using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using StellaOps.Scanner.Analyzers.OS.Windows.Msi;
using Xunit;

namespace StellaOps.Scanner.Analyzers.OS.Windows.Msi.Tests;

public class MsiPackageAnalyzerTests
{
    private readonly MsiPackageAnalyzer _analyzer;
    private readonly ILogger _logger;

    public MsiPackageAnalyzerTests()
    {
        _logger = NullLoggerFactory.Instance.CreateLogger<MsiPackageAnalyzer>();
        _analyzer = new MsiPackageAnalyzer((ILogger<MsiPackageAnalyzer>)_logger);
    }

    private OSPackageAnalyzerContext CreateContext(string rootPath)
    {
        return new OSPackageAnalyzerContext(
            rootPath,
            workspacePath: null,
            TimeProvider.System,
            _logger);
    }

    [Fact]
    public void AnalyzerId_ReturnsCorrectValue()
    {
        Assert.Equal("windows-msi", _analyzer.AnalyzerId);
    }

    [Fact]
    public async Task AnalyzeAsync_WithNoMsiDirectory_ReturnsEmptyList()
    {
        // Arrange
        var tempDir = Path.Combine(Path.GetTempPath(), "msi-analyzer-test-" + Guid.NewGuid().ToString("N")[..8]);
        Directory.CreateDirectory(tempDir);

        try
        {
            var context = CreateContext(tempDir);

            // Act
            var result = await _analyzer.AnalyzeAsync(context, CancellationToken.None);

            // Assert
            Assert.NotNull(result);
            Assert.Empty(result.Packages);
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public async Task AnalyzeAsync_WithMsiFiles_ReturnsPackageRecords()
    {
        // Arrange
        var tempDir = Path.Combine(Path.GetTempPath(), "msi-analyzer-test-" + Guid.NewGuid().ToString("N")[..8]);
        var installerDir = Path.Combine(tempDir, "Windows", "Installer");
        Directory.CreateDirectory(installerDir);

        // Create test MSI files
        CreateMinimalMsiFile(Path.Combine(installerDir, "TestApp-1.0.0.msi"));
        CreateMinimalMsiFile(Path.Combine(installerDir, "AnotherApp-2.5.0.msi"));

        try
        {
            var context = CreateContext(tempDir);

            // Act
            var result = await _analyzer.AnalyzeAsync(context, CancellationToken.None);

            // Assert
            Assert.Equal(2, result.Packages.Count);

            var testApp = result.Packages.FirstOrDefault(r => r.Name == "TestApp");
            Assert.NotNull(testApp);
            Assert.Equal("1.0.0", testApp.Version);
            Assert.Equal(PackageEvidenceSource.WindowsMsi, testApp.EvidenceSource);
            Assert.StartsWith("pkg:generic/windows-msi/testapp@1.0.0", testApp.PackageUrl);
            Assert.True(testApp.VendorMetadata.ContainsKey("msi:file_path"));

            var anotherApp = result.Packages.FirstOrDefault(r => r.Name == "AnotherApp");
            Assert.NotNull(anotherApp);
            Assert.Equal("2.5.0", anotherApp.Version);
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public async Task AnalyzeAsync_WithNestedMsiFiles_DiscoversMsisRecursively()
    {
        // Arrange
        var tempDir = Path.Combine(Path.GetTempPath(), "msi-analyzer-test-" + Guid.NewGuid().ToString("N")[..8]);
        var cacheDir = Path.Combine(tempDir, "ProgramData", "Package Cache", "subfolder");
        Directory.CreateDirectory(cacheDir);

        CreateMinimalMsiFile(Path.Combine(cacheDir, "NestedApp-3.0.0.msi"));

        try
        {
            var context = CreateContext(tempDir);

            // Act
            var result = await _analyzer.AnalyzeAsync(context, CancellationToken.None);

            // Assert
            Assert.Single(result.Packages);
            Assert.Equal("NestedApp", result.Packages[0].Name);
            Assert.Equal("3.0.0", result.Packages[0].Version);
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public async Task AnalyzeAsync_WithUserAppDataCache_ScansMsisInUserDirectories()
    {
        // Arrange
        var tempDir = Path.Combine(Path.GetTempPath(), "msi-analyzer-test-" + Guid.NewGuid().ToString("N")[..8]);
        var userCacheDir = Path.Combine(tempDir, "Users", "testuser", "AppData", "Local", "Package Cache");
        Directory.CreateDirectory(userCacheDir);

        CreateMinimalMsiFile(Path.Combine(userCacheDir, "UserApp-1.0.0.msi"));

        try
        {
            var context = CreateContext(tempDir);

            // Act
            var result = await _analyzer.AnalyzeAsync(context, CancellationToken.None);

            // Assert
            Assert.Single(result.Packages);
            Assert.Equal("UserApp", result.Packages[0].Name);
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public async Task AnalyzeAsync_WithInvalidMsiFile_SkipsInvalidFile()
    {
        // Arrange
        var tempDir = Path.Combine(Path.GetTempPath(), "msi-analyzer-test-" + Guid.NewGuid().ToString("N")[..8]);
        var installerDir = Path.Combine(tempDir, "Windows", "Installer");
        Directory.CreateDirectory(installerDir);

        // Create invalid MSI file
        File.WriteAllText(Path.Combine(installerDir, "Invalid.msi"), "Not an MSI");

        // Create valid MSI file
        CreateMinimalMsiFile(Path.Combine(installerDir, "Valid-1.0.0.msi"));

        try
        {
            var context = CreateContext(tempDir);

            // Act
            var result = await _analyzer.AnalyzeAsync(context, CancellationToken.None);

            // Assert - Only valid MSI should be returned
            Assert.Single(result.Packages);
            Assert.Equal("Valid", result.Packages[0].Name);
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public async Task AnalyzeAsync_ResultsAreSortedDeterministically()
    {
        // Arrange
        var tempDir = Path.Combine(Path.GetTempPath(), "msi-analyzer-test-" + Guid.NewGuid().ToString("N")[..8]);
        var installerDir = Path.Combine(tempDir, "Windows", "Installer");
        Directory.CreateDirectory(installerDir);

        // Create MSI files in random order
        CreateMinimalMsiFile(Path.Combine(installerDir, "ZetaApp-1.0.0.msi"));
        CreateMinimalMsiFile(Path.Combine(installerDir, "AlphaApp-1.0.0.msi"));
        CreateMinimalMsiFile(Path.Combine(installerDir, "MidApp-1.0.0.msi"));

        try
        {
            var context = CreateContext(tempDir);

            // Act
            var result = await _analyzer.AnalyzeAsync(context, CancellationToken.None);

            // Assert - Results should be sorted
            Assert.Equal(3, result.Packages.Count);
            Assert.Equal("AlphaApp", result.Packages[0].Name);
            Assert.Equal("MidApp", result.Packages[1].Name);
            Assert.Equal("ZetaApp", result.Packages[2].Name);
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public async Task AnalyzeAsync_WithDuplicateMsiFiles_DeduplicatesByPath()
    {
        // Arrange
        var tempDir = Path.Combine(Path.GetTempPath(), "msi-analyzer-test-" + Guid.NewGuid().ToString("N")[..8]);
        var installerDir = Path.Combine(tempDir, "Windows", "Installer");
        Directory.CreateDirectory(installerDir);

        var msiPath = Path.Combine(installerDir, "TestApp-1.0.0.msi");
        CreateMinimalMsiFile(msiPath);

        try
        {
            var context = CreateContext(tempDir);

            // Act - Execute twice to ensure no duplicates
            var result1 = await _analyzer.AnalyzeAsync(context, CancellationToken.None);
            var result2 = await _analyzer.AnalyzeAsync(context, CancellationToken.None);

            // Assert
            Assert.Single(result1.Packages);
            Assert.Single(result2.Packages);
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public async Task AnalyzeAsync_SetsCorrectFileEvidence()
    {
        // Arrange
        var tempDir = Path.Combine(Path.GetTempPath(), "msi-analyzer-test-" + Guid.NewGuid().ToString("N")[..8]);
        var installerDir = Path.Combine(tempDir, "Windows", "Installer");
        Directory.CreateDirectory(installerDir);

        CreateMinimalMsiFile(Path.Combine(installerDir, "TestApp-1.0.0.msi"));

        try
        {
            var context = CreateContext(tempDir);

            // Act
            var result = await _analyzer.AnalyzeAsync(context, CancellationToken.None);

            // Assert
            Assert.Single(result.Packages);
            var record = result.Packages[0];
            Assert.Single(record.Files);

            var file = record.Files[0];
            Assert.Contains("TestApp-1.0.0.msi", file.Path);
            Assert.NotNull(file.Sha256);
            Assert.StartsWith("sha256:", file.Sha256);
            Assert.True(file.SizeBytes > 0);
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    /// <summary>
    /// Creates a minimal valid OLE compound document (MSI) file for testing.
    /// </summary>
    private static void CreateMinimalMsiFile(string filePath)
    {
        var directory = Path.GetDirectoryName(filePath);
        if (!string.IsNullOrEmpty(directory) && !Directory.Exists(directory))
        {
            Directory.CreateDirectory(directory);
        }

        // OLE compound document header (512 bytes minimum)
        var header = new byte[512];

        // Magic number: D0 CF 11 E0 A1 B1 1A E1
        header[0] = 0xD0;
        header[1] = 0xCF;
        header[2] = 0x11;
        header[3] = 0xE0;
        header[4] = 0xA1;
        header[5] = 0xB1;
        header[6] = 0x1A;
        header[7] = 0xE1;

        // Minor version
        header[0x18] = 0x3E;
        header[0x19] = 0x00;

        // Major version
        header[0x1A] = 0x03;
        header[0x1B] = 0x00;

        // Byte order (little endian)
        header[0x1C] = 0xFE;
        header[0x1D] = 0xFF;

        // Sector size power
        header[0x1E] = 0x09;
        header[0x1F] = 0x00;

        // Mini sector size power
        header[0x20] = 0x06;
        header[0x21] = 0x00;

        File.WriteAllBytes(filePath, header);
    }
}