/*
 * Greenshot - a free and open source screenshot tool
 * Copyright (C) 2007-2014 Thomas Braun, Jens Klingen, Robin Krom
 * 
 * For more information see: http://getgreenshot.org/
 * The Greenshot project is hosted on Sourceforge: http://sourceforge.net/projects/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 GreenshotPlugin.UnmanagedHelpers;
using GreenshotPlugin.Core;

namespace Greenshot.Helpers {
	public class HookHelper {
		private static readonly log4net.ILog LOG = log4net.LogManager.GetLogger(typeof(HookHelper));
		private static List<IntPtr> hooks = new List<IntPtr>();
		private static WinEventDelegate _winEventProc;
		private static uint oleEventThread = 0;

		/// <summary>
		/// Remove the made hooks
		/// </summary>
		public static void Unhook() {
			LOG.Debug("Cleaning winEvent hooks");
			foreach (IntPtr hook in hooks) {
				if (hook != IntPtr.Zero) {
					User32.UnhookWinEvent(hook);
				}
			}
		}

		/// <summary>
		/// Hook the WinEvents we are interested in
		/// </summary>
		public static void Hook() {
			LOG.Debug("Starting winEvent hooks");
			_winEventProc = new WinEventDelegate(WinEventProc);
			int processID = 0; //Process.GetCurrentProcess().Id;
			hooks.Add(User32.SetWinEventHook(WinEvent.EVENT_OBJECT_CREATE, WinEvent.EVENT_OBJECT_HIDE, IntPtr.Zero, _winEventProc, processID, 0, WinEventHookFlags.WINEVENT_SKIPOWNPROCESS));
			hooks.Add(User32.SetWinEventHook(WinEvent.EVENT_OBJECT_LOCATIONCHANGE, WinEvent.EVENT_OBJECT_LOCATIONCHANGE, IntPtr.Zero, _winEventProc, 0, 0, WinEventHookFlags.WINEVENT_SKIPOWNPROCESS));
			hooks.Add(User32.SetWinEventHook(WinEvent.EVENT_SYSTEM_MENUSTART, WinEvent.EVENT_SYSTEM_MENUPOPUPEND, IntPtr.Zero, _winEventProc, processID, 0, WinEventHookFlags.WINEVENT_SKIPOWNPROCESS));
		}

		/// <summary>
		/// Handle the WinEvent
		/// </summary>
		/// <param name="hWinEventHook">The Hook IntPtr</param>
		/// <param name="eventType">Event Type to handle, enum WinEvent</param>
		/// <param name="hwnd">Window handle which caused the event</param>
		/// <param name="idObject">Object ID, enum EventObjects</param>
		/// <param name="idChild">Child ID of the window</param>
		/// <param name="dwEventThread">Thread which generated the ID</param>
		/// <param name="dwmsEventTime"></param>
		private static void WinEventProc(IntPtr hWinEventHook, WinEvent eventType, IntPtr hwnd, EventObjects idObject, int idChild, uint dwEventThread, uint dwmsEventTime) {
			// Check if it's an event generated by a Window
			if (hwnd == IntPtr.Zero || idObject != EventObjects.OBJID_WINDOW) {
				// Other events do not interest us.
				return;
			}
			String classname = null;
			// Check if the event was generated by the OLE Event Thread, which causes a lot of create/destroy
			if (oleEventThread != 0 && dwEventThread == oleEventThread) {
				return;
			}

			// Only get the classname when it's not a destroy (classname is not available)
			if (eventType == WinEvent.EVENT_OBJECT_CREATE) {
				classname = WindowDetails.GetClassName(hwnd);
				// Make sure the OleMainThreadWndClass events are ignored.
				if (oleEventThread == 0) {
					if (classname == "OleMainThreadWndClass") {
						oleEventThread = dwEventThread;
						return;
					}
				}
			}
				
			LOG.DebugFormat("eventType={0},hwnd={1},classname={4},idObject={2},idChild={3},dwEventThread={5}", eventType, hwnd, idObject, idChild, classname, dwEventThread);
		}
	}
}