using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Mesen.GUI.Forms
{
	public class BaseInputForm : BaseForm, IMessageFilter
	{
		private static Stack<Form> _inputForms = new Stack<Form>();

		private const int WM_KEYDOWN = 0x100;
		private const int WM_KEYUP = 0x101;
		private const int WM_SYSKEYDOWN = 0x104;
		private const int WM_SYSKEYUP = 0x105;
		private Timer _tmrUpdateBackground;

		public BaseInputForm()
		{
			bool designMode = (LicenseManager.UsageMode == LicenseUsageMode.Designtime);
			if(!designMode) {
				_inputForms.Push(this);
				Application.AddMessageFilter(this);
				this._tmrUpdateBackground = new Timer();
				this._tmrUpdateBackground.Start();
				this._tmrUpdateBackground.Tick += tmrUpdateBackground_Tick;
			}
		}

		protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
		{
			if(keyData == Keys.Escape) {
				CursorManager.ReleaseMouse();
			}

			return base.ProcessCmdKey(ref msg, keyData);
		}

		bool IMessageFilter.PreFilterMessage(ref Message m)
		{
			if(this.ContainsFocus) {
				if(m.Msg == WM_KEYUP || m.Msg == WM_SYSKEYUP) {
					int scanCode = (Int32)(((Int64)m.LParam & 0x1FF0000) >> 16);
					InteropEmu.SetKeyState(scanCode, false);
				} else if(m.Msg == WM_SYSKEYDOWN || m.Msg == WM_KEYDOWN) {
					int scanCode = (Int32)(((Int64)m.LParam & 0x1FF0000) >> 16);
					InteropEmu.SetKeyState(scanCode, true);
				}
			}
			return false;
		}

		protected override void OnFormClosed(FormClosedEventArgs e)
		{
			base.OnFormClosed(e);
			Application.RemoveMessageFilter(this);
			_tmrUpdateBackground.Stop();
			_tmrUpdateBackground.Dispose();
			_inputForms.Pop();
		}

		protected override void OnLoad(EventArgs e)
		{
			base.OnLoad(e);

			if(Program.IsMono) {
				//Mono does not trigger the activate/deactivate events when opening a modal popup, but it does set the form to disabled
				//Use this to reset key states
				this.EnabledChanged += (object s, EventArgs evt) => {
					InteropEmu.ResetKeyState();
				};
			}
		}

		protected override void OnDeactivate(EventArgs e)
		{
			base.OnDeactivate(e);
			InteropEmu.ResetKeyState();
		}

		protected override void OnActivated(EventArgs e)
		{
			base.OnActivated(e);
			InteropEmu.ResetKeyState();
		}

		private void tmrUpdateBackground_Tick(object sender, EventArgs e)
		{
			UpdateFocusFlag();
		}

		private void UpdateFocusFlag()
		{
			if(_inputForms.Peek() == this) {
				InteropEmu.SetFlag(EmulationFlags.InBackground, !this.ContainsFocus);
			}
		}
	}
}