from django.contrib.auth import get_user_model
from rest_framework import serializers

from users.serializers import UserSerializer
from .models import TimeEntry
from .services import save_period, validate_period


class TimeEntrySerializer(serializers.ModelSerializer):
    user = UserSerializer(read_only=True)

    class Meta:
        model = TimeEntry
        fields = [
            'id', 'user', 'group_id', 'start_date', 'start_time', 'end_date',
            'end_time', 'created_at', 'updated_at', 'duration', 'day_of_week',
            'is_complete', 'is_incomplete',
        ]
        read_only_fields = fields


class TimeEntryCreateSerializer(serializers.Serializer):
    user_id = serializers.PrimaryKeyRelatedField(
        source='user', queryset=get_user_model().objects.all(), required=False,
        write_only=True,
    )
    start_date = serializers.DateField()
    start_time = serializers.TimeField()
    end_date = serializers.DateField(required=False)
    end_time = serializers.TimeField(required=False, allow_null=True)

    def validate(self, attrs):
        validate_period(attrs)
        return attrs

    def create(self, validated_data):
        user = validated_data.pop('user', self.context['request'].user)
        return save_period(user, validated_data)


class TimeEntryUpdateSerializer(serializers.Serializer):
    start_date = serializers.DateField()
    start_time = serializers.TimeField()
    end_date = serializers.DateField()
    end_time = serializers.TimeField(allow_null=True)

    def validate(self, attrs):
        entries = self.context.get('entries', [self.instance])
        first, last = entries[0], entries[-1]
        values = dict(
            start_date=first.start_date, start_time=first.start_time,
            end_date=last.end_date, end_time=last.end_time,
        )
        values.update(attrs)
        validate_period(values)
        return values

    def update(self, instance, validated_data):
        return save_period(
            instance.user, validated_data,
            self.context.get('entries', [instance]),
        )


class WeeklySummarySerializer(serializers.Serializer):
    user = serializers.CharField()
    username = serializers.CharField()
    total_hours = serializers.FloatField()
    entries = serializers.ListField(child=serializers.DictField())