using System;
using System.IO;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using Microsoft.Data.Sqlite;
using Xunit;
using ytLive.Models;
using ytLive.Services;
using ytLive.ViewModels;

namespace ytLive.Tests;

/// <summary>
/// 2026-11-05 report: a video layer added and playing showed NOTHING in the preview pane. The decode
/// was healthy — the preview's <c>Image</c> is switched on by a whitelist of DataTriggers (image,
/// chat, alert, ticker, scoreboard, text, web, webcam) and a video layer matched none of them, so its
/// Image stayed Collapsed. Same class of defect as the invisible alert box (2026-09-26).
/// <para>These assert the two ends: the layer receives frames, and the pane actually shows it.</para>
/// </summary>
[Collection("RealApp")]
public sealed class MediaPreviewDisplayTests
{
    private readonly RealAppHost _app;

    public MediaPreviewDisplayTests(RealAppHost app) => _app = app;

    [Fact]
    public void VideoLayer_IsDrawnByThePreviewPane()
    {
        _app.Run(() =>
        {
            var tempDb = Path.Combine(Path.GetTempPath(), $"ytLlive-test-{Guid.NewGuid():N}.db");
            var videoPath = Path.Combine(Path.GetTempPath(), "preview-clip.mp4");
            var decoders = new System.Collections.Generic.List<FakeMediaSource>();
            MainViewModel.LayoutPathOverride = tempDb;
            MainViewModel.MediaFrameSourceFactoryOverride = key =>
            {
                var decoder = new FakeMediaSource(key);
                decoders.Add(decoder);
                return decoder;
            };
            MainViewModel.ChromaProbeOverride = new NoProbe();

            var window = new MainWindow();
            var vm = (MainViewModel)window.DataContext;
            try
            {
                window.Show();
                window.UpdateLayout();

                vm.AddMediaSource(videoPath);
                var layer = vm.StagedScene!.Elements.OfType<Source>().Single(s => s.IsMediaSource);

                // The layer receives a decoded frame…
                var frame = SolidFrame(64, 36);
                decoders.Single().Emit(frame);
                Assert.NotNull(layer.DisplaySource);

                window.UpdateLayout();

                // …and the preview pane actually renders it. Without the IsMediaSource trigger the
                // Image is Collapsed and the clip is invisible while everything else looks healthy.
                var pane = (UserControl)window.FindName("PreviewPane")!;
                var image = FindImageBoundTo(pane, layer.DisplaySource!);
                Assert.True(image != null,
                    "the preview pane has no Image bound to the video layer's frame — the layer is invisible");
                Assert.Equal(Visibility.Visible, image!.Visibility);
                Assert.True(image.ActualWidth > 0 && image.ActualHeight > 0,
                    $"the video layer's preview Image has no size ({image.ActualWidth}x{image.ActualHeight})");
            }
            finally
            {
                window.Close();
                MainViewModel.ChromaProbeOverride = null;
                MainViewModel.MediaFrameSourceFactoryOverride = null;
                MainViewModel.LayoutPathOverride = null;
                SqliteConnection.ClearAllPools();
                try { File.Delete(tempDb); } catch { /* best-effort cleanup */ }
            }
        });
    }

    private static Image? FindImageBoundTo(DependencyObject parent, ImageSource source)
    {
        for (var i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
        {
            var child = VisualTreeHelper.GetChild(parent, i);
            if (child is Image image && ReferenceEquals(image.Source, source)) return image;
            if (FindImageBoundTo(child, source) is { } found) return found;
        }
        return null;
    }

    private static VideoFrame SolidFrame(int w, int h)
    {
        var bytes = new byte[w * h * 4];
        for (var i = 0; i < bytes.Length; i += 4)
        {
            bytes[i] = 40; bytes[i + 1] = 200; bytes[i + 2] = 40; bytes[i + 3] = 255;
        }
        return new VideoFrame(w, h, bytes);
    }

    private sealed class FakeMediaSource : IMediaFrameSource
    {
        public FakeMediaSource(string key) => Key = key;
        public string Key { get; }
        public bool Looping { get; set; }
        public event Action<VideoFrame>? FrameAvailable;
        public event Action<ytLive.Services.Audio.AudioSample>? AudioAvailable { add { } remove { } }
        public event Action? Completed { add { } remove { } }
        public void Emit(VideoFrame frame) => FrameAvailable?.Invoke(frame);
        public Task StartAsync(CancellationToken cancellationToken = default) => Task.CompletedTask;
        public Task StopAsync() => Task.CompletedTask;
        public void Dispose() { }
    }

    private sealed class NoProbe : IChromaProbe
    {
        public Task<VideoFrame?> ProbeAsync(string path, CancellationToken cancellationToken = default)
            => Task.FromResult<VideoFrame?>(null);
    }
}