using System;
using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;
using Microsoft.Data.Sqlite;
using Xunit;
using ytLive.Services;
using ytLive.ViewModels;

namespace ytLive.Tests;

/// <summary>
/// The webcam is an app-level resource with ONE selection (the app default):
/// placing it in one scene must NOT grey it in the others (per-scene max, not
/// app-wide), "Add Webcam" places the existing default directly (no picker —
/// the picker only runs for the initial selection), and removing the last
/// placement keeps the identity so the layer stays offered.
/// Real-App + temp-DB + camera-seam pattern (camera seams are required: the
/// startup resource pass and Add both acquire, and must never touch real
/// hardware under test).
/// </summary>
[Collection("RealApp")]
public sealed class WebcamMenuGateTests
{
    [Fact]
    public void WebcamIsAppDefault_AddPlacesSameCamera_AnyScene_IdentitySurvivesRemoval()
    {
        _app.Run(Run);
    }

    private readonly RealAppHost _app;

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

    private void Run()
    {
        var tempDb = Path.Combine(Path.GetTempPath(), $"ytLlive-wcgate-{Guid.NewGuid():N}.db");
        MainViewModel.LayoutPathOverride = tempDb;
        MainViewModel.CameraEnumeratorOverride = new FakeEnumerator();
        MainViewModel.CameraFrameSourceFactoryOverride = id => new FakeFrameSource(id);
        var window = default(MainWindow);
        try
        {
            using (var schema = new ytLive.Services.LayoutStore(tempDb)) { }
            SqliteConnection.ClearAllPools();
            SeedDatabaseWithWebcam(tempDb);

            window = new MainWindow();
            var vm = (MainViewModel)window.DataContext;

            var starting = vm.Scenes.Single(s => s.Name == "Starting");
            var live = vm.Scenes.Single(s => s.Name == "Live");

            vm.StagedScene = live;
            Assert.Null(live.WebcamConfig);
            Assert.True(vm.CanAddWebcam,
                "webcam exists in Starting but that is NOT a block — the app default stays offered in Live");

            // Add Webcam must place the existing app default without opening a picker.
            vm.AddWebcamCommand.Execute(null);
            Assert.NotNull(live.WebcamConfig);
            Assert.Equal("wc-1", live.WebcamConfig!.WebcamId);

            // Per-scene max: the scene that already hosts the webcam stays greyed.
            vm.StagedScene = starting;
            Assert.False(vm.CanAddWebcam, "a scene already hosting the webcam must not offer it again");

            // Removing placements keeps the app-level identity alive.
            vm.RemoveSourceCommand.Execute(starting.WebcamConfig!);
            Assert.True(vm.CanAddWebcam, "removing a placement re-enables Add for the same app default");

            vm.StagedScene = live;
            vm.RemoveSourceCommand.Execute(live.WebcamConfig!);
            Assert.True(vm.CanAddWebcam, "the app default is still selected — Add stays offered");

            vm.SaveLayoutNow();
            using (var connection = new SqliteConnection($"Data Source={tempDb}"))
            {
                connection.Open();
                using var webcams = connection.CreateCommand();
                webcams.CommandText = "SELECT COUNT(*) FROM Webcam;";
                Assert.Equal(1L, (long)webcams.ExecuteScalar()!);
            }
        }
        finally
        {
            window?.Close();
            MainViewModel.LayoutPathOverride = null;
            MainViewModel.CameraEnumeratorOverride = null;
            MainViewModel.CameraFrameSourceFactoryOverride = null;
            SqliteConnection.ClearAllPools();
            try { File.Delete(tempDb); } catch { /* best-effort cleanup */ }
        }
    }

    /// <summary>Five canonical scenes + a webcam identity used by exactly one
    /// non-staged-by-default scene (Starting), so staging Live reproduces the
    /// old app-wide gate's false "unavailable".</summary>
    private static void SeedDatabaseWithWebcam(string path)
    {
        using var connection = new SqliteConnection($"Data Source={path}");
        connection.Open();

        var scenes = new (string Id, string Name)[]
        {
            ("scene-starting", "Starting"),
            ("scene-live", "Live"),
            ("scene-brb", "BRB"),
            ("scene-chat", "Chat"),
            ("scene-ending", "Ending"),
        };
        foreach (var (id, name) in scenes)
        {
            using var cmd = connection.CreateCommand();
            cmd.CommandText =
                "INSERT INTO Scene (Id, Name, HasBackground, SortOrder) VALUES ($id, $name, 1, $order);";
            cmd.Parameters.AddWithValue("$id", id);
            cmd.Parameters.AddWithValue("$name", name);
            cmd.Parameters.AddWithValue("$order", Array.IndexOf(scenes, (id, name)));
            cmd.ExecuteNonQuery();
        }

        using (var webcam = connection.CreateCommand())
        {
            webcam.CommandText =
                "INSERT INTO Webcam (Id, DeviceId, Name) VALUES ('wc-1', 'test-camera', 'Test Cam');";
            webcam.ExecuteNonQuery();
        }

        using (var config = connection.CreateCommand())
        {
            config.CommandText =
                @"INSERT INTO WebcamSceneConfig
                  (SceneId, WebcamId, IsVisible, X, Y, Width, Height, Opacity, SortOrder)
                  VALUES ('scene-starting', 'wc-1', 1, 100, 100, 480, 270, 1, 0);";
            config.ExecuteNonQuery();
        }
    }

    private sealed class FakeEnumerator : ICameraEnumerator
    {
        public Task<IReadOnlyList<CameraDeviceInfo>> GetCamerasAsync()
            => Task.FromResult<IReadOnlyList<CameraDeviceInfo>>(new[]
            {
                new CameraDeviceInfo("test-camera", "Test Cam"),
            });
    }

    private sealed class FakeFrameSource : ICameraFrameSource
    {
        public string DeviceId { get; }
        public event Action<VideoFrame>? FrameAvailable;
#pragma warning disable CS0067
        public event Action<string>? SourceFailed;
#pragma warning restore CS0067

        public FakeFrameSource(string deviceId) => DeviceId = deviceId;

        public Task StartAsync()
        {
            FrameAvailable?.Invoke(new VideoFrame(2, 2, new byte[16]));
            return Task.CompletedTask;
        }

        public Task StopAsync() => Task.CompletedTask;
    }
}