Firebase Crashlytics and Analytics in Flutter: solved exercise

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dependencies:
  firebase_core: ^3.13.0
  firebase_crashlytics: ^4.3.3
  firebase_analytics: ^11.4.4

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flutter pub add firebase_core firebase_crashlytics firebase_analytics
flutterfire configure

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import 'dart:async';
import 'package:firebase_analytics/firebase_analytics.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:firebase_crashlytics/firebase_crashlytics.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

// ── Observability service ──────────────────────────────────────────────────────
class ObservabilityService {
  static final _crashlytics = FirebaseCrashlytics.instance;
  static final _analytics = FirebaseAnalytics.instance;

  static Future<void> initialize() async {
    // Pass all Flutter errors to Crashlytics
    FlutterError.onError = _crashlytics.recordFlutterFatalError;

    // Capture async errors outside the widget tree
    PlatformDispatcher.instance.onError = (error, stack) {
      _crashlytics.recordError(error, stack, fatal: true);
      return true;
    };

    // Disable Crashlytics in debug (only active in release)
    await _crashlytics.setCrashlyticsCollectionEnabled(!kDebugMode);
  }

  // ── Crashlytics ──────────────────────────────────────────────────────────────

  static Future<void> setUser({required String userId, String? email}) async {
    await _crashlytics.setUserIdentifier(userId);
    await _crashlytics.setCustomKey('user_email', email ?? 'unknown');
  }

  static Future<void> setContext(String key, String value) =>
      _crashlytics.setCustomKey(key, value);

  static void log(String message) => _crashlytics.log(message);

  static Future<void> recordError(
    Object error,
    StackTrace? stack, {
    String? reason,
    bool fatal = false,
  }) =>
      _crashlytics.recordError(error, stack, reason: reason, fatal: fatal);

  // ── Analytics ────────────────────────────────────────────────────────────────

  static Future<void> setCurrentScreen(String screenName) =>
      _analytics.setCurrentScreen(screenName: screenName);

  static Future<void> logProductView({
    required String productId,
    required String productName,
    required double price,
  }) =>
      _analytics.logViewItem(
        items: [
          AnalyticsEventItem(
            itemId: productId,
            itemName: productName,
            price: price,
          )
        ],
      );

  static Future<void> logPurchase({
    required String transactionId,
    required double value,
    required String currency,
  }) =>
      _analytics.logPurchase(
        transactionId: transactionId,
        value: value,
        currency: currency,
      );

  static Future<void> logEvent(
    String name, {
    Map<String, Object>? parameters,
  }) =>
      _analytics.logEvent(name: name, parameters: parameters);

  static Future<void> setUserProperty({
    required String name,
    required String value,
  }) =>
      _analytics.setUserProperty(name: name, value: value);
}

// ── Main ───────────────────────────────────────────────────────────────────────
Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();

  runZonedGuarded(
    () async {
      await Firebase.initializeApp();
      await ObservabilityService.initialize();

      await ObservabilityService.setUser(
        userId: 'user_12345',
        email: 'demo@flutter.dev',
      );

      runApp(const CrashlyticsDemo());
    },
    (error, stack) {
      FirebaseCrashlytics.instance.recordError(error, stack, fatal: true);
    },
  );
}

// ── App ────────────────────────────────────────────────────────────────────────
class CrashlyticsDemo extends StatelessWidget {
  const CrashlyticsDemo({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Crashlytics + Analytics',
      navigatorObservers: [
        FirebaseAnalyticsObserver(analytics: FirebaseAnalytics.instance),
      ],
      home: const HomePage(),
    );
  }
}

// ── Home screen ────────────────────────────────────────────────────────────────
class HomePage extends StatefulWidget {
  const HomePage({super.key});
  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  final _logs = <String>[];

  @override
  void initState() {
    super.initState();
    ObservabilityService.setCurrentScreen('home');
    ObservabilityService.log('HomePage mounted');
  }

  void _addLog(String msg) =>
      setState(() => _logs.insert(0,
          '${DateTime.now().toIso8601String().substring(11, 19)} $msg'));

  Future<void> _testCrash() async {
    ObservabilityService.log('User taps test crash button');
    await ObservabilityService.setContext('last_action', 'test_crash');
    // In release this sends the crash to Crashlytics and closes the app
    FirebaseCrashlytics.instance.crash();
    _addLog('Test crash sent');
  }

  Future<void> _logNonFatal() async {
    try {
      throw StateError('Invalid state while processing order #42');
    } catch (e, stack) {
      await ObservabilityService.recordError(
        e,
        stack,
        reason: 'Error processing order at checkout',
        fatal: false,
      );
      _addLog('Non-fatal error recorded in Crashlytics');
    }
  }

  Future<void> _logProductView() async {
    await ObservabilityService.logProductView(
      productId: 'book_flutter_001',
      productName: 'Flutter in Depth',
      price: 29.99,
    );
    _addLog('Analytics: view_item recorded');
  }

  Future<void> _logPurchase() async {
    await ObservabilityService.logPurchase(
      transactionId: 'txn_${DateTime.now().millisecondsSinceEpoch}',
      value: 29.99,
      currency: 'USD',
    );
    _addLog('Analytics: purchase recorded');
  }

  Future<void> _logCustomEvent() async {
    await ObservabilityService.logEvent(
      'tutorial_complete',
      parameters: {
        'tutorial_id': 'flutter_basics',
        'success': true,
      },
    );
    _addLog('Analytics: tutorial_complete recorded');
  }

  Future<void> _setUserProperty() async {
    await ObservabilityService.setUserProperty(
      name: 'subscription_plan',
      value: 'premium',
    );
    _addLog('Analytics: user property subscription_plan=premium');
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Crashlytics + Analytics')),
      body: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            Text('Crashlytics',
                style: Theme.of(context).textTheme.titleMedium
                    ?.copyWith(color: Theme.of(context).colorScheme.primary)),
            const SizedBox(height: 8),
            FilledButton.icon(
              onPressed: _logNonFatal,
              icon: const Icon(Icons.warning_amber),
              label: const Text('Record non-fatal error'),
              style: FilledButton.styleFrom(backgroundColor: Colors.orange),
            ),
            const SizedBox(height: 4),
            OutlinedButton.icon(
              onPressed: _testCrash,
              icon: const Icon(Icons.dangerous),
              label: const Text('Test crash (release only)'),
              style: OutlinedButton.styleFrom(foregroundColor: Colors.red),
            ),

            const Divider(height: 24),

            Text('Analytics',
                style: Theme.of(context).textTheme.titleMedium
                    ?.copyWith(color: Theme.of(context).colorScheme.primary)),
            const SizedBox(height: 8),
            Wrap(
              spacing: 8,
              runSpacing: 8,
              children: [
                FilledButton.tonal(
                    onPressed: _logProductView,
                    child: const Text('view_item')),
                FilledButton.tonal(
                    onPressed: _logPurchase,
                    child: const Text('purchase')),
                FilledButton.tonal(
                    onPressed: _logCustomEvent,
                    child: const Text('tutorial_complete')),
                FilledButton.tonal(
                    onPressed: _setUserProperty,
                    child: const Text('user property')),
              ],
            ),

            const Divider(height: 24),

            Text('Local log:', style: Theme.of(context).textTheme.labelLarge),
            const SizedBox(height: 8),
            Expanded(
              child: _logs.isEmpty
                  ? const Center(
                      child: Text('Tap a button to record an event',
                          style: TextStyle(color: Colors.grey)))
                  : ListView.builder(
                      itemCount: _logs.length,
                      itemBuilder: (_, i) => Text(_logs[i],
                          style: const TextStyle(
                              fontSize: 12, fontFamily: 'monospace')),
                    ),
            ),
          ],
        ),
      ),
    );
  }
}