Implement country ggregation service

.env.example

@@ -52,3 +52,7 @@
 
 # OPTIONAL: Window for the /data API endpoints, in minutes.
 # RATE_LIMIT_DATA_API_WINDOW_MINUTES=60
+
+# OPTIONAL: The cache duration for the CountryQueryService, in minutes.
+# Defaults to 15 minutes if not specified.
+# COUNTRY_SERVICE_CACHE_MINUTES=15

analysis_options.yaml

@@ -10,6 +10,7 @@ analyzer:
     avoid_catching_errors: ignore
     document_ignores: ignore
     one_member_abstracts: ignore
+    cascade_invocations: ignore
   exclude:
     - build/**
 linter:

lib/src/config/app_dependencies.dart

@@ -9,6 +9,7 @@ import 'package:flutter_news_app_api_server_full_source_code/src/config/environm
 import 'package:flutter_news_app_api_server_full_source_code/src/rbac/permission_service.dart';
 import 'package:flutter_news_app_api_server_full_source_code/src/services/auth_service.dart';
 import 'package:flutter_news_app_api_server_full_source_code/src/services/auth_token_service.dart';
+import 'package:flutter_news_app_api_server_full_source_code/src/services/country_query_service.dart';
 import 'package:flutter_news_app_api_server_full_source_code/src/services/dashboard_summary_service.dart';
 import 'package:flutter_news_app_api_server_full_source_code/src/services/database_seeding_service.dart';
 import 'package:flutter_news_app_api_server_full_source_code/src/services/default_user_preference_limit_service.dart';
@@ -69,6 +70,7 @@ class AppDependencies {
   late final PermissionService permissionService;
   late final UserPreferenceLimitService userPreferenceLimitService;
   late final RateLimitService rateLimitService;
+  late final CountryQueryService countryQueryService;
 
   /// Initializes all application dependencies.
   ///
@@ -238,6 +240,11 @@ class AppDependencies {
         connectionManager: _mongoDbConnectionManager,
         log: Logger('MongoDbRateLimitService'),
       );
+      countryQueryService = CountryQueryService(
+        countryRepository: countryRepository,
+        log: Logger('CountryQueryService'),
+        cacheDuration: EnvironmentConfig.countryServiceCacheDuration,
+      );
 
       _isInitialized = true;
       _log.info('Application dependencies initialized successfully.');
@@ -255,6 +262,7 @@ class AppDependencies {
     await _mongoDbConnectionManager.close();
     tokenBlacklistService.dispose();
     rateLimitService.dispose();
+    countryQueryService.dispose(); // Dispose the new service
     _isInitialized = false;
     _log.info('Application dependencies disposed.');
   }

lib/src/config/environment_config.dart

@@ -172,4 +172,14 @@ abstract final class EnvironmentConfig {
         int.tryParse(_env['RATE_LIMIT_DATA_API_WINDOW_MINUTES'] ?? '60') ?? 60;
     return Duration(minutes: minutes);
   }
+
+  /// Retrieves the cache duration in minutes for the CountryQueryService.
+  ///
+  /// The value is read from the `COUNTRY_SERVICE_CACHE_MINUTES` environment
+  /// variable. Defaults to 15 minutes if not set or if parsing fails.
+  static Duration get countryServiceCacheDuration {
+    final minutes =
+        int.tryParse(_env['COUNTRY_SERVICE_CACHE_MINUTES'] ?? '15') ?? 15;
+    return Duration(minutes: minutes);
+  }
 }

lib/src/registry/data_operation_registry.dart

@@ -2,6 +2,7 @@ import 'package:core/core.dart';
 import 'package:dart_frog/dart_frog.dart';
 import 'package:data_repository/data_repository.dart';
 import 'package:flutter_news_app_api_server_full_source_code/src/middlewares/ownership_check_middleware.dart';
+import 'package:flutter_news_app_api_server_full_source_code/src/services/country_query_service.dart';
 import 'package:flutter_news_app_api_server_full_source_code/src/services/dashboard_summary_service.dart';
 
 // --- Typedefs for Data Operations ---
@@ -128,12 +129,27 @@ class DataOperationRegistry {
         sort: s,
         pagination: p,
       ),
-      'country': (c, uid, f, s, p) => c.read<DataRepository<Country>>().readAll(
-        userId: uid,
-        filter: f,
-        sort: s,
-        pagination: p,
-      ),
+      'country': (c, uid, f, s, p) async {
+        // Check for special filters that require aggregation.
+        if (f != null &&
+            (f.containsKey('hasActiveSources') ||
+                f.containsKey('hasActiveHeadlines'))) {
+          // Use the injected CountryQueryService for complex queries.
+          final countryQueryService = c.read<CountryQueryService>();
+          return countryQueryService.getFilteredCountries(
+            filter: f,
+            pagination: p,
+            sort: s,
+          );
+        }
+        // Fallback to standard readAll if no special filters are present.
+        return c.read<DataRepository<Country>>().readAll(
+          userId: uid,
+          filter: f,
+          sort: s,
+          pagination: p,
+        );
+      },
       'language': (c, uid, f, s, p) => c
           .read<DataRepository<Language>>()
           .readAll(userId: uid, filter: f, sort: s, pagination: p),