using System.Globalization;
using AcDream.App.Diagnostics;
using Xunit;

namespace AcDream.App.Tests;

public class FrameProfilerReportTests
{
    [Fact]
    public void WriteHistoryCsv_WritesHeaderThenOneInvariantRowPerRecord()
    {
        // 2026-07-24 measurement-tooling review: ACDREAM_FRAME_HISTORY export.
        // FrameBoundary itself needs a live GL context (GpuFrameTimer), so —
        // matching FormatReport's precedent above — the CSV writer is a pure
        // static method tested directly rather than driven through FrameBoundary.
        var records = new[]
        {
            new FrameHistoryRecord(0, 12.5, 1000, 500, 2048, 100, 200, 30, 40),
            new FrameHistoryRecord(1, 18.75, 1200, -1, -256, 110, 210, 31, 41),
        };
        var buffer = new StringWriter(CultureInfo.InvariantCulture);

        FrameProfiler.WriteHistoryCsv(records, buffer);

        string[] lines = buffer.ToString().Split(
            Environment.NewLine, StringSplitOptions.RemoveEmptyEntries);
        Assert.Equal(3, lines.Length);
        Assert.Equal(
            "frame,timestamp_ms,cpu_us,gpu_us,alloc_bytes,update_us,upload_us,imgui_us,pacing_us",
            lines[0]);
        Assert.Equal("0,12.500,1000,500,2048,100,200,30,40", lines[1]);
        // gpu_us=-1 marks "no GPU sample available"; alloc_bytes can go
        // negative (documented alloc-channel behavior, matches FrameStatsBuffer.Max).
        Assert.Equal("1,18.750,1200,-1,-256,110,210,31,41", lines[2]);
    }


    [Fact]
    public void FormatReport_IsInvariantAndComplete()
    {
        var cpu = new FrameStatsBuffer(16);
        var gpu = new FrameStatsBuffer(16);
        var alloc = new FrameStatsBuffer(16);
        var stages = new[]
        {
            new FrameStatsBuffer(16),
            new FrameStatsBuffer(16),
            new FrameStatsBuffer(16),
            new FrameStatsBuffer(16),
        };
        for (long i = 1; i <= 10; i++)
        {
            cpu.Push(i * 1000);      // 1..10 ms in µs
            gpu.Push(i * 100);
            alloc.Push(i * 1024);    // bytes
            stages[0].Push(i * 200);
            stages[1].Push(i * 50);
            stages[2].Push(i * 10);
            stages[3].Push(i * 300);
        }

        string line = FrameProfiler.FormatReport(
            frameCount: 10, cpu: cpu, gpu: gpu, gpuActive: true,
            alloc: alloc, gc0: 3, gc1: 1, gc2: 0, stages: stages);

        Assert.StartsWith("[frame-prof]", line);
        Assert.Contains("n=10", line);
        Assert.Contains("cpu_ms p50=5.0 p95=10.0 p99=10.0 max=10.0", line);
        Assert.Contains("gpu_ms p50=0.5", line);
        Assert.Contains("alloc_kb p50=5.0 max=10.0", line);
        Assert.Contains("gc=3/1/0", line);
        Assert.Contains("upd p50=1.0", line);   // stage 0: 200µs·5 = 1.0 ms
        Assert.Contains("pace p50=1.5", line);
        Assert.DoesNotContain(",0", line.Replace("gc=3/1/0", ""));  // no comma decimals (invariant culture)
    }

    [Fact]
    public void FormatReport_GpuInactive_SaysWhy()
    {
        var empty = new FrameStatsBuffer(4);
        string line = FrameProfiler.FormatReport(
            frameCount: 0, cpu: empty, gpu: empty, gpuActive: false,
            alloc: empty, gc0: 0, gc1: 0, gc2: 0,
            stages: new[] { empty, empty, empty });
        Assert.Contains("gpu=off(wbdiag)", line);
    }
}