from datetime import datetime

from django.core.exceptions import ValidationError
from django.db import models
from django.db.models.functions import Lower


def validate_answer_to_universe(value):
    if value != 42:
        raise ValidationError(
            "This is not the answer to life, universe and everything!", code="not42"
        )


class ModelToValidate(models.Model):
    name = models.CharField(max_length=100)
    created = models.DateTimeField(default=datetime.now)
    number = models.IntegerField(db_column="number_val")
    parent = models.ForeignKey(
        "self",
        models.SET_NULL,
        blank=True,
        null=True,
        limit_choices_to={"number": 10},
    )
    email = models.EmailField(blank=True)
    ufm = models.ForeignKey(
        "UniqueFieldsModel",
        models.SET_NULL,
        to_field="unique_charfield",
        blank=True,
        null=True,
    )
    url = models.URLField(blank=True)
    f_with_custom_validator = models.IntegerField(
        blank=True, null=True, validators=[validate_answer_to_universe]
    )
    f_with_iterable_of_validators = models.IntegerField(
        blank=True, null=True, validators=(validate_answer_to_universe,)
    )
    slug = models.SlugField(blank=True)

    def clean(self):
        super().clean()
        if self.number == 11:
            raise ValidationError("Invalid number supplied!")


class UniqueFieldsModel(models.Model):
    unique_charfield = models.CharField(max_length=100, unique=True)
    unique_integerfield = models.IntegerField(unique=True)
    non_unique_field = models.IntegerField()


class CustomPKModel(models.Model):
    my_pk_field = models.CharField(max_length=100, primary_key=True)


class UniqueTogetherModel(models.Model):
    cfield = models.CharField(max_length=100)
    ifield = models.IntegerField()
    efield = models.EmailField()

    class Meta:
        unique_together = (
            (
                "ifield",
                "cfield",
            ),
            ["ifield", "efield"],
        )


class UniqueForDateModel(models.Model):
    start_date = models.DateField()
    end_date = models.DateTimeField()
    count = models.IntegerField(
        unique_for_date="start_date", unique_for_year="end_date"
    )
    order = models.IntegerField(unique_for_month="end_date")
    name = models.CharField(max_length=100)


class CustomMessagesModel(models.Model):
    other = models.IntegerField(blank=True, null=True)
    number = models.IntegerField(
        db_column="number_val",
        error_messages={"null": "NULL", "not42": "AAARGH", "not_equal": "%s != me"},
        validators=[validate_answer_to_universe],
    )


class AuthorManager(models.Manager):
    def get_queryset(self):
        qs = super().get_queryset()
        return qs.filter(archived=False)


class Author(models.Model):
    name = models.CharField(max_length=100)
    archived = models.BooleanField(default=False)

    objects = AuthorManager()


class Article(models.Model):
    title = models.CharField(max_length=100)
    author = models.ForeignKey(Author, models.CASCADE)
    pub_date = models.DateTimeField(blank=True)

    def clean(self):
        if self.pub_date is None:
            self.pub_date = datetime.now()


class Post(models.Model):
    title = models.CharField(max_length=50, unique_for_date="posted", blank=True)
    slug = models.CharField(max_length=50, unique_for_year="posted", blank=True)
    subtitle = models.CharField(max_length=50, unique_for_month="posted", blank=True)
    posted = models.DateField()


class FlexibleDatePost(models.Model):
    title = models.CharField(max_length=50, unique_for_date="posted", blank=True)
    slug = models.CharField(max_length=50, unique_for_year="posted", blank=True)
    subtitle = models.CharField(max_length=50, unique_for_month="posted", blank=True)
    posted = models.DateField(blank=True, null=True)


class UniqueErrorsModel(models.Model):
    name = models.CharField(
        max_length=100,
        unique=True,
        error_messages={"unique": "Custom unique name message."},
    )
    no = models.IntegerField(
        unique=True, error_messages={"unique": "Custom unique number message."}
    )


class GenericIPAddressTestModel(models.Model):
    generic_ip = models.GenericIPAddressField(blank=True, null=True, unique=True)
    v4_ip = models.GenericIPAddressField(blank=True, null=True, protocol="ipv4")
    v6_ip = models.GenericIPAddressField(blank=True, null=True, protocol="ipv6")
    ip_verbose_name = models.GenericIPAddressField(
        "IP Address Verbose", blank=True, null=True
    )


class GenericIPAddrUnpackUniqueTest(models.Model):
    generic_v4unpack_ip = models.GenericIPAddressField(
        null=True, blank=True, unique=True, unpack_ipv4=True
    )


class UniqueFuncConstraintModel(models.Model):
    field = models.CharField(max_length=255)

    class Meta:
        required_db_features = {"supports_expression_indexes"}
        constraints = [
            models.UniqueConstraint(Lower("field"), name="func_lower_field_uq"),
        ]