import 'dart:convert';
import 'dart:io';
import 'package:drift/drift.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:http/http.dart' as http;
import 'package:intl/intl.dart';
import 'package:shared_preferences/shared_preferences.dart';
import '../../core/version/app_identity.dart';
import '../../database/database.dart';
import '../../features/records/records_service.dart';
import '../auth/auth_providers.dart';
import '../auth/auth_service.dart';
import '../export_service.dart';
import '../field_test/field_test_export_service.dart';
import '../sync/firebase_sync_provider.dart';
import '../sync/sync_models.dart';
import 'github_auth_service.dart';

enum GitHubUploadState { idle, queued, uploading, success, failed, authRequired }

class GitHubUploadResult {
  final bool success;
  final String message;
  final String? commitSha;
  final String? targetPath;
  final DateTime timestamp;

  GitHubUploadResult({
    required this.success,
    required this.message,
    this.commitSha,
    this.targetPath,
    DateTime? timestamp,
  }) : timestamp = timestamp ?? DateTime.now();
}

/// Compatibility facade for the historical ride-detail sync service.
///
/// Normal MotorSignal cloud backup is Firebase Authentication + Firestore + R2.
/// The historical GitHub PAT exporter remains available only through the
/// explicit `uploadRideToGitHub` developer/export path and is never used by
/// the normal History -> Upload Now action.
class GitHubSyncService extends ChangeNotifier {
  final AppDatabase _db;
  final GitHubAuthService _githubAuth;
  final AuthService _authService;
  final SharedPreferences _prefs;
  final http.Client _client;

  GitHubUploadState _state = GitHubUploadState.idle;
  String _statusMessage = '';
  final Set<int> _uploadQueue = {};

  /// Keeps the historical constructor compatible with tests/callers that pass
  /// an HTTP client as the optional fourth argument. Production additionally
  /// supplies the shared Firebase AuthService as the fifth argument.
  GitHubSyncService(
    this._db,
    this._githubAuth,
    this._prefs, [
    http.Client? client,
    AuthService? authService,
  ])  : _authService = authService ?? FirebaseAuthService(),
        _client = client ?? http.Client();

  GitHubUploadState get state => _state;
  String get statusMessage => _statusMessage;
  Set<int> get queuedRideIds => Set.unmodifiable(_uploadQueue);

  String? _userScopedKey(String key, int rideId) {
    final uid = _authService.currentUser?.uid;
    if (uid == null || uid.isEmpty) return null;
    return '${key}_${uid}_$rideId';
  }

  bool isRideUploaded(int rideId) {
    final key = _userScopedKey('motorcloud_uploaded_ride', rideId);
    if (key != null) return _prefs.getBool(key) ?? false;
    // Legacy unscoped key – used when no authenticated user is available.
    return _prefs.getBool('motorcloud_uploaded_ride_$rideId') ?? false;
  }

  String? getRideCommitSha(int rideId) {
    final key = _userScopedKey('motorcloud_ride_remote_id', rideId);
    if (key != null) return _prefs.getString(key);
    return _prefs.getString('motorcloud_ride_remote_id_$rideId');
  }

  String? getRideUploadTimestamp(int rideId) {
    final key = _userScopedKey('motorcloud_uploaded_at_ride', rideId);
    return key == null ? null : _prefs.getString(key);
  }

  void queueRideForUpload(int rideId) {
    if (isRideUploaded(rideId)) return;
    _uploadQueue.add(rideId);
    _state = GitHubUploadState.queued;
    _statusMessage = 'Ride #$rideId queued for cloud synchronization';
    notifyListeners();
    processQueue();
  }

  Future<void> processQueue() async {
    if (_uploadQueue.isEmpty || _state == GitHubUploadState.uploading) return;
    final toProcess = List<int>.from(_uploadQueue);
    for (final rideId in toProcess) {
      await uploadRide(rideId);
    }
  }

  /// Normal History -> Upload Now operation.
  ///
  /// Deliberately ignores any configured GitHub PAT. A user's ride must be
  /// written to that user's MotorCloud account, never to the developer's
  /// public repository.
  Future<GitHubUploadResult> uploadRide(int rideId, {bool isManual = false}) async {
    return _uploadToMotorCloud(rideId);
  }

  /// Explicit legacy/developer export. Not used by the normal ride UI.
  Future<GitHubUploadResult> uploadRideToGitHub(int rideId) async {
    final token = _githubAuth.getToken();
    if (token == null || token.isEmpty) {
      return GitHubUploadResult(
        success: false,
        message: 'GitHub export requires an explicitly configured GitHub token.',
      );
    }
    return _uploadToGitHub(rideId, token);
  }

  Future<GitHubUploadResult> _uploadToMotorCloud(int rideId) async {
    final user = _authService.currentUser;
    if (user == null || user.isAnonymous) {
      _state = GitHubUploadState.authRequired;
      _statusMessage = 'Sign in to MotorCloud before uploading a ride.';
      notifyListeners();
      return GitHubUploadResult(success: false, message: _statusMessage);
    }

    if (isRideUploaded(rideId)) {
      _state = GitHubUploadState.success;
      _statusMessage = 'Ride #$rideId is already backed up to your MotorCloud account.';
      notifyListeners();
      return GitHubUploadResult(
        success: true,
        message: _statusMessage,
        commitSha: getRideCommitSha(rideId),
        targetPath: 'MotorCloud',
      );
    }

    _state = GitHubUploadState.uploading;
    _statusMessage = 'Backing up Ride #$rideId to MotorCloud...';
    notifyListeners();

    try {
      final provider = FirebaseSyncProvider(db: _db, authService: _authService);
      final result = await provider.uploadRide(SyncItem(
        localRideId: rideId,
        providerId: 'firebase',
        createdAt: DateTime.now(),
      ));

      if (result.success) {
        await _prefs.setBool(_userScopedKey('motorcloud_uploaded_ride', rideId)!, true);
        await _prefs.setString(
          _userScopedKey('motorcloud_uploaded_at_ride', rideId)!,
          DateTime.now().toIso8601String(),
        );
        if (result.remoteId != null) {
          await _prefs.setString(
            _userScopedKey('motorcloud_ride_remote_id', rideId)!,
            result.remoteId!,
          );
        }
        _uploadQueue.remove(rideId);
        _state = GitHubUploadState.success;
        _statusMessage = 'Ride #$rideId backed up to your MotorCloud account';
        notifyListeners();
        return GitHubUploadResult(
          success: true,
          message: _statusMessage,
          commitSha: result.remoteId,
          targetPath: 'MotorCloud',
        );
      }

      _state = result.requiresAuth ? GitHubUploadState.authRequired : GitHubUploadState.failed;
      _statusMessage = result.errorMessage ?? 'MotorCloud backup failed';
      notifyListeners();
      return GitHubUploadResult(success: false, message: _statusMessage);
    } catch (e) {
      _state = GitHubUploadState.failed;
      _statusMessage = 'MotorCloud backup failed: $e';
      notifyListeners();
      return GitHubUploadResult(success: false, message: _statusMessage);
    }
  }

  Future<GitHubUploadResult> _uploadToGitHub(int rideId, String token) async {
    _state = GitHubUploadState.uploading;
    _statusMessage = 'Uploading Ride #$rideId to GitHub...';
    notifyListeners();

    try {
      final ride = await (_db.select(_db.rides)..where((r) => r.id.equals(rideId))).getSingleOrNull();
      if (ride == null) throw HttpException('Ride #$rideId not found in local database');

      final dateStr = DateFormat('yyyy-MM-dd-HHmmss').format(ride.startTime.toLocal());
      final folderName = 'field_test_session_${rideId}_$dateStr/field_test_session';
      final repo = _githubAuth.getRepository();
      final branch = _githubAuth.getBranch();
      final fieldTestExport = FieldTestExportService(_db);
      final exportService = ExportService(_db);
      final sessionJson = await fieldTestExport.generateFieldTestSessionJson(rideId);
      final eventsCsv = await fieldTestExport.generateFieldTestEventsCsv(rideId);
      final telemetryCsv = await exportService.exportRideCsv(rideId);
      final gpxContent = await exportService.exportRideGpx(rideId);

      final samples = await (_db.select(_db.telemetrySamples)
        ..where((t) => t.rideId.equals(rideId))
        ..orderBy([(t) => OrderingTerm(expression: t.timestamp)])).get();
      final events = await (_db.select(_db.fieldTestEvents)
        ..where((e) => e.rideId.equals(rideId))
        ..orderBy([(e) => OrderingTerm(expression: e.timestamp)])).get();
      final summaryRecord = await (_db.select(_db.fieldTestSummaries)
        ..where((s) => s.rideId.equals(rideId))).getSingleOrNull();
      final appIdentity = AppIdentity.current();

      final readme = StringBuffer()
        ..writeln('=====================================================')
        ..writeln('MOTORCYCLE DASH — FORENSIC FIELD TEST SESSION REPORT')
        ..writeln('=====================================================')
        ..writeln('Application Version: ${appIdentity.semanticVersion}')
        ..writeln('Build Number: ${appIdentity.buildNumber}')
        ..writeln('Git Revision: ${appIdentity.gitCommit}')
        ..writeln('Git Branch: ${appIdentity.gitBranch}')
        ..writeln('Release Channel: ${appIdentity.releaseChannel}')
        ..writeln('Telemetry Schema Version: ${appIdentity.telemetrySchemaVersion}')
        ..writeln('Export Format Version: ${appIdentity.exportSchemaVersion}')
        ..writeln('Build Timestamp: ${appIdentity.buildTimestamp}')
        ..writeln('Field Test Session / Ride ID: $rideId')
        ..writeln('Session Start: ${ride.startTime.toIso8601String()}')
        ..writeln('Session End: ${ride.endTime?.toIso8601String() ?? "IN_PROGRESS"}')
        ..writeln('Export Timestamp: ${DateTime.now().toIso8601String()}')
        ..writeln('Summary Result: ${summaryRecord?.rideQualityRating ?? "COMPLETED"}')
        ..writeln('Ride Quality Score: ${summaryRecord?.rideQualityScore ?? 100} / 100')
        ..writeln('Total Telemetry Samples: ${samples.length}')
        ..writeln('Total Forensic Events: ${events.length}');

      final rideSummaryJson = const JsonEncoder.withIndent('  ').convert({
        'rideId': ride.id,
        'startTime': ride.startTime.toIso8601String(),
        'endTime': ride.endTime?.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,
        'qualityScore': summaryRecord?.rideQualityScore ?? 100,
        'qualityRating': summaryRecord?.rideQualityRating ?? 'EXCELLENT',
        'software': appIdentity.toJson(),
      });

      final filesToUpload = <String, String>{
        '$folderName/README.txt': readme.toString(),
        '$folderName/ride_summary.json': rideSummaryJson,
        '$folderName/field_test_session.json': sessionJson,
        '$folderName/field_test_events.csv': eventsCsv,
        '$folderName/telemetry.csv': telemetryCsv,
      };
      if (gpxContent.isNotEmpty) filesToUpload['$folderName/telemetry.gpx'] = gpxContent;

      String? lastCommitSha;
      for (final entry in filesToUpload.entries) {
        final filePath = entry.key;
        final getRes = await _client.get(
          Uri.parse('https://api.github.com/repos/$repo/contents/$filePath?ref=$branch'),
          headers: {
            'Authorization': 'Bearer $token',
            'Accept': 'application/vnd.github.v3+json',
            'User-Agent': 'MotorSignal-Telemetry/1.0.2',
          },
        ).timeout(const Duration(seconds: 10));
        String? existingSha;
        if (getRes.statusCode == 200) existingSha = jsonDecode(getRes.body)['sha'];

        final payload = <String, dynamic>{
          'message': 'feat(telemetry): upload ride #$rideId forensic session data [v1.0.2+102]',
          'content': base64.encode(utf8.encode(entry.value)),
          'branch': branch,
        };
        if (existingSha != null) payload['sha'] = existingSha;

        final putRes = await _client.put(
          Uri.parse('https://api.github.com/repos/$repo/contents/$filePath'),
          headers: {
            'Authorization': 'Bearer $token',
            'Accept': 'application/vnd.github.v3+json',
            'Content-Type': 'application/json',
            'User-Agent': 'MotorSignal-Telemetry/1.0.2',
          },
          body: jsonEncode(payload),
        ).timeout(const Duration(seconds: 15));

        if (putRes.statusCode == 200 || putRes.statusCode == 201) {
          lastCommitSha = jsonDecode(putRes.body)['commit']?['sha'];
        } else if (putRes.statusCode == 401 || putRes.statusCode == 403) {
          throw HttpException('GitHub authorization rejected the upload (HTTP ${putRes.statusCode}).');
        } else {
          throw HttpException('Failed uploading $filePath (Status: ${putRes.statusCode})');
        }
      }

      _state = GitHubUploadState.success;
      _statusMessage = 'Ride #$rideId exported to $repo ($branch)';
      notifyListeners();
      return GitHubUploadResult(success: true, message: _statusMessage, commitSha: lastCommitSha, targetPath: folderName);
    } catch (e) {
      _state = GitHubUploadState.failed;
      _statusMessage = 'GitHub export failed for Ride #$rideId: $e';
      notifyListeners();
      return GitHubUploadResult(success: false, message: _statusMessage);
    }
  }
}

final githubSyncServiceProvider = ChangeNotifierProvider<GitHubSyncService>((ref) {
  final db = ref.watch(databaseProvider);
  final githubAuth = ref.watch(githubAuthServiceProvider);
  final prefs = ref.watch(sharedPreferencesProvider);
  final authService = ref.watch(authServiceProvider);
  return GitHubSyncService(db, githubAuth, prefs, null, authService);
});