOBJECT";

		public static IHTMLDocument2 GetIEObjFromHwnd(IntPtr targetHwnd, bool changeOwnershipToUSD = false, bool keepAlwaysOnTop = false) {
			IHTMLDocument2 retval = null;

			Application.Current.Dispatcher.Invoke(() => {
				var sendMessageResult = UIntPtr.Zero;
				var IID_IHTMLDocument = typeof(IHTMLDocument2).GUID;
				var aMssg = (uint)RegisterWindowMessage(WindowMessage);
				var childHwnd = Win32Helper.GetWindow(targetHwnd, GW_CHILD);
				var result = SendMessageTimeout(childHwnd, aMssg, UIntPtr.Zero, IntPtr.Zero,
												SendMessageTimeoutFlags.SMTO_ABORTIFHUNG,
												1000, out sendMessageResult);

				// Let's get underlying IHTMLDocument

				if (sendMessageResult != UIntPtr.Zero)
					retval = ObjectFromLresult(sendMessageResult, IID_IHTMLDocument, IntPtr.Zero) as IHTMLDocument2;

				// Do we need to change ownership of browser window/dialog

				if (changeOwnershipToUSD) {
					var usdHwnd = new WindowInteropHelper(Application.Current.MainWindow).Handle;
					Win32Helper.SetWindowLongPtr(targetHwnd, Win32Helper.GWL_HWNDPARENT, usdHwnd);
				}

				// Do we need to keep windows on top?

				if (keepAlwaysOnTop) {
					var onTopFlags = Win32Helper.SetWindowPosFlags.IgnoreMove | Win32Helper.SetWindowPosFlags.SwpNoSize;
					Win32Helper.SetWindowPos(targetHwnd, Win32Helper.HWND_TOPMOST, 0, 0, 0, 0, onTopFlags);
				}
			});

			return retval;
		}

		public static IWebBrowser2 GetBrowserFromHtmlWindow(IHTMLWindow2 window) {
			int hResult = 0;
			object refObject = null;
			IWebBrowser2 retval = null;
			var riid = IID_IWebBrowser2;
			var guid = IID_IWebBrowserApp;
			IServiceProvider svcProvider = null;

			if (window != null && (svcProvider = window as IServiceProvider) != null) {
				try {
					hResult = svcProvider.QueryService(ref guid, ref riid, out refObject);

					if (hResult == 0)
						retval = refObject as IWebBrowser2;
				} catch (Exception e) {
					// Safe to ignore. Just to protect ourselves from COM randomness

					var whatisit = e.Message;
				}
			}
			return retval;
		}
	}
}