using System;
using System.Linq;
using System.Runtime.Versioning;
using Microsoft.AspNetCore.Components.WebView;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Maui;
using Microsoft.Maui.Handlers;
 
namespace Microsoft.AspNetCore.Components.WebView.Maui
{
#if ANDROID
	[SupportedOSPlatform("android23.0")]
#endif
	public partial class BlazorWebViewHandler
	{
		private const string UseBlockingDisposalSwitch = "BlazorWebView.UseBlockingDisposal";
 
		private static bool IsBlockingDisposalEnabled =>
			AppContext.TryGetSwitch(UseBlockingDisposalSwitch, out var enabled) && enabled;
 
		/// <summary>
		/// This field is part of MAUI infrastructure and is not intended for use by application code.
		/// </summary>
		public static PropertyMapper<IBlazorWebView, BlazorWebViewHandler> BlazorWebViewMapper = new(ViewMapper)
		{
			[nameof(IBlazorWebView.HostPage)] = MapHostPage,
			[nameof(IBlazorWebView.RootComponents)] = MapRootComponents,
		};
 
		/// <summary>
		/// Initializes a new instance of <see cref="BlazorWebViewHandler"/> with default mappings.
		/// </summary>
		public BlazorWebViewHandler() : this(BlazorWebViewMapper)
		{
		}
 
		/// <summary>
		/// Initializes a new instance of <see cref="BlazorWebViewHandler"/> using the specified mappings.
		/// </summary>
		/// <param name="mapper">The property mappings.</param>
		public BlazorWebViewHandler(PropertyMapper? mapper) : base(mapper ?? BlazorWebViewMapper)
		{
		}
 
		internal BlazorWebViewDeveloperTools DeveloperTools => MauiContext!.Services.GetRequiredService<BlazorWebViewDeveloperTools>();
 
		/// <summary>
		/// Maps the <see cref="IBlazorWebView.HostPage"/> property to the specified handler.
		/// </summary>
		/// <param name="handler">The <see cref="BlazorWebViewHandler"/>.</param>
		/// <param name="webView">The <see cref="IBlazorWebView"/>.</param>
		public static void MapHostPage(BlazorWebViewHandler handler, IBlazorWebView webView)
		{
#if !(NETSTANDARD || !PLATFORM)
			handler.HostPage = webView.HostPage;
			handler.StartWebViewCoreIfPossible();
#endif
		}
 
		/// <summary>
		/// Maps the <see cref="IBlazorWebView.RootComponents"/> property to the specified handler.
		/// </summary>
		/// <param name="handler">The <see cref="BlazorWebViewHandler"/>.</param>
		/// <param name="webView">The <see cref="IBlazorWebView"/>.</param>
		public static void MapRootComponents(BlazorWebViewHandler handler, IBlazorWebView webView)
		{
#if !(NETSTANDARD || !PLATFORM)
			handler.RootComponents = webView.RootComponents;
			handler.StartWebViewCoreIfPossible();
#endif
		}
 
#if !(NETSTANDARD || !PLATFORM)
		private string? HostPage { get; set; }
 
		internal void UrlLoading(UrlLoadingEventArgs args) =>
			VirtualView.UrlLoading(args);
 
		private RootComponentsCollection? _rootComponents;
 
		private RootComponentsCollection? RootComponents
		{
			get => _rootComponents;
			set
			{
				if (_rootComponents != null)
				{
					// Remove any previously-known root components and unhook events
					_rootComponents.Clear();
					_rootComponents.CollectionChanged -= OnRootComponentsCollectionChanged;
				}
 
				_rootComponents = value;
 
				if (_rootComponents != null)
				{
					// Add new root components and hook events
					if (_rootComponents.Count > 0 && _webviewManager != null)
					{
						_webviewManager.Dispatcher.AssertAccess();
						foreach (var component in _rootComponents)
						{
							_ = component.AddToWebViewManagerAsync(_webviewManager);
						}
					}
					_rootComponents.CollectionChanged += OnRootComponentsCollectionChanged;
				}
			}
		}
 
		private void OnRootComponentsCollectionChanged(object? sender, global::System.Collections.Specialized.NotifyCollectionChangedEventArgs eventArgs)
		{
			// If we haven't initialized yet, this is a no-op
			if (_webviewManager != null)
			{
				// Dispatch because this is going to be async, and we want to catch any errors
				_ = _webviewManager.Dispatcher.InvokeAsync(async () =>
				{
					var newItems = eventArgs.NewItems!.Cast<RootComponent>();
					var oldItems = eventArgs.OldItems!.Cast<RootComponent>();
 
					foreach (var item in newItems.Except(oldItems))
					{
						await item.AddToWebViewManagerAsync(_webviewManager);
					}
 
					foreach (var item in oldItems.Except(newItems))
					{
						await item.RemoveFromWebViewManagerAsync(_webviewManager);
					}
				});
			}
		}
#endif
	}
}