using System;
using System.Drawing;
using System.Windows.Forms;
using System.Threading;
using System.Collections.Generic;

// Fade all monitors to black over a two second period
// Fade in when run again

// Based entirely on Thomas Malloch's very brilliant Dim All Monitors Except Primary
// Hope he will forgive the change to K&R style and general clean-up to be more abbreviated

// 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 = "BlackenMonitors_Run";
	private static Point OrigMousePos;

	public static void Run(IntPtr windowHandle) {
		//toggle the setting from run to not run, and vice versa
		ToggleSetting();

		if (RunFadeMonitors()) {
            var mmb = BFS.Monitor.GetMonitorBoundsByMouseCursor();
            OrigMousePos = Cursor.Position;
            BFS.Input.SetMousePosition(OrigMousePos.X, mmb.Height);
            
            //add all monitors to the list of monitors that will be dimmed
            var forms = new List<Form>();
            foreach(uint id in BFS.Monitor.GetMonitorIDs())
                forms.Add(new TransparentForm(id));


            //this will open the forms we added to the list by using our custom application context
            Application.Run(new MultipleFormApplicationContext(forms));
        }
	}

	//this function allows us to see the currect state of the script
	private static bool RunFadeMonitors() {
		return BFS.ScriptSettings.ReadValue(SettingName) == "run";
	}

	//this function toggles the script settings from running to not running
	private static void ToggleSetting() {
		BFS.ScriptSettings.WriteValue(SettingName, RunFadeMonitors() ? "not" : "run");
	}

	//extend the ApplicationContext class to support opening multiple forms
	private class MultipleFormApplicationContext : ApplicationContext {
		internal MultipleFormApplicationContext(List<Form> forms) {
			//open each of the forms, and add our closing event to them
			foreach(Form form in forms) {
				form.FormClosed += OnFormClosed;
				form.Show();
			}
		}

		//when all the forms close, make sure to exit the application
		private void OnFormClosed(object sender, EventArgs e) {
			if(Application.OpenForms.Count == 0) {
				ExitThread();
			}
		}
	}
	
	//extend the Form class to get the behavior we want
	private class TransparentForm : Form {
		//this will tell us what monitor to open on
		private uint MonitorId;
		private uint FadeWait;
		private decimal TransparentIncrement;
		
		//this will tell us our current transparency
		private decimal Transparency;
		
		//the contructor for our class
		internal TransparentForm(uint monitorId) {		
			MonitorId = monitorId;
			Transparency = 0m;
			const decimal FadeTime = 2.0m; // seconds
			TransparentIncrement = 1m; // percent
			FadeWait = (uint)(TransparentIncrement * 10m * FadeTime);
			
			SuspendLayout();

			//setup the layout of this form
			BackColor = Color.Black;
			FormBorderStyle = FormBorderStyle.None;
			ShowInTaskbar = false;
			
			//move the window to the desired monitor
			Rectangle bounds = BFS.Monitor.GetMonitorBoundsByID(MonitorId);
			Location = new Point(bounds.X, bounds.Y);
			Size = new Size(bounds.Width, bounds.Height);
			StartPosition = FormStartPosition.Manual;
			
			BFS.Window.SetAlwaysOnTop(Handle, true);
			BFS.Window.SetTransparency(Handle, Transparency);

			//setup the form load event
			Load += Form_Load;			
			
			ResumeLayout(false);
		}
		
		private void Form_Load(object sender, EventArgs e) {
            Cursor.Hide();

			//add a windows style to the current style that will
			//tell this window to ignore user input
			var style = (uint)BFS.Window.GetWindowStyleEx(Handle) | (uint)BFS.WindowEnum.WindowStyleEx.WS_EX_TRANSPARENT | (uint)BFS.WindowEnum.WindowStyleEx.WS_EX_LAYERED;
			BFS.Window.SetWindowStyleEx((BFS.WindowEnum.WindowStyleEx)style, Handle);

			//start up a thread to listen for an exit event
			new Thread(new ThreadStart(ExitListener)).Start();
		}

		private void ExitListener() {
			while(true) {
				if(RunFadeMonitors()) {
					// Fade to Black
					if (Transparency < 100m) {
						Transparency += TransparentIncrement;
						BFS.Window.SetTransparency(Handle, Transparency);
					}

					//sleep
					BFS.General.ThreadWait((Transparency < 100m) ? FadeWait : 250u);				
				}
				else {
					if (this.Transparency > 0m) {
						// Fade back in
						Transparency -= TransparentIncrement;
						BFS.Window.SetTransparency(Handle, Transparency);

						//sleep
						BFS.General.ThreadWait((Transparency < 100m) ? FadeWait : 250u);
					}
					else { // if we should close, tell the main thread to close the form
						try {
							this.Invoke((MethodInvoker) delegate {
                                Cursor.Position = OrigMousePos;
								Close();
							});
						}
						catch { //something went wrong, ignore
						}
						
						break;
					}
				}
			}
		}
	}
}