using LehrerApp.Core.Interfaces;
using LehrerApp.Core.Services;
using LehrerApp.Data;
using LehrerApp.Data.Repositories;
using LehrerApp.Desktop.ViewModels;
using LehrerApp.Desktop.ViewModels.Groups;
using LehrerApp.Desktop.ViewModels.Students;
using LehrerApp.Sync;
using LehrerApp.Sync.Crypto;
using LehrerApp.Sync.Models;
using Microsoft.Extensions.DependencyInjection;

namespace LehrerApp.Desktop;

/// <summary>
/// Konfiguriert den DI-Container für den Desktop-Client.
///
/// WICHTIG: Alle Repositories sind Singleton – eine LiteDB-Datei pro Nutzer.
/// Sync-Services werden nur registriert wenn eine Server-URL konfiguriert ist.
/// </summary>
public static class AppBootstrapper
{
    public static string DbPath      { get; private set; } = "";
    public static string AppDataPath { get; private set; } = "";

    public static IServiceProvider BuildServices()
    {
        var services = new ServiceCollection();

        // ── Pfade ─────────────────────────────────────────────────────────────
        var appData = Path.Combine(
            Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
            "LehrerApp");
        Directory.CreateDirectory(appData);
        AppDataPath   = appData;
        DbPath        = Path.Combine(appData, "lehrerapp.db");
        var queuePath = Path.Combine(appData, "syncqueue.db");
        var keyPath   = Path.Combine(appData, "sync.key");

        // ── Datenbank ─────────────────────────────────────────────────────────
        services.AddSingleton(_ => new LiteDbContext(DbPath));

        // ── Repositories ──────────────────────────────────────────────────────
        services.AddSingleton<IStudentRepository,       StudentRepository>();
        services.AddSingleton<IGroupRepository,         GroupRepository>();
        services.AddSingleton<IEnrollmentRepository,    EnrollmentRepository>();
        services.AddSingleton<IExamRepository,          ExamRepository>();
        services.AddSingleton<IExamResultRepository,    ExamResultRepository>();
        services.AddSingleton<IGradeRepository,         GradeRepository>();
        services.AddSingleton<IUnitRepository,          UnitRepository>();
        services.AddSingleton<ILessonRepository,        LessonRepository>();
        services.AddSingleton<IDocumentationRepository, DocumentationRepository>();
        services.AddSingleton<IWorkTaskRepository,      WorkTaskRepository>();
        services.AddSingleton<ITimeEntryRepository,     TimeEntryRepository>();

        // ── Services ──────────────────────────────────────────────────────────
        services.AddSingleton<GradingService>();
        services.AddSingleton<SchoolYearService>();

        // ── Sync (optional – nur wenn Server konfiguriert) ────────────────────
        services.AddSingleton(_ => new EventQueue(queuePath));
        services.AddSingleton(sp => new ConflictResolver(sp.GetRequiredService<EventQueue>()));
        services.AddSingleton<byte[]>(_ =>
        {
            var key = SyncCrypto.LoadKey(keyPath) ?? SyncCrypto.GenerateKey();
            SyncCrypto.SaveKey(key, keyPath);
            return key;
        });

        var serverUrl = LoadServerUrl(appData);
        var deviceId  = LoadOrCreateDeviceId(appData);

        if (!string.IsNullOrEmpty(serverUrl))
        {
            services.AddSingleton<SyncEngine>(sp => new SyncEngine(
                sp.GetRequiredService<EventQueue>(),
                sp.GetRequiredService<ConflictResolver>(),
                BuildHttp(serverUrl, appData),
                new SyncConfig
                {
                    ServerUrl               = serverUrl,
                    DeviceId                = deviceId,
                    DeviceType              = DeviceType.Desktop,
                    AutoSyncIntervalMinutes = 5,
                }));

            services.AddSingleton<SnapshotService>(sp => new SnapshotService(
                BuildHttp(serverUrl, appData),
                sp.GetRequiredService<LiteDbContext>(),
                sp.GetRequiredService<byte[]>(),
                DeviceType.Desktop, DbPath, keyPath));
        }

        // ── ViewModels ────────────────────────────────────────────────────────
        // Singleton: einmal erstellt, überall dieselbe Instanz
        services.AddSingleton<MainWindowViewModel>();
        services.AddSingleton<DashboardViewModel>();
        services.AddSingleton<SyncStatusViewModel>();
        services.AddSingleton<GroupListViewModel>();
        services.AddSingleton<StudentListViewModel>();

        // Transient: neue Instanz pro Navigation (für Detailseiten)
        services.AddTransient<GroupDetailViewModel>();
        services.AddTransient<StudentDetailViewModel>();

        return services.BuildServiceProvider();
    }

    // ── Hilfsmethoden ─────────────────────────────────────────────────────────

    private static HttpClient BuildHttp(string url, string appData)
    {
        var http = new HttpClient { BaseAddress = new Uri(url) };
        var tokenPath = Path.Combine(appData, "auth.token");
        if (File.Exists(tokenPath))
            http.DefaultRequestHeaders.Authorization =
                new System.Net.Http.Headers.AuthenticationHeaderValue(
                    "Bearer", File.ReadAllText(tokenPath).Trim());
        return http;
    }

    public static string LoadServerUrl(string? path = null) =>
        File.Exists(Path.Combine(path ?? AppDataPath, "server.txt"))
            ? File.ReadAllText(Path.Combine(path ?? AppDataPath, "server.txt")).Trim()
            : "";

    public static void SaveServerUrl(string url) =>
        File.WriteAllText(Path.Combine(AppDataPath, "server.txt"), url);

    private static string LoadOrCreateDeviceId(string appData)
    {
        var p = Path.Combine(appData, "device.id");
        if (File.Exists(p)) return File.ReadAllText(p).Trim();
        var id = Guid.NewGuid().ToString();
        File.WriteAllText(p, id);
        return id;
    }
}