load trending images from tmdb at startup

- need TMDB_API_KEY as environment variable
- mount /cache for data persistence

Signed-off-by: Peter Siegmund <developer@mars3142.org>

server/cinema/lib/feature/poster/data/repositories/image_loader.dart

@@ -0,0 +1,7 @@
+import 'package:cinema/feature/poster/domain/movie.dart';
+
+abstract class ImageLoader {
+  Future<List<Movie>> getPosterURIs({String? language = 'de'});
+
+  Future<bool> downloadImages(Movie movie);
+}

server/cinema/lib/feature/poster/data/repositories/tmdb_image_loader.dart

@@ -0,0 +1,57 @@
+import 'dart:io';
+
+import 'package:cinema/common/dio_module.dart';
+import 'package:cinema/common/domain/serializers.dart';
+import 'package:cinema/feature/poster/data/repositories/image_loader.dart';
+import 'package:cinema/feature/poster/domain/movie.dart';
+import 'package:cinema/feature/poster/domain/tmdb_trending_response.dart';
+import 'package:dio/dio.dart';
+import 'package:injectable/injectable.dart';
+
+@Injectable(as: ImageLoader)
+class TmDBImageLoader implements ImageLoader {
+  final Dio api;
+  final Dio images;
+  final String imageBaseUrl = 'https://image.tmdb.org/t/p/w500';
+
+  TmDBImageLoader(@Named(dioAPI) this.api, @Named(dioIMAGES) this.images);
+
+  @override
+  Future<List<Movie>> getPosterURIs({String? language = 'de'}) async {
+    final response = await api.get('/trending/movie/week?language=$language');
+    if (response.data != null) {
+      final data = serializers.deserializeWith(TmdbTrendingResponse.serializer, response.data);
+      return data?.results
+              .map(
+                (movie) => Movie(
+                  (b) => b
+                    ..id = movie.id
+                    ..poster = movie.posterPath
+                    ..backdrop = movie.backdropPath,
+                ),
+              )
+              .toList() ??
+          [];
+    }
+    return [];
+  }
+
+  @override
+  Future<bool> downloadImages(Movie movie) async {
+    await downloadImage(movie.poster, "cache/movie/${movie.id}/poster.png");
+    await downloadImage(movie.backdrop, "cache/movie/${movie.id}/backdrop.png");
+    return true;
+  }
+
+  Future<bool> downloadImage(String url, String filename) async {
+    final file = File(filename);
+    if (await file.exists()) {
+      return false;
+    }
+
+    await file.parent.create(recursive: true);
+    final response = await images.get(url, options: Options(responseType: ResponseType.bytes));
+    await file.writeAsBytes(response.data);
+    return true;
+  }
+}