using System.Diagnostics;
using System.Text;
using System.Text.RegularExpressions;
using Microsoft.Win32;
using ZA.CoreService.ESBCertificateManager.Models;

namespace ZA.CoreService.ESBCertificateManager.Services;

/// <summary>
/// Führt Sonic-Container-Operationen über die offizielle MF Management Runtime API aus
/// (JMSConnectorClient + MFProxyFactory + IAgentProxy.restart), per Java-Hilfsprogramm
/// und Client-JARs unter SonicHome/lib bzw. MfClientLibPath.
/// Nutzt ConnectionUrl + Username/Password aus appsettings (SMC / Domain Manager).
/// </summary>
public sealed class SonicMfApiExecutor
{
    private const int MaxJavaSearchDepth = 6;
    private const int MaxJavaFilesToScan = 80;
    private const int MaxCheckedPathsInError = 40;

    private readonly SonicConnection _connection;

    public SonicMfApiExecutor(SonicConnection connection)
    {
        _connection = connection;
    }

    /// <summary>
    /// Liefert den konfigurierten SonicHome-Pfad und die gefundene java.exe (oder null).
    /// Für UI-Status und Diagnose.
    /// </summary>
    public (string SonicHome, string? JavaExe) ResolveRuntimePaths()
    {
        JavaDiscoveryResult result = DiscoverJava();
        string sonicHome = string.IsNullOrWhiteSpace(_connection.SonicHome)
            ? "(leer)"
            : _connection.SonicHome.Trim();
        return (sonicHome, result.JavaExe);
    }

    public Task<(bool Success, string? Error)> TestConnectionAsync(CancellationToken cancellationToken = default)
        => RunAsync("ping", container: null, cancellationToken);

    public async Task<(bool Success, IReadOnlyList<string> Containers, string? Error)> ListContainersAsync(
        CancellationToken cancellationToken = default)
    {
        (bool ok, string? output, string? error) = await RunRawAsync("list", null, cancellationToken);
        if (!ok)
        {
            return (false, [], error ?? output);
        }

        List<string> names = (output ?? string.Empty)
            .Split(['\r', '\n'], StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
            .Where(l => !l.StartsWith("OK:", StringComparison.OrdinalIgnoreCase))
            .Where(l => !l.StartsWith("INFO:", StringComparison.OrdinalIgnoreCase))
            .Where(l => !l.StartsWith("ERROR:", StringComparison.OrdinalIgnoreCase))
            .Where(l => !l.StartsWith("WARN:", StringComparison.OrdinalIgnoreCase))
            .Where(l => !l.StartsWith("Usage:", StringComparison.OrdinalIgnoreCase))
            .ToList();

        return (true, names, null);
    }

    public async Task<(bool Success, string? Output, string? Error)> RestartAsync(
        string containerName,
        CancellationToken cancellationToken = default)
    {
        (bool ok, string? output, string? error) = await RunRawAsync("restart", containerName, cancellationToken);
        if (!ok)
        {
            return (false, output, error);
        }

        bool invoked = (output ?? string.Empty)
            .Contains("OK:RestartInvoked", StringComparison.OrdinalIgnoreCase);
        return invoked
            ? (true, output, error)
            : (false, output, error ?? "Kein OK:RestartInvoked von SonicMfContainerTool.");
    }

    private async Task<(bool Success, string? Error)> RunAsync(
        string command,
        string? container,
        CancellationToken cancellationToken)
    {
        (bool ok, string? output, string? error) = await RunRawAsync(command, container, cancellationToken);
        if (ok)
        {
            return (true, null);
        }

        return (false, error ?? output);
    }

    private async Task<(bool Success, string? Output, string? Error)> RunRawAsync(
        string command,
        string? container,
        CancellationToken cancellationToken)
    {
        (bool prepared, string? javaExe, string? classDir, string? classpath, string? prepareError) =
            await PrepareToolAsync(cancellationToken);
        if (!prepared)
        {
            return (false, null, prepareError);
        }

        List<string> args =
        [
            "-cp", Quote(classpath!),
            "SonicMfContainerTool",
            command,
            "--domain", _connection.DomainName,
            "--url", _connection.ConnectionUrl,
            "--user", _connection.Username,
            "--timeout", Math.Clamp(_connection.TimeoutSeconds, 5, 600).ToString()
        ];

        if (!string.IsNullOrWhiteSpace(container))
        {
            args.Add("--container");
            args.Add(container);
        }

        ProcessStartInfo psi = new()
        {
            FileName = javaExe!,
            Arguments = string.Join(" ", args.Select(EscapeArg)),
            UseShellExecute = false,
            RedirectStandardOutput = true,
            RedirectStandardError = true,
            CreateNoWindow = true,
            StandardOutputEncoding = Encoding.UTF8,
            StandardErrorEncoding = Encoding.UTF8,
            WorkingDirectory = classDir!
        };

        psi.Environment["ESB_SONIC_PASSWORD"] = _connection.Password ?? string.Empty;

        using Process process = new() { StartInfo = psi };
        if (!process.Start())
        {
            return (false, null, "Java-Prozess konnte nicht gestartet werden.");
        }

        using CancellationTokenSource timeoutCts =
            CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
        timeoutCts.CancelAfter(TimeSpan.FromSeconds(Math.Clamp(_connection.TimeoutSeconds, 10, 600)));

        Task<string> stdoutTask = process.StandardOutput.ReadToEndAsync(cancellationToken);
        Task<string> stderrTask = process.StandardError.ReadToEndAsync(cancellationToken);

        try
        {
            await process.WaitForExitAsync(timeoutCts.Token);
        }
        catch (OperationCanceledException) when (!cancellationToken.IsCancellationRequested)
        {
            try { process.Kill(entireProcessTree: true); } catch { /* ignore */ }
            return (false, null, $"MfApi Timeout nach {_connection.TimeoutSeconds}s.");
        }

        string stdout = (await stdoutTask).Trim();
        string stderr = (await stderrTask).Trim();
        string combined = string.Join("\n", new[] { stdout, stderr }.Where(s => s.Length > 0));

        if (process.ExitCode == 0
            && !combined.Contains("ERROR:", StringComparison.OrdinalIgnoreCase))
        {
            return (true, combined, null);
        }

        string err = ExtractError(combined)
            ?? $"SonicMfContainerTool ExitCode={process.ExitCode}";
        return (false, combined.Length > 0 ? combined : null, err);
    }

    private async Task<(bool Ok, string? JavaExe, string? ClassDir, string? Classpath, string? Error)>
        PrepareToolAsync(CancellationToken cancellationToken)
    {
        JavaDiscoveryResult javaResult = DiscoverJava();
        string? javaExe = javaResult.JavaExe;
        if (javaExe is null)
        {
            string sonicHome = string.IsNullOrWhiteSpace(_connection.SonicHome)
                ? "(SonicHome leer / nicht gesetzt)"
                : _connection.SonicHome.Trim();
            string checkedList = javaResult.CheckedPaths.Count == 0
                ? "(keine Kandidaten gesammelt)"
                : string.Join("\n  - ", javaResult.CheckedPaths.Take(MaxCheckedPathsInError));
            if (javaResult.CheckedPaths.Count > MaxCheckedPathsInError)
            {
                checkedList += $"\n  - … (+{javaResult.CheckedPaths.Count - MaxCheckedPathsInError} weitere)";
            }

            return (false, null, null, null,
                "Java nicht gefunden.\n" +
                $"Verwendetes SonicHome: '{sonicHome}'\n" +
                $"SonicHome existiert: {(Directory.Exists(sonicHome) ? "ja" : "nein")}\n" +
                "Konfiguration: SonicConnection.JavaHome / JavaPath, sonst Auto-Suche " +
                "(JAVA_HOME/JRE_HOME, setenv.bat, rekursiv unter SonicHome, MQ/ESB-Nachbarn, Registry, where).\n" +
                "Geprüfte Pfade:\n  - " + checkedList + "\n" +
                "Tipp: JavaHome oder JavaPath in appsettings auf die echte java.exe setzen " +
                "(z.B. C:\\Sonic\\MQ10.0\\jre\\bin\\java.exe).");
        }

        (string? libDir, string? libError) = ResolveLibDirectoryDetailed();
        if (libDir is null)
        {
            return (false, null, null, null, libError);
        }

        int runtimeMajor = await GetJavaClassMajorAsync(javaExe, cancellationToken);
        // Sonic/SMC nutzt typisch Java 8 (major 52). Nie mit höherer Class-Version starten.

        // Vorcompilierte .class/.jar nur nutzen, wenn Class-Version zur Runtime passt.
        if (TryResolvePrebuiltTool(runtimeMajor, out string? prebuiltDir, out string? prebuiltEntry, out string? prebuiltError)
            && prebuiltDir is not null && prebuiltEntry is not null)
        {
            string classpath = BuildClasspath(libDir, prebuiltEntry);
            return (true, javaExe, prebuiltDir, classpath, null);
        }

        // Zur Laufzeit aus .java für Java 8 kompilieren (--release 8 / -source 1.8 -target 1.8).
        string? sourcePath = ResolveToolSourcePath();
        if (sourcePath is null)
        {
            return (false, null, null, null,
                (prebuiltError ?? "Kein SonicMfContainerTool gefunden.") +
                " Tools\\SonicMfContainerTool.java/.class fehlen.\n" +
                $"Runtime-Java: {javaExe} (class major max={runtimeMajor}).");
        }

        string workDir = Path.Combine(Path.GetTempPath(), "esb-sonic-mf-j8");
        Directory.CreateDirectory(workDir);

        string javaTarget = Path.Combine(workDir, "SonicMfContainerTool.java");
        string classFile = Path.Combine(workDir, "SonicMfContainerTool.class");

        File.Copy(sourcePath, javaTarget, overwrite: true);

        string compileClasspath = BuildClasspath(libDir, null);
        string runtimeClasspath = BuildClasspath(libDir, workDir);

        bool classOk = File.Exists(classFile)
            && ReadClassFileMajorVersion(classFile) is int existingMajor
            && existingMajor <= runtimeMajor
            && File.GetLastWriteTimeUtc(classFile) >= File.GetLastWriteTimeUtc(sourcePath);

        if (!classOk)
        {
            string? javac = ResolveJavacExecutable(javaExe);
            if (javac is null)
            {
                return (false, null, null, null,
                    "SonicMfContainerTool muss für Java 8 gebaut werden, aber javac fehlt.\n" +
                    "Tools\\SonicMfContainerTool.class (major<=52) mit ausliefern oder JDK installieren.\n" +
                    $"Gefundene java.exe: {javaExe}");
            }

            // Wichtig: ohne --release 8 erzeugt modernes javac major 65 → UnsupportedClassVersionError auf Sonic-JRE 8.
            string releaseArgs = SupportsJavacRelease8(javac)
                ? "--release 8"
                : "-source 1.8 -target 1.8";

            ProcessStartInfo compilePsi = new()
            {
                FileName = javac,
                Arguments =
                    $"{releaseArgs} -encoding UTF-8 -cp {Quote(compileClasspath)} -d {Quote(workDir)} {Quote(javaTarget)}",
                UseShellExecute = false,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                CreateNoWindow = true,
                StandardOutputEncoding = Encoding.UTF8,
                StandardErrorEncoding = Encoding.UTF8
            };

            using Process compile = new() { StartInfo = compilePsi };
            if (!compile.Start())
            {
                return (false, null, null, null, "javac konnte nicht gestartet werden.");
            }

            string cOut = await compile.StandardOutput.ReadToEndAsync(cancellationToken);
            string cErr = await compile.StandardError.ReadToEndAsync(cancellationToken);
            await compile.WaitForExitAsync(cancellationToken);

            int? builtMajor = File.Exists(classFile) ? ReadClassFileMajorVersion(classFile) : null;
            if (compile.ExitCode != 0 || builtMajor is null || builtMajor > runtimeMajor)
            {
                return (false, null, null, null,
                    "Kompilieren von SonicMfContainerTool für Java 8 fehlgeschlagen.\n" +
                    Truncate((cErr + "\n" + cOut).Trim()) +
                    $"\nErzeugt major={builtMajor?.ToString() ?? "?"}, Runtime erlaubt <={runtimeMajor}.\n" +
                    $"Classpath-Lib: {libDir}");
            }
        }

        return (true, javaExe, workDir, runtimeClasspath, null);
    }

    private bool TryResolvePrebuiltTool(
        int runtimeMajor,
        out string? workDir,
        out string? classpathEntry,
        out string? error)
    {
        workDir = null;
        classpathEntry = null;
        error = null;

        string[] searchDirs =
        [
            Path.Combine(AppContext.BaseDirectory, "Tools"),
            Path.Combine(Directory.GetCurrentDirectory(), "Tools"),
            AppContext.BaseDirectory
        ];

        foreach (string dir in searchDirs.Where(Directory.Exists))
        {
            string classFile = Path.Combine(dir, "SonicMfContainerTool.class");
            if (File.Exists(classFile))
            {
                int? major = ReadClassFileMajorVersion(classFile);
                if (major is not null && major <= runtimeMajor)
                {
                    workDir = dir;
                    classpathEntry = dir;
                    return true;
                }

                error =
                    $"Tools\\SonicMfContainerTool.class ist zu neu (major={major}, braucht <={runtimeMajor} / Java 8).";
                continue;
            }

            // JAR absichtlich nicht blind nutzen – oft noch mit Java 21 gebaut.
            // Nur .class mit geprüftem major<=runtimeMajor.
        }

        error ??= "Tools\\SonicMfContainerTool.class (Java 8) nicht gefunden.";
        return false;
    }

    private static int? ReadClassFileMajorVersion(string classFile)
    {
        try
        {
            byte[] header = new byte[8];
            using FileStream fs = File.OpenRead(classFile);
            if (fs.Read(header, 0, 8) < 8)
            {
                return null;
            }

            // CA FE BA BE | minor | major
            if (header[0] != 0xCA || header[1] != 0xFE || header[2] != 0xBA || header[3] != 0xBE)
            {
                return null;
            }

            return (header[6] << 8) | header[7];
        }
        catch
        {
            return null;
        }
    }

    private static async Task<int> GetJavaClassMajorAsync(string javaExe, CancellationToken cancellationToken)
    {
        try
        {
            ProcessStartInfo psi = new()
            {
                FileName = javaExe,
                Arguments = "-version",
                UseShellExecute = false,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                CreateNoWindow = true
            };

            using Process p = new() { StartInfo = psi };
            if (!p.Start())
            {
                return 52; // Sonic-Default Java 8
            }

            string err = await p.StandardError.ReadToEndAsync(cancellationToken);
            string output = await p.StandardOutput.ReadToEndAsync(cancellationToken);
            await p.WaitForExitAsync(cancellationToken);
            string text = (err + "\n" + output).ToLowerInvariant();

            if (text.Contains("version \"1.8") || text.Contains("version \"8"))
            {
                return 52;
            }

            Match m = Regex.Match(text, @"version ""(\d+)");
            if (m.Success && int.TryParse(m.Groups[1].Value, out int major) && major >= 9)
            {
                // Java 9+ class major = 44 + version  => 9→53, 11→55, 17→61, 21→65
                return 44 + major;
            }
        }
        catch
        {
            // ignore
        }

        return 52;
    }

    private static bool SupportsJavacRelease8(string javacPath)
    {
        try
        {
            using Process p = Process.Start(new ProcessStartInfo
            {
                FileName = javacPath,
                Arguments = "-version",
                UseShellExecute = false,
                RedirectStandardError = true,
                RedirectStandardOutput = true,
                CreateNoWindow = true
            })!;
            string text = (p.StandardError.ReadToEnd() + p.StandardOutput.ReadToEnd()).ToLowerInvariant();
            p.WaitForExit(5000);
            // javac 9+ supports --release
            return !text.Contains("1.8") && !text.Contains("1.7") && !text.Contains("1.6");
        }
        catch
        {
            return false;
        }
    }

    private (string? Dir, string? Error) ResolveLibDirectoryDetailed()
    {
        List<(string Path, string Label)> candidates = [];

        if (!string.IsNullOrWhiteSpace(_connection.MfClientLibPath))
        {
            candidates.Add((_connection.MfClientLibPath.Trim(), "MfClientLibPath"));
        }

        string? mqHome = Environment.GetEnvironmentVariable("MQ_HOME");
        string? esbHome = Environment.GetEnvironmentVariable("ESB_HOME")
            ?? Environment.GetEnvironmentVariable("SONIC_HOME")
            ?? Environment.GetEnvironmentVariable("SONICMQ_HOME");

        if (!string.IsNullOrWhiteSpace(mqHome))
        {
            candidates.Add((Path.Combine(mqHome.Trim().Trim('"'), "lib"), "MQ_HOME\\lib"));
        }

        if (!string.IsNullOrWhiteSpace(esbHome))
        {
            string esb = esbHome.Trim().Trim('"');
            candidates.Add((Path.Combine(esb, "lib"), "ESB_HOME\\lib"));
            candidates.Add((Path.Combine(esb, "MQ", "lib"), "ESB_HOME\\MQ\\lib"));
            candidates.Add((Path.Combine(esb, "mq", "lib"), "ESB_HOME\\mq\\lib"));
        }

        if (!string.IsNullOrWhiteSpace(_connection.SonicHome))
        {
            string sonicHome = _connection.SonicHome.Trim();
            candidates.Add((Path.Combine(sonicHome, "lib"), "SonicHome\\lib"));
            candidates.Add((sonicHome, "SonicHome"));

            // ESB-Home zeigt oft auf Broker/ESB; Client-JARs liegen unter MQ*/lib oder sibling MQ.
            foreach (string nested in EnumerateLikelyLibRoots(sonicHome))
            {
                candidates.Add((nested, "SonicHome-nested\\lib"));
            }

            string? parent = Directory.GetParent(sonicHome)?.FullName;
            if (!string.IsNullOrWhiteSpace(parent))
            {
                candidates.Add((Path.Combine(parent, "lib"), "SonicHome-Parent\\lib"));
                foreach (string nested in EnumerateLikelyLibRoots(parent))
                {
                    candidates.Add((nested, "SonicHome-Parent-nested\\lib"));
                }
            }
        }

        List<string> checkedPaths = [];
        HashSet<string> seen = new(StringComparer.OrdinalIgnoreCase);
        foreach ((string path, string label) in candidates)
        {
            if (string.IsNullOrWhiteSpace(path) || !seen.Add(path))
            {
                continue;
            }

            checkedPaths.Add($"{label}='{path}'");
            if (!Directory.Exists(path))
            {
                continue;
            }

            if (DirectoryHasSonicClientJars(path))
            {
                return (path, null);
            }
        }

        string sonicHomeVal = _connection.SonicHome ?? string.Empty;
        bool sonicHomeExists = !string.IsNullOrWhiteSpace(sonicHomeVal) && Directory.Exists(sonicHomeVal);
        string libPath = string.IsNullOrWhiteSpace(sonicHomeVal)
            ? "(SonicHome leer)"
            : Path.Combine(sonicHomeVal, "lib");

        if (sonicHomeExists && Directory.Exists(libPath)
            && !Directory.EnumerateFiles(libPath, "*.jar", SearchOption.TopDirectoryOnly).Any())
        {
            return (null,
                $"Sonic-Client-JARs fehlen unter '{libPath}' (Ordner existiert, aber keine *.jar).\n" +
                $"Verwendetes SonicHome: '{sonicHomeVal}'\n" +
                "MfApi braucht u.a. mgmt_client.jar / mfcontext.jar / sonic_Client.jar.\n" +
                "Falls SonicHome auf ESB zeigt: auf MQ-Home setzen oder MfClientLibPath auf den MQ\\lib-Ordner.\n" +
                $"Geprüft: {string.Join("; ", checkedPaths)}");
        }

        if (sonicHomeExists && !Directory.Exists(libPath))
        {
            return (null,
                $"SonicHome='{sonicHomeVal}' gefunden, aber Lib-Ordner fehlt: '{libPath}'.\n" +
                "Sonic-Client-Installation prüfen oder MfClientLibPath setzen " +
                "(erwartet *.jar, u.a. mgmt_client.jar).\n" +
                $"Geprüft: {string.Join("; ", checkedPaths)}");
        }

        return (null,
            "Sonic-Client-JARs nicht gefunden. SonicHome\\lib, MQ_HOME\\lib, ESB_HOME\\lib oder MfClientLibPath setzen.\n" +
            $"Verwendetes SonicHome: '{(string.IsNullOrWhiteSpace(sonicHomeVal) ? "(leer)" : sonicHomeVal)}'\n" +
            $"Geprüft:\n  - {string.Join("\n  - ", checkedPaths)}\n" +
            "Benötigt u.a. mgmt_client.jar / mfcontext.jar / sonic_Client.jar.");
    }

    private static IEnumerable<string> EnumerateLikelyLibRoots(string root)
    {
        if (!Directory.Exists(root))
        {
            yield break;
        }

        string[] preferred =
        [
            Path.Combine(root, "MQ", "lib"),
            Path.Combine(root, "mq", "lib"),
            Path.Combine(root, "ESB", "lib"),
            Path.Combine(root, "esb", "lib"),
            Path.Combine(root, "client", "lib"),
            Path.Combine(root, "Client", "lib")
        ];

        foreach (string path in preferred)
        {
            if (Directory.Exists(path))
            {
                yield return path;
            }
        }

        IEnumerable<string> children;
        try
        {
            children = Directory.EnumerateDirectories(root);
        }
        catch
        {
            yield break;
        }

        foreach (string child in children)
        {
            string name = Path.GetFileName(child);
            if (name.StartsWith("MQ", StringComparison.OrdinalIgnoreCase)
                || name.StartsWith("ESB", StringComparison.OrdinalIgnoreCase)
                || name.Contains("Sonic", StringComparison.OrdinalIgnoreCase))
            {
                string lib = Path.Combine(child, "lib");
                if (Directory.Exists(lib))
                {
                    yield return lib;
                }
            }
        }
    }

    private static bool DirectoryHasSonicClientJars(string path)
    {
        try
        {
            string[] jars = Directory.EnumerateFiles(path, "*.jar", SearchOption.TopDirectoryOnly).ToArray();
            if (jars.Length == 0)
            {
                return false;
            }

            // Bevorzugt echte Sonic-Client-Libs; sonst jeder JAR-Ordner als Fallback.
            string[] markers =
            [
                "mgmt_client", "mfcontext", "sonic_Client", "sonic_client", "mf_client", "Sonic"
            ];
            if (jars.Any(j => markers.Any(m =>
                    Path.GetFileName(j).Contains(m, StringComparison.OrdinalIgnoreCase))))
            {
                return true;
            }

            return jars.Length > 0;
        }
        catch
        {
            return false;
        }
    }

    private static string BuildClasspath(string libDir, string? extraEntry)
    {
        // Java-Classpath-Wildcard für alle JARs im Lib-Ordner
        string jars = Path.Combine(libDir, "*");
        return string.IsNullOrWhiteSpace(extraEntry)
            ? jars
            : jars + Path.PathSeparator + extraEntry;
    }

    private static string? ResolveToolSourcePath()
    {
        string[] candidates =
        [
            Path.Combine(AppContext.BaseDirectory, "Tools", "SonicMfContainerTool.java"),
            Path.Combine(Directory.GetCurrentDirectory(), "Tools", "SonicMfContainerTool.java"),
            Path.Combine(AppContext.BaseDirectory, "SonicMfContainerTool.java")
        ];

        return candidates.FirstOrDefault(File.Exists);
    }

    private sealed class JavaDiscoveryResult
    {
        public string? JavaExe { get; set; }
        public List<string> CheckedPaths { get; } = [];
    }

    private string? ResolveJavaExecutable() => DiscoverJava().JavaExe;

    private JavaDiscoveryResult DiscoverJava()
    {
        JavaDiscoveryResult result = new();
        List<string> checkedPaths = result.CheckedPaths;

        foreach (string? configured in new[] { _connection.JavaPath, _connection.JavaHome })
        {
            if (string.IsNullOrWhiteSpace(configured))
            {
                continue;
            }

            string? fromConfig = ResolveToolFromConfiguredPath(configured, JavaExeName, checkedPaths);
            if (fromConfig is not null)
            {
                result.JavaExe = fromConfig;
                return result;
            }
        }

        foreach (string envName in new[] { "JAVA_HOME", "JRE_HOME", "JDK_HOME" })
        {
            string? home = Environment.GetEnvironmentVariable(envName);
            string? fromEnv = ResolveJavaFromHomeDir(home, checkedPaths, envName);
            if (fromEnv is not null)
            {
                result.JavaExe = fromEnv;
                return result;
            }
        }

        string? fromPath = FindOnPath(JavaExeName, checkedPaths) ?? FindOnPath("java", checkedPaths);
        if (fromPath is not null)
        {
            result.JavaExe = fromPath;
            return result;
        }

        string? sonicHome = string.IsNullOrWhiteSpace(_connection.SonicHome)
            ? null
            : _connection.SonicHome.Trim();

        if (!string.IsNullOrWhiteSpace(sonicHome))
        {
            string? fromScripts = FindJavaFromSonicScripts(sonicHome, checkedPaths);
            if (fromScripts is not null)
            {
                result.JavaExe = fromScripts;
                return result;
            }

            string? direct = TryKnownJavaLayouts(sonicHome, checkedPaths);
            if (direct is not null)
            {
                result.JavaExe = direct;
                return result;
            }

            string? nested = FindJavaUnderSonicHome(sonicHome, checkedPaths);
            if (nested is not null)
            {
                result.JavaExe = nested;
                return result;
            }

            string? recursive = FindJavaRecursive(sonicHome, checkedPaths, MaxJavaSearchDepth);
            if (recursive is not null)
            {
                result.JavaExe = recursive;
                return result;
            }

            // Parent / sibling MQ / ESB Layouts
            string? parent = Directory.GetParent(sonicHome)?.FullName;
            if (!string.IsNullOrWhiteSpace(parent))
            {
                string? fromParent = TryKnownJavaLayouts(parent, checkedPaths)
                    ?? FindJavaUnderSonicHome(parent, checkedPaths)
                    ?? FindJavaRecursive(parent, checkedPaths, depth: 3);
                if (fromParent is not null)
                {
                    result.JavaExe = fromParent;
                    return result;
                }

                foreach (string siblingRoot in EnumerateSiblingMqEsbRoots(parent, sonicHome))
                {
                    string? fromSibling = TryKnownJavaLayouts(siblingRoot, checkedPaths)
                        ?? FindJavaUnderSonicHome(siblingRoot, checkedPaths);
                    if (fromSibling is not null)
                    {
                        result.JavaExe = fromSibling;
                        return result;
                    }
                }
            }
        }

        foreach (string commonRoot in EnumerateCommonSonicRoots())
        {
            string? found = TryKnownJavaLayouts(commonRoot, checkedPaths)
                ?? FindJavaUnderSonicHome(commonRoot, checkedPaths);
            if (found is not null)
            {
                result.JavaExe = found;
                return result;
            }
        }

        string? fromRegistry = FindJavaInWindowsRegistry(checkedPaths);
        if (fromRegistry is not null)
        {
            result.JavaExe = fromRegistry;
            return result;
        }

        string? fromWhere = FindJavaViaWhereExe(checkedPaths);
        if (fromWhere is not null)
        {
            result.JavaExe = fromWhere;
            return result;
        }

        string? fromCommon = FindJavaInCommonInstallLocations(checkedPaths);
        if (fromCommon is not null)
        {
            result.JavaExe = fromCommon;
            return result;
        }

        return result;
    }

    private string? ResolveJavacExecutable(string javaExe)
    {
        string javacName = OperatingSystem.IsWindows() ? "javac.exe" : "javac";
        List<string> ignored = [];

        string? dir = Path.GetDirectoryName(javaExe);
        if (!string.IsNullOrWhiteSpace(dir))
        {
            string sibling = Path.Combine(dir, javacName);
            if (File.Exists(sibling))
            {
                return sibling;
            }
        }

        foreach (string? configured in new[] { _connection.JavaPath, _connection.JavaHome })
        {
            string? fromConfig = ResolveToolFromConfiguredPath(configured, javacName, ignored);
            if (fromConfig is not null)
            {
                return fromConfig;
            }
        }

        foreach (string envName in new[] { "JAVA_HOME", "JDK_HOME" })
        {
            string? javaHome = Environment.GetEnvironmentVariable(envName);
            if (!string.IsNullOrWhiteSpace(javaHome))
            {
                string candidate = Path.Combine(javaHome.Trim().Trim('"'), "bin", javacName);
                if (File.Exists(candidate))
                {
                    return candidate;
                }
            }
        }

        if (!string.IsNullOrWhiteSpace(_connection.SonicHome))
        {
            foreach (string root in EnumerateJdkRootsUnderSonicHome(_connection.SonicHome))
            {
                string candidate = Path.Combine(root, "bin", javacName);
                if (File.Exists(candidate))
                {
                    return candidate;
                }
            }
        }

        return FindOnPath(javacName, ignored) ?? FindOnPath("javac", ignored);
    }

    private static string? ResolveToolFromConfiguredPath(
        string? configured,
        string exeName,
        List<string> checkedPaths)
    {
        if (string.IsNullOrWhiteSpace(configured))
        {
            return null;
        }

        string path = configured.Trim().Trim('"');
        NoteChecked(checkedPaths, $"config:{path}");

        if (File.Exists(path))
        {
            if (path.EndsWith(exeName, StringComparison.OrdinalIgnoreCase))
            {
                return path;
            }

            string? parent = Path.GetDirectoryName(path);
            if (!string.IsNullOrWhiteSpace(parent))
            {
                string sibling = Path.Combine(parent, exeName);
                NoteChecked(checkedPaths, sibling);
                if (File.Exists(sibling))
                {
                    return sibling;
                }
            }

            string fileName = Path.GetFileName(path);
            if (fileName.Equals(Path.GetFileNameWithoutExtension(exeName), StringComparison.OrdinalIgnoreCase)
                || fileName.Equals(exeName, StringComparison.OrdinalIgnoreCase))
            {
                return path;
            }
        }

        string fromHome = Path.Combine(path, "bin", exeName);
        NoteChecked(checkedPaths, fromHome);
        return File.Exists(fromHome) ? fromHome : null;
    }

    private static string? ResolveJavaFromHomeDir(string? home, List<string> checkedPaths, string label)
    {
        if (string.IsNullOrWhiteSpace(home))
        {
            NoteChecked(checkedPaths, $"{label}=(leer)");
            return null;
        }

        string trimmed = home.Trim().Trim('"');
        string candidate = Path.Combine(trimmed, "bin", JavaExeName);
        NoteChecked(checkedPaths, $"{label}:{candidate}");
        if (File.Exists(candidate))
        {
            return candidate;
        }

        // Manchmal zeigt JAVA_HOME bereits auf ...\bin
        string asBin = Path.Combine(trimmed, JavaExeName);
        NoteChecked(checkedPaths, $"{label}:{asBin}");
        return File.Exists(asBin) ? asBin : null;
    }

    private static string? TryKnownJavaLayouts(string root, List<string> checkedPaths)
    {
        if (string.IsNullOrWhiteSpace(root))
        {
            return null;
        }

        string[] relatives =
        [
            Path.Combine("jre", "bin", JavaExeName),
            Path.Combine("jdk", "bin", JavaExeName),
            Path.Combine("JRE", "bin", JavaExeName),
            Path.Combine("JDK", "bin", JavaExeName),
            Path.Combine("jre64", "bin", JavaExeName),
            Path.Combine("jdk64", "bin", JavaExeName),
            Path.Combine("Java", "jre", "bin", JavaExeName),
            Path.Combine("Java", "jdk", "bin", JavaExeName),
            Path.Combine("java", "bin", JavaExeName),
            Path.Combine("bin", JavaExeName)
        ];

        foreach (string rel in relatives)
        {
            string candidate = Path.Combine(root, rel);
            NoteChecked(checkedPaths, candidate);
            if (File.Exists(candidate))
            {
                return candidate;
            }
        }

        return null;
    }

    private static string? FindJavaUnderSonicHome(string sonicHome, List<string> checkedPaths)
    {
        if (!Directory.Exists(sonicHome))
        {
            NoteChecked(checkedPaths, $"SonicHome-missing:{sonicHome}");
            return null;
        }

        foreach (string root in EnumerateJdkRootsUnderSonicHome(sonicHome))
        {
            string candidate = Path.Combine(root, "bin", JavaExeName);
            NoteChecked(checkedPaths, candidate);
            if (File.Exists(candidate))
            {
                return candidate;
            }
        }

        return null;
    }

    private static IEnumerable<string> EnumerateJdkRootsUnderSonicHome(string sonicHome)
    {
        if (!Directory.Exists(sonicHome))
        {
            yield break;
        }

        string[] preferredNames =
        [
            "jre", "jdk", "JRE", "JDK", "jre64", "jdk64", "Java", "java"
        ];

        foreach (string name in preferredNames)
        {
            string path = Path.Combine(sonicHome, name);
            if (Directory.Exists(path))
            {
                yield return path;
                string nestedJre = Path.Combine(path, "jre");
                if (Directory.Exists(nestedJre))
                {
                    yield return nestedJre;
                }
            }
        }

        IEnumerable<string> children;
        try
        {
            children = Directory.EnumerateDirectories(sonicHome);
        }
        catch
        {
            yield break;
        }

        foreach (string child in children)
        {
            foreach (string leaf in new[] { "jre", "jdk", "JRE", "JDK", "jre64", "jdk64" })
            {
                string nested = Path.Combine(child, leaf);
                if (Directory.Exists(nested))
                {
                    yield return nested;
                }
            }

            string leafName = Path.GetFileName(child);
            if (leafName.StartsWith("jre", StringComparison.OrdinalIgnoreCase)
                || leafName.StartsWith("jdk", StringComparison.OrdinalIgnoreCase))
            {
                yield return child;
            }
        }
    }

    private static string? FindJavaFromSonicScripts(string sonicHome, List<string> checkedPaths)
    {
        if (!Directory.Exists(sonicHome))
        {
            return null;
        }

        string[] scriptDirs =
        [
            Path.Combine(sonicHome, "bin"),
            sonicHome,
            Path.Combine(sonicHome, "MQ", "bin"),
            Path.Combine(sonicHome, "mq", "bin")
        ];

        string[] scriptNames =
        [
            "setenv.bat", "setenv.sh", "setenv.cmd",
            "sonic_env.bat", "sonic_env.sh", "sonic_env.cmd",
            "startcontainer.bat", "startcontainer.sh",
            "startmc.bat", "startmc.sh",
            "startbroker.bat", "startbroker.sh"
        ];

        List<string> scripts = [];
        foreach (string dir in scriptDirs.Where(Directory.Exists))
        {
            foreach (string name in scriptNames)
            {
                string path = Path.Combine(dir, name);
                if (File.Exists(path))
                {
                    scripts.Add(path);
                }
            }

            try
            {
                foreach (string path in Directory.EnumerateFiles(dir, "sonic_env*", SearchOption.TopDirectoryOnly))
                {
                    scripts.Add(path);
                }

                foreach (string path in Directory.EnumerateFiles(dir, "setenv*", SearchOption.TopDirectoryOnly))
                {
                    scripts.Add(path);
                }
            }
            catch
            {
                // ignore
            }
        }

        foreach (string script in scripts.Distinct(StringComparer.OrdinalIgnoreCase))
        {
            NoteChecked(checkedPaths, $"script:{script}");
            string? found = ParseJavaFromEnvScript(script, sonicHome, checkedPaths);
            if (found is not null)
            {
                return found;
            }
        }

        return null;
    }

    private static string? ParseJavaFromEnvScript(string scriptPath, string sonicHome, List<string> checkedPaths)
    {
        string text;
        try
        {
            text = File.ReadAllText(scriptPath);
        }
        catch
        {
            return null;
        }

        // JAVA_HOME / JRE_HOME / JDK_HOME Assignments
        Regex homeAssign = new(
            @"(?im)(?:set\s+)?(?<key>JAVA_HOME|JRE_HOME|JDK_HOME)\s*=\s*(?<val>[^\r\n]+)");
        foreach (Match match in homeAssign.Matches(text))
        {
            string raw = ExpandScriptPath(match.Groups["val"].Value, sonicHome);
            string? resolved = ResolveJavaFromHomeDir(raw, checkedPaths, Path.GetFileName(scriptPath));
            if (resolved is not null)
            {
                return resolved;
            }
        }

        // Direkte java.exe-Pfade in Scripten
        Regex javaExeRef = new(
            @"(?i)(?<path>(?:[A-Za-z]:\\|/)[^\s""']+?[/\\]java(?:\.exe)?)");
        foreach (Match match in javaExeRef.Matches(text))
        {
            string raw = ExpandScriptPath(match.Groups["path"].Value, sonicHome);
            NoteChecked(checkedPaths, $"script-java:{raw}");
            if (File.Exists(raw))
            {
                return raw;
            }
        }

        return null;
    }

    private static string ExpandScriptPath(string raw, string sonicHome)
    {
        string value = raw.Trim().Trim('"', '\'', '`');

        // Zuerst Variablen expandieren, danach Rauschen (Kommentare/Operatoren) abschneiden.
        value = Regex.Replace(value, "%~dp0", sonicHome + Path.DirectorySeparatorChar,
            RegexOptions.IgnoreCase);
        value = Regex.Replace(value, "%SONIC_HOME%", sonicHome, RegexOptions.IgnoreCase);
        value = Regex.Replace(value, "%MQ_HOME%",
            Environment.GetEnvironmentVariable("MQ_HOME") ?? sonicHome, RegexOptions.IgnoreCase);
        value = Regex.Replace(value, "%ESB_HOME%",
            Environment.GetEnvironmentVariable("ESB_HOME") ?? sonicHome, RegexOptions.IgnoreCase);
        value = Regex.Replace(value, "%JAVA_HOME%",
            Environment.GetEnvironmentVariable("JAVA_HOME") ?? string.Empty, RegexOptions.IgnoreCase);
        value = Regex.Replace(value, "%JRE_HOME%",
            Environment.GetEnvironmentVariable("JRE_HOME") ?? string.Empty, RegexOptions.IgnoreCase);

        value = Regex.Replace(value, @"\$\{?SONIC_HOME\}?", sonicHome, RegexOptions.IgnoreCase);
        value = Regex.Replace(value, @"\$\{?MQ_HOME\}?",
            Environment.GetEnvironmentVariable("MQ_HOME") ?? sonicHome, RegexOptions.IgnoreCase);
        value = Regex.Replace(value, @"\$\{?JAVA_HOME\}?",
            Environment.GetEnvironmentVariable("JAVA_HOME") ?? string.Empty, RegexOptions.IgnoreCase);
        value = Regex.Replace(value, @"\$\{?JRE_HOME\}?",
            Environment.GetEnvironmentVariable("JRE_HOME") ?? string.Empty, RegexOptions.IgnoreCase);

        // trailing " & rem ..." / " && ..." entfernen
        int cut = value.IndexOfAny(['&', '|', '>', '<', '`']);
        if (cut >= 0)
        {
            value = value[..cut];
        }

        int rem = value.IndexOf(" rem ", StringComparison.OrdinalIgnoreCase);
        if (rem >= 0)
        {
            value = value[..rem];
        }

        if (value.StartsWith('.') || value.StartsWith(".."))
        {
            try
            {
                value = Path.GetFullPath(Path.Combine(sonicHome, value));
            }
            catch
            {
                // keep as-is
            }
        }

        return value.Trim().Trim('"', '\'');
    }

    private static string? FindJavaRecursive(string root, List<string> checkedPaths, int depth)
    {
        if (!Directory.Exists(root) || depth < 1)
        {
            return null;
        }

        List<string> preferred = [];
        List<string> others = [];
        int scanned = 0;

        void Walk(string dir, int remaining)
        {
            if (scanned >= MaxJavaFilesToScan || remaining < 0)
            {
                return;
            }

            try
            {
                string candidate = Path.Combine(dir, JavaExeName);
                if (File.Exists(candidate))
                {
                    scanned++;
                    string normalized = candidate.Replace('/', Path.DirectorySeparatorChar);
                    if (normalized.Contains($"{Path.DirectorySeparatorChar}jre{Path.DirectorySeparatorChar}bin{Path.DirectorySeparatorChar}",
                            StringComparison.OrdinalIgnoreCase)
                        || normalized.Contains($"{Path.DirectorySeparatorChar}jdk{Path.DirectorySeparatorChar}bin{Path.DirectorySeparatorChar}",
                            StringComparison.OrdinalIgnoreCase))
                    {
                        preferred.Add(candidate);
                    }
                    else
                    {
                        others.Add(candidate);
                    }
                }

                if (remaining == 0 || scanned >= MaxJavaFilesToScan)
                {
                    return;
                }

                foreach (string child in Directory.EnumerateDirectories(dir))
                {
                    string name = Path.GetFileName(child);
                    if (name.Equals("tmp", StringComparison.OrdinalIgnoreCase)
                        || name.Equals("temp", StringComparison.OrdinalIgnoreCase)
                        || name.Equals("logs", StringComparison.OrdinalIgnoreCase)
                        || name.Equals("log", StringComparison.OrdinalIgnoreCase)
                        || name.Equals(".git", StringComparison.OrdinalIgnoreCase)
                        || name.Equals("node_modules", StringComparison.OrdinalIgnoreCase))
                    {
                        continue;
                    }

                    Walk(child, remaining - 1);
                    if (scanned >= MaxJavaFilesToScan)
                    {
                        return;
                    }
                }
            }
            catch
            {
                // inaccessible directory
            }
        }

        Walk(root, depth);

        string? best = preferred.FirstOrDefault() ?? others.FirstOrDefault();
        if (best is not null)
        {
            NoteChecked(checkedPaths, $"recursive-hit:{best}");
            return best;
        }

        NoteChecked(checkedPaths, $"recursive-miss:{root} (depth<={depth}, scanned={scanned})");
        return null;
    }

    private static IEnumerable<string> EnumerateSiblingMqEsbRoots(string parent, string currentSonicHome)
    {
        if (!Directory.Exists(parent))
        {
            yield break;
        }

        IEnumerable<string> children;
        try
        {
            children = Directory.EnumerateDirectories(parent);
        }
        catch
        {
            yield break;
        }

        foreach (string child in children)
        {
            if (string.Equals(child, currentSonicHome, StringComparison.OrdinalIgnoreCase))
            {
                continue;
            }

            string name = Path.GetFileName(child);
            if (name.StartsWith("MQ", StringComparison.OrdinalIgnoreCase)
                || name.StartsWith("ESB", StringComparison.OrdinalIgnoreCase)
                || name.Contains("Sonic", StringComparison.OrdinalIgnoreCase))
            {
                yield return child;
            }
        }
    }

    private static IEnumerable<string> EnumerateCommonSonicRoots()
    {
        string[] roots =
        [
            @"C:\Sonic",
            @"C:\Program Files\Progress",
            @"C:\Program Files\Aurea",
            @"C:\Program Files (x86)\Progress",
            @"C:\Program Files (x86)\Aurea",
            @"D:\Sonic",
            Environment.GetEnvironmentVariable("MQ_HOME") ?? string.Empty,
            Environment.GetEnvironmentVariable("ESB_HOME") ?? string.Empty,
            Environment.GetEnvironmentVariable("SONIC_HOME") ?? string.Empty
        ];

        foreach (string root in roots.Where(r => !string.IsNullOrWhiteSpace(r)).Distinct(StringComparer.OrdinalIgnoreCase))
        {
            if (Directory.Exists(root))
            {
                yield return root;
            }

            string? parentExists = Directory.Exists(root) ? root : null;
            if (parentExists is null)
            {
                continue;
            }

            IEnumerable<string> children;
            try
            {
                children = Directory.EnumerateDirectories(parentExists);
            }
            catch
            {
                continue;
            }

            foreach (string child in children)
            {
                string name = Path.GetFileName(child);
                if (name.StartsWith("MQ", StringComparison.OrdinalIgnoreCase)
                    || name.StartsWith("ESB", StringComparison.OrdinalIgnoreCase)
                    || name.Contains("Sonic", StringComparison.OrdinalIgnoreCase))
                {
                    yield return child;
                }
            }
        }
    }

    private static string? FindJavaInWindowsRegistry(List<string> checkedPaths)
    {
        if (!OperatingSystem.IsWindows())
        {
            return null;
        }

        string[] keyPaths =
        [
            @"SOFTWARE\JavaSoft\Java Runtime Environment",
            @"SOFTWARE\JavaSoft\JDK",
            @"SOFTWARE\JavaSoft\Java Development Kit",
            @"SOFTWARE\Eclipse Adoptium\JRE",
            @"SOFTWARE\Eclipse Adoptium\JDK",
            @"SOFTWARE\WOW6432Node\JavaSoft\Java Runtime Environment",
            @"SOFTWARE\WOW6432Node\JavaSoft\JDK"
        ];

        foreach (string keyPath in keyPaths)
        {
            try
            {
                using RegistryKey? baseKey = Registry.LocalMachine.OpenSubKey(keyPath);
                if (baseKey is null)
                {
                    NoteChecked(checkedPaths, $"registry-miss:HKLM\\{keyPath}");
                    continue;
                }

                NoteChecked(checkedPaths, $"registry:HKLM\\{keyPath}");

                string? current = baseKey.GetValue("CurrentVersion") as string;
                if (!string.IsNullOrWhiteSpace(current))
                {
                    using RegistryKey? verKey = baseKey.OpenSubKey(current);
                    string? javaHome = verKey?.GetValue("JavaHome") as string;
                    string? resolved = ResolveJavaFromHomeDir(javaHome, checkedPaths, $"registry:{current}");
                    if (resolved is not null)
                    {
                        return resolved;
                    }
                }

                foreach (string subName in baseKey.GetSubKeyNames().OrderByDescending(s => s))
                {
                    using RegistryKey? verKey = baseKey.OpenSubKey(subName);
                    string? javaHome = verKey?.GetValue("JavaHome") as string
                        ?? verKey?.GetValue("Path") as string;
                    string? resolved = ResolveJavaFromHomeDir(javaHome, checkedPaths, $"registry:{subName}");
                    if (resolved is not null)
                    {
                        return resolved;
                    }
                }
            }
            catch
            {
                NoteChecked(checkedPaths, $"registry-error:HKLM\\{keyPath}");
            }
        }

        return null;
    }

    private static string? FindJavaViaWhereExe(List<string> checkedPaths)
    {
        if (!OperatingSystem.IsWindows())
        {
            return null;
        }

        try
        {
            ProcessStartInfo psi = new()
            {
                FileName = "where.exe",
                Arguments = "java",
                UseShellExecute = false,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                CreateNoWindow = true
            };

            using Process process = new() { StartInfo = psi };
            if (!process.Start())
            {
                NoteChecked(checkedPaths, "where.exe:start-failed");
                return null;
            }

            string output = process.StandardOutput.ReadToEnd();
            process.WaitForExit(3000);
            foreach (string line in output.Split(['\r', '\n'], StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries))
            {
                NoteChecked(checkedPaths, $"where:{line}");
                if (File.Exists(line)
                    && Path.GetFileName(line).Equals(JavaExeName, StringComparison.OrdinalIgnoreCase))
                {
                    return line;
                }
            }
        }
        catch (Exception ex)
        {
            NoteChecked(checkedPaths, $"where.exe:error:{ex.GetType().Name}");
        }

        return null;
    }

    private static string? FindJavaInCommonInstallLocations(List<string> checkedPaths)
    {
        string[] roots =
        [
            Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles),
            Environment.GetFolderPath(Environment.SpecialFolder.ProgramFilesX86),
            @"C:\Program Files",
            @"C:\Program Files (x86)"
        ];

        string[] vendorFolders =
        [
            "Java",
            "Eclipse Adoptium",
            "AdoptOpenJDK",
            "Microsoft",
            "Amazon Corretto",
            "Zulu",
            "BellSoft",
            "Semeru",
            "Progress",
            "Aurea"
        ];

        foreach (string root in roots.Where(r => !string.IsNullOrWhiteSpace(r)).Distinct(StringComparer.OrdinalIgnoreCase))
        {
            foreach (string vendor in vendorFolders)
            {
                string vendorDir = Path.Combine(root, vendor);
                if (!Directory.Exists(vendorDir))
                {
                    continue;
                }

                string direct = Path.Combine(vendorDir, "bin", JavaExeName);
                NoteChecked(checkedPaths, direct);
                if (File.Exists(direct))
                {
                    return direct;
                }

                try
                {
                    foreach (string sub in Directory.EnumerateDirectories(vendorDir)
                                 .OrderByDescending(d => d, StringComparer.OrdinalIgnoreCase))
                    {
                        string candidate = Path.Combine(sub, "bin", JavaExeName);
                        NoteChecked(checkedPaths, candidate);
                        if (File.Exists(candidate))
                        {
                            return candidate;
                        }

                        string nestedJre = Path.Combine(sub, "jre", "bin", JavaExeName);
                        NoteChecked(checkedPaths, nestedJre);
                        if (File.Exists(nestedJre))
                        {
                            return nestedJre;
                        }
                    }
                }
                catch
                {
                    // ignore inaccessible vendor dirs
                }
            }
        }

        return null;
    }

    private static void NoteChecked(List<string> checkedPaths, string path)
    {
        if (checkedPaths.Count >= MaxCheckedPathsInError * 2)
        {
            return;
        }

        if (!checkedPaths.Contains(path, StringComparer.OrdinalIgnoreCase))
        {
            checkedPaths.Add(path);
        }
    }

    private static string JavaExeName => OperatingSystem.IsWindows() ? "java.exe" : "java";

    private static string? FindOnPath(string fileName, List<string> checkedPaths)
    {
        string? pathEnv = Environment.GetEnvironmentVariable("PATH");
        if (string.IsNullOrWhiteSpace(pathEnv))
        {
            NoteChecked(checkedPaths, "PATH=(leer)");
            return null;
        }

        foreach (string dir in pathEnv.Split(Path.PathSeparator, StringSplitOptions.RemoveEmptyEntries))
        {
            try
            {
                string candidate = Path.Combine(dir.Trim().Trim('"'), fileName);
                NoteChecked(checkedPaths, $"PATH:{candidate}");
                if (File.Exists(candidate))
                {
                    return candidate;
                }
            }
            catch
            {
                // ignore bad PATH entries
            }
        }

        return null;
    }

    private static string? ExtractError(string combined)
    {
        foreach (string line in combined.Split(['\r', '\n'], StringSplitOptions.RemoveEmptyEntries))
        {
            if (line.StartsWith("ERROR:", StringComparison.OrdinalIgnoreCase))
            {
                return line["ERROR:".Length..].Trim();
            }
        }

        return string.IsNullOrWhiteSpace(combined) ? null : Truncate(combined);
    }

    private static string Quote(string value)
        => "\"" + value.Replace("\"", "\\\"") + "\"";

    private static string EscapeArg(string value)
    {
        if (value.Length == 0)
        {
            return "\"\"";
        }

        bool needsQuotes = value.Contains(' ') || value.Contains('\t') || value.Contains('"')
            || value.Contains('*') || value.Contains(';');
        if (!needsQuotes)
        {
            return value;
        }

        return "\"" + value.Replace("\"", "\\\"") + "\"";
    }

    private static string Truncate(string s, int max = 800)
        => s.Length <= max ? s : s[..max] + "…";
}