using System;
using Xamarin.Forms.Internals;
using Ooui.Forms;
using System.IO;
using System.Reflection;
using System.Threading;
using System.Threading.Tasks;
using Ooui;
using System.Net.Http;

namespace Xamarin.Forms
{
    public static class Forms
    {
        public static bool IsInitialized { get; private set; }

        public static void Init ()
        {
            if (IsInitialized)
                return;
            IsInitialized = true;

            Log.Listeners.Add (new DelegateLogListener ((c, m) => System.Diagnostics.Debug.WriteLine (m, c)));

            Device.SetIdiom (TargetIdiom.Desktop);
            Device.PlatformServices = new OouiPlatformServices ();
            Device.Info = new OouiDeviceInfo ();
            Color.SetAccent (Color.FromHex ("#337ab7")); // Bootstrap Blue

            Registrar.RegisterAll (new[] {
                typeof(ExportRendererAttribute),
                typeof(ExportCellAttribute),
                typeof(ExportImageSourceHandlerAttribute),
            });
        }

        public static event EventHandler<ViewInitializedEventArgs> ViewInitialized;

        public static HttpClientHandler HttpClientHandler { get; set; }


        public static void SendViewInitialized (this VisualElement self, Ooui.Element nativeView)
        {
            ViewInitialized?.Invoke (self, new ViewInitializedEventArgs { View = self, NativeView = nativeView });
        }

        class OouiDeviceInfo : DeviceInfo
        {
            public override Size PixelScreenSize => new Size (640, 480);

            public override Size ScaledScreenSize => PixelScreenSize;

            public override double ScalingFactor => 1;
        }

        class OouiPlatformServices : IPlatformServices
        {
            public bool IsInvokeRequired => false;

            public string RuntimePlatform => "Ooui";

            public void BeginInvokeOnMainThread (Action action)
            {
                Task.Run (action);
            }

            public Assembly[] GetAssemblies ()
            {
                return AppDomain.CurrentDomain.GetAssemblies ();
            }

            public string GetMD5Hash (string input)
            {
                return Utilities.GetMd5Hash(input);
            }

            public double GetNamedSize (NamedSize size, Type targetElementType, bool useOldSizes)
            {
                switch (size) {
                    default:
                    case NamedSize.Default:
                        return 16;
                    case NamedSize.Micro:
                        return 9;
                    case NamedSize.Small:
                        return 12;
                    case NamedSize.Medium:
                        return 22;
                    case NamedSize.Large:
                        return 32;
                }
            }


            public async Task<Stream> GetStreamAsync (Uri uri, CancellationToken cancellationToken)
            {
                //NOTE:  Wanted to use the same facility that ImageLoaderSourceHandler uses,
                //       but couldn't find an optional way to ignore certificate errors with self-signed 
                //       certificates with that approach.  Calling:
                //          ServicePointManager.ServerCertificateValidationCallback += (o, cert, chain, errors) => true;
                //       in web application seemed to get ignored.

                //var imageSource = new UriImageSource() { Uri = uri };
                //return imageSource.GetStreamAsync(cancellationToken);

                using (var client = HttpClientHandler == null ? new HttpClient() : new HttpClient(HttpClientHandler))
                {
                    HttpResponseMessage streamResponse = await client.GetAsync(uri.AbsoluteUri).ConfigureAwait(false);

                    if (!streamResponse.IsSuccessStatusCode)
                    {
                        Log.Warning("HTTP Request", $"Could not retrieve {uri}, status code {streamResponse.StatusCode}");
                        return null;
                    }

                    return await streamResponse.Content.ReadAsStreamAsync().ConfigureAwait(false);
                }
            }

            public IIsolatedStorageFile GetUserStoreForApplication ()
            {
                return new LocalIsolatedStorageFile ();
            }

            public void OpenUriAction (Uri uri)
            {
                throw new NotImplementedException ();
            }

            public void StartTimer (TimeSpan interval, Func<bool> callback)
            {
                Timer timer = null;
                timer = new Timer ((_ => {
                    if (!callback ()) {
                        timer?.Dispose ();
                        timer = null;
                    }
                }), null, (int)interval.TotalMilliseconds, (int)interval.TotalMilliseconds);
            }

            public Ticker CreateTicker ()
            {
                return new OouiTicker ();
            }

            class OouiTicker : Ticker
            {
                Timer timer;
                protected override void DisableTimer ()
                {
                    var t = timer;
                    timer = null;
                    t?.Dispose ();
                }
                protected override void EnableTimer ()
                {
                    if (timer != null)
                        return;
                    var interval = TimeSpan.FromSeconds (1.0 / Ooui.UI.MaxFps);
                    timer = new Timer ((_ => {
                        this.SendSignals ();
                    }), null, (int)interval.TotalMilliseconds, (int)interval.TotalMilliseconds);
                }
            }

            public void QuitApplication()
            {
            }

            public SizeRequest GetNativeSize(VisualElement view, double widthConstraint, double heightConstraint)
            {
                var renderer = Ooui.Forms.Platform.GetRenderer(view);
                return renderer.GetDesiredSize(widthConstraint, heightConstraint);
            }
        }

        public class ViewInitializedEventArgs
        {
            public VisualElement View { get; set; }
            public Ooui.Element NativeView { get; set; }
        }

        public static void LoadApplication (Application application)
        {
            Application.Current = application;
            var mainPage = application.MainPage;
            if (mainPage != null) {
                UI.Publish ("/", application.MainPage.GetOouiElement ());
            }
        }
    }
}