import uuid

from django.core.exceptions import ValidationError
from django.db import models


def validate_weekday(value: int):
    if value < 0 or value > 6:
        raise ValidationError("Weekday must be between 0 (Mo) and 6 (Su)")


class Slot(models.Model):
    slot_id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)

    start_time = models.TimeField()
    end_time = models.TimeField()

    duration = models.DurationField()

    start_weekday = models.SmallIntegerField(validators=[validate_weekday])
    end_weekday = models.SmallIntegerField(validators=[validate_weekday])

    def __str__(self):
        days = [
            "Mo",
            "Tu",
            "We",
            "Th",
            "Fr",
            "Sa",
            "Su"
        ]
        return "[{}] {} - [{}] {}".format(days[self.start_weekday], self.start_time, days[self.end_weekday],
                                          self.end_time)