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)
	{
        // Get the current monitor ID
        uint currentMonitor = BFS.Monitor.GetMonitorIDByWindow(windowHandle);
        
        // Get all of the monitor IDs
        uint[] ids = BFS.Monitor.GetMonitorIDs();
        
        // Find where we are in the monitor ID array
        int index = -1;
        for(int i = 0; i < ids.Length; i++)
        {
            if(ids[i] != currentMonitor)
                continue;
                
            index = i;
            break;
        }
        
        // If we didn't find the index, exit the script
        if(index == -1)
            return;
            
        // Find the next monitor ID
        uint nextMonitorID = ids[++index % ids.Length];
        
        // Find the topmost window on the next monitor
        IntPtr window = GetTopmostWindowOnMonitor(nextMonitorID);
        
        // 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;
	}
}