using System.Runtime.CompilerServices;
using FluentAssertions;
using Workflow.Application.BuildFlow.Common.Services;
using Xunit;
using Xunit.Abstractions;

namespace BuildFlow.Workflow.Tests.Performance;

/// <summary>OpenXML 顺序导出的托管内存峰值门禁。</summary>
public sealed class OpenXmlMemoryProfileTests(ITestOutputHelper output)
{
    private const int ExportRows = 50_000;
    private const long MaxPeakDeltaBytes = 128L * 1024 * 1024;

    [Fact]
    public async Task LargeAsyncExportKeepsManagedMemoryBounded()
    {
        var filePath = Path.Combine(
            Path.GetTempPath(),
            $"buildflow-openxml-memory-{Guid.NewGuid():N}.xlsx");
        GC.Collect();
        GC.WaitForPendingFinalizers();
        GC.Collect();
        var baselineBytes = GC.GetTotalMemory(true);
        var peakBytes = baselineBytes;

        void SampleManagedMemory()
        {
            peakBytes = Math.Max(peakBytes, GC.GetTotalMemory(false));
        }

        try
        {
            var service = new FormSchemaExcelService();
            await using var file = new FileStream(
                filePath,
                FileMode.CreateNew,
                FileAccess.ReadWrite,
                FileShare.None,
                81_920,
                FileOptions.Asynchronous | FileOptions.SequentialScan);
            await service.WriteExportAsync(
                SchemaJson,
                "内存门禁",
                CreateRowsAsync(ExportRows, SampleManagedMemory),
                file,
                CancellationToken.None);
            await file.FlushAsync(CancellationToken.None);
            SampleManagedMemory();

            new FileInfo(filePath).Length.Should().BeGreaterThan(0);
            var peakDeltaBytes = Math.Max(0, peakBytes - baselineBytes);
            peakDeltaBytes.Should().BeLessThan(
                MaxPeakDeltaBytes,
                "OpenXML 导出应按行顺序写入，不能把全部 JSON 行或工作表加载到内存");
            output.WriteLine($"SOP_METRIC excel_export_peak_managed_bytes={peakDeltaBytes}");
            output.WriteLine($"SOP_METRIC excel_export_rows={ExportRows}");
        }
        finally
        {
            System.IO.File.Delete(filePath);
        }
    }

    private static async IAsyncEnumerable<string> CreateRowsAsync(
        int count,
        Action sampleManagedMemory,
        [EnumeratorCancellation] CancellationToken ct = default)
    {
        for (var index = 0; index < count; index++)
        {
            ct.ThrowIfCancellationRequested();
            if (index % 128 == 0)
            {
                sampleManagedMemory();
            }

            yield return $$"""{"id":{{index}},"name":"row-{{index}}","active":{{(index % 2 == 0).ToString().ToLowerInvariant()}}}""";
            if (index % 1024 == 0)
            {
                await Task.Yield();
            }
        }

        sampleManagedMemory();
    }

    private const string SchemaJson = """
    {
      "type": "object",
      "properties": {
        "id": { "type": "number", "title": "编号", "x-component": "InputNumber" },
        "name": { "type": "string", "title": "名称", "x-component": "Input" },
        "active": { "type": "boolean", "title": "启用", "x-component": "Switch" }
      }
    }
    """;
}