using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Text.Json;
using System.Security.Cryptography;
using StellaOps.Feedser.Exporter.TrivyDb;

namespace StellaOps.Feedser.Exporter.TrivyDb.Tests;

public sealed class TrivyDbOciWriterTests : IDisposable
{
    private readonly string _root;

    public TrivyDbOciWriterTests()
    {
        _root = Directory.CreateTempSubdirectory("feedser-trivy-oci-tests").FullName;
    }

    [Fact]
    public async Task WritesOciLayoutWithManifestIndex()
    {
        var metadata = Encoding.UTF8.GetBytes("{\"generatedAt\":\"2024-08-01T00:00:00Z\",\"schema\":1}");
        var archive = Enumerable.Range(0, 128).Select(static b => (byte)b).ToArray();
        var generatedAt = DateTimeOffset.Parse("2024-08-01T00:00:00Z");
        var archivePath = Path.Combine(_root, "db.bin");
        File.WriteAllBytes(archivePath, archive);
        var archiveDigest = ComputeDigest(archive);
        var request = new TrivyDbPackageRequest(metadata, archivePath, archiveDigest, archive.LongLength, generatedAt, "2024.08.01");

        var builder = new TrivyDbPackageBuilder();
        var package = builder.BuildPackage(request);

        var writer = new TrivyDbOciWriter();
        var result = await writer.WriteAsync(package, Path.Combine(_root, "oci"), "feedser:v2024.08.01", CancellationToken.None);

        Assert.Equal(package.Manifest.Layers[0].Digest, package.Config.DatabaseDigest);
        Assert.NotEmpty(result.BlobDigests);
        Assert.Contains(result.ManifestDigest, result.BlobDigests);

        var layoutPath = Path.Combine(result.RootDirectory, "oci-layout");
        Assert.True(File.Exists(layoutPath));
        var layoutJson = await File.ReadAllTextAsync(layoutPath, CancellationToken.None);
        Assert.Contains("\"imageLayoutVersion\":\"1.0.0\"", layoutJson, StringComparison.Ordinal);

        var metadataPath = Path.Combine(result.RootDirectory, "metadata.json");
        Assert.True(File.Exists(metadataPath));
        var roundTripMetadata = await File.ReadAllBytesAsync(metadataPath, CancellationToken.None);
        Assert.Equal(metadata, roundTripMetadata);

        var indexPath = Path.Combine(result.RootDirectory, "index.json");
        Assert.True(File.Exists(indexPath));
        using var indexDocument = JsonDocument.Parse(await File.ReadAllBytesAsync(indexPath, CancellationToken.None));
        var manifestElement = indexDocument.RootElement.GetProperty("manifests")[0];
        Assert.Equal(result.ManifestDigest, manifestElement.GetProperty("digest").GetString());
        Assert.Equal(TrivyDbMediaTypes.OciManifest, manifestElement.GetProperty("mediaType").GetString());
        Assert.Equal("feedser:v2024.08.01", manifestElement.GetProperty("annotations").GetProperty("org.opencontainers.image.ref.name").GetString());

        var manifestPath = Path.Combine(result.RootDirectory, "blobs", "sha256", result.ManifestDigest.Split(':')[1]);
        var manifestBytes = await File.ReadAllBytesAsync(manifestPath, CancellationToken.None);
        using var manifestDocument = JsonDocument.Parse(manifestBytes);
        var configDescriptor = manifestDocument.RootElement.GetProperty("config");
        Assert.Equal(package.Manifest.Config.Digest, configDescriptor.GetProperty("digest").GetString());
        Assert.Equal(package.Manifest.Config.MediaType, configDescriptor.GetProperty("mediaType").GetString());
        var layer = manifestDocument.RootElement.GetProperty("layers")[0];
        Assert.Equal(package.Manifest.Layers[0].Digest, layer.GetProperty("digest").GetString());
        Assert.Equal(package.Manifest.Layers[0].MediaType, layer.GetProperty("mediaType").GetString());

        foreach (var digest in package.Blobs.Keys)
        {
            var blobPath = Path.Combine(result.RootDirectory, "blobs", "sha256", digest.Split(':')[1]);
            Assert.True(File.Exists(blobPath));
        }
    }

    [Fact]
    public async Task ThrowsOnUnsupportedDigest()
    {
        var package = new TrivyDbPackage(
            new OciManifest(2, TrivyDbMediaTypes.OciManifest, new OciDescriptor(TrivyDbMediaTypes.TrivyConfig, "sha256:abcd", 4), Array.Empty<OciDescriptor>()),
            new TrivyConfigDocument(TrivyDbMediaTypes.TrivyConfig, DateTimeOffset.UtcNow, "1", "sha256:abcd", 4),
            new Dictionary<string, TrivyDbBlob>
            {
                ["md5:deadbeef"] = TrivyDbBlob.FromBytes(new byte[] { 1, 2, 3, 4 }),
            },
            new byte[] { 123 });

        var writer = new TrivyDbOciWriter();
        await Assert.ThrowsAsync<InvalidOperationException>(() => writer.WriteAsync(package, Path.Combine(_root, "invalid"), "feedser:bad", CancellationToken.None));
    }

    public void Dispose()
    {
        try
        {
            if (Directory.Exists(_root))
            {
                Directory.Delete(_root, recursive: true);
            }
        }
        catch
        {
            // ignore cleanup issues
        }
    }

    private static string ComputeDigest(byte[] payload)
    {
        var hash = SHA256.HashData(payload);
        return "sha256:" + Convert.ToHexString(hash).ToLowerInvariant();
    }
}