using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text.RegularExpressions;
using System.Windows.Media;
using Xunit;
using ytLive.Services.Compositor;

namespace ytLive.Tests;

/// <summary>On-stream graphics cannot read application resources (the frame pump is not the UI
/// thread), so their colours live in <see cref="OutputPalette"/>. That duplication is safe only
/// if it is checked: this test proves every brand token there equals the brush in
/// <c>Themes/Tokens.xaml</c>, and that the renderers carry no colour literals of their own.
///
/// <para>Without it, the broadcast picture would drift away from the UI one "quick fix" at a
/// time — the exact failure mode DESIGN.md exists to stop.</para></summary>
public class OutputPaletteTests
{
    [Fact]
    public void The_on_stream_palette_matches_the_theme_and_the_renderers_carry_no_literals()
    {
        var brushes = Tokens();

        var mirrored = new (string Brush, Color Colour)[]
        {
            ("Brush.Primary", OutputPalette.Live),
            ("Brush.PrimaryContainer", OutputPalette.LiveDark),
            ("Brush.Secondary", OutputPalette.Amber),
            ("Brush.Attention", OutputPalette.Attention),
            ("Brush.Positive", OutputPalette.Positive),
            ("Brush.Error", OutputPalette.Error),
            ("Brush.ErrorContainer", OutputPalette.ErrorSurface),
            ("Brush.Tertiary", OutputPalette.Tertiary),
            ("Brush.OnSurface", OutputPalette.TextPrimary),
            ("Brush.OnSurfaceVariant", OutputPalette.TextMuted),
            ("Brush.Background", OutputPalette.Background),
            ("Brush.SurfaceContainer", OutputPalette.Surface),
            ("Brush.SurfaceContainerHigh", OutputPalette.SurfaceHigh),
            ("Brush.Outline", OutputPalette.Outline),
        };

        foreach (var (brushKey, colour) in mirrored)
        {
            Assert.True(brushes.ContainsKey(brushKey), $"{brushKey} missing from Themes/Tokens.xaml");
            Assert.True(brushes[brushKey] == colour,
                $"{brushKey} is {brushes[brushKey]} in the theme but {colour} in OutputPalette — the " +
                "broadcast picture and the UI have drifted apart");
        }

        // The renderers must not introduce colours of their own; the alert accents belong to
        // OutputPalette too, so one file owns every on-stream value.
        foreach (var file in new[]
                 {
                     "Services/AlertRenderer.cs", "Services/Compositor/AlertTickerRenderer.cs",
                     "Services/Compositor/BrandFlashPresenter.cs",
                 })
        {
            var text = SourceAssert.Text(file.Split('/'));
            Assert.DoesNotContain("Color.FromRgb(0x", text);
            Assert.DoesNotContain("\"Segoe UI\"", text);
        }
    }

    private static Dictionary<string, Color> Tokens()
    {
        var text = SourceAssert.Text("Themes", "Tokens.xaml");
        var result = new Dictionary<string, Color>(StringComparer.Ordinal);
        foreach (Match m in Regex.Matches(text, "x:Key=\"(Brush\\.[^\"]+)\"\\s+Color=\"#([0-9a-fA-F]{6,8})\""))
        {
            var hex = m.Groups[2].Value;
            if (hex.Length == 8) hex = hex[2..];   // drop the alpha the palette does not mirror
            var r = int.Parse(hex[..2], NumberStyles.HexNumber, CultureInfo.InvariantCulture);
            var g = int.Parse(hex[2..4], NumberStyles.HexNumber, CultureInfo.InvariantCulture);
            var b = int.Parse(hex[4..6], NumberStyles.HexNumber, CultureInfo.InvariantCulture);
            result[m.Groups[1].Value] = Color.FromRgb((byte)r, (byte)g, (byte)b);
        }
        return result;
    }
}