import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:crypto/crypto.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:intl/intl.dart';
import '../../core/version/app_identity.dart';
import '../../database/database.dart';
import '../auth/auth_service.dart';
import 'r2_upload_service.dart';
import 'sync_bundle_worker.dart';
import 'sync_models.dart';
import 'sync_provider.dart';

/// Authoritative Firebase + Cloudflare R2 Synchronization Provider.
/// Synchronizes structured ride metadata to Cloud Firestore and streams
/// compressed 20Hz forensic bundles to Cloudflare R2 via the authenticated Worker gateway.
class FirebaseSyncProvider implements SyncProvider {
  final AppDatabase _db;
  final AuthService _authService;
  final FirebaseFirestore? _firestore;
  final R2UploadService _r2UploadService;
  final SyncBundleWorker _bundleWorker;

  FirebaseSyncProvider({
    required AppDatabase db,
    required AuthService authService,
    FirebaseFirestore? firestore,
    R2UploadService? r2UploadService,
    SyncBundleWorker? bundleWorker,
  })  : _db = db,
        // ignore: prefer_initializing_formals
        _authService = authService,
        _firestore = firestore ?? _resolveFirestore(),
        _r2UploadService = r2UploadService ?? R2UploadService(),
        _bundleWorker = bundleWorker ?? SyncBundleWorker(db);

  static FirebaseFirestore? _resolveFirestore() {
    try {
      if (Firebase.apps.isNotEmpty) {
        return FirebaseFirestore.instance;
      }
    } catch (_) {}
    return null;
  }

  @override
  String get providerId => 'firebase';

  @override
  Future<bool> isAvailable() async {
    try {
      if (Firebase.apps.isEmpty) return false;
      if (_firestore == null) return false;
      return true;
    } catch (_) {
      return false;
    }
  }

  @override
  Future<bool> requiresAuthentication() async {
    final user = _authService.currentUser;
    if (user == null) return true;
    return false;
  }

  @override
  Future<SyncResult> uploadRide(SyncItem item) async {
    final available = await isAvailable();
    if (!available) {
      return SyncResult.temporaryFailure(
        'Firebase services are unavailable or unconfigured. Ride remains safely stored locally.',
      );
    }

    final user = _authService.currentUser;
    if (user == null) {
      return SyncResult.authRequired(
        message: 'Sign in to MotorCloud is required for cloud backup.',
      );
    }

    final idToken = await _authService.getIdToken();
    if (idToken == null || idToken.isEmpty) {
      return SyncResult.authRequired(
        message: 'Valid Firebase authentication token required for cloud sync.',
      );
    }

    try {
      // 1. Read authoritative local ride record
      final ride = await (_db.select(_db.rides)..where((r) => r.id.equals(item.localRideId))).getSingleOrNull();
      if (ride == null) {
        return SyncResult.permanentFailure(
          'Local ride #${item.localRideId} not found in database.',
        );
      }

      // 2. Generate deterministic remote document and bundle identifiers
      final dateStr = DateFormat('yyyyMMdd_HHmmss').format(ride.startTime.toUtc());
      final remoteRideId = 'ride_${item.localRideId}_$dateStr';
      final appIdentity = AppIdentity.current();

      // 3. Generate compressed forensic bundle in background worker isolate
      final zipBytes = await _bundleWorker.generateCompressedBundle(item.localRideId);
      if (zipBytes == null || zipBytes.isEmpty) {
        return SyncResult.permanentFailure(
          'Failed generating compressed telemetry bundle for ride #${item.localRideId}.',
        );
      }

      final sha256Hash = sha256.convert(zipBytes).toString();

      // 4. Stream binary telemetry.zip to Cloudflare R2 via secure Worker gateway with verified Firebase ID token
      final r2Result = await _r2UploadService.uploadTelemetryBundle(
        idToken: idToken,
        remoteRideId: remoteRideId,
        zipBytes: zipBytes,
        sha256Hash: sha256Hash,
        appVersion: appIdentity.semanticVersion,
      );

      if (!r2Result.success) {
        if (r2Result.requiresAuth) {
          return SyncResult.authRequired(message: r2Result.errorMessage ?? 'R2 Gateway authentication required');
        }
        if (r2Result.isRetryable) {
          return SyncResult.temporaryFailure(r2Result.errorMessage ?? 'Temporary R2 upload error');
        }
        return SyncResult.permanentFailure(r2Result.errorMessage ?? 'Permanent R2 upload rejection');
      }

      final objectKey = r2Result.objectKey ?? 'users/${user.uid}/rides/$remoteRideId/telemetry.zip';

      // 5. Query discrete events and performance benchmarks for rich metadata
      final events = await (_db.select(_db.rideEvents)..where((e) => e.rideId.equals(item.localRideId))).get();
      final performanceRuns = await (_db.select(_db.performanceRuns)..where((p) => p.rideId.equals(item.localRideId))).get();
      final summary = await (_db.select(_db.fieldTestSummaries)..where((s) => s.rideId.equals(item.localRideId))).getSingleOrNull();

      // 6. Build queryable Firestore metadata document referencing Cloudflare R2
      final firestorePayload = <String, dynamic>{
        'localRideId': ride.id,
        'remoteRideId': remoteRideId,
        'uid': user.uid,
        'startTime': ride.startTime.toUtc().toIso8601String(),
        'endTime': ride.endTime?.toUtc().toIso8601String(),
        'distanceMiles': ride.distanceMiles,
        'topSpeedMph': ride.topSpeedMph,
        'maxLeanLeft': ride.maxLeanLeft,
        'maxLeanRight': ride.maxLeanRight,
        'maxAccelG': ride.maxAccelG,
        'maxBrakingG': ride.maxBrakingG,
        'averageSpeed': ride.averageSpeed,
        'movingTime': ride.movingTime,
        'stoppedTime': ride.stoppedTime,
        'elevationGain': ride.elevationGain,
        'elevationLoss': ride.elevationLoss,
        'qualityScore': summary?.rideQualityScore ?? 100,
        'qualityRating': summary?.rideQualityRating ?? 'EXCELLENT',
        'motorcycleId': ride.motorcycleId,
        'motorcycleMake': ride.motorcycleMake,
        'motorcycleModel': ride.motorcycleModel,
        'motorcycleYear': ride.motorcycleYear,
        'motorcycleVariant': ride.motorcycleVariant,
        'hardBrakingEvents': events.where((e) => e.eventType.contains('Braking')).length,
        'extremeLeanEvents': events.where((e) => e.eventType.contains('Lean') || e.eventType.contains('Corner')).length,
        'highSpeedEvents': events.where((e) => e.eventType.contains('Speed')).length,
        'totalEventsCount': events.length,
        'performanceRuns': performanceRuns.map((r) => {
          'type': r.type,
          'timeMs': r.timeMs,
          'topSpeedReached': r.topSpeedReached,
          'timestamp': r.timestamp.toUtc().toIso8601String(),
        }).toList(),
        'telemetryBundle': {
          'provider': 'cloudflare-r2',
          'objectKey': objectKey,
          'status': 'uploaded',
          'bundleSizeBytes': zipBytes.length,
          'sha256': sha256Hash,
        },
        'telemetryBundlePath': objectKey,
        'bundleSizeBytes': zipBytes.length,
        'syncVersion': 2,
        'uploadedAt': FieldValue.serverTimestamp(),
        'software': appIdentity.toJson(),
      };

      // 7. Write / Merge Firestore summary document idempotently
      await _firestore!
          .collection('users')
          .doc(user.uid)
          .collection('rides')
          .doc(remoteRideId)
          .set(firestorePayload, SetOptions(merge: true));

      return SyncResult.success(remoteId: remoteRideId);
    } on FirebaseException catch (e) {
      if (e.code == 'permission-denied' || e.code == 'unauthenticated') {
        return SyncResult.authRequired(
          message: 'Firebase authorization error: ${e.message}',
        );
      }
      if (e.code == 'unavailable' || e.code == 'network-request-failed' || e.code == 'retry-limit-exceeded') {
        return SyncResult.temporaryFailure(
          'Network or Firebase service temporary error (${e.code}): ${e.message}',
        );
      }
      return SyncResult.permanentFailure(
        'Firebase sync error (${e.code}): ${e.message}',
      );
    } catch (e) {
      return SyncResult.temporaryFailure('Unexpected sync exception: $e');
    }
  }
}