using Bunit;
using ZB.MOM.WW.ScadaBridge.CentralUI.Components.Shared;
using ZB.MOM.WW.ScadaBridge.Commons.Types.Kpi;

namespace ZB.MOM.WW.ScadaBridge.CentralUI.Tests.Components.Shared;

/// <summary>
/// bUnit tests for <see cref="KpiTrendChart"/> — the reusable
/// dependency-free SVG trend chart. Coverage pins the three render states
/// (multi-point chart, unavailable placeholder, single-sample note), the stable
/// <c>data-test</c> slug, and the coordinate-math edge guards (all-equal
/// timestamps, all-zero values) that must not divide by zero or throw.
/// </summary>
public class KpiTrendChartTests : BunitContext
{
    private static readonly DateTime Base = new(2026, 6, 15, 10, 0, 0, DateTimeKind.Utc);

    private static IReadOnlyList<KpiSeriesPoint> ThreePoints() => new[]
    {
        new KpiSeriesPoint(Base, 1.0),
        new KpiSeriesPoint(Base.AddMinutes(5), 4.0),
        new KpiSeriesPoint(Base.AddMinutes(10), 2.0),
    };

    /// <summary>Verifies that an available series with three points renders a polyline, a title and a data-test attribute.</summary>
    [Fact]
    public void Available_WithThreePoints_RendersPolylineTitleAndDataTest()
    {
        var cut = Render<KpiTrendChart>(p => p
            .Add(c => c.Points, ThreePoints())
            .Add(c => c.Title, "Queue Depth")
            .Add(c => c.IsAvailable, true));

        var markup = cut.Markup;
        Assert.Contains("<polyline", markup);
        Assert.Contains("Queue Depth", markup);
        Assert.Contains("data-test=\"kpi-trend-queue-depth\"", markup);
        // The SVG must carry an accessible title.
        Assert.Contains("<title>", markup);
    }

    /// <summary>Verifies that a unit is appended to the rendered value labels.</summary>
    [Fact]
    public void Available_WithUnit_AppendsUnitToValueLabels()
    {
        var cut = Render<KpiTrendChart>(p => p
            .Add(c => c.Points, ThreePoints())
            .Add(c => c.Title, "Oldest Pending")
            .Add(c => c.Unit, "s")
            .Add(c => c.IsAvailable, true));

        // Max value label is "4 s" with the unit suffix applied.
        Assert.Contains("max 4 s", cut.Markup);
    }

    /// <summary>Verifies that an unavailable series renders an em dash placeholder and the error text without a polyline.</summary>
    [Fact]
    public void Unavailable_RendersEmDashPlaceholderAndError_NoPolyline()
    {
        var cut = Render<KpiTrendChart>(p => p
            .Add(c => c.Points, ThreePoints())
            .Add(c => c.Title, "Queue Depth")
            .Add(c => c.IsAvailable, false)
            .Add(c => c.ErrorMessage, "KPI query failed"));

        var markup = cut.Markup;
        Assert.Contains("—", markup); // em dash
        Assert.Contains("KPI query failed", markup);
        Assert.DoesNotContain("<polyline", markup);
    }

    /// <summary>Verifies that null points render the placeholder without a polyline.</summary>
    [Fact]
    public void NullPoints_RendersPlaceholder_NoPolyline()
    {
        var cut = Render<KpiTrendChart>(p => p
            .Add(c => c.Points, (IReadOnlyList<KpiSeriesPoint>?)null)
            .Add(c => c.Title, "Stuck Count")
            .Add(c => c.IsAvailable, true));

        var markup = cut.Markup;
        Assert.Contains("—", markup);
        Assert.DoesNotContain("<polyline", markup);
    }

    /// <summary>Verifies that a single point renders the single-sample state without a polyline and does not throw.</summary>
    [Fact]
    public void SinglePoint_RendersSingleSampleState_NoPolyline_DoesNotThrow()
    {
        var cut = Render<KpiTrendChart>(p => p
            .Add(c => c.Points, new[] { new KpiSeriesPoint(Base, 7.0) })
            .Add(c => c.Title, "Backlog")
            .Add(c => c.IsAvailable, true));

        var markup = cut.Markup;
        Assert.Contains("Only one sample in range.", markup);
        Assert.DoesNotContain("<polyline", markup);
    }

    /// <summary>Verifies that points with identical timestamps render a polyline without throwing.</summary>
    [Fact]
    public void AllEqualTimestamps_DoesNotThrow_AndRendersPolyline()
    {
        // Zero time span would divide by zero without the even-spacing guard.
        var cut = Render<KpiTrendChart>(p => p
            .Add(c => c.Points, new[]
            {
                new KpiSeriesPoint(Base, 1.0),
                new KpiSeriesPoint(Base, 2.0),
                new KpiSeriesPoint(Base, 3.0),
            })
            .Add(c => c.Title, "Flat Time")
            .Add(c => c.IsAvailable, true));

        var markup = cut.Markup;
        Assert.Contains("<polyline", markup);
        // The even-spacing fallback must produce finite coordinates — no NaN or Infinity
        // from the divide-by-zero guard path.
        Assert.DoesNotContain("NaN", markup);
        Assert.DoesNotContain("Infinity", markup);
    }

    /// <summary>Verifies that all-zero values render a flat polyline without throwing.</summary>
    [Fact]
    public void AllZeroValues_DoesNotThrow_AndRendersFlatPolyline()
    {
        // Zero max value would divide by zero without the flat-line guard.
        var cut = Render<KpiTrendChart>(p => p
            .Add(c => c.Points, new[]
            {
                new KpiSeriesPoint(Base, 0.0),
                new KpiSeriesPoint(Base.AddMinutes(5), 0.0),
                new KpiSeriesPoint(Base.AddMinutes(10), 0.0),
            })
            .Add(c => c.Title, "Quiet")
            .Add(c => c.IsAvailable, true));

        var markup = cut.Markup;
        Assert.Contains("<polyline", markup);
        // The zero-max flat-line guard must produce finite coordinates — no NaN or Infinity
        // from the yFrac divide-by-zero protection path.
        Assert.DoesNotContain("NaN", markup);
        Assert.DoesNotContain("Infinity", markup);
    }

    /// <summary>Verifies that a chart title is converted to a stable data-test slug.</summary>
    /// <param name="title">The chart title to slugify.</param>
    /// <param name="expectedDataTest">The expected data-test slug.</param>
    [Theory]
    [InlineData("Queue Depth", "kpi-trend-queue-depth")]
    [InlineData("Oldest Pending (s)", "kpi-trend-oldest-pending-s")]
    [InlineData("  Trailing  Spaces  ", "kpi-trend-trailing-spaces")]
    [InlineData("!!!", "kpi-trend-chart")]
    [InlineData("", "kpi-trend-chart")]
    public void Slugify_ProducesStableSlug(string title, string expectedDataTest)
    {
        Assert.Equal(expectedDataTest, $"kpi-trend-{KpiTrendChart.Slugify(title)}");
    }
}