using System;
using System.Collections.Generic;
using System.Threading;
using Xunit;
using ytLive.Services;
using ytLive.Services.Compositor;

namespace ytLive.Tests;

/// <summary>The strip is state, not events: everything enabled is always on screen. These checks
/// paint the real frame, because a renderer that silently draws nothing would still pass a
/// structural test.</summary>
public class ScoreboardRendererTests
{
    private static readonly List<string> Tiles = new() { "Members 12", "Milestones 3", "SC $47.00" };

    [Fact]
    public void The_strip_paints_the_plate_and_the_text_and_never_needs_a_scroll()
    {
        Exception? failure = null;

        var thread = new Thread(() =>
        {
            try
            {
                // Plate on: half-transparent blue behind white text.
                var plated = ScoreboardRenderer.Render(Tiles, new ScoreboardStyle("#FFFFFF", true, "#0000FF", 0.5));
                Assert.NotNull(plated);
                Assert.Equal(ScoreboardRenderer.Width, plated!.Width);
                Assert.True(plated.Height > 0);

                Assert.True(Count(plated, (r, g, b, a) => b > 150 && r < 60 && g < 60 && a is > 100 and < 170) > 500,
                    "the plate must fill at the chosen colour and opacity");
                Assert.True(Count(plated, (r, g, b, a) => r > 200 && g > 200 && b > 200 && a > 200) > 20,
                    "the text must be painted in the chosen colour");

                // Plate off: the same area is transparent, the text survives.
                var bare = ScoreboardRenderer.Render(Tiles, new ScoreboardStyle("#FFFFFF", false, "#0000FF", 0.5));
                Assert.NotNull(bare);
                Assert.Equal(0, Count(bare!, (r, g, b, a) => b > 150 && r < 60 && g < 60 && a > 100));
                Assert.True(Count(bare!, (r, g, b, a) => r > 200 && g > 200 && b > 200 && a > 200) > 20);

                // Text colour reaches the glyphs.
                var red = ScoreboardRenderer.Render(Tiles, new ScoreboardStyle("#FF0000", false, "#000000", 0.5));
                Assert.True(Count(red!, (r, g, b, a) => r > 180 && g < 80 && b < 80 && a > 200) > 20);

                // The PLATE TOGGLE itself: same text, plate off vs on, different pixels. This is the
                // check that answers "the checkbox has no code behind it".
                var off = ScoreboardRenderer.Render(Tiles, new ScoreboardStyle("#FFFFFF", false, "#0000FF", 0.5));
                var on = ScoreboardRenderer.Render(Tiles, new ScoreboardStyle("#FFFFFF", true, "#0000FF", 0.5));
                Assert.True(Count(on!, (r, g, b, a) => b > 150 && r < 60 && g < 60 && a > 100)
                            > Count(off!, (r, g, b, a) => b > 150 && r < 60 && g < 60 && a > 100) + 500,
                    "turning the plate on must add plate pixels");

                // Opacity: 20% and 80% must produce visibly different plate transparency.
                var faint = ScoreboardRenderer.Render(Tiles, new ScoreboardStyle("#FFFFFF", true, "#0000FF", 0.2));
                var solid = ScoreboardRenderer.Render(Tiles, new ScoreboardStyle("#FFFFFF", true, "#0000FF", 0.8));
                // Sample a plate-only pixel (5px in from the left edge, vertical middle): the text is
                // centred, so nothing anti-aliased can pollute the alpha reading.
                static int AlphaOf(VideoFrame f) => f.BgraPixels[((f.Height / 2) * f.Width + 5) * 4 + 3];
                Assert.InRange(AlphaOf(faint!), 35, 70);     // ~20% of 255
                Assert.InRange(AlphaOf(solid!), 190, 220);   // ~80% of 255
                Assert.True(AlphaOf(solid!) > AlphaOf(faint!) + 100, "the opacity slider must move the alpha");

                // Nothing enabled: no frame at all (the layer draws nothing).
                Assert.Null(ScoreboardRenderer.Render(Array.Empty<string>(), new ScoreboardStyle()));
            }
            catch (Exception ex) { failure = ex; }
        });
        thread.SetApartmentState(ApartmentState.STA);
        thread.Start();
        thread.Join();

        Assert.Null(failure);
    }

    private static int Count(VideoFrame frame, Func<int, int, int, int, bool> predicate)
    {
        var hits = 0;
        for (var i = 0; i < frame.BgraPixels.Length; i += 4)
            if (predicate(frame.BgraPixels[i + 2], frame.BgraPixels[i + 1], frame.BgraPixels[i], frame.BgraPixels[i + 3]))
                hits++;
        return hits;
    }
}