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;

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

        // ── Pfade ─────────────────────────────────────────────────────────────
        var appData = Path.Combine(
            Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
            "LehrerApp");
        Directory.CreateDirectory(appData);

        var 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>();

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

        // ── Sync ──────────────────────────────────────────────────────────────
        services.AddSingleton(_ => new EventQueue(queuePath));
        services.AddSingleton(sp =>
            new ConflictResolver(sp.GetRequiredService<EventQueue>()));

        // Schlüssel laden oder neu generieren
        services.AddSingleton<byte[]>(_ =>
        {
            var key = SyncCrypto.LoadKey(keyPath) ?? SyncCrypto.GenerateKey();
            SyncCrypto.SaveKey(key, keyPath);
            return key;
        });

        // EventApplier – wendet gezogene Events auf LiteDB an
        services.AddSingleton<EventApplier>(sp => new EventApplier(
            key:          sp.GetRequiredService<byte[]>(),
            students:     sp.GetRequiredService<IStudentRepository>(),
            groups:       sp.GetRequiredService<IGroupRepository>(),
            enrollments:  sp.GetRequiredService<IEnrollmentRepository>(),
            exams:        sp.GetRequiredService<IExamRepository>(),
            examResults:  sp.GetRequiredService<IExamResultRepository>(),
            grades:       sp.GetRequiredService<IGradeRepository>(),
            units:        sp.GetRequiredService<IUnitRepository>(),
            lessons:      sp.GetRequiredService<ILessonRepository>(),
            docs:         sp.GetRequiredService<IDocumentationRepository>(),
            tasks:        sp.GetRequiredService<IWorkTaskRepository>(),
            timeEntries:  sp.GetRequiredService<ITimeEntryRepository>()));

        // SyncEngine + ReadableSnapshotService nur wenn Server konfiguriert
        var serverUrl  = LoadServerUrl(appData);
        var deviceId   = LoadOrCreateDeviceId(appData);

        services.AddSingleton<SyncEngine?>(sp =>
        {
            if (string.IsNullOrEmpty(serverUrl)) return null;

            var http   = BuildHttpClient(serverUrl, appData);
            var config = new SyncConfig
            {
                ServerUrl               = serverUrl,
                DeviceId                = deviceId,
                DeviceType              = DeviceType.Desktop,
                AutoSyncIntervalMinutes = 5,
            };
            return new SyncEngine(
                sp.GetRequiredService<EventQueue>(),
                sp.GetRequiredService<ConflictResolver>(),
                http,
                config);
        });

        services.AddSingleton<ReadableSnapshotService?>(sp =>
        {
            if (string.IsNullOrEmpty(serverUrl)) return null;

            return new ReadableSnapshotService(
                http:        BuildHttpClient(serverUrl, appData),
                students:    sp.GetRequiredService<IStudentRepository>(),
                groups:      sp.GetRequiredService<IGroupRepository>(),
                enrollments: sp.GetRequiredService<IEnrollmentRepository>(),
                exams:       sp.GetRequiredService<IExamRepository>(),
                examResults: sp.GetRequiredService<IExamResultRepository>(),
                grades:      sp.GetRequiredService<IGradeRepository>(),
                units:       sp.GetRequiredService<IUnitRepository>(),
                lessons:     sp.GetRequiredService<ILessonRepository>(),
                tasks:       sp.GetRequiredService<IWorkTaskRepository>(),
                schoolYear:  sp.GetRequiredService<SchoolYearService>(),
                deviceId:    deviceId);
        });

        services.AddSingleton<SnapshotService?>(sp =>
        {
            if (string.IsNullOrEmpty(serverUrl)) return null;

            return new SnapshotService(
                http:       BuildHttpClient(serverUrl, appData),
                db:         sp.GetRequiredService<LiteDbContext>(),
                syncKey:    sp.GetRequiredService<byte[]>(),
                deviceType: DeviceType.Desktop,
                dbPath:     dbPath,
                keyPath:    keyPath);
        });

        // ── ViewModels ────────────────────────────────────────────────────────
        services.AddSingleton<MainWindowViewModel>();
        services.AddSingleton<DashboardViewModel>();
        services.AddTransient<GroupListViewModel>();
        services.AddTransient<GroupDetailViewModel>();
        services.AddTransient<StudentListViewModel>();
        services.AddTransient<StudentDetailViewModel>();
        services.AddSingleton<SyncStatusViewModel>();
        services.AddTransient<DevicePairingViewModel>(sp =>
            new DevicePairingViewModel(
                sp.GetRequiredService<SnapshotService?>()
                ?? throw new InvalidOperationException(
                    "Kein Server konfiguriert.")));

        return services.BuildServiceProvider();
    }

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

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

    private static string LoadServerUrl(string appData)
    {
        var path = Path.Combine(appData, "server.txt");
        return File.Exists(path) ? File.ReadAllText(path).Trim() : "";
    }

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