from django.conf import settings
from django.core.exceptions import ValidationError
from django.db import models
from django.utils import timezone

from bookings.models import Reservation


class CheckIn(models.Model):
    class Source(models.TextChoices):
        QR_SCAN = "qr_scan", "QR scan"
        MANUAL = "manual", "Manual"

    reservation = models.OneToOneField(
        Reservation,
        on_delete=models.PROTECT,
        related_name="check_in",
    )
    checked_in_at = models.DateTimeField(default=timezone.now)
    checked_in_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.PROTECT,
        related_name="checkins",
    )
    source = models.CharField(max_length=20, choices=Source.choices, default=Source.QR_SCAN)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ["-checked_in_at"]
        indexes = [
            models.Index(fields=["checked_in_at"]),
            models.Index(fields=["checked_in_by"]),
        ]

    def __str__(self):
        return f"Check-in for reservation {self.reservation_id}"

    def clean(self):
        super().clean()
        if self.reservation_id and not self.reservation.is_confirmed:
            raise ValidationError({"reservation": "Only confirmed reservations can be checked in."})

    def save(self, *args, **kwargs):
        self.full_clean()
        return super().save(*args, **kwargs)