using System;
using System.Collections.Generic;
using System.Drawing;
using System.Runtime.InteropServices;

// The 'windowHandle' parameter will contain the window handle for the:
//   - Active window when run by hotkey
//   - Window Location target when run by a Window Location rule
//   - TitleBar Button owner when run by a TitleBar Button
//   - Jump List owner when run from a Taskbar Jump List
//   - Currently focused window if none of these match
public static class DisplayFusionFunction
{
	[DllImport("user32.dll", SetLastError = true)]
	static extern IntPtr GetWindow(IntPtr hWnd, uint uCmd);
	
	//some constants
	const uint GW_HWNDNEXT = 2;

	public static void Run(IntPtr windowHandle)
	{
        BFS.Window.Focus(GetWindowByZOrder(2));
	}
	
	private static IntPtr GetWindowByZOrder(uint zOrder)
	{
		if(zOrder == 1)
			return BFS.Window.GetFocusedWindow();

		//get the visible window handles for that monitor
		HashSet<IntPtr> visibleWindows = new HashSet<IntPtr>( BFS.Window.GetVisibleWindowHandles() );

		//enumerate through the monitors, starting with the focused window, and moving down
		//only enumerate if we havn't found the windows yet
		IntPtr topmost = BFS.Window.GetFocusedWindow();
		int lastZOrderFound = 1;
		for (IntPtr window = GetWindow(topmost, GW_HWNDNEXT); ; window = GetWindow(window, GW_HWNDNEXT))
		{
			//check to see if there are no windows left
			if(window == IntPtr.Zero)
				break;
				
            //check to see if the window is visible. if it's not, ignore it
			if(!visibleWindows.Contains(window))
                continue;
				
			//if it is a window we should ignore, ignore it
			if(IsDisplayFusionWindowOrHiddenExplorerWindow(window))
				continue;

			//this is a cantidate! increment the lastZOrderFound, and see if we're at the level we want
			lastZOrderFound++;
			if (lastZOrderFound != zOrder)
				continue;

			return window;
		}
	
        //return IntPtr.Zero if we didn't find anything
        return IntPtr.Zero;
	}
	
	private static bool IsDisplayFusionWindowOrHiddenExplorerWindow(IntPtr window)
	{
        //ignore any DisplayFusion windows (title bar buttons, etc.)
        //ignore pesky hidden explorer.exe windows
        if((BFS.Window.GetClass(window).StartsWith("DF", StringComparison.OrdinalIgnoreCase)) ||
            (BFS.Window.GetClass(window).Equals("EdgeUiInputTopWndClass", StringComparison.OrdinalIgnoreCase)) ||
            (BFS.Window.GetClass(window).Equals("EdgeUiInputWndClass", StringComparison.OrdinalIgnoreCase)) ||
            (BFS.Window.GetClass(window).Equals("NativeHWNDHost", StringComparison.OrdinalIgnoreCase)) ||
            (BFS.Window.GetClass(window).Equals("ModeInputWnd", StringComparison.OrdinalIgnoreCase)) ||
            (BFS.Window.GetClass(window).Equals("MetroGhostWindow", StringComparison.OrdinalIgnoreCase)) ||
            (BFS.Window.GetClass(window).Equals("ImmersiveLauncher", StringComparison.OrdinalIgnoreCase)) ||
            (BFS.Window.GetClass(window).Equals("ApplicationManager_ImmersiveShellWindow", StringComparison.OrdinalIgnoreCase)) ||
            (BFS.Window.GetClass(window).Equals("Shell_TrayWnd", StringComparison.OrdinalIgnoreCase)) ||
            (BFS.Window.GetClass(window).Equals("WorkerW", StringComparison.OrdinalIgnoreCase)) ||
            (BFS.Window.GetClass(window).Equals("Progman", StringComparison.OrdinalIgnoreCase)) ||
            (BFS.Window.GetClass(window).Equals("SearchPane", StringComparison.OrdinalIgnoreCase)) ||
            (BFS.Window.GetText(window).Equals("")))
        {
            return true;
        }
        
        return false;
	}
}