from django.conf import settings
from django.db import models


class Notification(models.Model):
    """Tells `recipient` that `actor` did something (`verb`) involving
    `moment` (and, for comment/reply verbs, the specific `comment`).
    Created by signal handlers in signals.py — never directly by API
    consumers."""

    class Verb(models.TextChoices):
        LIKE = "like", "Like"
        COMMENT = "comment", "Comment"
        REPLY = "reply", "Reply"

    recipient = models.ForeignKey(settings.AUTH_USER_MODEL, related_name="notifications", on_delete=models.CASCADE)
    actor = models.ForeignKey(settings.AUTH_USER_MODEL, related_name="+", on_delete=models.CASCADE)
    verb = models.CharField(max_length=10, choices=Verb.choices)
    moment = models.ForeignKey("moments.Moment", related_name="notifications", on_delete=models.CASCADE)
    comment = models.ForeignKey(
        "moments.Comment", null=True, blank=True, related_name="notifications", on_delete=models.CASCADE
    )
    is_read = models.BooleanField(default=False)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        ordering = ["-created_at"]
        indexes = [models.Index(fields=["recipient", "is_read"])]

    def __str__(self):
        return f"{self.actor} {self.verb} -> {self.recipient}"