import 'dart:convert';
import 'package:shared_preferences/shared_preferences.dart';
import '../models/action_template.dart';

/// Service for caching server lists to prevent categories from disappearing
/// when SDK Bridge is temporarily unavailable during service restarts
class ServerCacheService {
  static const String _gcoreServersKey = 'cached_gcore_servers';
  static const String _gscServersKey = 'cached_gsc_servers';
  static const String _cacheTimestampKey = 'server_cache_timestamp';

  /// Save G-Core servers to cache
  static Future<void> cacheGCoreServers(List<ServerInfo> servers) async {
    final prefs = await SharedPreferences.getInstance();
    final json = jsonEncode(servers.map((s) => s.toJson()).toList());
    await prefs.setString(_gcoreServersKey, json);
    await prefs.setInt(_cacheTimestampKey, DateTime.now().millisecondsSinceEpoch);
    print('[ServerCache] Cached ${servers.length} G-Core servers');
  }

  /// Save GSC servers to cache
  static Future<void> cacheGSCServers(List<ServerInfo> servers) async {
    final prefs = await SharedPreferences.getInstance();
    final json = jsonEncode(servers.map((s) => s.toJson()).toList());
    await prefs.setString(_gscServersKey, json);
    await prefs.setInt(_cacheTimestampKey, DateTime.now().millisecondsSinceEpoch);
    print('[ServerCache] Cached ${servers.length} GSC servers');
  }

  /// Save both server lists
  static Future<void> cacheServers({
    required List<ServerInfo> gcoreServers,
    required List<ServerInfo> gscServers,
  }) async {
    await cacheGCoreServers(gcoreServers);
    await cacheGSCServers(gscServers);
  }

  /// Load cached G-Core servers
  static Future<List<ServerInfo>> getCachedGCoreServers() async {
    final prefs = await SharedPreferences.getInstance();
    final json = prefs.getString(_gcoreServersKey);
    if (json == null) {
      print('[ServerCache] No cached G-Core servers found');
      return [];
    }

    try {
      final list = jsonDecode(json) as List<dynamic>;
      final servers = list.map((item) => ServerInfo.fromJson(item as Map<String, dynamic>)).toList();
      print('[ServerCache] Loaded ${servers.length} cached G-Core servers');
      return servers;
    } catch (e) {
      print('[ServerCache] Error loading cached G-Core servers: $e');
      return [];
    }
  }

  /// Load cached GSC servers
  static Future<List<ServerInfo>> getCachedGSCServers() async {
    final prefs = await SharedPreferences.getInstance();
    final json = prefs.getString(_gscServersKey);
    if (json == null) {
      print('[ServerCache] No cached GSC servers found');
      return [];
    }

    try {
      final list = jsonDecode(json) as List<dynamic>;
      final servers = list.map((item) => ServerInfo.fromJson(item as Map<String, dynamic>)).toList();
      print('[ServerCache] Loaded ${servers.length} cached GSC servers');
      return servers;
    } catch (e) {
      print('[ServerCache] Error loading cached GSC servers: $e');
      return [];
    }
  }

  /// Get cache age in milliseconds
  static Future<int?> getCacheAge() async {
    final prefs = await SharedPreferences.getInstance();
    final timestamp = prefs.getInt(_cacheTimestampKey);
    if (timestamp == null) return null;
    return DateTime.now().millisecondsSinceEpoch - timestamp;
  }

  /// Clear all cached server data
  static Future<void> clearCache() async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.remove(_gcoreServersKey);
    await prefs.remove(_gscServersKey);
    await prefs.remove(_cacheTimestampKey);
    print('[ServerCache] Cache cleared');
  }
}