// lib/services/user_preferences_service.dart

import 'package:flutter/foundation.dart';
import 'package:environment_monitoring_app/services/api_service.dart'; // Contains DatabaseHelper

/// A dedicated service to manage the user's local preferences for
/// module-specific submission destinations.
class UserPreferencesService {
  final DatabaseHelper _dbHelper = DatabaseHelper();

  /// Retrieves a module's master submission preferences.
  /// If no preference has been saved for this module, it returns a default
  /// where both API and FTP are enabled.
  Future<Map<String, dynamic>> getModulePreference(String moduleName) async {
    final preference = await _dbHelper.getModulePreference(moduleName);
    if (preference != null) {
      return preference;
    }
    // Return a default value if no preference is found in the database.
    return {
      'module_name': moduleName,
      'is_api_enabled': true,
      'is_ftp_enabled': true,
    };
  }

  /// Saves or updates a module's master on/off switches for API and FTP submissions.
  Future<void> saveModulePreference({
    required String moduleName,
    required bool isApiEnabled,
    required bool isFtpEnabled,
  }) async {
    await _dbHelper.saveModulePreference(
      moduleName: moduleName,
      isApiEnabled: isApiEnabled,
      isFtpEnabled: isFtpEnabled,
    );
  }

  /// Retrieves all available API configurations and merges them with the user's
  /// saved preferences for a specific module.
  ///
  /// This is primarily for the Settings UI to display all possible destinations
  /// with their current enabled/disabled state (e.g., checkboxes).
  Future<List<Map<String, dynamic>>> getAllApiConfigsWithModulePreferences(String moduleName) async {
    // 1. Get all possible API destinations that have been synced to the device.
    final allApiConfigs = await _dbHelper.loadApiConfigs() ?? [];
    if (allApiConfigs.isEmpty) return [];

    // 2. Get the specific links the user has previously saved for this module.
    final savedLinks = await _dbHelper.getAllApiLinksForModule(moduleName);

    // 3. Merge the two lists.
    return allApiConfigs.map((config) {
      final configId = config['api_config_id'];
      bool isEnabled = false; // Default to disabled

      try {
        // Find if a link exists for this config ID in the user's saved preferences.
        final matchingLink = savedLinks.firstWhere(
              (link) => link['api_config_id'] == configId,
          // If no link is found, 'orElse' is not triggered, it throws.
        );
        isEnabled = matchingLink['is_enabled'] as bool? ?? false;
      } catch (e) {
        // A 'firstWhere' with no match throws an error. We catch it here.
        // This means no link was saved for this config, so it remains disabled.
        isEnabled = false;
      }

      // Return a new map containing the original config details plus the 'is_enabled' flag.
      return {
        ...config,
        'is_enabled': isEnabled,
      };
    }).toList();
  }

  /// Retrieves all available FTP configurations and merges them with the user's
  /// saved preferences for a specific module. (For the Settings UI).
  Future<List<Map<String, dynamic>>> getAllFtpConfigsWithModulePreferences(String moduleName) async {
    final allFtpConfigs = await _dbHelper.loadFtpConfigs() ?? [];
    if (allFtpConfigs.isEmpty) return [];

    final savedLinks = await _dbHelper.getAllFtpLinksForModule(moduleName);

    return allFtpConfigs.map((config) {
      final configId = config['ftp_config_id'];
      bool isEnabled = false;
      try {
        final matchingLink = savedLinks.firstWhere(
              (link) => link['ftp_config_id'] == configId,
        );
        isEnabled = matchingLink['is_enabled'] as bool? ?? false;
      } catch (e) {
        isEnabled = false;
      }
      return {
        ...config,
        'is_enabled': isEnabled,
      };
    }).toList();
  }

  /// Saves the complete set of enabled/disabled API links for a specific module.
  /// This will replace all previous links for that module.
  Future<void> saveApiLinksForModule(String moduleName, List<Map<String, dynamic>> links) async {
    await _dbHelper.saveApiLinksForModule(moduleName, links);
  }

  /// Saves the complete set of enabled/disabled FTP links for a specific module.
  Future<void> saveFtpLinksForModule(String moduleName, List<Map<String, dynamic>> links) async {
    await _dbHelper.saveFtpLinksForModule(moduleName, links);
  }

  /// Retrieves only the API configurations that are actively enabled for a given module.
  ///
  /// This is primarily for the submission services to know exactly which
  /// destinations to send data to.
  Future<List<Map<String, dynamic>>> getEnabledApiConfigsForModule(String moduleName) async {
    // 1. Check the master switch for the module.
    final pref = await getModulePreference(moduleName);
    if (!(pref['is_api_enabled'] as bool)) {
      debugPrint("API submissions are disabled for module '$moduleName' via master switch.");
      return []; // Return empty list if API is globally disabled for this module.
    }

    // 2. Get all configs with their preference flags.
    final allConfigsWithPrefs = await getAllApiConfigsWithModulePreferences(moduleName);

    // 3. Filter for only those that are enabled.
    final enabledConfigs = allConfigsWithPrefs.where((config) => config['is_enabled'] == true).toList();

    debugPrint("Found ${enabledConfigs.length} enabled API destinations for module '$moduleName'.");
    return enabledConfigs;
  }

  /// Retrieves only the FTP configurations that are actively enabled for a given module.
  Future<List<Map<String, dynamic>>> getEnabledFtpConfigsForModule(String moduleName) async {
    final pref = await getModulePreference(moduleName);
    if (!(pref['is_ftp_enabled'] as bool)) {
      debugPrint("FTP submissions are disabled for module '$moduleName' via master switch.");
      return [];
    }

    final allConfigsWithPrefs = await getAllFtpConfigsWithModulePreferences(moduleName);
    final enabledConfigs = allConfigsWithPrefs.where((config) => config['is_enabled'] == true).toList();

    debugPrint("Found ${enabledConfigs.length} enabled FTP destinations for module '$moduleName'.");
    return enabledConfigs;
  }
}