from __future__ import annotations

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


class AuditLogImmutableError(Exception):
    """Audit rows are append-only."""


class AuditLog(models.Model):
    created_at = models.DateTimeField(auto_now_add=True, db_index=True)
    actor = models.ForeignKey(
        settings.AUTH_USER_MODEL, null=True, blank=True, on_delete=models.SET_NULL, related_name="+"
    )
    organization = models.ForeignKey(
        "organizations.Organization", null=True, blank=True, on_delete=models.SET_NULL, related_name="+"
    )
    action = models.CharField(max_length=80, db_index=True)
    entity_type = models.CharField(max_length=80, blank=True, default="")
    entity_id = models.CharField(max_length=64, blank=True, default="")
    before = models.JSONField(null=True, blank=True)
    after = models.JSONField(null=True, blank=True)
    ip_address = models.GenericIPAddressField(null=True, blank=True)

    class Meta:
        db_table = "audit_logs"
        ordering = ["-id"]
        indexes = [models.Index(fields=["organization", "-id"])]

    def save(self, *args, **kwargs):
        if self.pk is not None:
            raise AuditLogImmutableError("Audit log entries cannot be modified.")
        super().save(*args, **kwargs)

    def delete(self, *args, **kwargs):
        raise AuditLogImmutableError("Audit log entries cannot be deleted.")

    def __str__(self):
        return f"{self.created_at:%Y-%m-%d %H:%M} {self.action}"