using System.Collections.Generic;
using System.IO.Compression;
using System.Linq;
using System.Text;
using System.Threading;
using StellaOps.Scanner.Analyzers.Lang.Java.Internal;
using StellaOps.Scanner.Analyzers.Lang.Java.Internal.ClassPath;
using StellaOps.Scanner.Analyzers.Lang.Java.Internal.ServiceProviders;
using StellaOps.Scanner.Analyzers.Lang.Tests.TestUtilities;
using Xunit;

namespace StellaOps.Scanner.Analyzers.Lang.Java.Tests;

public sealed class JavaServiceProviderScannerTests
{
    [Fact]
    public void Scan_SelectsFirstProviderByClasspathOrder()
    {
        var root = TestPaths.CreateTemporaryDirectory();
        try
        {
            var servicesA = new Dictionary<string, string[]>
            {
                ["java.sql.Driver"] = new[] { "com.example.ADriver" },
            };

            var servicesB = new Dictionary<string, string[]>
            {
                ["java.sql.Driver"] = new[] { "com.example.BDriver" },
            };

            CreateJarWithClasses(root, "libs/a.jar", new[] { "com.example.ADriver" }, servicesA);
            CreateJarWithClasses(root, "libs/b.jar", new[] { "com.example.BDriver" }, servicesB);

            var cancellationToken = CancellationToken.None;
            var context = new LanguageAnalyzerContext(root, TimeProvider.System);
            var workspace = JavaWorkspaceNormalizer.Normalize(context, cancellationToken);
            var classPath = JavaClassPathBuilder.Build(workspace, cancellationToken);
            var analysis = JavaServiceProviderScanner.Scan(classPath, JavaSpiCatalog.Default, cancellationToken);

            var service = Assert.Single(analysis.Services, record => record.ServiceId == "java.sql.Driver");
            Assert.Equal("jdk", service.Category);

            var selected = Assert.Single(service.Candidates.Where(candidate => candidate.IsSelected));
            Assert.Equal("com.example.ADriver", selected.ProviderClass);
            Assert.Empty(service.Warnings);
        }
        finally
        {
            TestPaths.SafeDelete(root);
        }
    }

    [Fact]
    public void Scan_FlagsDuplicateProviders()
    {
        var root = TestPaths.CreateTemporaryDirectory();
        try
        {
            var services = new Dictionary<string, string[]>
            {
                ["java.sql.Driver"] = new[] { "com.example.DuplicateDriver" },
            };

            CreateJarWithClasses(root, "libs/a.jar", new[] { "com.example.DuplicateDriver" }, services);
            CreateJarWithClasses(root, "libs/b.jar", new[] { "com.example.Other" }, services);

            var cancellationToken = CancellationToken.None;
            var context = new LanguageAnalyzerContext(root, TimeProvider.System);
            var workspace = JavaWorkspaceNormalizer.Normalize(context, cancellationToken);
            var classPath = JavaClassPathBuilder.Build(workspace, cancellationToken);
            var analysis = JavaServiceProviderScanner.Scan(classPath, JavaSpiCatalog.Default, cancellationToken);

            var service = Assert.Single(analysis.Services, record => record.ServiceId == "java.sql.Driver");
            Assert.NotEmpty(service.Warnings);
            Assert.Contains(service.Warnings, warning => warning.Contains("duplicate-provider", StringComparison.OrdinalIgnoreCase));
        }
        finally
        {
            TestPaths.SafeDelete(root);
        }
    }

    [Fact]
    public void Scan_RespectsBootFatJarOrdering()
    {
        var root = TestPaths.CreateTemporaryDirectory();
        try
        {
            JavaFixtureBuilder.CreateSpringBootFatJar(root, "apps/app-fat.jar");

            var cancellationToken = CancellationToken.None;
            var context = new LanguageAnalyzerContext(root, TimeProvider.System);
            var workspace = JavaWorkspaceNormalizer.Normalize(context, cancellationToken);
            var classPath = JavaClassPathBuilder.Build(workspace, cancellationToken);
            var analysis = JavaServiceProviderScanner.Scan(classPath, JavaSpiCatalog.Default, cancellationToken);

            var service = Assert.Single(analysis.Services, record => record.ServiceId == "java.sql.Driver");
            var selected = Assert.Single(service.Candidates.Where(candidate => candidate.IsSelected));
            Assert.Equal("com.example.AppDriver", selected.ProviderClass);
            Assert.Contains(service.Candidates.Select(candidate => candidate.ProviderClass), provider => provider == "com.example.LibDriver");
        }
        finally
        {
            TestPaths.SafeDelete(root);
        }
    }

    private static void CreateJarWithClasses(
        string rootDirectory,
        string relativePath,
        IEnumerable<string> classNames,
        IDictionary<string, string[]> serviceDefinitions)
    {
        ArgumentNullException.ThrowIfNull(rootDirectory);
        ArgumentException.ThrowIfNullOrEmpty(relativePath);

        var jarPath = Path.Combine(rootDirectory, relativePath.Replace('/', Path.DirectorySeparatorChar));
        Directory.CreateDirectory(Path.GetDirectoryName(jarPath)!);

        using var fileStream = new FileStream(jarPath, FileMode.Create, FileAccess.ReadWrite, FileShare.None);
        using var archive = new ZipArchive(fileStream, ZipArchiveMode.Create, leaveOpen: false);

        var timestamp = new DateTimeOffset(2024, 01, 01, 0, 0, 0, TimeSpan.Zero);

        foreach (var className in classNames)
        {
            var entryPath = className.Replace('.', '/') + ".class";
            var entry = archive.CreateEntry(entryPath, CompressionLevel.NoCompression);
            entry.LastWriteTime = timestamp;
            using var writer = new BinaryWriter(entry.Open(), Encoding.UTF8, leaveOpen: false);
            writer.Write(new byte[] { 0xCA, 0xFE, 0xBA, 0xBE });
        }

        foreach (var pair in serviceDefinitions)
        {
            var entryPath = "META-INF/services/" + pair.Key;
            var entry = archive.CreateEntry(entryPath, CompressionLevel.NoCompression);
            entry.LastWriteTime = timestamp;
            using var writer = new StreamWriter(entry.Open(), Encoding.UTF8, leaveOpen: false);
            foreach (var provider in pair.Value)
            {
                writer.WriteLine(provider);
            }
        }
    }
}