using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
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.ViewModels;

namespace ytLive.Tests;

/// <summary>
/// TASK 47 Good Dog (take four, 2026-09-26): the alert announcement strip must be
/// DRAWN by the preview pane, in all three display methods, at a pace that is
/// actually readable.
/// <para>The bug: the strip is a global 1920x48 overlay that existed only as a frame-
/// pump callback (<c>alertTicker: () => _alertLayer.AlertTickerFrame</c>), so it
/// reached the stream and never the pane the creator watches — the same class of
/// defect as the missing IsAlertBox trigger, one layer up: something is produced and
/// consumed, but nothing ever displays it. The fix is a preview sink on the layer
/// plus a global <c>AlertTickerElement</c> in PreviewPane.xaml.</para>
/// </summary>
[Collection("RealApp")]
public sealed class AlertTickerPreviewDisplayTests
{
    private readonly RealAppHost _app;

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

    private const string TickerText = "Funder — Super Chat$10.00";
    private const double ClipSeconds = 10.0;

    // ---------- the pane actually draws the strip ----------

    [Fact]
    public void PreviewPane_DrawsTheTickerStrip_AndCollapsesWhenTheAlertEnds()
    {
        _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();

                var frame = AlertTickerRenderer.Render(
                    TickerText, 0.2, AlertDisplayMethod.TickerScroll, ClipSeconds);
                Assert.NotNull(frame);

                vm.PublishAlertTickerPreview(frame);
                window.UpdateLayout();

                var pane = (UserControl)window.FindName("PreviewPane")!;
                var holder = Find(pane, e => e is FrameworkElement f
                    && f.Name == "AlertTickerElement") as FrameworkElement;
                Assert.True(holder != null,
                    "PreviewPane.xaml has no AlertTickerElement — the strip is global, 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 alert ticker element never bound a bitmap, so the strip is never rendered");
                Assert.IsType<System.Windows.Media.Imaging.WriteableBitmap>(image!.Source);

                // The alert ends: the strip must go away again, not sit on top of
                // the next scene forever.
                vm.PublishAlertTickerPreview(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 layer actually publishes to that sink ----------

    [Fact]
    public void AlertLayer_PublishesARealTickerFrameToThePreviewSink()
    {
        _app.Run(() =>
        {
            foreach (var method in new[]
                     {
                         AlertDisplayMethod.TickerScroll,
                         AlertDisplayMethod.Flash,
                         AlertDisplayMethod.Solid,
                     })
            {
                var published = new List<VideoFrame?>();
                var layer = new AlertOverlayLayer(new AlertRenderer(),
                    tickerPreviewSink: f => published.Add(f));
                try
                {
                    var box = new Source
                    {
                        Name = "Stream Alerts",
                        Type = SourceType.AlertBox,
                        AlertShowTicker = true,
                        AlertDisplayMethod = method,
                    };
                    var scene = new Scene { Name = "Live" };
                    scene.Elements.Add(box);

                    // The production entry from the chat feed.
                    layer.OnMessageReceived(new ChatMessage
                    {
                        AuthorName = "Funder",
                        Kind = ChatEventKind.SuperChat,
                        SuperChatDisplayString = "$10.00",
                    }, new[] { scene });

                    var frame = published.LastOrDefault();
                    Assert.True(frame != null, $"{method}: the layer published no ticker frame to the preview");
                    Assert.Equal(1920, frame!.Width);
                    Assert.Equal(48, frame.Height);
                }
                finally
                {
                    layer.Dispose();
                }
            }
        });
    }

    [Fact]
    public void AlertLayer_TickerOff_StaysOffThePreviewSink()
    {
        _app.Run(() =>
        {
            var published = new List<VideoFrame?>();
            var layer = new AlertOverlayLayer(new AlertRenderer(),
                tickerPreviewSink: f => published.Add(f));
            try
            {
                var box = new Source
                {
                    Name = "Stream Alerts",
                    Type = SourceType.AlertBox,
                    AlertShowTicker = false, // creator's existing "Message ticker" switch
                    AlertDisplayMethod = AlertDisplayMethod.Solid,
                };
                var scene = new Scene { Name = "Live" };
                scene.Elements.Add(box);

                layer.OnMessageReceived(new ChatMessage
                {
                    AuthorName = "Funder",
                    Kind = ChatEventKind.SuperChat,
                    SuperChatDisplayString = "$10.00",
                }, new[] { scene });

                Assert.NotEmpty(published);
                Assert.All(published, f => Assert.Null(f));
            }
            finally
            {
                layer.Dispose();
            }
        });
    }

    // ---------- the three methods behave as specified ----------

    [Fact]
    public void TickerScroll_CompletesThreeCrossingsInTheTenSecondAlert()
    {
        // The old constant (140px/s) needed ~17s per pass, so a 10s alert showed the
        // message barely once, entering from the right and never crossing. This is
        // the creator's "readable three times" requirement.
        //
        // The marquee is SEAMLESS — a new copy enters from the right the instant the
        // old one clears the left — so the frame is never blank and "empty frame"
        // can't count a pass. Count the pill's leading edge instead: it sweeps left
        // across one pass, then snaps back to the right edge to start the next.
        var resets = 0;
        var previousEdge = -1;
        for (var t = 0.0; t < ClipSeconds; t += 1.0 / 60.0)
        {
            var frame = AlertTickerRenderer.Render(
                TickerText, t, AlertDisplayMethod.TickerScroll, ClipSeconds);
            Assert.NotNull(frame);
            var edge = LeftmostVisibleColumn(frame!);
            Assert.True(edge >= 0, $"the marquee drew nothing at t={t:0.00}s");
            if (previousEdge >= 0 && edge > previousEdge) resets++;
            previousEdge = edge;
        }

        // Resets are the pass boundaries. The old fixed 140px/s produced zero of them
        // inside a 10s alert (one pass took ~17s), which is the bug this pins.
        Assert.True(resets >= 3,
            $"expected at least three readable passes in {ClipSeconds}s, counted {resets}");
    }

    private static int LeftmostVisibleColumn(VideoFrame frame)
    {
        for (var x = 0; x < frame.Width; x++)
            for (var y = 0; y < frame.Height; y++)
                if (frame.BgraPixels[(y * frame.Stride) + (x * 4) + 3] != 0)
                    return x;
        return -1;
    }

    [Fact]
    public void TickerScroll_MidPassFrame_CarriesVisiblePixels()
    {
        // The empty frame at t=0 is the strip still sitting exactly on the right
        // edge; a pass must actually put the announcement on screen.
        var frame = AlertTickerRenderer.Render(
            TickerText, 1.0, AlertDisplayMethod.TickerScroll, ClipSeconds);
        Assert.NotNull(frame);
        Assert.True(frame!.BgraPixels.Any(b => b != 0), "the marquee never drew anything");
    }

    [Fact]
    public void Solid_IsIdenticalAtEveryMoment()
    {
        var first = AlertTickerRenderer.Render(TickerText, 0.0, AlertDisplayMethod.Solid, ClipSeconds);
        var last = AlertTickerRenderer.Render(TickerText, 9.9, AlertDisplayMethod.Solid, ClipSeconds);
        Assert.NotNull(first);
        Assert.Equal(first!.BgraPixels, last!.BgraPixels);
    }

    [Fact]
    public void Flash_IsOnForHalfOfEachSecond()
    {
        Assert.NotNull(AlertTickerRenderer.Render(TickerText, 0.2, AlertDisplayMethod.Flash, ClipSeconds));
        Assert.Null(AlertTickerRenderer.Render(TickerText, 0.7, AlertDisplayMethod.Flash, ClipSeconds));
        Assert.NotNull(AlertTickerRenderer.Render(TickerText, 1.2, AlertDisplayMethod.Flash, ClipSeconds));
    }

    [Fact]
    public void Render_IgnoresEmptyTextAndDefaultsToScroll()
    {
        Assert.Null(AlertTickerRenderer.Render(null, 1.0));
        Assert.Null(AlertTickerRenderer.Render("   ", 1.0));
    }

    // ---------- the properties panel offers the three methods ----------

    [Theory]
    [InlineData(AlertDisplayMethod.TickerScroll, "Scroll")]
    [InlineData(AlertDisplayMethod.Flash, "Flash")]
    [InlineData(AlertDisplayMethod.Solid, "Solid")]
    public void PropertiesPanel_ShowsTheChosenDisplayMethod(AlertDisplayMethod method, string label)
    {
        _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();
                var box = new Source
                {
                    Name = "Stream Alerts",
                    Type = SourceType.AlertBox,
                    AlertDisplayMethod = method,
                };
                vm.StagedScene!.Elements.Add(box);
                vm.SelectedElement = box;
                window.UpdateLayout();

                var panel = (UserControl)window.FindName("LeftPanel")!;
                var combo = FindDisplayComboBox(panel);
                Assert.True(combo != null,
                    "the alert properties panel has no display-method selector");
                Assert.Equal(label, ((ComboBoxItem)combo!.SelectedItem!).Content);
            }
            finally
            {
                window.Close();
                MainViewModel.LayoutPathOverride = null;
                SqliteConnection.ClearAllPools();
                try { File.Delete(tempDb); } catch { /* best-effort cleanup */ }
            }
        });
    }

    [Fact]
    public void PropertiesPanel_WritesTheChosenDisplayMethodBackToTheModel()
    {
        _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();
                var box = new Source
                {
                    Name = "Stream Alerts",
                    Type = SourceType.AlertBox,
                    AlertDisplayMethod = AlertDisplayMethod.TickerScroll,
                };
                vm.StagedScene!.Elements.Add(box);
                vm.SelectedElement = box;
                window.UpdateLayout();

                var panel = (UserControl)window.FindName("LeftPanel")!;
                var combo = FindDisplayComboBox(panel)!;
                var solid = combo.Items.OfType<ComboBoxItem>().Single(i => (string)i.Content == "Solid");

                combo.SelectedItem = solid;
                window.UpdateLayout();

                // The selector is bound by string ("Solid" -> the enum), so prove the
                // round trip rather than trusting the XAML.
                Assert.Equal(AlertDisplayMethod.Solid, box.AlertDisplayMethod);
            }
            finally
            {
                window.Close();
                MainViewModel.LayoutPathOverride = null;
                SqliteConnection.ClearAllPools();
                try { File.Delete(tempDb); } catch { /* best-effore cleanup */ }
            }
        });
    }

    /// <summary>The alert display selector is the ComboBox offering exactly
    /// Scroll / Flash / Solid (the chat Font selector offers font names instead).</summary>
    private static ComboBox? FindDisplayComboBox(DependencyObject parent)
        => Find(parent, e => e is ComboBox c
            && c.Items.OfType<ComboBoxItem>().Any(i => (string)i.Content == "Scroll")
            && c.Items.OfType<ComboBoxItem>().Any(i => (string)i.Content == "Solid")) as ComboBox;

    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;
    }
}