using System;
using System.Drawing;
using System.Windows.Forms;
using System.Threading;
using System.Collections.Generic;
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
{
    private static readonly string SettingName = "ActivlyDimUnfocusedMonitorsWhileWindowIsRunning_TransparentForm_Running";
	public static void Run(IntPtr windowHandle)
	{
		//toggle the setting from running to not running, and vice versa
		ToggleSetting();
		
		//check to see if we should exit
		bool isExiting = !IsTransparentWindowRunning();
				
		//if we are exiting, exit
		if(isExiting)
			return;
			
		//add forms for each monitor except the used one
		List<TransparentForm> forms = new List<TransparentForm>();
		foreach(uint id in BFS.Monitor.GetMonitorIDs())
		{
            if(BFS.Monitor.GetMonitorIDByWindow(windowHandle) == id)
                continue;
		
			forms.Add(new TransparentForm(0, id));
        }
				
		try
        {
            //this will open the forms we added to the list by using our custom application context
            Application.Run(new MultipleFormApplicationContext(windowHandle, forms));
        }
        catch (Exception ex)
        {
            BFS.Dialog.ShowMessageError(ex.Message);
        }
	}
	
	//this function toggles the script settings from running to not running
	private static void ToggleSetting()
	{
		string status = BFS.ScriptSettings.ReadValue(SettingName);
		if(status.Equals("running", StringComparison.Ordinal))
			BFS.ScriptSettings.WriteValue(SettingName, "not");
		else
			BFS.ScriptSettings.WriteValue(SettingName, "running");
	}
	
	//this function allows us to see the currect state of the script
	private static bool IsTransparentWindowRunning()
	{
		string status = BFS.ScriptSettings.ReadValue(SettingName);
		return status.Equals("running", StringComparison.Ordinal);
	}
	
	//extend the ApplicationContext class to support opening multiple forms
	//this class will also listen for active window changes, and play with the form transparency
	private class MultipleFormApplicationContext : ApplicationContext 
	{
        //this is the function signature for the hook callback
        private delegate void WinEventProcDelegate(IntPtr hWinEventHook, uint e, IntPtr hwnd, int idObject, int idChild, uint dwEventThread, uint dwmsEventTime);

        //this function will let us listen to windows events
        [DllImport("User32.dll")]
        private static extern IntPtr SetWinEventHook(uint eventMin, uint eventMax, IntPtr hmodWinEventProc, WinEventProcDelegate lpfnWinEventProc, uint idProcess, uint idThread, uint dwflags);
        
        //this function will let us stop listening to windows events
        [DllImport("User32.dll")]
        private static extern bool UnhookWinEvent(IntPtr hWinEventHook);
	
        private IntPtr WindowChangedHookHandle;
        private WinEventProcDelegate HookDelegateReference;
        private List<TransparentForm> Forms;
        private readonly IntPtr SelectedWindow;
	
        private const uint EVENT_SYSTEM_FOREGROUND = 0x0003;
	
		internal MultipleFormApplicationContext(IntPtr selectedWindow, List<TransparentForm> forms)
		{
            this.Forms = forms;
            this.SelectedWindow = selectedWindow;
		
            //store the reference to the function so .NET doesn't feel like disposing it
            this.HookDelegateReference = this.WindowChanged;
            
            //start the window hook
            this.WindowChangedHookHandle = SetWinEventHook(EVENT_SYSTEM_FOREGROUND, EVENT_SYSTEM_FOREGROUND, IntPtr.Zero, this.HookDelegateReference, 0, 0, 0);
            
			//open each of the forms, and add our closing event to them		
			foreach(Form form in forms)
			{
				form.FormClosed += this.OnFormClosed;
				form.Show();
			}
			
			this.SetFormsTransparency(this.SelectedWindow);
		}
		
		//when all the forms close, make sure to exit the application
		private void OnFormClosed(object sender, EventArgs e)
		{
            try
            {
                if(Application.OpenForms.Count != 0)
                    return;
                
                //release the window hooks and exit the application
                if(this.WindowChangedHookHandle != IntPtr.Zero)
                    UnhookWinEvent(this.WindowChangedHookHandle);
                
                this.HookDelegateReference = null;
                this.ExitThread();
            }
            catch //ignore any errors
            {
            }
		}
		
		private void SetFormsTransparency(IntPtr focusedWindow)
		{
            try
            {                         
                //loop through each form and toggle the visibility
                foreach(TransparentForm form in this.Forms)
                    BFS.Window.SetTransparency(form.Handle, (focusedWindow == this.SelectedWindow) ? 40m : 0);
            }
            catch //ignore any errors
            {
            }
		}
		
		private void WindowChanged(IntPtr hWinEventHook, uint e, IntPtr hwnd, int idObject, int idChild, uint dwEventThread, uint dwmsEventTime)
		{
            try
            {
                this.SetFormsTransparency(hwnd);
            }
            catch //ignore any errors
            {
            }
		}
	}
	
	//extend the Form class to get the behavior we want
	private class TransparentForm : Form 
	{
		//this will tell us what transparency to use
		private decimal Transparency;
		
		//a variable to store the monitor id this form is on
		public uint MonitorId {get; private set;}
		
		//the contructor for our class
		internal TransparentForm(decimal transparency, uint id)
		{		
			this.Transparency = transparency;
			this.MonitorId = id;
			
			this.SuspendLayout();
			
			//setup the layout of this form
			this.BackColor = Color.Black;
			this.FormBorderStyle = FormBorderStyle.None;
			this.ShowInTaskbar = false;
			
			//setup the form load event
			this.Load += Form_Load;			
			
			this.ResumeLayout(false);
		}
		
		private void Form_Load(object sender, EventArgs e)
		{
			//make the window transparent
			BFS.Window.SetTransparency(this.Handle, this.Transparency);
			
			//add a windows style to the current style that will
			//tell this window to ignore user input
			uint style = (uint)BFS.Window.GetWindowStyleEx(this.Handle);
			BFS.Window.SetWindowStyleEx((BFS.WindowEnum.WindowStyleEx)(style | (uint)BFS.WindowEnum.WindowStyleEx.WS_EX_TRANSPARENT | (uint)BFS.WindowEnum.WindowStyleEx.WS_EX_LAYERED), this.Handle);
			
			//set the form's bounds to the monitor
			this.Bounds = BFS.Monitor.GetMonitorBoundsByID(this.MonitorId);
			
			//set topmost
			BFS.Window.SetAlwaysOnTop(this.Handle, true);
			
			//start up a thread to listen for an exit event
			new Thread(new ThreadStart(ExitListener)).Start();
		}
		
		private void ExitListener()
		{
            try
            {
                while(true)
                {
                    //if we should close, tell the main thread to close the form
                    if(!IsTransparentWindowRunning())
                    {
                        try
                        {
                            this.Invoke((MethodInvoker) delegate
                            {
                                this.Close();
                            });
                        }
                        catch //something went wrong, ignore
                        {
                        }
                            
                        break;
                    }
                    
                    //sleep for a quarter of a second
                    BFS.General.ThreadWait(500);
                }
			}
            catch //ignore errors
            {
            }
		}
	}
}