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

public static class DisplayFusionFunction
{
	[DllImport("user32.dll", SetLastError = true)]
	private static extern IntPtr GetWindow(IntPtr hWnd, uint uCmd);
	
	// Some constants
	const uint GW_HWNDNEXT = 2;
	
	public static void Run(IntPtr windowHandle)
	{
        // Set the monitor ID here
        uint monitorID = 401;
        
        // Find the topmost window on the next monitor
        IntPtr window = GetTopmostWindowOnMonitor(monitorID);
        
        // Focus the next window on the next monitor
        BFS.Window.Focus(window);
    }
	
	private static IntPtr GetTopmostWindowOnMonitor(uint id)
	{
        // Get the visible window handles for that monitor
        HashSet<IntPtr> visibleWindows = new HashSet<IntPtr>( BFS.Window.GetVisibleWindowHandlesByMonitor(id) );
	
        // Enumerate through the monitors, starting with the focused window, and moving down
		// Only enumerate if we havn't found the windows yet
		for(IntPtr window = BFS.Window.GetFocusedWindow(); ; 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;
			
			// Get the monitor this window is in
			uint monitor = BFS.Monitor.GetMonitorIDByWindow(window);
			
			// If the monitor isn't in our collection, get the next window
			if(id != monitor)
				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)))
        {
            return true;
        }
        
        return false;
	}
}