/// Service WebSocket pour temps réel (Kafka events)
library websocket_service;

import 'dart:async';
import 'dart:convert';

import 'package:injectable/injectable.dart';
import 'package:web_socket_channel/web_socket_channel.dart';
import 'package:web_socket_channel/status.dart' as status;

import '../config/environment.dart';
import '../utils/logger.dart';

/// Events WebSocket typés
abstract class WebSocketEvent {
  final String eventType;
  final DateTime timestamp;
  final Map<String, dynamic> data;

  WebSocketEvent({
    required this.eventType,
    required this.timestamp,
    required this.data,
  });

  factory WebSocketEvent.fromJson(Map<String, dynamic> json) {
    final eventType = json['eventType'] as String;
    final timestamp = json['timestamp'] != null
        ? DateTime.parse(json['timestamp'] as String)
        : DateTime.now();
    final data = (json['data'] as Map<String, dynamic>?) ?? <String, dynamic>{};

    switch (eventType) {
      case 'APPROVAL_PENDING':
      case 'APPROVAL_APPROVED':
      case 'APPROVAL_REJECTED':
        return FinanceApprovalEvent(
          eventType: eventType,
          timestamp: timestamp,
          data: data,
          organizationId: json['organizationId'] as String?,
        );

      case 'DASHBOARD_STATS_UPDATED':
      case 'KPI_UPDATED':
        return DashboardStatsEvent(
          eventType: eventType,
          timestamp: timestamp,
          data: data,
          organizationId: json['organizationId'] as String?,
        );

      case 'USER_NOTIFICATION':
      case 'BROADCAST_NOTIFICATION':
        return NotificationEvent(
          eventType: eventType,
          timestamp: timestamp,
          data: data,
          userId: json['userId'] as String?,
          organizationId: json['organizationId'] as String?,
        );

      case 'MEMBER_CREATED':
      case 'MEMBER_UPDATED':
        return MemberEvent(
          eventType: eventType,
          timestamp: timestamp,
          data: data,
          organizationId: json['organizationId'] as String?,
        );

      case 'CONTRIBUTION_PAID':
        return ContributionEvent(
          eventType: eventType,
          timestamp: timestamp,
          data: data,
          organizationId: json['organizationId'] as String?,
        );

      case 'NOUVEAU_MESSAGE':
      case 'MESSAGE_SUPPRIME':
      case 'CONVERSATION_LUE':
        return ChatMessageEvent(
          eventType: eventType,
          timestamp: timestamp,
          data: data,
          conversationId: json['conversationId'] as String?,
          organizationId: json['organizationId'] as String?,
        );

      default:
        return GenericEvent(
          eventType: eventType,
          timestamp: timestamp,
          data: data,
        );
    }
  }
}

class FinanceApprovalEvent extends WebSocketEvent {
  final String? organizationId;

  FinanceApprovalEvent({
    required super.eventType,
    required super.timestamp,
    required super.data,
    this.organizationId,
  });
}

class DashboardStatsEvent extends WebSocketEvent {
  final String? organizationId;

  DashboardStatsEvent({
    required super.eventType,
    required super.timestamp,
    required super.data,
    this.organizationId,
  });
}

class NotificationEvent extends WebSocketEvent {
  final String? userId;
  final String? organizationId;

  NotificationEvent({
    required super.eventType,
    required super.timestamp,
    required super.data,
    this.userId,
    this.organizationId,
  });
}

class MemberEvent extends WebSocketEvent {
  final String? organizationId;

  MemberEvent({
    required super.eventType,
    required super.timestamp,
    required super.data,
    this.organizationId,
  });
}

class ContributionEvent extends WebSocketEvent {
  final String? organizationId;

  ContributionEvent({
    required super.eventType,
    required super.timestamp,
    required super.data,
    this.organizationId,
  });
}

class ChatMessageEvent extends WebSocketEvent {
  final String? conversationId;
  final String? organizationId;

  ChatMessageEvent({
    required super.eventType,
    required super.timestamp,
    required super.data,
    this.conversationId,
    this.organizationId,
  });
}

class GenericEvent extends WebSocketEvent {
  GenericEvent({
    required super.eventType,
    required super.timestamp,
    required super.data,
  });
}

/// Service WebSocket pour recevoir les events temps réel du backend
@singleton
class WebSocketService {
  WebSocketChannel? _channel;
  Timer? _reconnectTimer;
  Timer? _heartbeatTimer;

  final StreamController<WebSocketEvent> _eventController = StreamController.broadcast();
  final StreamController<bool> _connectionStatusController = StreamController.broadcast();

  bool _isConnected = false;
  bool _shouldReconnect = true;
  int _reconnectAttempts = 0;

  /// Stream des events WebSocket typés
  Stream<WebSocketEvent> get eventStream => _eventController.stream;

  /// Stream du statut de connexion
  Stream<bool> get connectionStatusStream => _connectionStatusController.stream;

  /// Statut de connexion actuel
  bool get isConnected => _isConnected;

  /// Connexion au WebSocket
  void connect() {
    if (_isConnected || _channel != null) {
      AppLogger.info('WebSocket déjà connecté');
      return;
    }

    try {
      final wsUrl = _buildWebSocketUrl();
      AppLogger.info('Connexion WebSocket à $wsUrl...');

      _channel = WebSocketChannel.connect(Uri.parse(wsUrl));

      _channel!.stream.listen(
        _onMessage,
        onError: _onError,
        onDone: _onDone,
        cancelOnError: false,
      );

      _isConnected = true;
      _reconnectAttempts = 0;
      _connectionStatusController.add(true);

      // Heartbeat toutes les 30 secondes
      _startHeartbeat();

      AppLogger.info('✅ WebSocket connecté avec succès');
    } catch (e) {
      AppLogger.error('Erreur connexion WebSocket', error: e);
      _scheduleReconnect();
    }
  }

  /// Déconnexion du WebSocket
  void disconnect() {
    AppLogger.info('Déconnexion WebSocket...');
    _shouldReconnect = false;
    _stopHeartbeat();
    _stopReconnectTimer();

    _channel?.sink.close(status.normalClosure);
    _channel = null;

    _isConnected = false;
    _connectionStatusController.add(false);
  }

  /// Dispose des ressources
  void dispose() {
    disconnect();
    _eventController.close();
    _connectionStatusController.close();
  }

  /// Construit l'URL WebSocket depuis l'URL backend
  String _buildWebSocketUrl() {
    var baseUrl = AppConfig.apiBaseUrl;

    // Remplacer http/https par ws/wss
    if (baseUrl.startsWith('https://')) {
      baseUrl = baseUrl.replaceFirst('https://', 'wss://');
    } else if (baseUrl.startsWith('http://')) {
      baseUrl = baseUrl.replaceFirst('http://', 'ws://');
    }

    return '$baseUrl/ws/dashboard';
  }

  // ─────────────────────────────────────────────────────────────────────────
  // Helpers de conversion de types (Flutter Web / dart2js compatibility)
  // ─────────────────────────────────────────────────────────────────────────

  /// Convertit récursivement un objet JSON (potentiellement JS) en types Dart natifs.
  /// Nécessaire sur Flutter Web où jsonDecode peut retourner des LegacyJavaScriptObject.
  static dynamic _toDart(dynamic value) {
    if (value is Map) {
      return Map<String, dynamic>.fromEntries(
        (value as Map).entries.map(
          (e) => MapEntry(e.key.toString(), _toDart(e.value)),
        ),
      );
    }
    if (value is List) {
      return (value as List).map(_toDart).toList();
    }
    return value;
  }

  /// Gestion des messages reçus
  void _onMessage(dynamic message) {
    try {
      if (AppConfig.enableLogging) {
        AppLogger.debug('WebSocket message reçu: $message');
      }

      // Sur Flutter Web (web_socket_channel ^3.0.x avec package:web), les messages
      // text peuvent arriver comme JSString/LegacyJavaScriptObject plutôt que String.
      // toString() fonctionne pour les strings JS primitifs.
      final String rawMessage = message is String ? message : message.toString();
      if (rawMessage.isEmpty) return;

      // Convertir en types Dart natifs pour éviter les LegacyJavaScriptObject imbriqués
      final dynamic decoded = jsonDecode(rawMessage);
      if (decoded is! Map) {
        AppLogger.warning('WebSocket: message ignoré (non-objet): type=${decoded.runtimeType}');
        return;
      }
      final json = _toDart(decoded) as Map<String, dynamic>;
      final type = json['type'] as String?;

      // Gérer les messages système
      if (type == 'connected') {
        final connectedMsg = (json['data'] as Map<String, dynamic>?)?['message'] ?? 'WebSocket connecté';
        AppLogger.info('🔗 WebSocket: $connectedMsg');
        return;
      }

      if (type == 'pong') {
        if (AppConfig.enableLogging) {
          AppLogger.debug('WebSocket heartbeat pong reçu');
        }
        return;
      }

      if (type == 'ack') {
        return; // Accusé de réception, ignoré
      }

      // Event métier (Kafka)
      if (json.containsKey('eventType')) {
        final event = WebSocketEvent.fromJson(json);
        _eventController.add(event);
        AppLogger.info('📨 Event reçu: ${event.eventType}');
      }
    } catch (e) {
      AppLogger.error('Erreur parsing message WebSocket', error: e);
    }
  }

  /// Gestion des erreurs
  void _onError(dynamic error) {
    AppLogger.error('WebSocket error', error: error);
    _isConnected = false;
    _stopHeartbeat();
    _channel = null;
    _connectionStatusController.add(false);
    _scheduleReconnect();
  }

  /// Gestion de la fermeture de connexion
  void _onDone() {
    if (!_isConnected) return; // Déjà traité par _onError
    AppLogger.info('WebSocket connexion fermée');
    _isConnected = false;
    _channel = null;
    _connectionStatusController.add(false);
    _stopHeartbeat();
    _scheduleReconnect();
  }

  /// Planifier une reconnexion avec backoff exponentiel
  void _scheduleReconnect() {
    if (!_shouldReconnect) {
      return;
    }

    if (_reconnectTimer != null) {
      return; // Reconnexion déjà planifiée
    }

    _stopReconnectTimer();

    // Backoff exponentiel : 2^attempts secondes (max 60s)
    final delaySeconds = (2 << _reconnectAttempts).clamp(1, 60);
    _reconnectAttempts++;

    AppLogger.info('⏳ Reconnexion WebSocket dans ${delaySeconds}s (tentative $_reconnectAttempts)');

    _reconnectTimer = Timer(Duration(seconds: delaySeconds), () {
      _channel = null;
      AppLogger.info('🔄 Tentative de reconnexion WebSocket...');
      connect();
    });
  }

  /// Arrêter le timer de reconnexion
  void _stopReconnectTimer() {
    _reconnectTimer?.cancel();
    _reconnectTimer = null;
  }

  /// Démarrer le heartbeat (ping toutes les 30s)
  void _startHeartbeat() {
    _stopHeartbeat();

    _heartbeatTimer = Timer.periodic(const Duration(seconds: 30), (timer) {
      if (_isConnected && _channel != null) {
        try {
          _channel!.sink.add(jsonEncode({'type': 'ping'}));
          if (AppConfig.enableLogging) {
            AppLogger.debug('WebSocket heartbeat ping envoyé');
          }
        } catch (e) {
          AppLogger.error('Erreur envoi heartbeat', error: e);
        }
      }
    });
  }

  /// Arrêter le heartbeat
  void _stopHeartbeat() {
    _heartbeatTimer?.cancel();
    _heartbeatTimer = null;
  }
}