using System;
using System.Collections.Generic;
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.Services.Compositor;
using ytLive.Services.Encoder;
using ytLive.ViewModels;

namespace ytLive.Tests;

/// <summary>
/// Good Dog (2026-09-26): the free-tier branding credit must be COMPOSITED INTO THE
/// BROADCAST, and must be exactly what the creator sees in the preview.
/// <para>The bug: the credit existed only as a WPF <c>BrandFlashLayer</c> in
/// PreviewPane.xaml — a 0.25-opacity TextBlock on a 300s timer. A viewer of the
/// stream or the recording never saw it, so the "free tier shows branding" promise was
/// simply not being kept. The frame pump has carried an unused <c>flashFrame</c> slot
/// for exactly this and it was never wired.</para>
/// <para>The fix routes ONE rendered frame to both consumers: the output compositor and
/// the preview pane. These facts pin the behaviour the creator specified — in the
/// recording, 2 seconds, random spot every time, inside the frame, and never for a
/// paying customer.</para>
/// </summary>
[Collection("RealApp")]
public sealed class BrandFlashOutputTests
{
    private readonly RealAppHost _app;

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

    // ---------- the headline: the credit is in the encoded output ----------

    [Fact]
    public async Task FreeTier_Credit_ReachesTheEncodedOutputFrame()
    {
        await _app.RunAsync(async () =>
        {
            // A real 1920x1080 pump: the credit is authored at master size, so a
            // toy-sized canvas would clip it away and prove nothing.
            var scene = new Scene { Name = "Live" };
            scene.Elements.Add(new Source
            {
                Type = SourceType.DisplayCapture, IsBackground = true, CaptureKey = "monitor:0",
            });

            using var presenter = new BrandFlashPresenter(new Random(1));
            presenter.Show();
            presenter.Advance(0.5); // land at the top of the full-opacity hold
            var credit = presenter.Frame;
            Assert.NotNull(credit);

            var encoder = new CapturingEncoder();
            using var pump = new FramePump(
                sceneProvider: () => scene,
                frameResolver: _ => null,
                compositorOptions: () => new CompositorOptions
                {
                    SourceRectX = 0, SourceRectY = 0,
                    SourceRectWidth = BrandFlashPresenter.MasterWidth,
                    SourceRectHeight = BrandFlashPresenter.MasterHeight,
                    OutputWidth = BrandFlashPresenter.MasterWidth,
                    OutputHeight = BrandFlashPresenter.MasterHeight,
                },
                encoderOptions: () => new EncoderOptions
                {
                    RtmpUrl = "rtmp://a.rtmp.youtube.com/live2/abc",
                    Width = BrandFlashPresenter.MasterWidth,
                    Height = BrandFlashPresenter.MasterHeight,
                    Fps = 30,
                },
                encoderFactory: () => encoder,
                pacingDelay: (_, _) => Task.CompletedTask,
                brandFlash: () => presenter.Frame);

            using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(20));
            await pump.StartAsync(cts.Token);
            await encoder.FirstFrame.Task.WaitAsync(TimeSpan.FromSeconds(15));
            await pump.StopAsync();

            var sent = encoder.Frames[0];
            Assert.True(HasBrightPixels(sent),
                "the branding credit never reached a frame submitted to the encoder — "
                + "it is still preview-only, so nobody watching the stream sees it");

            // The preview must show the very same thing, not a separate XAML text block.
            Assert.Equal(BrandFlashPresenter.MasterWidth, sent.Width);
            Assert.Equal(BrandFlashPresenter.MasterHeight, sent.Height);
        });
    }

    // ---------- a fully static scene must not swallow it ----------

    [Fact]
    public async Task FullyStaticScene_StillShowsTheCredit()
    {
        await _app.RunAsync(async () =>
        {
            // Regression on a PRE-EXISTING defect found while wiring this up: the
            // fully-static shortcut stretched the cached bake and returned it, dropping
            // every per-frame overlay on the floor — the credit, and (before this
            // change) the social bar and the alert ticker too. A creator with a single
            // static background would have seen the flash preview-only, forever.
            var black = SolidBlackFrame();
            var scene = new Scene { Name = "Live" };
            // One Background element and nothing dynamic => GetSplitPoint ==
            // Elements.Count, which is the branch that used to drop the overlays.
            scene.Elements.Add(new Source { Type = SourceType.Background });

            using var presenter = new BrandFlashPresenter(new Random(2));
            presenter.Show();
            presenter.Advance(0.5);
            Assert.NotNull(presenter.Frame);

            var encoder = new CapturingEncoder();
            using var pump = new FramePump(
                sceneProvider: () => scene,
                frameResolver: e => e is Source { Type: SourceType.Background } ? black : null,
                compositorOptions: () => new CompositorOptions
                {
                    SourceRectX = 0, SourceRectY = 0,
                    SourceRectWidth = BrandFlashPresenter.MasterWidth,
                    SourceRectHeight = BrandFlashPresenter.MasterHeight,
                    OutputWidth = BrandFlashPresenter.MasterWidth,
                    OutputHeight = BrandFlashPresenter.MasterHeight,
                },
                encoderOptions: () => new EncoderOptions
                {
                    RtmpUrl = "rtmp://a.rtmp.youtube.com/live2/abc",
                    Width = BrandFlashPresenter.MasterWidth,
                    Height = BrandFlashPresenter.MasterHeight,
                    Fps = 30,
                },
                encoderFactory: () => encoder,
                pacingDelay: (_, _) => Task.CompletedTask,
                brandFlash: () => presenter.Frame,
                sceneGraph: new SceneGraph());

            using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(20));
            await pump.StartAsync(cts.Token);
            await encoder.FirstFrame.Task.WaitAsync(TimeSpan.FromSeconds(15));
            await pump.StopAsync();

            Assert.True(HasBrightPixels(encoder.Frames[0]),
                "a fully static scene dropped the branding credit — the fully-static path "
                + "stretches the cached bake and used to discard every per-frame overlay");
        });
    }

    // ---------- the preview shows the same rendered credit ----------

    [Fact]
    public void PreviewPane_ShowsTheSameCreditThatGoesToTheStream()
    {
        _app.Run(() =>
        {
            var tempDb = Path.Combine(Path.GetTempPath(), $"ytLlive-test-{Guid.NewGuid():N}.db");
            MainViewModel.LayoutPathOverride = tempDb;
            var window = new MainWindow();
            var vm = (MainViewModel)window.DataContext;
            try
            {
                window.Show();
                window.UpdateLayout();

                using var presenter = new BrandFlashPresenter(new Random(3));
                presenter.Show();
                presenter.Advance(0.5);
                var credit = presenter.Frame;
                Assert.NotNull(credit);

                vm.PublishBrandFlashPreview(credit);
                window.UpdateLayout();

                var pane = (UserControl)window.FindName("PreviewPane")!;
                var holder = Find(pane, e => e is FrameworkElement f
                    && f.Name == "BrandFlashElement") as FrameworkElement;
                Assert.True(holder != null,
                    "PreviewPane.xaml has no BrandFlashElement — the credit is a global "
                    + "overlay, so it needs its own root, not a Source's Image");
                Assert.Equal(Visibility.Visible, holder!.Visibility);

                var image = Find(holder, e => e is Image) as Image;
                Assert.True(image != null && image.Source != null,
                    "the branding element never bound a bitmap, so the credit is never drawn");
                Assert.IsType<System.Windows.Media.Imaging.WriteableBitmap>(image!.Source);

                // It must go away again rather than sit on the next scene forever.
                vm.PublishBrandFlashPreview(null);
                window.UpdateLayout();
                Assert.Equal(Visibility.Collapsed, holder.Visibility);
            }
            finally
            {
                window.Close();
                MainViewModel.LayoutPathOverride = null;
                SqliteConnection.ClearAllPools();
                try { File.Delete(tempDb); } catch { /* best-effort cleanup */ }
            }
        });
    }

    // ---------- the specified numbers ----------

    [Fact]
    public void Credit_LastsTwoSeconds_ThenIsGone()
    {
        // 500ms fade in, 1000ms held, 500ms fade out.
        Assert.Equal(0.0, BrandFlashPresenter.OpacityAt(0.0), 3);
        Assert.Equal(0.5, BrandFlashPresenter.OpacityAt(0.25), 3);
        Assert.Equal(1.0, BrandFlashPresenter.OpacityAt(0.5), 3);
        Assert.Equal(1.0, BrandFlashPresenter.OpacityAt(1.49), 3);
        Assert.Equal(0.5, BrandFlashPresenter.OpacityAt(1.75), 3);
        Assert.Equal(0.0, BrandFlashPresenter.OpacityAt(2.0), 3);
        Assert.Equal(2.0, BrandFlashPresenter.PresentationSeconds, 3);
    }

    [Fact]
    public void Credit_IsGoneExactlyWhenTheTwoSecondsAreUp()
    {
        _app.Run(() =>
        {
            using var presenter = new BrandFlashPresenter(new Random(4));
            presenter.Show();
            // At exactly t=0 the fade-in has not started, so opacity is 0 and there is
            // deliberately nothing to blit — the credit appears on the next tick.
            Assert.Null(presenter.Frame);

            presenter.Advance(1.8);
            Assert.NotNull(presenter.Frame); // 1.8s: inside the fade-out
            Assert.True(presenter.IsPresenting);

            presenter.Advance(0.3);
            Assert.Null(presenter.Frame); // 2.1s in — over
            Assert.False(presenter.IsPresenting);
        });
    }

    [Fact]
    public void EveryPresentation_PicksADifferentSpot_AndAlwaysLandsOnTheCanvas()
    {
        _app.Run(() =>
        {
            using var presenter = new BrandFlashPresenter(new Random(7));
            var spots = new List<Point>();

            for (var run = 0; run < 40; run++)
            {
                presenter.Show();
                presenter.Advance(0.5);
                var frame = presenter.Frame;
                Assert.NotNull(frame);

                // The credit must be FULLY on the canvas — this is the "how far can the
                // left margin travel" limit: 0 .. (canvas - creditWidth), never wrapped.
                var (minX, minY, maxX, maxY) = AlphaBounds(frame!);
                Assert.True(minX >= 0 && minY >= 0,
                    $"the credit hangs off the top-left at ({minX},{minY})");
                Assert.True(maxX < frame.Width && maxY < frame.Height,
                    $"the credit runs off the bottom-right at ({maxX},{maxY})");
                spots.Add(new Point(minX, minY));
            }

            Assert.True(spots.Distinct().Count() > spots.Count / 2,
                "the spot barely changed across 40 presentations — it is not random per flash");
        });
    }

    [Fact]
    public void Placement_StaysInsideTheFrameForAnyTextSize()
    {
        var rand = new Random(11);
        for (var i = 0; i < 500; i++)
        {
            var w = rand.Next(1, 4000);
            var h = rand.Next(1, 3000);
            var p = BrandFlashPresenter.ComputePlacement(w, h,
                BrandFlashPresenter.MasterWidth, BrandFlashPresenter.MasterHeight, rand);
            Assert.InRange(p.X, 0, Math.Max(0, BrandFlashPresenter.MasterWidth - w));
            Assert.InRange(p.Y, 0, Math.Max(0, BrandFlashPresenter.MasterHeight - h));
        }

        // A credit wider than the canvas still gets a legal offset rather than throwing.
        var over = BrandFlashPresenter.ComputePlacement(5000, 5000,
            BrandFlashPresenter.MasterWidth, BrandFlashPresenter.MasterHeight, rand);
        Assert.Equal(0, over.X);
        Assert.Equal(0, over.Y);
    }

    [Fact]
    public void Cadence_RepeatsEveryThirtyToSixtySeconds()
    {
        _app.Run(() =>
        {
            using var presenter = new BrandFlashPresenter(new Random(5));
            presenter.Start();
            try
            {
                // First credit 5s after go-live, then not again inside 30s.
                Step(presenter, 4.0);
                Assert.Null(presenter.Frame);
                Step(presenter, 1.5);
                Assert.NotNull(presenter.Frame);

                // Sample the start-to-start intervals the presenter actually schedules
                // rather than trusting the constants. A rising edge is a new credit.
                // The first gap is the deliberate 5s opener, so it is excluded.
                var starts = new List<double>();
                var t = 0.0;
                var wasPresenting = presenter.IsPresenting;
                while (t < 1200.0)
                {
                    presenter.Advance(0.05);
                    t += 0.05;
                    var presenting = presenter.IsPresenting;
                    if (!wasPresenting && presenting) starts.Add(t);
                    wasPresenting = presenting;
                }

                var intervals = starts.Zip(starts.Skip(1), (a, b) => b - a)
                    .Where(g => g > 6.0) // drops the single 5s opener
                    .ToList();
                Assert.True(intervals.Count >= 15,
                    $"expected ~20 credits in 1200s of a 30-60s cadence, saw {starts.Count}");

                // The whole point: no beat a viewer could tune out, and none of the
                // collapsing gaps an absolute-deadline bug produces.
                Assert.All(intervals, g => Assert.InRange(g, 30.0 - 0.2, 60.0 + 0.2));
                Assert.True(intervals.Distinct().Count() > intervals.Count / 2,
                    "the cadence barely varied — it is not random per flash");
            }
            finally
            {
                presenter.Stop();
            }
        });
    }

    [Fact]
    public void Credit_IsNeverEmittedForAPayingCustomer()
    {
        _app.Run(() =>
        {
            using var presenter = new BrandFlashPresenter(new Random(6));
            presenter.Show();
            presenter.Advance(0.5);
            Assert.NotNull(presenter.Frame);

            // A key entered mid-credit must kill it on the next tick, not let the
            // advertisement finish playing.
            presenter.Enabled = false;
            Assert.Null(presenter.Frame);
            Assert.False(presenter.IsPresenting);

            presenter.Advance(0.1);
            presenter.Show();
            Assert.Null(presenter.Frame);

            // Going back to free tier restores it.
            presenter.Enabled = true;
            presenter.Show();
            presenter.Advance(0.5);
            Assert.NotNull(presenter.Frame);
        });
    }

    [Fact]
    public void BrandFlashEnabled_IsDerivedFromTheLicence_AndCannotBeSwitchedOn()
    {
        var prop = typeof(MainViewModel).GetProperty(nameof(MainViewModel.BrandFlashEnabled));
        Assert.NotNull(prop);
        Assert.Null(prop!.SetMethod);
        Assert.True(prop.CanRead, "the preview needs to read the gate state");
    }

    // ---------- the credit is NOT a go-live-only behaviour ----------

    /// <summary>Reported 2026-09-26: "the made with llamacasty flash should appear in
    /// all scenes, not just live" and "should also appear in recordings". The presenter
    /// used to be Start/Stop-ed from <c>UpdateLiveVisuals</c>'s IsLive branch, so a
    /// recording made WITHOUT ever going live carried no credit at all.
    /// <para>This drives a real, freshly-constructed ViewModel that has never gone
    /// live, advances past the 5s first-flash delay and asks the frame the frame pump
    /// would composite. A non-null frame here is the whole fix: the cadence is running
    /// for the life of the app, and since go-live and local recording are the SAME
    /// FramePump (both call <c>StartAsync</c> with the same <c>brandFlash:</c> delegate)
    /// the recording carries the credit too.</para></summary>
    [Fact]
    public void Credit_IsComposited_WithNoLiveSession_AndSoARecordingCarriesIt()
    {
        _app.Run(() =>
        {
            var tempDb = Path.Combine(Path.GetTempPath(), $"ytLlive-test-{Guid.NewGuid():N}.db");
            MainViewModel.LayoutPathOverride = tempDb;
            var window = new MainWindow();
            var vm = (MainViewModel)window.DataContext;
            try
            {
                window.Show();
                window.UpdateLayout();

                // The precondition that used to guarantee an empty credit: offline,
                // not recording, never broadcast.
                Assert.False(vm.IsLive, "this test is about the NOT-live case");
                Assert.False(vm.IsRecording);
                Assert.Equal(StreamStatus.Offline, vm.StreamStatus);

                // No credit is due yet — the first one lands 5s in.
                Assert.Null(vm.BrandFlashFrame());

                // Step it in 1/30s increments like the real DispatcherTimer. Do NOT
                // pass 5.1 in one call: Advance both opens the presentation AND ages
                // it by the same delta, so a single 5.1s step would blow clean through
                // the 2s window and the credit would be gone before it was ever read.
                Step(vm, 5.1);

                var frame = vm.BrandFlashFrame();
                Assert.True(frame != null,
                    "no credit with no live session: the cadence is still gated on "
                    + "IsLive, so recordings made without going live carry no branding");
                Assert.Equal(1920, frame!.Width);
                Assert.Equal(1080, frame.Height);

                // And it reaches the preview pane in this state too, not just the encoder.
                vm.PublishBrandFlashPreview(frame);
                window.UpdateLayout();
                var pane = (UserControl)window.FindName("PreviewPane")!;
                var holder = Find(pane, e => e is FrameworkElement f
                    && f.Name == "BrandFlashElement") as FrameworkElement;
                Assert.Equal(Visibility.Visible, holder!.Visibility);
            }
            finally
            {
                window.Close();
                MainViewModel.LayoutPathOverride = null;
                SqliteConnection.ClearAllPools();
                try { File.Delete(tempDb); } catch { /* best-effort cleanup */ }
            }
        });
    }

    /// <summary>The presenter is started ONCE for the life of the app now, so the
    /// premium edge stopping its timer is no longer rescued by the next go-live
    /// calling <c>Start()</c> again: a key entered mid-session used to leave the credit
    /// dead until the process restarted. Re-enabling must resume the cadence.</summary>
    [Fact]
    public void ADowngradeMidSession_RestartsTheCadenceTimer()
    {
        _app.Run(() =>
        {
            using var presenter = new BrandFlashPresenter(new Random(11));
            presenter.Start();
            Assert.True(presenter.IsCadenceTimerEnabled,
                "Start() must leave the cadence timer running");

            presenter.Enabled = false;   // premium -> the advertisement is cut and the timer stops
            Assert.False(presenter.IsCadenceTimerEnabled);

            presenter.Enabled = true;    // key entered mid-session: no second Start() will come
            Assert.True(presenter.IsCadenceTimerEnabled,
                "the credit stayed dead after a downgrade — the premium edge stopped the "
                + "timer and nothing restarted it, because Start() is now a one-time "
                + "app-startup call rather than a per-go-live one");
        });
    }

    // ---------- helpers ----------

    private static DependencyObject? Find(DependencyObject parent, Func<DependencyObject, bool> predicate)
    {
        for (var i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
        {
            var child = VisualTreeHelper.GetChild(parent, i);
            if (predicate(child)) return child;
            var found = Find(child, predicate);
            if (found != null) return found;
        }
        return null;
    }

    /// <summary>Drive the clock in 1/30s steps, like the real timer does.</summary>
    private static void Step(BrandFlashPresenter presenter, double seconds)
    {
        for (var t = 0.0; t < seconds; t += 1.0 / 30.0) presenter.Advance(1.0 / 30.0);
    }

    /// <summary>Same stepping, against the ViewModel's own presenter.</summary>
    private static void Step(MainViewModel vm, double seconds)
    {
        for (var t = 0.0; t < seconds; t += 1.0 / 30.0) vm.AdvanceBrandFlash(1.0 / 30.0);
    }

    /// <summary>Alpha bounding box of everything the frame actually drew.</summary>
    private static (int MinX, int MinY, int MaxX, int MaxY) AlphaBounds(VideoFrame frame)
    {
        var minX = int.MaxValue;
        var minY = int.MaxValue;
        var maxX = -1;
        var maxY = -1;
        for (var y = 0; y < frame.Height; y++)
        for (var x = 0; x < frame.Width; x++)
        {
            if (frame.BgraPixels[(y * frame.Stride) + (x * 4) + 3] == 0) continue;
            if (x < minX) minX = x;
            if (x > maxX) maxX = x;
            if (y < minY) minY = y;
            if (y > maxY) maxY = y;
        }
        Assert.True(maxX >= 0, "the credit frame drew no visible pixels at all");
        return (minX, minY, maxX, maxY);
    }

    /// <summary>True when the frame carries near-white opaque pixels — the credit's core.
    /// A black background cannot produce them, so this cannot false-positive.</summary>
    private static bool HasBrightPixels(VideoFrame frame)
    {
        for (var i = 0; i < frame.BgraPixels.Length; i += 4)
        {
            if (frame.BgraPixels[i + 3] < 200) continue;
            if (frame.BgraPixels[i] > 200 && frame.BgraPixels[i + 1] > 200 && frame.BgraPixels[i + 2] > 200)
                return true;
        }
        return false;
    }

    /// <summary>An opaque black master frame. The credit's core is near-white, so it
    /// cannot false-positive against this and the assertion stays honest.</summary>
    private static VideoFrame SolidBlackFrame()
    {
        var w = BrandFlashPresenter.MasterWidth;
        var h = BrandFlashPresenter.MasterHeight;
        var pixels = new byte[w * h * 4];
        for (var i = 0; i < pixels.Length; i += 4) pixels[i + 3] = 255;
        return new VideoFrame(w, h, pixels) { IsOpaque = true };
    }

    /// <summary>Captures the frames the pump actually submits — the same trick the
    /// production encoder uses, so the assertion is about the bytes on the wire.</summary>
    private sealed class CapturingEncoder : IFfmpegEncoder
    {
        public readonly List<VideoFrame> Frames = new();
        public readonly TaskCompletionSource FirstFrame =
            new(TaskCreationOptions.RunContinuationsAsynchronously);

        public int DroppedFrames { get; set; }

        public event EventHandler<StreamHealth>? HealthUpdated;
        public event EventHandler<string>? ProcessFailed;

        public Task StartAsync(EncoderOptions options, CancellationToken ct = default)
            => Task.CompletedTask;

        public Task SubmitFrameAsync(VideoFrame frame, CancellationToken ct = default)
        {
            Frames.Add(new VideoFrame(frame.Width, frame.Height, (byte[])frame.BgraPixels.Clone()));
            FirstFrame.TrySetResult();
            return Task.CompletedTask;
        }

        public Task StopAsync(CancellationToken ct = default) => Task.CompletedTask;
        public void Dispose() { }

        // Never invoked here; present so the fake satisfies the interface the same way
        // FramePumpTests' fake does.
        public void RaiseFailed(string message) => ProcessFailed?.Invoke(this, message);
        public void RaiseHealth(StreamHealth health) => HealthUpdated?.Invoke(this, health);
    }
}