''' alert a user to activity '''
from django.db import models
from .base_model import BookWyrmModel


NotificationType = models.TextChoices(
    'NotificationType',
    'FAVORITE REPLY MENTION TAG FOLLOW FOLLOW_REQUEST BOOST IMPORT ADD')

class Notification(BookWyrmModel):
    ''' you've been tagged, liked, followed, etc '''
    user = models.ForeignKey('User', on_delete=models.CASCADE)
    related_book = models.ForeignKey(
        'Edition', on_delete=models.CASCADE, null=True)
    related_user = models.ForeignKey(
        'User',
        on_delete=models.CASCADE, null=True, related_name='related_user')
    related_status = models.ForeignKey(
        'Status', on_delete=models.CASCADE, null=True)
    related_import = models.ForeignKey(
        'ImportJob', on_delete=models.CASCADE, null=True)
    related_list_item = models.ForeignKey(
        'ListItem', on_delete=models.CASCADE, null=True)
    read = models.BooleanField(default=False)
    notification_type = models.CharField(
        max_length=255, choices=NotificationType.choices)

    def save(self, *args, **kwargs):
        ''' save, but don't make dupes '''
        # there's probably a better way to do this
        if self.__class__.objects.filter(
                user=self.user,
                related_book=self.related_book,
                related_user=self.related_user,
                related_status=self.related_status,
                related_import=self.related_import,
                related_list_item=self.related_list_item,
                notification_type=self.notification_type,
            ).exists():
            return
        super().save(*args, **kwargs)

    class Meta:
        ''' checks if notifcation is in enum list for valid types '''
        constraints = [
            models.CheckConstraint(
                check=models.Q(notification_type__in=NotificationType.values),
                name="notification_type_valid",
            )
        ]