import uuid

from django.contrib.postgres.fields import JSONField
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
from django.conf import settings
from django.db import models, transaction
from django.utils import timezone
from django.urls import reverse

from funkwhale_api.federation import utils as federation_utils


class LocalFromFidQuerySet:
    def local(self, include=True):
        host = settings.FEDERATION_HOSTNAME
        query = models.Q(fid__startswith="http://{}/".format(host)) | models.Q(
            fid__startswith="https://{}/".format(host)
        )
        if include:
            return self.filter(query)
        else:
            return self.filter(~query)


class MutationQuerySet(models.QuerySet):
    def get_for_target(self, target):
        content_type = ContentType.objects.get_for_model(target)
        return self.filter(target_content_type=content_type, target_id=target.pk)


class Mutation(models.Model):
    fid = models.URLField(unique=True, max_length=500, db_index=True)
    uuid = models.UUIDField(unique=True, db_index=True, default=uuid.uuid4)
    created_by = models.ForeignKey(
        "federation.Actor",
        related_name="created_mutations",
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
    )
    approved_by = models.ForeignKey(
        "federation.Actor",
        related_name="approved_mutations",
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
    )

    type = models.CharField(max_length=100, db_index=True)
    # None = no choice, True = approved, False = refused
    is_approved = models.NullBooleanField(default=None)

    # None = not applied, True = applied, False = failed
    is_applied = models.NullBooleanField(default=None)
    creation_date = models.DateTimeField(default=timezone.now, db_index=True)
    applied_date = models.DateTimeField(null=True, blank=True, db_index=True)
    summary = models.TextField(max_length=2000, null=True, blank=True)

    payload = JSONField()
    previous_state = JSONField(null=True, default=None)

    target_id = models.IntegerField(null=True)
    target_content_type = models.ForeignKey(
        ContentType,
        null=True,
        on_delete=models.CASCADE,
        related_name="targeting_mutations",
    )
    target = GenericForeignKey("target_content_type", "target_id")

    objects = MutationQuerySet.as_manager()

    def get_federation_id(self):
        if self.fid:
            return self.fid

        return federation_utils.full_url(
            reverse("federation:edits-detail", kwargs={"uuid": self.uuid})
        )

    def save(self, **kwargs):
        if not self.pk and not self.fid:
            self.fid = self.get_federation_id()

        return super().save(**kwargs)

    @transaction.atomic
    def apply(self):
        from . import mutations

        if self.is_applied:
            raise ValueError("Mutation was already applied")

        previous_state = mutations.registry.apply(
            type=self.type, obj=self.target, payload=self.payload
        )
        self.previous_state = previous_state
        self.is_applied = True
        self.applied_date = timezone.now()
        self.save(update_fields=["is_applied", "applied_date", "previous_state"])
        return previous_state