using System.Diagnostics;
using ZA.CoreService.ESBCertificateManager.Models;

namespace ZA.CoreService.ESBCertificateManager.Services;

public sealed class RuntimeEnvironmentValidator
{
    public async Task<RuntimeValidationResult> ValidateAsync(
        RuntimeSettings settings,
        CancellationToken cancellationToken = default)
    {
        List<string> issues = [];

        string javaExecutablePath =
            PathResolver.ResolvePath(
                settings.JavaExecutablePath);

        string sonicClientLibraryPath =
            PathResolver.ResolvePath(
                settings.SonicClientLibraryPath);

        string javaVersion = string.Empty;

        if (!File.Exists(javaExecutablePath))
        {
            issues.Add(
                $"Java wurde nicht gefunden: {javaExecutablePath}");
        }
        else
        {
            try
            {
                javaVersion = await ReadJavaVersionAsync(
                    javaExecutablePath,
                    cancellationToken);

                if (!ContainsJava8Version(javaVersion))
                {
                    issues.Add(
                        "Die gefundene Java-Version ist nicht Java 8. " +
                        $"Ausgabe: {javaVersion}");
                }
            }
            catch (Exception ex)
            {
                issues.Add(
                    $"Java konnte nicht ausgeführt werden: {ex.Message}");
            }
        }

        if (!Directory.Exists(sonicClientLibraryPath))
        {
            issues.Add(
                "Der Sonic-Client-Bibliotheksordner wurde " +
                $"nicht gefunden: {sonicClientLibraryPath}");
        }
        else
        {
            string[] requiredJarNames =
            [
                "mgmt_client.jar",
                "mfcontext.jar"
            ];

            foreach (string requiredJarName in requiredJarNames)
            {
                string requiredJarPath = Path.Combine(
                    sonicClientLibraryPath,
                    requiredJarName);

                if (!File.Exists(requiredJarPath))
                {
                    issues.Add(
                        $"Erforderliche Sonic-Bibliothek fehlt: " +
                        $"{requiredJarPath}");
                }
            }
        }

        return new RuntimeValidationResult
        {
            IsValid = issues.Count == 0,
            JavaExecutablePath = javaExecutablePath,
            SonicClientLibraryPath = sonicClientLibraryPath,
            JavaVersion = javaVersion,
            Issues = issues
        };
    }

    private static async Task<string> ReadJavaVersionAsync(
        string javaExecutablePath,
        CancellationToken cancellationToken)
    {
        ProcessStartInfo startInfo = new()
        {
            FileName = javaExecutablePath,
            UseShellExecute = false,
            RedirectStandardOutput = true,
            RedirectStandardError = true,
            CreateNoWindow = true
        };

        startInfo.ArgumentList.Add("-version");

        using Process process = new()
        {
            StartInfo = startInfo
        };

        if (!process.Start())
        {
            throw new InvalidOperationException(
                "Der Java-Prozess konnte nicht gestartet werden.");
        }

        Task<string> outputTask =
            process.StandardOutput.ReadToEndAsync(
                cancellationToken);

        Task<string> errorTask =
            process.StandardError.ReadToEndAsync(
                cancellationToken);

        await process.WaitForExitAsync(
            cancellationToken);

        string output = await outputTask;
        string error = await errorTask;

        string combined = string.Join(
            Environment.NewLine,
            new[] { output, error }
                .Where(value =>
                    !string.IsNullOrWhiteSpace(value)));

        if (process.ExitCode != 0)
        {
            throw new InvalidOperationException(
                $"java -version endete mit Code {process.ExitCode}. " +
                combined);
        }

        return combined.Trim();
    }

    private static bool ContainsJava8Version(
        string javaVersionOutput)
    {
        return javaVersionOutput.Contains(
                   "\"1.8.",
                   StringComparison.OrdinalIgnoreCase)
               || javaVersionOutput.Contains(
                   "version 8",
                   StringComparison.OrdinalIgnoreCase);
    }
}

public sealed class RuntimeValidationResult
{
    public bool IsValid { get; init; }

    public string JavaExecutablePath { get; init; } =
        string.Empty;

    public string SonicClientLibraryPath { get; init; } =
        string.Empty;

    public string JavaVersion { get; init; } =
        string.Empty;

    public IReadOnlyList<string> Issues { get; init; } = [];
}