// Licensed to StellaOps under the AGPL-3.0-or-later license.

using System.Collections.Immutable;
using StellaOps.Scanner.EntryTrace.Binary;
using Xunit;

namespace StellaOps.Scanner.EntryTrace.Tests.Binary;

/// <summary>
/// Unit tests for <see cref="IFingerprintIndex"/> implementations.
/// </summary>
public sealed class FingerprintIndexTests
{
    [Fact]
    public async Task InMemoryIndex_Add_IncreasesCount()
    {
        // Arrange
        var index = new InMemoryFingerprintIndex();
        var fingerprint = CreateFingerprint("test-001");
        
        // Act
        await index.AddAsync(fingerprint, "pkg:npm/lodash@4.17.21", "lodash", null);
        
        // Assert
        var stats = index.GetStatistics();
        Assert.Equal(1, stats.TotalFingerprints);
    }

    [Fact]
    public async Task InMemoryIndex_LookupExact_FindsMatch()
    {
        // Arrange
        var index = new InMemoryFingerprintIndex();
        var fingerprint = CreateFingerprint("test-001");
        
        await index.AddAsync(fingerprint, "pkg:npm/lodash@4.17.21", "_.map", null);
        
        // Act
        var matches = await index.LookupAsync(fingerprint);
        
        // Assert
        Assert.Single(matches);
        Assert.Equal("_.map", matches[0].FunctionName);
        Assert.Equal("pkg:npm/lodash@4.17.21", matches[0].SourcePackage);
    }

    [Fact]
    public async Task InMemoryIndex_LookupExactAsync_FindsMatch()
    {
        // Arrange
        var index = new InMemoryFingerprintIndex();
        var fingerprint = CreateFingerprint("test-001");
        
        await index.AddAsync(fingerprint, "pkg:npm/lodash@4.17.21", "_.map", null);
        
        // Act
        var match = await index.LookupExactAsync(fingerprint);
        
        // Assert
        Assert.NotNull(match);
        Assert.Equal("_.map", match.FunctionName);
    }

    [Fact]
    public async Task InMemoryIndex_LookupSimilar_LimitsResults()
    {
        // Arrange
        var index = new InMemoryFingerprintIndex();
        
        // Add many fingerprints
        for (var i = 0; i < 20; i++)
        {
            var fp = CreateFingerprint($"test-{i:D3}");
            await index.AddAsync(fp, $"pkg:npm/lib{i}@1.0.0", $"func_{i}", null);
        }
        
        var queryFp = CreateFingerprint("query");
        
        // Act
        var matches = await index.LookupAsync(queryFp, minSimilarity: 0.1f, maxResults: 5);
        
        // Assert
        Assert.True(matches.Length <= 5);
    }

    [Fact]
    public async Task InMemoryIndex_Clear_RemovesAll()
    {
        // Arrange
        var index = new InMemoryFingerprintIndex();
        
        for (var i = 0; i < 10; i++)
        {
            var fp = CreateFingerprint($"test-{i:D3}");
            await index.AddAsync(fp, $"pkg:npm/lib{i}@1.0.0", $"func_{i}", null);
        }
        
        // Act
        await index.ClearAsync();
        
        // Assert
        var stats = index.GetStatistics();
        Assert.Equal(0, stats.TotalFingerprints);
    }

    [Fact]
    public async Task InMemoryIndex_Statistics_TracksPackages()
    {
        // Arrange
        var index = new InMemoryFingerprintIndex();
        
        var fp1 = CreateFingerprint("test-001");
        var fp2 = CreateFingerprint("test-002");
        var fp3 = CreateFingerprint("test-003");
        
        await index.AddAsync(fp1, "pkg:npm/lodash@4.17.21", "func_a", null);
        await index.AddAsync(fp2, "pkg:npm/lodash@4.17.21", "func_b", null);
        await index.AddAsync(fp3, "pkg:npm/express@4.18.0", "func_c", null);
        
        // Act
        var stats = index.GetStatistics();
        
        // Assert
        Assert.Equal(3, stats.TotalFingerprints);
        Assert.Equal(2, stats.TotalPackages);
    }

    [Fact]
    public async Task VulnerableIndex_TracksVulnerabilities()
    {
        // Arrange
        var index = new VulnerableFingerprintIndex();
        var fp = CreateFingerprint("test-001");
        
        // Act
        await index.AddVulnerableAsync(
            fp, 
            "pkg:npm/lodash@4.17.20", 
            "_.template", 
            "CVE-2021-23337",
            "4.17.0-4.17.20",
            VulnerabilitySeverity.High);
        
        // Assert
        var matches = await index.LookupAsync(fp);
        Assert.Single(matches);
    }

    [Fact]
    public async Task VulnerableIndex_CheckVulnerable_ReturnsMatch()
    {
        // Arrange
        var index = new VulnerableFingerprintIndex();
        var fp = CreateFingerprint("test-001");
        
        await index.AddVulnerableAsync(
            fp, 
            "pkg:npm/lodash@4.17.20", 
            "_.template", 
            "CVE-2021-23337",
            "4.17.0-4.17.20",
            VulnerabilitySeverity.High);
        
        // Act
        var match = await index.CheckVulnerableAsync(fp, 0x1000);
        
        // Assert
        Assert.NotNull(match);
        Assert.Equal("CVE-2021-23337", match.VulnerabilityId);
    }

    [Fact]
    public async Task VulnerableIndex_Statistics_TracksVulns()
    {
        // Arrange
        var index = new VulnerableFingerprintIndex();
        var fp1 = CreateFingerprint("test-001");
        var fp2 = CreateFingerprint("test-002");
        
        await index.AddVulnerableAsync(
            fp1, "pkg:npm/lodash@4.17.20", "_.template", "CVE-2021-23337", "4.17.x", VulnerabilitySeverity.High);
        await index.AddVulnerableAsync(
            fp2, "pkg:npm/moment@2.29.0", "moment.locale", "CVE-2022-24785", "2.29.x", VulnerabilitySeverity.Medium);
        
        // Act
        var stats = index.GetStatistics();
        
        // Assert
        Assert.Equal(2, stats.TotalFingerprints);
        Assert.True(stats.TotalVulnerabilities >= 2);
    }

    [Fact]
    public async Task InMemoryIndex_AddBatch_AddsMultiple()
    {
        // Arrange
        var index = new InMemoryFingerprintIndex();
        
        var matches = Enumerable.Range(0, 10)
            .Select(i => new FingerprintMatch(
                Fingerprint: CreateFingerprint($"test-{i:D3}"),
                FunctionName: $"func_{i}",
                SourcePackage: "pkg:npm/test@1.0.0",
                SourceVersion: "1.0.0",
                SourceFile: null,
                SourceLine: null,
                VulnerabilityIds: ImmutableArray<string>.Empty,
                Similarity: 1.0f,
                MatchedAt: DateTimeOffset.UtcNow))
            .ToList();
        
        // Act
        foreach (var match in matches)
        {
            await index.AddAsync(match);
        }
        
        // Assert
        var stats = index.GetStatistics();
        Assert.Equal(10, stats.TotalFingerprints);
    }

    [Fact]
    public void InMemoryIndex_Count_ReturnsCorrectValue()
    {
        // Arrange
        var index = new InMemoryFingerprintIndex();
        
        // Assert initial
        Assert.Equal(0, index.Count);
    }
    
    [Fact]
    public void InMemoryIndex_IndexedPackages_ReturnsEmptyInitially()
    {
        // Arrange
        var index = new InMemoryFingerprintIndex();
        
        // Assert
        Assert.Empty(index.IndexedPackages);
    }

    private static CodeFingerprint CreateFingerprint(string id)
    {
        return new CodeFingerprint(
            Id: id,
            Algorithm: FingerprintAlgorithm.BasicBlockHash,
            Hash: ImmutableArray.Create<byte>(0x01, 0x02, 0x03, 0x04),
            FunctionSize: 100,
            BasicBlockCount: 5,
            InstructionCount: 20,
            Metadata: ImmutableDictionary<string, string>.Empty);
    }
}