/*
 * Greenshot - a free and open source screenshot tool
 * Copyright (C) 2007-2020 Thomas Braun, Jens Klingen, Robin Krom
 * 
 * For more information see: http://getgreenshot.org/
 * The Greenshot project is hosted on GitHub https://github.com/greenshot/greenshot
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 1 of the License, or
 * (at your option) any later version.
 * 
 * This program 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 for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

using System;
using System.Collections.Generic;
using System.IO;
using System.Reflection;
using log4net;
using Microsoft.Win32;

namespace GreenshotPlugin.Core {
	/// <summary>
	/// Description of IEHelper.
	/// </summary>
	public static class IEHelper {
		private static readonly ILog Log = LogManager.GetLogger(typeof(IEHelper));
		// Internet explorer Registry key
		private const string IeKey = @"Software\Microsoft\Internet Explorer";

		/// <summary>
		///     Get the current browser version
		/// </summary>
		/// <returns>int with browser version</returns>
		public static int IEVersion
		{
			get
			{
				var maxVer = 7;
				using (var ieKey = Registry.LocalMachine.OpenSubKey(IeKey, false))
				{
					foreach (var value in new[] { "svcVersion", "svcUpdateVersion", "Version", "W2kVersion" })
					{
						var objVal = ieKey.GetValue(value, "0");
						var strVal = Convert.ToString(objVal);

						var iPos = strVal.IndexOf('.');
						if (iPos > 0)
						{
							strVal = strVal.Substring(0, iPos);
						}

                        if (int.TryParse(strVal, out var res))
						{
							maxVer = Math.Max(maxVer, res);
						}
					}
				}

				return maxVer;
			}
		}

		/// <summary>
		///     Get the highest possible version for the embedded browser
		/// </summary>
		/// <param name="ignoreDoctype">true to ignore the doctype when loading a page</param>
		/// <returns>IE Feature</returns>
		public static int GetEmbVersion(bool ignoreDoctype = true)
		{
			var ieVersion = IEVersion;

			if (ieVersion > 9)
			{
				return ieVersion * 1000 + (ignoreDoctype ? 1 : 0);
			}

			if (ieVersion > 7)
			{
				return ieVersion * 1111;
			}

			return 7000;
		}

		/// <summary>
		///     Fix browser version to the highest possible
		/// </summary>
		/// <param name="ignoreDoctype">true to ignore the doctype when loading a page</param>
		public static void FixBrowserVersion(bool ignoreDoctype = true)
		{
			var applicationName = Path.GetFileNameWithoutExtension(Assembly.GetEntryAssembly().Location);
			FixBrowserVersion(applicationName, ignoreDoctype);
		}

		/// <summary>
		///     Fix the browser version for the specified application
		/// </summary>
		/// <param name="applicationName">Name of the process</param>
		/// <param name="ignoreDoctype">true to ignore the doctype when loading a page</param>
		public static void FixBrowserVersion(string applicationName, bool ignoreDoctype = true)
		{
			FixBrowserVersion(applicationName, GetEmbVersion(ignoreDoctype));
		}

		/// <summary>
		///     Fix the browser version for the specified application
		/// </summary>
		/// <param name="applicationName">Name of the process</param>
		/// <param name="ieVersion">
		///     Version, see
		///     <a href="https://msdn.microsoft.com/en-us/library/ee330730(v=vs.85).aspx#browser_emulation">Browser Emulation</a>
		/// </param>
		public static void FixBrowserVersion(string applicationName, int ieVersion)
		{
			ModifyRegistry("HKEY_CURRENT_USER", applicationName + ".exe", ieVersion);
#if DEBUG
			ModifyRegistry("HKEY_CURRENT_USER", applicationName + ".vshost.exe", ieVersion);
#endif
		}

		/// <summary>
		///     Make the change to the registry
		/// </summary>
		/// <param name="root">HKEY_CURRENT_USER or something</param>
		/// <param name="applicationName">Name of the executable</param>
		/// <param name="ieFeatureVersion">Version to use</param>
		private static void ModifyRegistry(string root, string applicationName, int ieFeatureVersion)
		{
			var regKey = root + @"\Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION";
			try
			{
				Registry.SetValue(regKey, applicationName, ieFeatureVersion);
			}
			catch (Exception ex)
			{
				// some config will hit access rights exceptions
				// this is why we try with both LOCAL_MACHINE and CURRENT_USER
				Log.Error(ex);
				Log.ErrorFormat("couldn't modify the registry key {0}", regKey);
			}
		}

		/// <summary>
		/// Find the DirectUI window for MSAA (Accessible)
		/// </summary>
		/// <param name="browserWindowDetails">The browser WindowDetails</param>
		/// <returns>WindowDetails for the DirectUI window</returns>
		public static WindowDetails GetDirectUI(WindowDetails browserWindowDetails) {
			if (browserWindowDetails == null) {
				return null;
			}
			WindowDetails tmpWd = browserWindowDetails;
			// Since IE 9 the TabBandClass is less deep!
			if (IEVersion < 9) {
				tmpWd = tmpWd.GetChild("CommandBarClass");
				tmpWd = tmpWd?.GetChild("ReBarWindow32");
			}
			tmpWd = tmpWd?.GetChild("TabBandClass");
			tmpWd = tmpWd?.GetChild("DirectUIHWND");
			return tmpWd;
		}
		
		/// <summary>
		/// Return an IEnumerable with the currently opened IE urls
		/// </summary>
		/// <returns></returns>
		public static IEnumerable<string> GetIEUrls() {
			// Find the IE window
			foreach (WindowDetails ieWindow in WindowDetails.GetAllWindows("IEFrame")) {
				WindowDetails directUIWD = GetDirectUI(ieWindow);
				if (directUIWD != null) {
					Accessible ieAccessible = new Accessible(directUIWD.Handle);
					foreach(string url in ieAccessible.IETabUrls)
					{
						yield return url;
					}
				}
			}
		}
	}
}