// -----------------------------------------------------------------------------
// IdGenerationBenchmarks.cs
// Sprint: SPRINT_0501_0001_0001_proof_evidence_chain_master
// Task: PROOF-MASTER-0005
// Description: Benchmarks for content-addressed ID generation
// -----------------------------------------------------------------------------

using System.Security.Cryptography;
using System.Text;
using System.Text.Json;
using BenchmarkDotNet.Attributes;

namespace StellaOps.Bench.ProofChain.Benchmarks;

/// <summary>
/// Benchmarks for content-addressed ID generation operations.
/// Target: Evidence ID generation < 50μs for 10KB payload.
/// </summary>
[MemoryDiagnoser]
[SimpleJob(warmupCount: 3, iterationCount: 10)]
public class IdGenerationBenchmarks
{
    private byte[] _smallPayload = null!;
    private byte[] _mediumPayload = null!;
    private byte[] _largePayload = null!;
    private string _canonicalJson = null!;
    private Dictionary<string, object> _bundleData = null!;

    [GlobalSetup]
    public void Setup()
    {
        // Small: 1KB
        _smallPayload = new byte[1024];
        RandomNumberGenerator.Fill(_smallPayload);

        // Medium: 10KB
        _mediumPayload = new byte[10 * 1024];
        RandomNumberGenerator.Fill(_mediumPayload);

        // Large: 100KB
        _largePayload = new byte[100 * 1024];
        RandomNumberGenerator.Fill(_largePayload);

        // Canonical JSON for bundle ID generation
        _bundleData = new Dictionary<string, object>
        {
            ["statements"] = Enumerable.Range(0, 5).Select(i => new
            {
                statementId = $"sha256:{Guid.NewGuid():N}",
                predicateType = "evidence.stella/v1",
                predicate = new { index = i, data = Convert.ToBase64String(_smallPayload) }
            }).ToList(),
            ["signatures"] = new[]
            {
                new { keyId = "key-1", algorithm = "ES256" },
                new { keyId = "key-2", algorithm = "ES256" }
            }
        };

        _canonicalJson = JsonSerializer.Serialize(_bundleData, new JsonSerializerOptions
        {
            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
            WriteIndented = false
        });
    }

    /// <summary>
    /// Baseline: Generate evidence ID from small (1KB) payload.
    /// Target: < 20μs
    /// </summary>
    [Benchmark(Baseline = true)]
    public string GenerateEvidenceId_Small()
    {
        return GenerateContentAddressedId(_smallPayload, "evidence");
    }

    /// <summary>
    /// Generate evidence ID from medium (10KB) payload.
    /// Target: < 50μs
    /// </summary>
    [Benchmark]
    public string GenerateEvidenceId_Medium()
    {
        return GenerateContentAddressedId(_mediumPayload, "evidence");
    }

    /// <summary>
    /// Generate evidence ID from large (100KB) payload.
    /// Target: < 200μs
    /// </summary>
    [Benchmark]
    public string GenerateEvidenceId_Large()
    {
        return GenerateContentAddressedId(_largePayload, "evidence");
    }

    /// <summary>
    /// Generate proof bundle ID from JSON content.
    /// Target: < 500μs
    /// </summary>
    [Benchmark]
    public string GenerateProofBundleId()
    {
        return GenerateContentAddressedId(Encoding.UTF8.GetBytes(_canonicalJson), "bundle");
    }

    /// <summary>
    /// Generate SBOM entry ID (includes PURL formatting).
    /// Target: < 30μs
    /// </summary>
    [Benchmark]
    public string GenerateSbomEntryId()
    {
        var digest = "sha256:" + Convert.ToHexString(SHA256.HashData(_smallPayload)).ToLowerInvariant();
        var purl = "pkg:npm/%40scope/package@1.0.0";
        return $"{digest}:{purl}";
    }

    /// <summary>
    /// Generate reasoning ID with timestamp.
    /// Target: < 25μs
    /// </summary>
    [Benchmark]
    public string GenerateReasoningId()
    {
        var timestamp = DateTimeOffset.UtcNow.ToString("O");
        var input = Encoding.UTF8.GetBytes($"reasoning:{timestamp}:{_canonicalJson}");
        var hash = SHA256.HashData(input);
        return $"sha256:{Convert.ToHexString(hash).ToLowerInvariant()}";
    }

    private static string GenerateContentAddressedId(byte[] content, string prefix)
    {
        var hash = SHA256.HashData(content);
        return $"sha256:{Convert.ToHexString(hash).ToLowerInvariant()}";
    }
}