using System.Text.Json;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using Xunit;

namespace StellaOps.Scanner.Analyzers.Native.Index.Tests;

/// <summary>
/// Unit tests for <see cref="OfflineBuildIdIndex"/>.
/// </summary>
public sealed class OfflineBuildIdIndexTests : IDisposable
{
    private readonly string _tempDir;

    public OfflineBuildIdIndexTests()
    {
        _tempDir = Path.Combine(Path.GetTempPath(), $"buildid-test-{Guid.NewGuid():N}");
        Directory.CreateDirectory(_tempDir);
    }

    public void Dispose()
    {
        if (Directory.Exists(_tempDir))
        {
            Directory.Delete(_tempDir, recursive: true);
        }
    }

    #region Loading Tests

    [Fact]
    public async Task LoadAsync_EmptyIndex_WhenNoPathConfigured()
    {
        var options = Options.Create(new BuildIdIndexOptions { IndexPath = null });
        var index = new OfflineBuildIdIndex(options, NullLogger<OfflineBuildIdIndex>.Instance);

        await index.LoadAsync();

        Assert.True(index.IsLoaded);
        Assert.Equal(0, index.Count);
    }

    [Fact]
    public async Task LoadAsync_EmptyIndex_WhenFileNotFound()
    {
        var options = Options.Create(new BuildIdIndexOptions { IndexPath = "/nonexistent/file.ndjson" });
        var index = new OfflineBuildIdIndex(options, NullLogger<OfflineBuildIdIndex>.Instance);

        await index.LoadAsync();

        Assert.True(index.IsLoaded);
        Assert.Equal(0, index.Count);
    }

    [Fact]
    public async Task LoadAsync_ParsesNdjsonEntries()
    {
        var indexPath = Path.Combine(_tempDir, "index.ndjson");
        await File.WriteAllTextAsync(indexPath, """
            {"build_id":"gnu-build-id:abc123","purl":"pkg:deb/debian/libc6@2.31","distro":"debian","confidence":"exact","indexed_at":"2025-01-15T10:00:00Z"}
            {"build_id":"pe-cv:12345678-1234-1234-1234-123456789012-1","purl":"pkg:nuget/System.Text.Json@8.0.0","confidence":"inferred"}
            {"build_id":"macho-uuid:fedcba9876543210fedcba9876543210","purl":"pkg:brew/openssl@3.0.0","distro":"macos","confidence":"exact"}
            """);

        var options = Options.Create(new BuildIdIndexOptions { IndexPath = indexPath, RequireSignature = false });
        var index = new OfflineBuildIdIndex(options, NullLogger<OfflineBuildIdIndex>.Instance);

        await index.LoadAsync();

        Assert.True(index.IsLoaded);
        Assert.Equal(3, index.Count);
    }

    [Fact]
    public async Task LoadAsync_SkipsEmptyLines()
    {
        var indexPath = Path.Combine(_tempDir, "index-empty-lines.ndjson");
        await File.WriteAllTextAsync(indexPath, """
            {"build_id":"gnu-build-id:abc123","purl":"pkg:deb/debian/libc6@2.31"}
            
            {"build_id":"gnu-build-id:def456","purl":"pkg:deb/debian/libssl@1.1"}
            
            """);

        var options = Options.Create(new BuildIdIndexOptions { IndexPath = indexPath, RequireSignature = false });
        var index = new OfflineBuildIdIndex(options, NullLogger<OfflineBuildIdIndex>.Instance);

        await index.LoadAsync();

        Assert.Equal(2, index.Count);
    }

    [Fact]
    public async Task LoadAsync_SkipsCommentLines()
    {
        var indexPath = Path.Combine(_tempDir, "index-comments.ndjson");
        await File.WriteAllTextAsync(indexPath, """
            # This is a comment
            {"build_id":"gnu-build-id:abc123","purl":"pkg:deb/debian/libc6@2.31"}
            // Another comment style
            {"build_id":"gnu-build-id:def456","purl":"pkg:deb/debian/libssl@1.1"}
            """);

        var options = Options.Create(new BuildIdIndexOptions { IndexPath = indexPath, RequireSignature = false });
        var index = new OfflineBuildIdIndex(options, NullLogger<OfflineBuildIdIndex>.Instance);

        await index.LoadAsync();

        Assert.Equal(2, index.Count);
    }

    [Fact]
    public async Task LoadAsync_SkipsInvalidJsonLines()
    {
        var indexPath = Path.Combine(_tempDir, "index-invalid.ndjson");
        await File.WriteAllTextAsync(indexPath, """
            {"build_id":"gnu-build-id:abc123","purl":"pkg:deb/debian/libc6@2.31"}
            not valid json at all
            {"build_id":"gnu-build-id:def456","purl":"pkg:deb/debian/libssl@1.1"}
            """);

        var options = Options.Create(new BuildIdIndexOptions { IndexPath = indexPath, RequireSignature = false });
        var index = new OfflineBuildIdIndex(options, NullLogger<OfflineBuildIdIndex>.Instance);

        await index.LoadAsync();

        Assert.Equal(2, index.Count);
    }

    #endregion

    #region Lookup Tests

    [Fact]
    public async Task LookupAsync_ReturnsNull_WhenNotFound()
    {
        var indexPath = Path.Combine(_tempDir, "index.ndjson");
        await File.WriteAllTextAsync(indexPath, """
            {"build_id":"gnu-build-id:abc123","purl":"pkg:deb/debian/libc6@2.31"}
            """);

        var options = Options.Create(new BuildIdIndexOptions { IndexPath = indexPath, RequireSignature = false });
        var index = new OfflineBuildIdIndex(options, NullLogger<OfflineBuildIdIndex>.Instance);
        await index.LoadAsync();

        var result = await index.LookupAsync("gnu-build-id:notfound");

        Assert.Null(result);
    }

    [Fact]
    public async Task LookupAsync_ReturnsNull_ForNullOrEmpty()
    {
        var indexPath = Path.Combine(_tempDir, "index.ndjson");
        await File.WriteAllTextAsync(indexPath, """
            {"build_id":"gnu-build-id:abc123","purl":"pkg:deb/debian/libc6@2.31"}
            """);

        var options = Options.Create(new BuildIdIndexOptions { IndexPath = indexPath, RequireSignature = false });
        var index = new OfflineBuildIdIndex(options, NullLogger<OfflineBuildIdIndex>.Instance);
        await index.LoadAsync();

        Assert.Null(await index.LookupAsync(null!));
        Assert.Null(await index.LookupAsync(""));
        Assert.Null(await index.LookupAsync("   "));
    }

    [Fact]
    public async Task LookupAsync_FindsExactMatch()
    {
        var indexPath = Path.Combine(_tempDir, "index.ndjson");
        await File.WriteAllTextAsync(indexPath, """
            {"build_id":"gnu-build-id:abc123def456","purl":"pkg:deb/debian/libc6@2.31","version":"2.31","distro":"debian","confidence":"exact","indexed_at":"2025-01-15T10:00:00Z"}
            """);

        var options = Options.Create(new BuildIdIndexOptions { IndexPath = indexPath, RequireSignature = false });
        var index = new OfflineBuildIdIndex(options, NullLogger<OfflineBuildIdIndex>.Instance);
        await index.LoadAsync();

        var result = await index.LookupAsync("gnu-build-id:abc123def456");

        Assert.NotNull(result);
        Assert.Equal("gnu-build-id:abc123def456", result.BuildId);
        Assert.Equal("pkg:deb/debian/libc6@2.31", result.Purl);
        Assert.Equal("2.31", result.Version);
        Assert.Equal("debian", result.SourceDistro);
        Assert.Equal(BuildIdConfidence.Exact, result.Confidence);
    }

    [Fact]
    public async Task LookupAsync_CaseInsensitive()
    {
        var indexPath = Path.Combine(_tempDir, "index.ndjson");
        await File.WriteAllTextAsync(indexPath, """
            {"build_id":"gnu-build-id:ABC123DEF456","purl":"pkg:deb/debian/libc6@2.31"}
            """);

        var options = Options.Create(new BuildIdIndexOptions { IndexPath = indexPath, RequireSignature = false });
        var index = new OfflineBuildIdIndex(options, NullLogger<OfflineBuildIdIndex>.Instance);
        await index.LoadAsync();

        // Query with lowercase
        var result = await index.LookupAsync("gnu-build-id:abc123def456");

        Assert.NotNull(result);
        Assert.Equal("pkg:deb/debian/libc6@2.31", result.Purl);
    }

    #endregion

    #region Batch Lookup Tests

    [Fact]
    public async Task BatchLookupAsync_ReturnsFoundEntries()
    {
        var indexPath = Path.Combine(_tempDir, "index.ndjson");
        await File.WriteAllTextAsync(indexPath, """
            {"build_id":"gnu-build-id:aaa","purl":"pkg:deb/debian/liba@1.0"}
            {"build_id":"gnu-build-id:bbb","purl":"pkg:deb/debian/libb@1.0"}
            {"build_id":"gnu-build-id:ccc","purl":"pkg:deb/debian/libc@1.0"}
            """);

        var options = Options.Create(new BuildIdIndexOptions { IndexPath = indexPath, RequireSignature = false });
        var index = new OfflineBuildIdIndex(options, NullLogger<OfflineBuildIdIndex>.Instance);
        await index.LoadAsync();

        var results = await index.BatchLookupAsync(["gnu-build-id:aaa", "gnu-build-id:notfound", "gnu-build-id:ccc"]);

        Assert.Equal(2, results.Count);
        Assert.Contains(results, r => r.Purl == "pkg:deb/debian/liba@1.0");
        Assert.Contains(results, r => r.Purl == "pkg:deb/debian/libc@1.0");
    }

    [Fact]
    public async Task BatchLookupAsync_SkipsNullAndEmpty()
    {
        var indexPath = Path.Combine(_tempDir, "index.ndjson");
        await File.WriteAllTextAsync(indexPath, """
            {"build_id":"gnu-build-id:aaa","purl":"pkg:deb/debian/liba@1.0"}
            """);

        var options = Options.Create(new BuildIdIndexOptions { IndexPath = indexPath, RequireSignature = false });
        var index = new OfflineBuildIdIndex(options, NullLogger<OfflineBuildIdIndex>.Instance);
        await index.LoadAsync();

        var results = await index.BatchLookupAsync([null!, "", "   ", "gnu-build-id:aaa"]);

        Assert.Single(results);
        Assert.Equal("pkg:deb/debian/liba@1.0", results[0].Purl);
    }

    #endregion

    #region Confidence Parsing Tests

    [Theory]
    [InlineData("exact", BuildIdConfidence.Exact)]
    [InlineData("EXACT", BuildIdConfidence.Exact)]
    [InlineData("inferred", BuildIdConfidence.Inferred)]
    [InlineData("Inferred", BuildIdConfidence.Inferred)]
    [InlineData("heuristic", BuildIdConfidence.Heuristic)]
    [InlineData("unknown", BuildIdConfidence.Heuristic)] // Defaults to heuristic
    [InlineData("", BuildIdConfidence.Heuristic)]
    public async Task LoadAsync_ParsesConfidenceLevels(string confidenceValue, BuildIdConfidence expected)
    {
        var indexPath = Path.Combine(_tempDir, "index.ndjson");
        var entry = new { build_id = "gnu-build-id:test", purl = "pkg:test/test@1.0", confidence = confidenceValue };
        await File.WriteAllTextAsync(indexPath, JsonSerializer.Serialize(entry));

        var options = Options.Create(new BuildIdIndexOptions { IndexPath = indexPath, RequireSignature = false });
        var index = new OfflineBuildIdIndex(options, NullLogger<OfflineBuildIdIndex>.Instance);
        await index.LoadAsync();

        var result = await index.LookupAsync("gnu-build-id:test");

        Assert.NotNull(result);
        Assert.Equal(expected, result.Confidence);
    }

    #endregion
}