Solution

.gitignore

@@ -7,4 +7,5 @@ venv/
 .pytest_cache/
 **__pycache__/
 *.pyc
-app/db.sqlite3
+app/db.sqlite3
+db.sqlite3

cinema/pagination.py

@@ -0,0 +1,7 @@
+from rest_framework.pagination import PageNumberPagination
+
+
+class OrderPagination(PageNumberPagination):
+    page_size = 5
+    page_size_query_param = "page_size"
+    max_page_size = 10

cinema/serializers.py

@@ -1,6 +1,15 @@
+from django.db import transaction
 from rest_framework import serializers
 
-from cinema.models import Genre, Actor, CinemaHall, Movie, MovieSession
+from cinema.models import (
+    Genre,
+    Actor,
+    CinemaHall,
+    Movie,
+    MovieSession,
+    Ticket,
+    Order,
+)
 
 
 class GenreSerializer(serializers.ModelSerializer):
@@ -60,6 +69,8 @@ class MovieSessionListSerializer(MovieSessionSerializer):
         source="cinema_hall.capacity", read_only=True
     )
 
+    tickets_available = serializers.IntegerField(read_only=True)
+
     class Meta:
         model = MovieSession
         fields = (
@@ -68,13 +79,61 @@ class Meta:
             "movie_title",
             "cinema_hall_name",
             "cinema_hall_capacity",
+            "tickets_available",
         )
 
 
+class TicketSeatRowSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = Ticket
+        fields = ("row", "seat")
+
+
 class MovieSessionDetailSerializer(MovieSessionSerializer):
     movie = MovieListSerializer(many=False, read_only=True)
     cinema_hall = CinemaHallSerializer(many=False, read_only=True)
 
+    taken_places = TicketSeatRowSerializer(
+        many=True,
+        read_only=True,
+        source="tickets",
+    )
+
     class Meta:
         model = MovieSession
-        fields = ("id", "show_time", "movie", "cinema_hall")
+        fields = ("id", "show_time", "movie", "cinema_hall", "taken_places")
+
+
+class TicketSerializer(serializers.ModelSerializer):
+    movie_session = MovieSessionListSerializer(many=False, read_only=True)
+
+    class Meta:
+        model = Ticket
+        fields = ("id", "row", "seat", "movie_session")
+
+    def validate(self, data):
+        data = super(TicketSerializer, self).validate(data)
+
+        ticket = Ticket(
+            movie_session=data.get("movie_session"),
+            row=data.get("row"),
+            seat=data.get("seat"),
+        )
+        ticket.full_clean()
+        return data
+
+
+class OrderSerializer(serializers.ModelSerializer):
+    tickets = TicketSerializer(many=True, read_only=False, allow_empty=False)
+
+    class Meta:
+        model = Order
+        fields = ["id", "tickets", "created_at"]
+
+    def create(self, validated_data):
+        with transaction.atomic():
+            tickets_data = validated_data.pop("tickets")
+            order = Order.objects.create(**validated_data)
+            for ticket_data in tickets_data:
+                Ticket.objects.create(order=order, **ticket_data)
+            return order

cinema/urls.py

@@ -7,6 +7,8 @@
     CinemaHallViewSet,
     MovieViewSet,
     MovieSessionViewSet,
+    TicketViewSet,
+    OrderViewSet,
 )
 
 router = routers.DefaultRouter()
@@ -15,6 +17,8 @@
 router.register("cinema_halls", CinemaHallViewSet)
 router.register("movies", MovieViewSet)
 router.register("movie_sessions", MovieSessionViewSet)
+router.register("tickets", TicketViewSet)
+router.register("orders", OrderViewSet)
 
 urlpatterns = [path("", include(router.urls))]
 

cinema/views.py

@@ -1,7 +1,17 @@
+from django.db.models import F, Count
 from rest_framework import viewsets
 
-from cinema.models import Genre, Actor, CinemaHall, Movie, MovieSession
+from cinema.models import (
+    Genre,
+    Actor,
+    CinemaHall,
+    Movie,
+    MovieSession,
+    Ticket,
+    Order,
+)
 
+from cinema.pagination import OrderPagination
 from cinema.serializers import (
     GenreSerializer,
     ActorSerializer,
@@ -12,6 +22,8 @@
     MovieDetailSerializer,
     MovieSessionDetailSerializer,
     MovieListSerializer,
+    TicketSerializer,
+    OrderSerializer,
 )
 
 
@@ -43,6 +55,28 @@ def get_serializer_class(self):
 
         return MovieSerializer
 
+    def get_queryset(self):
+        queryset = super().get_queryset()
+        if self.action == ("list", "retrieve"):
+            queryset = self.queryset.prefetch_related("actors", "genres")
+
+        actors = self.request.query_params.get("actors")
+        genres = self.request.query_params.get("genres")
+        title = self.request.query_params.get("title")
+
+        if actors:
+            actors_ids = [int(str_id) for str_id in actors.split(",")]
+            queryset = queryset.filter(actors__id__in=actors_ids)
+
+        if genres:
+            genres_ids = [int(str_id) for str_id in genres.split(",")]
+            queryset = queryset.filter(genres__id__in=genres_ids)
+
+        if title:
+            queryset = queryset.filter(title__icontains=title)
+
+        return queryset.distinct()
+
 
 class MovieSessionViewSet(viewsets.ModelViewSet):
     queryset = MovieSession.objects.all()
@@ -56,3 +90,47 @@ def get_serializer_class(self):
             return MovieSessionDetailSerializer
 
         return MovieSessionSerializer
+
+    def get_queryset(self):
+        queryset = super().get_queryset()
+
+        if self.action == "retrieve":
+            queryset = queryset.select_related("movie")
+
+        elif self.action == "list":
+            queryset = (
+                queryset.select_related("cinema_hall").annotate(
+                    tickets_available=(
+                            F("cinema_hall__rows") * F("cinema_hall__seats_in_row") # noqa
+                            - Count("tickets") # noqa
+                    )
+                )
+            ).order_by("id")
+
+        movie = self.request.query_params.get("movie")
+        date = self.request.query_params.get("date")
+
+        if movie:
+            queryset = queryset.filter(movie__id=movie)
+
+        if date:
+            queryset = queryset.filter(show_time__date=date)
+
+        return queryset.distinct()
+
+
+class TicketViewSet(viewsets.ModelViewSet):
+    queryset = Ticket.objects.all()
+    serializer_class = TicketSerializer
+
+
+class OrderViewSet(viewsets.ModelViewSet):
+    queryset = Order.objects.all()
+    serializer_class = OrderSerializer
+    pagination_class = OrderPagination
+
+    def get_queryset(self):
+        return self.queryset.filter(user=self.request.user)
+
+    def perform_create(self, serializer):
+        serializer.save(user=self.request.user)