from django.contrib.auth import models as auth
from django.db import models
from django.utils.encoding import python_2_unicode_compatible


# No related name is needed here, since symmetrical relations are not
# explicitly reversible.
@python_2_unicode_compatible
class SelfRefer(models.Model):
    name = models.CharField(max_length=10)
    references = models.ManyToManyField('self')
    related = models.ManyToManyField('self')

    def __str__(self):
        return self.name


@python_2_unicode_compatible
class Tag(models.Model):
    name = models.CharField(max_length=10)

    def __str__(self):
        return self.name


# Regression for #11956 -- a many to many to the base class
@python_2_unicode_compatible
class TagCollection(Tag):
    tags = models.ManyToManyField(Tag, related_name='tag_collections')

    def __str__(self):
        return self.name


# A related_name is required on one of the ManyToManyField entries here because
# they are both addressable as reverse relations from Tag.
@python_2_unicode_compatible
class Entry(models.Model):
    name = models.CharField(max_length=10)
    topics = models.ManyToManyField(Tag)
    related = models.ManyToManyField(Tag, related_name="similar")

    def __str__(self):
        return self.name


# Two models both inheriting from a base model with a self-referential m2m field
class SelfReferChild(SelfRefer):
    pass


class SelfReferChildSibling(SelfRefer):
    pass


# Many-to-Many relation between models, where one of the PK's isn't an Autofield
class Line(models.Model):
    name = models.CharField(max_length=100)


class Worksheet(models.Model):
    id = models.CharField(primary_key=True, max_length=100)
    lines = models.ManyToManyField(Line, blank=True, null=True)


# Regression for #11226 -- A model with the same name that another one to
# which it has a m2m relation. This shouldn't cause a name clash between
# the automatically created m2m intermediary table FK field names when
# running migrate
class User(models.Model):
    name = models.CharField(max_length=30)
    friends = models.ManyToManyField(auth.User)


class BadModelWithSplit(models.Model):
    name = models.CharField(max_length=1)

    def split(self):
        raise RuntimeError('split should not be called')

    class Meta:
        abstract = True


class RegressionModelSplit(BadModelWithSplit):
    """
    Model with a split method should not cause an error in add_lazy_relation
    """
    others = models.ManyToManyField('self')
