import 'dart:async';
import 'dart:io';

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:flutter_riverpod/misc.dart' show Override;

import 'package:sharedinbox/core/models/user_preferences.dart';
import 'package:sharedinbox/core/services/notification_service.dart';
import 'package:sharedinbox/core/sync/background_sync.dart';
import 'package:sharedinbox/data/db/database.dart';
import 'package:sharedinbox/di.dart';
import 'package:sharedinbox/ui/router.dart';
import 'package:sharedinbox/ui/screens/crash_screen.dart';
import 'package:stack_trace/stack_trace.dart' as stack_trace;

void main({List<Override> overrides = const []}) {
  unawaited(
    runZonedGuarded(
      () async {
        WidgetsFlutterBinding.ensureInitialized();

        // Dart's async machinery propagates stack traces in chain format
        // (with '===== asynchronous gap =====' separators). Flutter's
        // StackFrame parser asserts on those lines, so strip them first.
        FlutterError.demangleStackTrace = (StackTrace s) {
          if (s is stack_trace.Chain) return s.toTrace().vmTrace;
          if (s is stack_trace.Trace) return s.vmTrace;
          return s;
        };

        // Catch errors during build (e.g. layout exceptions) and show CrashScreen.
        ErrorWidget.builder = (details) => CrashScreen(
              exception: details.exception,
              stackTrace: details.stack,
            );

        // Catch framework-level errors (e.g. from gestures, timers).
        FlutterError.onError = (details) {
          FlutterError.presentError(details);
          runApp(
            CrashScreen(
              exception: details.exception,
              stackTrace: details.stack,
            ),
          );
        };

        await initDatabasePath();
        if (Platform.isAndroid) {
          await initNotifications();
          await registerBackgroundSync();
          await _registerPrefetchTaskFromStoredPrefs();
        }
        runApp(
          ProviderScope(overrides: overrides, child: const SharedInboxApp()),
        );
      },
      // This handler runs in the parent zone — runApp cannot be called here.
      // Framework errors are already handled by FlutterError.onError above.
      (error, stack) => FlutterError.reportError(
        FlutterErrorDetails(exception: error, stack: stack),
      ),
    ),
  );
}

/// Reads the stored prefetch preference and registers the WorkManager task
/// with the correct network constraint for it. Opens and immediately closes
/// a temporary DB connection; safe because initDatabasePath() has already run.
Future<void> _registerPrefetchTaskFromStoredPrefs() async {
  final db = AppDatabase();
  try {
    final row = await db.select(db.userPreferences).getSingleOrNull();
    final mode = PrefetchMode.fromString(row?.prefetchMode);
    await registerBodyPrefetchTask(mode);
  } finally {
    await db.close();
  }
}

class SharedInboxApp extends ConsumerStatefulWidget {
  const SharedInboxApp({super.key});

  @override
  ConsumerState<SharedInboxApp> createState() => _SharedInboxAppState();
}

class _SharedInboxAppState extends ConsumerState<SharedInboxApp> {
  @override
  void initState() {
    super.initState();
    // Start background IMAP sync once — runs for the lifetime of the app.
    ref.read(syncManagerProvider).start();
    ref.read(reliabilityRunnerProvider).start();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp.router(
      title: 'sharedinbox.de',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.indigo),
        useMaterial3: true,
      ),
      darkTheme: ThemeData(
        colorScheme: ColorScheme.fromSeed(
          seedColor: Colors.indigo,
          brightness: Brightness.dark,
        ),
        useMaterial3: true,
      ),
      routerConfig: router,
    );
  }
}