Split oott_api.dart into per-domain modules

Break the 372-line frontend API client into focused files under
lib/utils/api/: error mapping (api_error.dart), Dio setup behind a
buildDio factory (dio_config.dart), and device/scanner/notification
endpoints as extensions in part files. Collapse the five near-identical
scanner-status methods via a generic _getModel helper and de-duplicate
the pagination logic via a shared _paginate helper.

The BackendAPI singleton and dioErrorToUserMessage remain importable
from oott_api.dart unchanged, so no call sites are affected.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

TODO.md

@@ -18,7 +18,7 @@
 ## Frontend
 
 - [ ] Can we add front-end tests?
-- [ ] Break down oott_api.dart in modules
+- [x] Break down oott_api.dart in modules
 
 ## Improve engine
 

frontend/lib/utils/api/api_error.dart

@@ -0,0 +1,40 @@
+import 'package:dio/dio.dart';
+import 'package:flutter/foundation.dart';
+
+String dioErrorToUserMessage(Object error) {
+  if (error is TypeError || error is FormatException) {
+    debugPrint('Backend response shape error: $error');
+    return 'Unexpected response shape from backend.';
+  }
+  if (error is! DioException) {
+    debugPrint('Non-Dio error from backend call: $error');
+    return 'Unexpected error.';
+  }
+  switch (error.type) {
+    case DioExceptionType.connectionTimeout:
+    case DioExceptionType.sendTimeout:
+    case DioExceptionType.receiveTimeout:
+      return 'Backend did not respond in time.';
+    case DioExceptionType.connectionError:
+      return 'Cannot reach backend. Check the base URL and your network.';
+    case DioExceptionType.badCertificate:
+      return 'Backend TLS certificate could not be verified.';
+    case DioExceptionType.cancel:
+      return 'Request canceled.';
+    case DioExceptionType.badResponse:
+      final status = error.response?.statusCode;
+      if (status == 401 || status == 403) {
+        return 'Authentication failed. Check your API key in Settings.';
+      }
+      if (status == 404) {
+        return 'Not found.';
+      }
+      if (status != null && status >= 500 && status < 600) {
+        return 'Backend error (status $status). Please try again.';
+      }
+      return 'Unexpected response from backend (status ${status ?? 'unknown'}).';
+    case DioExceptionType.unknown:
+      debugPrint('Unknown Dio error: ${error.message}');
+      return 'Unexpected error contacting backend.';
+  }
+}

frontend/lib/utils/api/dio_config.dart

@@ -0,0 +1,89 @@
+import 'dart:io';
+
+import 'package:dio/dio.dart';
+import 'package:dio_smart_retry/dio_smart_retry.dart';
+import 'package:flutter/foundation.dart';
+
+import '../backend_reachability.dart';
+
+const _connectTimeout = Duration(seconds: 5);
+const _receiveTimeout = Duration(seconds: 15);
+const _sendTimeout = Duration(seconds: 15);
+
+const _retryableStatuses = {408, 429, 500, 502, 503, 504};
+
+/// Builds a [Dio] client configured for the OOTT backend: base options,
+/// authentication header, retry/reachability interceptors and, in debug
+/// builds, request logging.
+Dio buildDio({
+  required String baseUrl,
+  required String apiKey,
+  bool withRetry = true,
+  bool withReachability = true,
+}) {
+  final headers = <String, String>{
+    HttpHeaders.contentTypeHeader: 'application/json',
+  };
+  if (apiKey.isNotEmpty) {
+    headers[HttpHeaders.authorizationHeader] = 'Bearer $apiKey';
+  }
+
+  final dio = Dio(
+    BaseOptions(
+      baseUrl: baseUrl,
+      connectTimeout: _connectTimeout,
+      receiveTimeout: _receiveTimeout,
+      sendTimeout: _sendTimeout,
+      headers: headers,
+    ),
+  );
+
+  if (withRetry) {
+    dio.interceptors.add(_buildRetryInterceptor(dio));
+  }
+  if (withReachability) {
+    dio.interceptors.add(_buildReachabilityInterceptor());
+  }
+  if (kDebugMode) {
+    dio.interceptors.add(_buildLogInterceptor());
+  }
+  return dio;
+}
+
+RetryInterceptor _buildRetryInterceptor(Dio dio) => RetryInterceptor(
+  dio: dio,
+  retries: 2,
+  retryDelays: const [Duration(seconds: 1), Duration(seconds: 3)],
+  logPrint: kDebugMode ? (msg) => debugPrint(msg.toString()) : null,
+  retryEvaluator: (error, attempt) {
+    if (error.requestOptions.method != 'GET') return false;
+    if (error.type == DioExceptionType.cancel) return false;
+    if (error.error is FormatException) return false;
+    if (error.type == DioExceptionType.badResponse) {
+      final status = error.response?.statusCode;
+      return status != null && _retryableStatuses.contains(status);
+    }
+    return true;
+  },
+);
+
+InterceptorsWrapper _buildReachabilityInterceptor() => InterceptorsWrapper(
+  onResponse: (response, handler) {
+    BackendReachability.instance.recordSuccess();
+    handler.next(response);
+  },
+  onError: (error, handler) {
+    BackendReachability.instance.recordFailure(error);
+    handler.next(error);
+  },
+);
+
+LogInterceptor _buildLogInterceptor() => LogInterceptor(
+  request: true,
+  requestHeader: false,
+  requestBody: false,
+  responseHeader: false,
+  responseBody: false,
+  error: true,
+  logPrint: (obj) => debugPrint(obj.toString()),
+);

frontend/lib/utils/api/oott_api_devices.dart

@@ -0,0 +1,108 @@
+part of '../oott_api.dart';
+
+/// Device endpoints: lookup, listing, registration, updates and event history.
+extension DeviceApi on BackendAPI {
+  Future<Device> getDevice(String macAddress) =>
+      _getModel('/devices/$macAddress', Device.fromJson);
+
+  Future<({List<Device> items, bool hasNextPage})> listDevices({
+    bool? isRegistered,
+    String? owner,
+    DeviceType? deviceType,
+    String? sortBy,
+    bool? sortAscending,
+    int page = 0,
+    int perPage = 10,
+    CancelToken? cancelToken,
+  }) async {
+    final params = <String, dynamic>{};
+    if (isRegistered != null) params['is_registered'] = isRegistered;
+    if (owner != null && owner.isNotEmpty) params['owner'] = owner;
+    if (deviceType != null) {
+      params['device_type'] = deviceType == DeviceType.unknown
+          ? ''
+          : deviceType.apiName;
+    }
+    if (sortBy != null) params['sort_by'] = sortBy;
+    if (sortAscending != null) {
+      params['sort_order'] = sortAscending ? 'asc' : 'desc';
+    }
+    params['page_offset'] = page * perPage;
+    params['page_limit'] = perPage + 1;
+
+    final response = await _dio.get(
+      '/devices',
+      queryParameters: params,
+      cancelToken: cancelToken,
+    );
+
+    return _paginate(
+      response.data as List,
+      (item) => Device.fromJson(item as Map<String, dynamic>),
+      perPage,
+    );
+  }
+
+  Future<void> registerDevice(
+    String macAddress,
+    String owner,
+    String deviceType, {
+    String? name,
+  }) async {
+    await _dio.put(
+      '/devices',
+      data: {
+        'mac_address': macAddress,
+        'owner': owner,
+        'device_type': deviceType,
+        'name': ?name,
+      },
+    );
+  }
+
+  Future<void> updateDevice(
+    String macAddress,
+    String owner,
+    String deviceType,
+    String vendor, {
+    String? name,
+  }) async {
+    await _dio.put(
+      '/devices/$macAddress',
+      data: {
+        'owner': owner,
+        'device_type': deviceType,
+        'vendor': vendor,
+        'name': name,
+      },
+    );
+  }
+
+  Future<void> forgetDevice(String macAddress) async {
+    await _dio.delete('/devices/$macAddress');
+  }
+
+  Future<List<DeviceEvent>> getDeviceEvents(
+    String macAddress, {
+    DateTime? createdFrom,
+  }) async {
+    final queryParams = <String, dynamic>{};
+    if (createdFrom != null) {
+      queryParams['created_from'] = createdFrom.toUtc().toIso8601String();
+    }
+    final response = await _dio.get(
+      '/devices/$macAddress/events',
+      queryParameters: queryParams.isEmpty ? null : queryParams,
+    );
+    return (response.data as List)
+        .map((item) => DeviceEvent.fromJson(item as Map<String, dynamic>))
+        .toList();
+  }
+
+  Future<DeviceSummary> getDeviceSummary({CancelToken? cancelToken}) =>
+      _getModel(
+        '/devices/summary',
+        DeviceSummary.fromJson,
+        cancelToken: cancelToken,
+      );
+}

frontend/lib/utils/api/oott_api_notifications.dart

@@ -0,0 +1,39 @@
+part of '../oott_api.dart';
+
+/// Notification endpoints: listing and read/new state transitions.
+extension NotificationApi on BackendAPI {
+  Future<void> markNotificationAsRead(int id) async {
+    await _dio.get('/notifications/$id');
+  }
+
+  Future<void> markNotificationAsNew(int id) async {
+    await _dio.post('/notifications/$id/mark_as_new');
+  }
+
+  Future<void> markAllNotificationsAsRead() async {
+    await _dio.post('/notifications/mark_all_as_old');
+  }
+
+  Future<({List<Notification> items, bool hasNextPage})> listNotifications(
+    bool? isNew, {
+    int page = 0,
+    int perPage = 5,
+    CancelToken? cancelToken,
+  }) async {
+    final response = await _dio.get(
+      '/notifications',
+      queryParameters: {
+        'is_new': isNew ?? '',
+        'page_offset': page * perPage,
+        'page_limit': perPage + 1,
+      },
+      cancelToken: cancelToken,
+    );
+
+    return _paginate(
+      response.data as List<dynamic>,
+      (item) => Notification.fromJson(item),
+      perPage,
+    );
+  }
+}

frontend/lib/utils/api/oott_api_scanners.dart

@@ -0,0 +1,40 @@
+part of '../oott_api.dart';
+
+/// Per-scanner status endpoints. Every scanner exposes the same
+/// `/<scanner>_scanner/status` shape, so each getter just decodes its model.
+extension ScannerApi on BackendAPI {
+  Future<ArpScannerStatus> getArpScannerStatus({CancelToken? cancelToken}) =>
+      _getModel(
+        '/arp_scanner/status',
+        ArpScannerStatus.fromJson,
+        cancelToken: cancelToken,
+      );
+
+  Future<MdnsScannerStatus> getMdnsScannerStatus({CancelToken? cancelToken}) =>
+      _getModel(
+        '/mdns_scanner/status',
+        MdnsScannerStatus.fromJson,
+        cancelToken: cancelToken,
+      );
+
+  Future<SsdpScannerStatus> getSsdpScannerStatus({CancelToken? cancelToken}) =>
+      _getModel(
+        '/ssdp_scanner/status',
+        SsdpScannerStatus.fromJson,
+        cancelToken: cancelToken,
+      );
+
+  Future<DhcpScannerStatus> getDhcpScannerStatus({CancelToken? cancelToken}) =>
+      _getModel(
+        '/dhcp_scanner/status',
+        DhcpScannerStatus.fromJson,
+        cancelToken: cancelToken,
+      );
+
+  Future<SnmpScannerStatus> getSnmpScannerStatus({CancelToken? cancelToken}) =>
+      _getModel(
+        '/snmp_scanner/status',
+        SnmpScannerStatus.fromJson,
+        cancelToken: cancelToken,
+      );
+}

frontend/lib/utils/oott_api.dart

@@ -1,11 +1,12 @@
-import 'dart:io';
+library;
 
 import 'package:dio/dio.dart';
-import 'package:dio_smart_retry/dio_smart_retry.dart';
 import 'package:encrypter/encrypter/xor.dart';
-import 'package:flutter/foundation.dart';
+
-import 'package:frontend/utils/backend_reachability.dart';
+import 'api/api_error.dart';
-import 'package:frontend/utils/pref_utils.dart';
+import 'api/dio_config.dart';
+import 'backend_reachability.dart';
+import 'pref_utils.dart';
 import '../model/arp_scanner_status.dart';
 import '../model/dhcp_scanner_status.dart';
 import '../model/mdns_scanner_status.dart';
@@ -17,87 +18,11 @@ import '../model/device_summary.dart';
 import '../model/device_type.dart';
 import '../model/notification.dart';
 
-const _connectTimeout = Duration(seconds: 5);
+export 'api/api_error.dart';
-const _receiveTimeout = Duration(seconds: 15);
-const _sendTimeout = Duration(seconds: 15);
 
-const _retryableStatuses = {408, 429, 500, 502, 503, 504};
+part 'api/oott_api_devices.dart';
-
+part 'api/oott_api_scanners.dart';
-RetryInterceptor _buildRetryInterceptor(Dio dio) => RetryInterceptor(
+part 'api/oott_api_notifications.dart';
-  dio: dio,
-  retries: 2,
-  retryDelays: const [Duration(seconds: 1), Duration(seconds: 3)],
-  logPrint: kDebugMode ? (msg) => debugPrint(msg.toString()) : null,
-  retryEvaluator: (error, attempt) {
-    if (error.requestOptions.method != 'GET') return false;
-    if (error.type == DioExceptionType.cancel) return false;
-    if (error.error is FormatException) return false;
-    if (error.type == DioExceptionType.badResponse) {
-      final status = error.response?.statusCode;
-      return status != null && _retryableStatuses.contains(status);
-    }
-    return true;
-  },
-);
-
-InterceptorsWrapper _buildReachabilityInterceptor() => InterceptorsWrapper(
-  onResponse: (response, handler) {
-    BackendReachability.instance.recordSuccess();
-    handler.next(response);
-  },
-  onError: (error, handler) {
-    BackendReachability.instance.recordFailure(error);
-    handler.next(error);
-  },
-);
-
-LogInterceptor _buildLogInterceptor() => LogInterceptor(
-  request: true,
-  requestHeader: false,
-  requestBody: false,
-  responseHeader: false,
-  responseBody: false,
-  error: true,
-  logPrint: (obj) => debugPrint(obj.toString()),
-);
-
-String dioErrorToUserMessage(Object error) {
-  if (error is TypeError || error is FormatException) {
-    debugPrint('Backend response shape error: $error');
-    return 'Unexpected response shape from backend.';
-  }
-  if (error is! DioException) {
-    debugPrint('Non-Dio error from backend call: $error');
-    return 'Unexpected error.';
-  }
-  switch (error.type) {
-    case DioExceptionType.connectionTimeout:
-    case DioExceptionType.sendTimeout:
-    case DioExceptionType.receiveTimeout:
-      return 'Backend did not respond in time.';
-    case DioExceptionType.connectionError:
-      return 'Cannot reach backend. Check the base URL and your network.';
-    case DioExceptionType.badCertificate:
-      return 'Backend TLS certificate could not be verified.';
-    case DioExceptionType.cancel:
-      return 'Request canceled.';
-    case DioExceptionType.badResponse:
-      final status = error.response?.statusCode;
-      if (status == 401 || status == 403) {
-        return 'Authentication failed. Check your API key in Settings.';
-      }
-      if (status == 404) {
-        return 'Not found.';
-      }
-      if (status != null && status >= 500 && status < 600) {
-        return 'Backend error (status $status). Please try again.';
-      }
-      return 'Unexpected response from backend (status ${status ?? 'unknown'}).';
-    case DioExceptionType.unknown:
-      debugPrint('Unknown Dio error: ${error.message}');
-      return 'Unexpected error contacting backend.';
-  }
-}
 
 class BackendAPI {
   static final BackendAPI _instance = BackendAPI._internal();
@@ -107,59 +32,30 @@ class BackendAPI {
     reconfigureFromPrefs();
   }
 
+  late String _baseUrl;
+  late String _apiKey;
+  late Dio _dio;
+
   void reconfigureFromPrefs() {
     _baseUrl =
         PrefUtil.getValue("base_url", "http://localhost:3000/api") as String;
     _apiKey = XOR().xorDecode(PrefUtil.getValue("api_key", "") as String);
 
-    final headers = <String, String>{
+    _dio = buildDio(baseUrl: _baseUrl, apiKey: _apiKey);
-      HttpHeaders.contentTypeHeader: 'application/json',
-    };
-    if (_apiKey.isNotEmpty) {
-      headers[HttpHeaders.authorizationHeader] = 'Bearer $_apiKey';
-    }
-
-    _dio = Dio(
-      BaseOptions(
-        baseUrl: _baseUrl,
-        connectTimeout: _connectTimeout,
-        receiveTimeout: _receiveTimeout,
-        sendTimeout: _sendTimeout,
-        headers: headers,
-      ),
-    );
-    _dio.interceptors.add(_buildRetryInterceptor(_dio));
-    _dio.interceptors.add(_buildReachabilityInterceptor());
-    if (kDebugMode) {
-      _dio.interceptors.add(_buildLogInterceptor());
-    }
     BackendReachability.instance.setProber(() => _dio.get('/test'));
   }
 
   // Returns null if the test was successful, and a String with a message about the issue if not
   static Future<String?> test(String baseUrl, String apiKey) async {
-    final headers = <String, String>{
+    final dio = buildDio(
-      HttpHeaders.contentTypeHeader: 'application/json',
+      baseUrl: baseUrl,
-    };
+      apiKey: apiKey,
-    if (apiKey.isNotEmpty) {
+      withRetry: false,
-      headers[HttpHeaders.authorizationHeader] = 'Bearer $apiKey';
+      withReachability: false,
-    }
-
-    Dio dio = Dio(
-      BaseOptions(
-        baseUrl: baseUrl,
-        connectTimeout: _connectTimeout,
-        receiveTimeout: _receiveTimeout,
-        sendTimeout: _sendTimeout,
-        headers: headers,
-      ),
     );
-    if (kDebugMode) {
-      dio.interceptors.add(_buildLogInterceptor());
-    }
 
     try {
-      Response response = await dio.get('/test');
+      final response = await dio.get('/test');
       return response.data == 'OOTT_API_OK'
           ? null
           : "URL successfully called but didn't return the expected value. Check your URL and make sure it points to your OOTT backend base URL.";
@@ -168,201 +64,25 @@ class BackendAPI {
     }
   }
 
-  late String _baseUrl;
+  /// Fetches [path] and decodes the JSON object response with [fromJson].
-  late String _apiKey;
+  Future<T> _getModel<T>(
-  late Dio _dio;
+    String path,
-
+    T Function(Map<String, dynamic>) fromJson, {
-  Future<void> markNotificationAsRead(int id) async {
-    await _dio.get('/notifications/$id');
-  }
-
-  Future<void> markNotificationAsNew(int id) async {
-    await _dio.post('/notifications/$id/mark_as_new');
-  }
-
-  Future<void> markAllNotificationsAsRead() async {
-    await _dio.post('/notifications/mark_all_as_old');
-  }
-
-  Future<Device> getDevice(String macAddress) async {
-    final response = await _dio.get('/devices/$macAddress');
-    return Device.fromJson(response.data as Map<String, dynamic>);
-  }
-
-  Future<({List<Device> items, bool hasNextPage})> listDevices({
-    bool? isRegistered,
-    String? owner,
-    DeviceType? deviceType,
-    String? sortBy,
-    bool? sortAscending,
-    int page = 0,
-    int perPage = 10,
     CancelToken? cancelToken,
   }) async {
-    final params = <String, dynamic>{};
+    final response = await _dio.get(path, cancelToken: cancelToken);
-    if (isRegistered != null) params['is_registered'] = isRegistered;
+    return fromJson(response.data as Map<String, dynamic>);
-    if (owner != null && owner.isNotEmpty) params['owner'] = owner;
-    if (deviceType != null) {
-      params['device_type'] = deviceType == DeviceType.unknown
-          ? ''
-          : deviceType.apiName;
-    }
-    if (sortBy != null) params['sort_by'] = sortBy;
-    if (sortAscending != null) {
-      params['sort_order'] = sortAscending ? 'asc' : 'desc';
-    }
-    params['page_offset'] = page * perPage;
-    params['page_limit'] = perPage + 1;
-
-    final response = await _dio.get(
-      '/devices',
-      queryParameters: params,
-      cancelToken: cancelToken,
-    );
-
-    final results = (response.data as List)
-        .map((item) => Device.fromJson(item as Map<String, dynamic>))
-        .toList();
-    final hasNextPage = results.length > perPage;
-    return (
-      items: hasNextPage ? results.take(perPage).toList() : results,
-      hasNextPage: hasNextPage,
-    );
   }
 
-  Future<void> registerDevice(
+  /// Splits a "fetch one extra item" page into its items and a [hasNextPage]
-    String macAddress,
+  /// flag. Callers request `perPage + 1` items so a full extra item signals
-    String owner,
+  /// that another page exists.
-    String deviceType, {
+  ({List<T> items, bool hasNextPage}) _paginate<T>(
-    String? name,
+    List<dynamic> data,
-  }) async {
+    T Function(dynamic) fromItem,
-    await _dio.put(
+    int perPage,
-      '/devices',
+  ) {
-      data: {
+    final results = data.map(fromItem).toList();
-        'mac_address': macAddress,
-        'owner': owner,
-        'device_type': deviceType,
-        'name': ?name,
-      },
-    );
-  }
-
-  Future<void> updateDevice(
-    String macAddress,
-    String owner,
-    String deviceType,
-    String vendor, {
-    String? name,
-  }) async {
-    await _dio.put(
-      '/devices/$macAddress',
-      data: {
-        'owner': owner,
-        'device_type': deviceType,
-        'vendor': vendor,
-        'name': name,
-      },
-    );
-  }
-
-  Future<void> forgetDevice(String macAddress) async {
-    await _dio.delete('/devices/$macAddress');
-  }
-
-  Future<List<DeviceEvent>> getDeviceEvents(
-    String macAddress, {
-    DateTime? createdFrom,
-  }) async {
-    final queryParams = <String, dynamic>{};
-    if (createdFrom != null) {
-      queryParams['created_from'] = createdFrom.toUtc().toIso8601String();
-    }
-    final response = await _dio.get(
-      '/devices/$macAddress/events',
-      queryParameters: queryParams.isEmpty ? null : queryParams,
-    );
-    return (response.data as List)
-        .map((item) => DeviceEvent.fromJson(item as Map<String, dynamic>))
-        .toList();
-  }
-
-  Future<DeviceSummary> getDeviceSummary({CancelToken? cancelToken}) async {
-    final response = await _dio.get(
-      '/devices/summary',
-      cancelToken: cancelToken,
-    );
-    return DeviceSummary.fromJson(response.data as Map<String, dynamic>);
-  }
-
-  Future<ArpScannerStatus> getArpScannerStatus({
-    CancelToken? cancelToken,
-  }) async {
-    final response = await _dio.get(
-      '/arp_scanner/status',
-      cancelToken: cancelToken,
-    );
-    return ArpScannerStatus.fromJson(response.data as Map<String, dynamic>);
-  }
-
-  Future<MdnsScannerStatus> getMdnsScannerStatus({
-    CancelToken? cancelToken,
-  }) async {
-    final response = await _dio.get(
-      '/mdns_scanner/status',
-      cancelToken: cancelToken,
-    );
-    return MdnsScannerStatus.fromJson(response.data as Map<String, dynamic>);
-  }
-
-  Future<SsdpScannerStatus> getSsdpScannerStatus({
-    CancelToken? cancelToken,
-  }) async {
-    final response = await _dio.get(
-      '/ssdp_scanner/status',
-      cancelToken: cancelToken,
-    );
-    return SsdpScannerStatus.fromJson(response.data as Map<String, dynamic>);
-  }
-
-  Future<DhcpScannerStatus> getDhcpScannerStatus({
-    CancelToken? cancelToken,
-  }) async {
-    final response = await _dio.get(
-      '/dhcp_scanner/status',
-      cancelToken: cancelToken,
-    );
-    return DhcpScannerStatus.fromJson(response.data as Map<String, dynamic>);
-  }
-
-  Future<SnmpScannerStatus> getSnmpScannerStatus({
-    CancelToken? cancelToken,
-  }) async {
-    final response = await _dio.get(
-      '/snmp_scanner/status',
-      cancelToken: cancelToken,
-    );
-    return SnmpScannerStatus.fromJson(response.data as Map<String, dynamic>);
-  }
-
-  Future<({List<Notification> items, bool hasNextPage})> listNotifications(
-    bool? isNew, {
-    int page = 0,
-    int perPage = 5,
-    CancelToken? cancelToken,
-  }) async {
-    final response = await _dio.get(
-      '/notifications',
-      queryParameters: {
-        'is_new': isNew ?? '',
-        'page_offset': page * perPage,
-        'page_limit': perPage + 1,
-      },
-      cancelToken: cancelToken,
-    );
-
-    final results = (response.data as List<dynamic>)
-        .map((item) => Notification.fromJson(item))
-        .toList();
     final hasNextPage = results.length > perPage;
     return (
       items: hasNextPage ? results.take(perPage).toList() : results,