import 'dart:convert';
import 'dart:io';

import 'package:mnemo_cards_common_backend/mnemo_cards_common_backend.dart';

/// HTTP client for backend API calls
/// Replaces direct Isar DB access with API endpoints
class BackendClient {
  final String backendUrl;
  final String apiKey;
  final HttpClient _httpClient;

  BackendClient({
    required this.backendUrl,
    required this.apiKey,
  }) : _httpClient = HttpClient();

  /// Make HTTP request with retry logic
  Future<Map<String, dynamic>> _request({
    required String method,
    required String path,
    Map<String, dynamic>? body,
    int maxRetries = 3,
    Duration timeout = const Duration(seconds: 10),
  }) async {
    Exception? lastException;
    
    for (int attempt = 0; attempt < maxRetries; attempt++) {
      try {
        final uri = Uri.parse('$backendUrl/api/v2$path');
        final request = await _httpClient.openUrl(method, uri)
            .timeout(timeout);
        
        request.headers.contentType = ContentType.json;
        request.headers.set('X-API-Key', apiKey);
        
        if (body != null) {
          request.write(jsonEncode(body));
        }
        
        final response = await request.close().timeout(timeout);
        final responseBody = await response
            .transform(utf8.decoder)
            .join()
            .timeout(timeout);
        
        if (response.statusCode >= 200 && response.statusCode < 300) {
          if (responseBody.isEmpty) {
            return {};
          }
          return jsonDecode(responseBody) as Map<String, dynamic>;
        } else {
          throw HttpException(
            'HTTP ${response.statusCode}: $responseBody',
            uri: uri,
          );
        }
      } catch (e) {
        lastException = e is Exception ? e : Exception(e.toString());
        if (attempt < maxRetries - 1) {
          // Exponential backoff: 1s, 2s, 4s
          await Future.delayed(Duration(seconds: 1 << attempt));
        }
      }
    }
    
    throw lastException ?? Exception('Request failed after $maxRetries attempts');
  }

  /// Generate a Telegram auth code for a user
  /// Calls backend API to generate the code
  Future<String?> generateAuthCode({
    required String telegramUserId,
    String? telegramUsername,
    String? firstName,
    String? lastName,
  }) async {
    try {
      final response = await _request(
        method: 'POST',
        path: '/auth/telegram/generate-code',
        body: {
          'telegramUserId': telegramUserId,
          if (telegramUsername != null) 'telegramUsername': telegramUsername,
          if (firstName != null) 'firstName': firstName,
          if (lastName != null) 'lastName': lastName,
        },
      );
      return response['code'] as String?;
    } catch (e, s) {
      print('Error generating Telegram auth code: $e\n$s');
      return null;
    }
  }

  /// Claim a web-generated Telegram auth code for a user.
  /// Returns true when the backend confirmed the claim.
  Future<bool> claimWebAuthCode({
    required String code,
    required String telegramUserId,
    String? telegramUsername,
    String? firstName,
    String? lastName,
  }) async {
    try {
      await _request(
        method: 'POST',
        path: '/auth/telegram/claim-code',
        body: {
          'code': code,
          'telegramUserId': telegramUserId,
          if (telegramUsername != null) 'telegramUsername': telegramUsername,
          if (firstName != null) 'firstName': firstName,
          if (lastName != null) 'lastName': lastName,
        },
      );
      return true;
    } catch (e, s) {
      print('Error claiming Telegram auth code: $e\n$s');
      return false;
    }
  }

  /// Check if user can share today (rate limiting)
  /// Returns true if user has not exceeded daily limit
  Future<bool> canShareToday(String telegramUserId, int dailyLimit) async {
    try {
      final response = await _request(
        method: 'POST',
        path: '/telegram-bot/share/check-limit',
        body: {
          'telegramUserId': telegramUserId,
          'dailyLimit': dailyLimit,
        },
      );
      return response['canShare'] as bool? ?? true;
    } catch (e, s) {
      print('Error checking share limit: $e\n$s');
      return true; // Allow on error to prevent blocking users
    }
  }

  /// Record a share request for a user
  Future<void> recordShareRequest({
    required String telegramUserId,
    String? telegramUsername,
    String? sharedCardId,
  }) async {
    try {
      await _request(
        method: 'POST',
        path: '/telegram-bot/share/record',
        body: {
          'telegramUserId': telegramUserId,
          if (telegramUsername != null) 'telegramUsername': telegramUsername,
          if (sharedCardId != null) 'sharedCardId': sharedCardId,
        },
      );
      print(
          '[SHARE_RECORDED] User $telegramUserId shared card $sharedCardId');
    } catch (e, s) {
      print('Error recording share request: $e\n$s');
    }
  }

  /// Get a random card from the database
  /// Returns null if no cards are found
  Future<GameCardModel?> getRandomCard() async {
    try {
      final response = await _request(
        method: 'GET',
        path: '/telegram-bot/random-card',
      );
      
      if (response.isEmpty) {
        return null;
      }
      
      // Convert response to GameCardModel
      // Note: GameCardModel requires non-nullable fields, so we provide defaults
      return GameCardModel(
        id: response['id'] as String,
        original: response['original'] as String? ?? '',
        translation: response['translation'] as String? ?? '',
        mnemo: response['mnemo'] as String? ?? '',
        image: response['image'] as String? ?? '',
        transcription: response['transcription'] as String?,
        transcriptionMnemo: response['transcriptionMnemo'] as String?,
        imageBack: response['imageBack'] as String?,
        back: response['back'] as String?,
      );
    } catch (e, s) {
      print('Error getting random card: $e\n$s');
      return null;
    }
  }

  /// Get user information
  Future<String> userInfo(String userId) async {
    try {
      final response = await _request(
        method: 'GET',
        path: '/telegram-bot/users/info?userId=$userId',
      );
      
      if (response['multiple'] == true) {
        final users = response['users'] as List;
        return 'Found multiple:\n${users.map((u) => '${u['id']} ${u['email'] ?? ''} ${u['name'] ?? ''}').join('\n')}';
      }
      
      final sub = response['subscription'] as Map<String, dynamic>?;
      final packs = response['packs'] as List?;
      
      return '''
${response['id']} ${response['email'] ?? ''} ${response['name'] ?? ''}
Tags: ${response['tags'] ?? ''}
Packs (${packs?.length ?? 0}):
${packs?.map((p) => '${p['id']} ${p['title']}').join('\n') ?? ''}
Purchases: ${response['purchases'] ?? 0}
Subscription ${sub == null ? '' : '(${sub['start']} - ${sub['finish']})'}:
${sub?['features']?.join(' ') ?? ''}
      '''
          .trim();
    } catch (e, s) {
      print('Error getting user info: $e\n$s');
      return 'Error: $e';
    }
  }

  /// Get all users summary
  Future<String> info() async {
    try {
      final response = await _request(
        method: 'GET',
        path: '/telegram-bot/users/info',
      );
      
      final users = response['users'] as List;
      return 'Users (${response['total']}):\n'
          '${users.map((u) => '${u['email'] ?? '${u['id']}'} ${u['lastTimeOnline'] ?? ''}').join('\n')}';
    } catch (e, s) {
      print('Error getting users info: $e\n$s');
      return 'Error: $e';
    }
  }

  /// Get all words from cards
  Future<List<String>> words() async {
    try {
      final response = await _request(
        method: 'GET',
        path: '/telegram-bot/words',
      );
      
      final wordsList = response['words'] as List?;
      return wordsList?.map((w) => w.toString()).toList() ?? [];
    } catch (e, s) {
      print('Error getting words: $e\n$s');
      return [];
    }
  }

  void dispose() {
    _httpClient.close(force: true);
  }
}