Merge pull request #231 from blazern/news-feed1

Create NewsFeedManager, NewsPiece, blank NewsFeedPage and a few other things

lib/base/build_value_helper.dart

@@ -1,4 +1,5 @@
 import 'package:built_collection/built_collection.dart';
+import 'package:built_value/json_object.dart';
 import 'package:built_value/serializer.dart';
 import 'package:built_value/standard_json_plugin.dart';
 import 'package:plante/contributions/user_contribution.dart';
@@ -16,6 +17,9 @@ import 'package:plante/outside/backend/backend_product.dart';
 import 'package:plante/outside/backend/backend_products_at_shop.dart';
 import 'package:plante/outside/backend/backend_shop.dart';
 import 'package:plante/outside/backend/mobile_app_config.dart';
+import 'package:plante/outside/backend/news/news_data_response.dart';
+import 'package:plante/outside/backend/news/news_piece.dart';
+import 'package:plante/outside/backend/news/news_piece_product_at_shop.dart';
 import 'package:plante/outside/backend/shops_in_bounds_response.dart';
 import 'package:plante/outside/map/osm/osm_address.dart';
 import 'package:plante/outside/map/osm/osm_road.dart';
@@ -48,13 +52,20 @@ part 'build_value_helper.g.dart';
   UserLangs,
   ShopsInBoundsResponse,
   UserContribution,
+  NewsPiece,
+  NewsPiece,
+  NewsPieceProductAtShop,
+  NewsDataResponse,
 ])
 final Serializers _serializers = _$_serializers;
 final _jsonSerializers = (_serializers.toBuilder()
       ..add(OsmUIDBuildValueSerializer())
       ..addPlugin(StandardJsonPlugin())
       ..addBuilderFactory(const FullType(BuiltList, [FullType(Ingredient)]),
-          () => ListBuilder<Ingredient>()))
+          () => ListBuilder<Ingredient>())
+      ..addBuilderFactory(
+          const FullType(BuiltMap, [FullType(String), FullType(JsonObject)]),
+          () => MapBuilder<String, JsonObject>()))
     .build();
 
 class BuildValueHelper {

lib/model/coord.dart

@@ -7,6 +7,8 @@ import 'package:plante/model/coords_bounds.dart';
 /// Very similar to the LatLng class from Google libs,
 /// **BUT** tails are being cut to certain precision - [lat] and [lon] will
 /// have up to [precision] digits after the dot.
+/// **AND** if the cut tail is 9 in period (999..), the value is rounded to the
+/// next integer (e.g. 1.999 => 2.000).
 ///
 /// Also, this class has some additional methods.
 @immutable
@@ -26,7 +28,18 @@ class Coord {
     final scaledBack = rounded / factor;
     // scaledBack=1.23400
     // 1.23456=>1.23400
-    return scaledBack;
+
+    final minWithGivenPrecision = (1 / factor) * scaledBack.sign;
+    // =0.001
+    final scaledBackPlusMin = scaledBack + minWithGivenPrecision;
+    // 1.23400=>1.23500
+    if (scaledBackPlusMin.toInt() != scaledBack.toInt()) {
+      // if scaledBack=1.999, scaledBackPlusMin would be 2.000
+      return scaledBackPlusMin;
+    } else {
+      // if scaledBack=1.998, scaledBackPlusMin would be 1.999
+      return scaledBack;
+    }
   }
 
   /// Creates a geographical location specified in degrees [lat] and

lib/outside/backend/backend.dart

@@ -24,6 +24,7 @@ import 'package:plante/outside/backend/backend_products_at_shop.dart';
 import 'package:plante/outside/backend/backend_response.dart';
 import 'package:plante/outside/backend/backend_shop.dart';
 import 'package:plante/outside/backend/mobile_app_config.dart';
+import 'package:plante/outside/backend/news/news_data_response.dart';
 import 'package:plante/outside/backend/product_at_shop_source.dart';
 import 'package:plante/outside/backend/product_presence_vote_result.dart';
 import 'package:plante/outside/backend/requested_products_result.dart';
@@ -366,6 +367,29 @@ class Backend {
       ..productsCount = 0));
   }
 
+  Future<Result<NewsDataResponse, BackendError>> requestNews(
+      CoordsBounds bounds,
+      {required int page}) async {
+    final jsonRes = await _backendGetJson('/news_data/', {
+      'north': '${bounds.north}',
+      'south': '${bounds.south}',
+      'west': '${bounds.west}',
+      'east': '${bounds.east}',
+      'page': '$page'
+    });
+    if (jsonRes.isErr) {
+      return Err(jsonRes.unwrapErr());
+    }
+    final json = jsonRes.unwrap();
+
+    try {
+      return Ok(NewsDataResponse.fromJson(json)!);
+    } catch (e) {
+      Log.w('Invalid news_data response: $json', ex: e);
+      return Err(BackendError.invalidDecodedJson(json));
+    }
+  }
+
   Result<None, BackendError> _noneOrErrorFrom(BackendResponse response) {
     if (response.isError) {
       return Err(_errFromResp(response));

lib/outside/backend/news/news_data_response.dart

@@ -0,0 +1,26 @@
+import 'package:built_collection/built_collection.dart';
+import 'package:built_value/built_value.dart';
+import 'package:built_value/serializer.dart';
+import 'package:plante/base/build_value_helper.dart';
+import 'package:plante/outside/backend/news/news_piece.dart';
+
+part 'news_data_response.g.dart';
+
+abstract class NewsDataResponse
+    implements Built<NewsDataResponse, NewsDataResponseBuilder> {
+  @BuiltValueField(wireName: 'last_page')
+  bool get lastPage;
+  @BuiltValueField(wireName: 'results')
+  BuiltList<NewsPiece> get results;
+
+  static NewsDataResponse? fromJson(Map<String, dynamic> json) {
+    return BuildValueHelper.jsonSerializers
+        .deserializeWith(NewsDataResponse.serializer, json);
+  }
+
+  factory NewsDataResponse([void Function(NewsDataResponseBuilder) updates]) =
+      _$NewsDataResponse;
+  NewsDataResponse._();
+  static Serializer<NewsDataResponse> get serializer =>
+      _$newsDataResponseSerializer;
+}

lib/outside/backend/news/news_feed_manager.dart

@@ -0,0 +1,32 @@
+import 'package:plante/base/coord_utils.dart';
+import 'package:plante/base/general_error.dart';
+import 'package:plante/base/result.dart';
+import 'package:plante/logging/log.dart';
+import 'package:plante/outside/backend/backend.dart';
+import 'package:plante/outside/backend/news/news_piece.dart';
+import 'package:plante/ui/map/latest_camera_pos_storage.dart';
+
+class NewsFeedManager {
+  static const _REQUESTED_AREA_SIZE_KMS = 35.0;
+  final Backend _backend;
+  final LatestCameraPosStorage _cameraPosStorage;
+
+  NewsFeedManager(this._backend, this._cameraPosStorage);
+
+  Future<Result<List<NewsPiece>, GeneralError>> obtainNews(
+      {required int page}) async {
+    final pos = await _cameraPosStorage.get();
+    if (pos == null) {
+      Log.w('No camera position for some reason');
+      return Ok(const []);
+    }
+    final backendNewsRes = await _backend.requestNews(
+        pos.makeSquare(kmToGrad(_REQUESTED_AREA_SIZE_KMS)),
+        page: page);
+    if (backendNewsRes.isErr) {
+      return Err(backendNewsRes.unwrapErr().toGeneral());
+    }
+    final backendNews = backendNewsRes.unwrap();
+    return Ok(backendNews.results.toList());
+  }
+}