creating first structure of cinema backend server

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

server/cinema/lib/feature/poster/poster.service.dart

@@ -0,0 +1,37 @@
+import 'dart:convert';
+
+import 'package:cinema/feature/poster/models/poster_request.schema.dart';
+import 'package:injectable/injectable.dart';
+import 'package:shelf/shelf.dart';
+import 'package:shelf_router/shelf_router.dart';
+
+part 'poster.service.g.dart';
+
+@injectable
+class PosterService {
+  @Route.get('/')
+  Future<Response> listPosters(Request request) async {
+    return Response.ok('deprecated poster endpoint. use POST /poster instead');
+  }
+
+  @Route.post('/')
+  Future<Response> createPoster(Request request) async {
+    final payload = await request.readAsString();
+    final body = jsonDecode(payload);
+    final params = posterSchema.safeParse(body);
+    if (!params.success) {
+      return Response(
+        400,
+        body: jsonEncode({
+          'error': 'Invalid request',
+          'details': params.error?.messages,
+        }),
+        headers: {'Content-Type': 'application/json'},
+      );
+    }
+    return Response.ok(jsonEncode(params.data), headers: {'Content-Type': 'application/json'});
+  }
+
+  // Create router using the generate function defined in 'poster.g.dart'.
+  Router get router => _$PosterServiceRouter(this);
+}