namespace StellaOps.Interop.Tests;

using System.Diagnostics;
using System.Security.Cryptography;
using System.Text;

/// <summary>
/// Test harness for SBOM interoperability testing.
/// Coordinates Syft, Grype, Trivy, and cosign tools.
/// </summary>
public sealed class InteropTestHarness : IAsyncLifetime
{
    private readonly ToolManager _toolManager;
    private readonly string _workDir;

    public InteropTestHarness()
    {
        _workDir = Path.Combine(Path.GetTempPath(), $"interop-{Guid.NewGuid():N}");
        _toolManager = new ToolManager(_workDir);
    }

    public async Task InitializeAsync()
    {
        Directory.CreateDirectory(_workDir);

        // Verify tools are available
        await _toolManager.VerifyToolAsync("syft", "--version");
        await _toolManager.VerifyToolAsync("grype", "--version");
        await _toolManager.VerifyToolAsync("cosign", "version");
    }

    /// <summary>
    /// Generate SBOM using Syft.
    /// </summary>
    public async Task<SbomResult> GenerateSbomWithSyft(
        string imageRef,
        SbomFormat format,
        CancellationToken ct = default)
    {
        var formatArg = format switch
        {
            SbomFormat.CycloneDx16 => "cyclonedx-json",
            SbomFormat.Spdx30 => "spdx-json",
            _ => throw new ArgumentException($"Unsupported format: {format}")
        };

        var outputPath = Path.Combine(_workDir, $"sbom-syft-{format}.json");
        var result = await _toolManager.RunAsync(
            "syft",
            $"{imageRef} -o {formatArg}={outputPath}",
            ct);

        if (!result.Success)
            return SbomResult.Failed(result.Error ?? "Syft execution failed");

        var content = await File.ReadAllTextAsync(outputPath, ct);
        var digest = ComputeDigest(content);

        return new SbomResult(
            Success: true,
            Path: outputPath,
            Format: format,
            Content: content,
            Digest: digest);
    }

    /// <summary>
    /// Generate SBOM using Stella scanner.
    /// </summary>
    public async Task<SbomResult> GenerateSbomWithStella(
        string imageRef,
        SbomFormat format,
        CancellationToken ct = default)
    {
        var formatArg = format switch
        {
            SbomFormat.CycloneDx16 => "cyclonedx",
            SbomFormat.Spdx30 => "spdx",
            _ => throw new ArgumentException($"Unsupported format: {format}")
        };

        var outputPath = Path.Combine(_workDir, $"stella-sbom-{format}.json");
        var result = await _toolManager.RunAsync(
            "stella",
            $"scan {imageRef} --sbom-format {formatArg} --sbom-output {outputPath}",
            ct);

        if (!result.Success)
            return SbomResult.Failed(result.Error ?? "Stella execution failed");

        var content = await File.ReadAllTextAsync(outputPath, ct);
        var digest = ComputeDigest(content);

        return new SbomResult(
            Success: true,
            Path: outputPath,
            Format: format,
            Content: content,
            Digest: digest);
    }

    /// <summary>
    /// Attest SBOM using cosign.
    /// </summary>
    public async Task<AttestationResult> AttestWithCosign(
        string sbomPath,
        string imageRef,
        CancellationToken ct = default)
    {
        var result = await _toolManager.RunAsync(
            "cosign",
            $"attest --predicate {sbomPath} --type cyclonedx {imageRef} --yes",
            ct);

        if (!result.Success)
            return AttestationResult.Failed(result.Error ?? "Cosign attestation failed");

        return new AttestationResult(Success: true, ImageRef: imageRef);
    }

    /// <summary>
    /// Scan using Grype from SBOM (no image pull).
    /// </summary>
    public async Task<GrypeScanResult> ScanWithGrypeFromSbom(
        string sbomPath,
        CancellationToken ct = default)
    {
        var outputPath = Path.Combine(_workDir, "grype-findings.json");
        var result = await _toolManager.RunAsync(
            "grype",
            $"sbom:{sbomPath} -o json --file {outputPath}",
            ct);

        if (!result.Success)
            return GrypeScanResult.Failed(result.Error ?? "Grype scan failed");

        var content = await File.ReadAllTextAsync(outputPath, ct);
        var findings = ParseGrypeFindings(content);

        return new GrypeScanResult(
            Success: true,
            Findings: findings,
            RawOutput: content);
    }

    /// <summary>
    /// Compare findings between Stella and Grype.
    /// </summary>
    public FindingsComparisonResult CompareFindings(
        IReadOnlyList<Finding> stellaFindings,
        IReadOnlyList<GrypeFinding> grypeFindings,
        decimal tolerancePercent = 5)
    {
        var stellaVulns = stellaFindings
            .Select(f => (f.VulnerabilityId, f.PackagePurl))
            .ToHashSet();

        var grypeVulns = grypeFindings
            .Select(f => (f.VulnerabilityId, f.PackagePurl))
            .ToHashSet();

        var onlyInStella = stellaVulns.Except(grypeVulns).ToList();
        var onlyInGrype = grypeVulns.Except(stellaVulns).ToList();
        var inBoth = stellaVulns.Intersect(grypeVulns).ToList();

        var totalUnique = stellaVulns.Union(grypeVulns).Count();
        var parityPercent = totalUnique > 0
            ? (decimal)inBoth.Count / totalUnique * 100
            : 100;

        return new FindingsComparisonResult(
            ParityPercent: parityPercent,
            IsWithinTolerance: parityPercent >= (100 - tolerancePercent),
            StellaTotalFindings: stellaFindings.Count,
            GrypeTotalFindings: grypeFindings.Count,
            MatchingFindings: inBoth.Count,
            OnlyInStella: onlyInStella.Count,
            OnlyInGrype: onlyInGrype.Count,
            OnlyInStellaDetails: onlyInStella,
            OnlyInGrypeDetails: onlyInGrype);
    }

    public Task DisposeAsync()
    {
        if (Directory.Exists(_workDir))
            Directory.Delete(_workDir, recursive: true);
        return Task.CompletedTask;
    }

    private static string ComputeDigest(string content) =>
        Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(content))).ToLowerInvariant();

    private static IReadOnlyList<GrypeFinding> ParseGrypeFindings(string json)
    {
        // Placeholder: In real implementation, parse Grype JSON output
        // For now, return empty list
        return Array.Empty<GrypeFinding>();
    }
}