// =============================================================================
// StellaOps.Integration.Performance - Performance Test Fixture
// Sprint 3500.0004.0003 - T7: Performance Baseline Tests
// =============================================================================

using System.Text.Json;

namespace StellaOps.Integration.Performance;

/// <summary>
/// Test fixture for performance baseline tests.
/// Manages baseline data and measurement recording.
/// </summary>
public sealed class PerformanceTestFixture : IDisposable
{
    private readonly string _baselinesPath;
    private readonly string _outputPath;
    private readonly Dictionary<string, double> _baselines;
    private readonly Dictionary<string, double> _measurements = new();

    public PerformanceTestFixture()
    {
        _baselinesPath = Path.Combine(AppContext.BaseDirectory, "baselines");
        _outputPath = Path.Combine(AppContext.BaseDirectory, "output");

        Directory.CreateDirectory(_outputPath);

        _baselines = LoadBaselines();
    }

    /// <summary>
    /// Gets the baseline value for a metric.
    /// Returns default if baseline not found.
    /// </summary>
    public double GetBaseline(string metric)
    {
        return _baselines.TryGetValue(metric, out var baseline) ? baseline : GetDefaultBaseline(metric);
    }

    /// <summary>
    /// Records a measurement for a metric.
    /// </summary>
    public void RecordMeasurement(string metric, double value)
    {
        _measurements[metric] = value;
    }

    /// <summary>
    /// Gets all recorded measurements.
    /// </summary>
    public IEnumerable<(string metric, double value)> GetAllMeasurements()
    {
        return _measurements.Select(kv => (kv.Key, kv.Value));
    }

    /// <summary>
    /// Gets the path to a test assembly.
    /// </summary>
    public string GetTestAssemblyPath(string name)
    {
        var path = Path.Combine(AppContext.BaseDirectory, "test-assemblies", $"{name}.dll");
        return File.Exists(path) ? path : Path.Combine(AppContext.BaseDirectory, "StellaOps.Integration.Performance.dll");
    }

    /// <summary>
    /// Gets available test assemblies.
    /// </summary>
    public IEnumerable<(string Name, string Path)> GetTestAssemblies()
    {
        var testAssembliesDir = Path.Combine(AppContext.BaseDirectory, "test-assemblies");

        if (Directory.Exists(testAssembliesDir))
        {
            foreach (var file in Directory.GetFiles(testAssembliesDir, "*.dll"))
            {
                yield return (Path.GetFileNameWithoutExtension(file), file);
            }
        }
        else
        {
            // Use self as test assembly
            var selfPath = Path.Combine(AppContext.BaseDirectory, "StellaOps.Integration.Performance.dll");
            if (File.Exists(selfPath))
            {
                yield return ("Self", selfPath);
            }
        }
    }

    /// <summary>
    /// Saves a report file.
    /// </summary>
    public void SaveReport(string filename, string content)
    {
        var path = Path.Combine(_outputPath, filename);
        File.WriteAllText(path, content);
    }

    private Dictionary<string, double> LoadBaselines()
    {
        var baselinesFile = Path.Combine(_baselinesPath, "performance-baselines.json");

        if (File.Exists(baselinesFile))
        {
            var json = File.ReadAllText(baselinesFile);
            return JsonSerializer.Deserialize<Dictionary<string, double>>(json) ?? GetDefaultBaselines();
        }

        return GetDefaultBaselines();
    }

    private static Dictionary<string, double> GetDefaultBaselines()
    {
        return new Dictionary<string, double>
        {
            // Score computation
            ["score_computation_ms"] = 100,
            ["score_computation_large_ms"] = 500,

            // Proof bundle
            ["proof_bundle_generation_ms"] = 200,
            ["proof_signing_ms"] = 50,

            // Call graph
            ["dotnet_callgraph_extraction_ms"] = 500,

            // Reachability
            ["reachability_computation_ms"] = 100,
            ["reachability_large_graph_ms"] = 500,
            ["reachability_deep_path_ms"] = 200
        };
    }

    private static double GetDefaultBaseline(string metric)
    {
        // Default to 1 second for unknown metrics
        return 1000;
    }

    public void Dispose()
    {
        // Save measurements for potential baseline updates
        var measurementsFile = Path.Combine(_outputPath, "measurements.json");
        var json = JsonSerializer.Serialize(_measurements, new JsonSerializerOptions { WriteIndented = true });
        File.WriteAllText(measurementsFile, json);
    }
}