"""Serializer for app timetable"""
from rest_framework import serializers
from timetable.models import Timetable
from establishment.models import Establishment


class ScheduleRUDSerializer(serializers.ModelSerializer):
    """Serializer for Establishment model."""
    weekday_display = serializers.CharField(source='get_weekday_display',
                                            read_only=True)

    class Meta:
        """Meta class."""
        model = Timetable
        fields = [
            'id',
            'weekday_display',
            'lunch_start',
            'lunch_end',
            'dinner_start',
            'dinner_end',
        ]


class ScheduleCreateSerializer(ScheduleRUDSerializer):
    """Serializer for Establishment model."""
    weekday = serializers.IntegerField(write_only=True)

    class Meta:
        """Meta class."""
        model = Timetable
        fields = ScheduleRUDSerializer.Meta.fields + [
            'weekday',
        ]

    def validate(self, attrs):
        """Override validate method"""
        return attrs

    def create(self, validated_data):
        """Override create method"""
        instance = super().create(validated_data)
        weekday = validated_data.get('weekday')
        establishment_pk = self.context.get('request')\
                                       .parser_context.get('view')\
                                       .kwargs.get('pk')

        establishment_qs = Establishment.objects.filter(pk=establishment_pk)
        if not establishment_qs.exists():
            # todo: replace on appropriate exception
            raise serializers.ValidationError()

        establishment = establishment_qs.first()
        schedule_qs = establishment.schedule.filter(weekday=weekday)
        if schedule_qs.exists():
            schedule_qs.delete()
        establishment.schedule.add(instance)
        return instance