#nullable enable
 
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.ComponentModel;
using Microsoft.Maui.Controls.Internals;
using Microsoft.Maui.Graphics;
 
namespace Microsoft.Maui.Controls.Platform
{
	internal class GestureManager
	{
		readonly IControlsView _view;
		object? _containerView;
		object? _platformView;
		object? _handler;
		bool _didHaveWindow;
 
		public bool IsConnected => GesturePlatformManager != null;
		public GesturePlatformManager? GesturePlatformManager { get; private set; }
 
		public GestureManager(IControlsView view)
		{
			_view = view;
			view.HandlerChanging += OnHandlerChanging;
			view.HandlerChanged += OnHandlerChanged;
			view.WindowChanged += OnWindowChanged;
			view.PlatformContainerViewChanged += OnPlatformContainerViewChanged;
 
			SetupGestureManager();
		}
 
		void OnPlatformContainerViewChanged(object? sender, EventArgs e) =>
			SetupGestureManager();
 
		void OnWindowChanged(object? sender, EventArgs e) =>
			SetupGestureManager();
 
		void OnHandlerChanged(object? sender, EventArgs e) =>
			SetupGestureManager();
 
		void OnHandlerChanging(object? sender, HandlerChangingEventArgs e) =>
			DisconnectGestures();
 
		void DisconnectGestures()
		{
			GesturePlatformManager?.Dispose();
			GesturePlatformManager = null;
			_handler = null;
			_didHaveWindow = false;
			_containerView = null;
			_platformView = null;
		}
 
		void SetupGestureManager()
		{
			var handler = _view.Handler;
 
			if (handler == null ||
				(_didHaveWindow && _view.Window == null))
			{
				DisconnectGestures();
				return;
			}
 
			if (_containerView != handler.ContainerView ||
				_platformView != handler.PlatformView ||
				_handler != handler)
			{
				DisconnectGestures();
			}
 
			// The connected Gesture Manager is already setup and watching the correct view
			if (GesturePlatformManager != null)
				return;
 
			GesturePlatformManager = new GesturePlatformManager(handler);
			_handler = handler;
			_containerView = handler.ContainerView;
			_platformView = handler.PlatformView;
			_didHaveWindow = _view.Window != null;
		}
	}
}