from datetime import datetime

from django.db import models


# M2M described on one of the models
class Person(models.Model):
    name = models.CharField(max_length=128)

    class Meta:
        ordering = ("name",)


class PersonChild(Person):
    pass


class Group(models.Model):
    name = models.CharField(max_length=128)
    members = models.ManyToManyField(Person, through="Membership")
    custom_members = models.ManyToManyField(
        Person, through="CustomMembership", related_name="custom"
    )
    nodefaultsnonulls = models.ManyToManyField(
        Person,
        through="TestNoDefaultsOrNulls",
        related_name="testnodefaultsnonulls",
    )

    class Meta:
        ordering = ("name",)


class Membership(models.Model):
    person = models.ForeignKey(Person, models.CASCADE)
    group = models.ForeignKey(Group, models.CASCADE)
    date_joined = models.DateTimeField(default=datetime.now)
    invite_reason = models.CharField(max_length=64, null=True)

    class Meta:
        ordering = ("date_joined", "invite_reason", "group")

    def __str__(self):
        return "%s is a member of %s" % (self.person.name, self.group.name)


class CustomMembership(models.Model):
    person = models.ForeignKey(
        Person,
        models.CASCADE,
        db_column="custom_person_column",
        related_name="custom_person_related_name",
    )
    group = models.ForeignKey(Group, models.CASCADE)
    weird_fk = models.ForeignKey(Membership, models.SET_NULL, null=True)
    date_joined = models.DateTimeField(default=datetime.now)

    class Meta:
        db_table = "test_table"
        ordering = ["date_joined"]

    def __str__(self):
        return "%s is a member of %s" % (self.person.name, self.group.name)


class TestNoDefaultsOrNulls(models.Model):
    person = models.ForeignKey(Person, models.CASCADE)
    group = models.ForeignKey(Group, models.CASCADE)
    nodefaultnonull = models.IntegerField()


class PersonSelfRefM2M(models.Model):
    name = models.CharField(max_length=5)
    friends = models.ManyToManyField("self", through="Friendship", symmetrical=False)
    sym_friends = models.ManyToManyField(
        "self", through="SymmetricalFriendship", symmetrical=True
    )


class Friendship(models.Model):
    first = models.ForeignKey(
        PersonSelfRefM2M, models.CASCADE, related_name="rel_from_set"
    )
    second = models.ForeignKey(
        PersonSelfRefM2M, models.CASCADE, related_name="rel_to_set"
    )
    date_friended = models.DateTimeField()


class SymmetricalFriendship(models.Model):
    first = models.ForeignKey(PersonSelfRefM2M, models.CASCADE)
    second = models.ForeignKey(PersonSelfRefM2M, models.CASCADE, related_name="+")
    date_friended = models.DateField()


# Custom through link fields
class Event(models.Model):
    title = models.CharField(max_length=50)
    invitees = models.ManyToManyField(
        to=Person,
        through="Invitation",
        through_fields=["event", "invitee"],
        related_name="events_invited",
    )


class Invitation(models.Model):
    event = models.ForeignKey(Event, models.CASCADE, related_name="invitations")
    # field order is deliberately inverted. the target field is "invitee".
    inviter = models.ForeignKey(Person, models.CASCADE, related_name="invitations_sent")
    invitee = models.ForeignKey(Person, models.CASCADE, related_name="invitations")


class Employee(models.Model):
    name = models.CharField(max_length=5)
    subordinates = models.ManyToManyField(
        "self",
        through="Relationship",
        through_fields=("source", "target"),
        symmetrical=False,
    )

    class Meta:
        ordering = ("pk",)


class Relationship(models.Model):
    # field order is deliberately inverted.
    another = models.ForeignKey(
        Employee, models.SET_NULL, related_name="rel_another_set", null=True
    )
    target = models.ForeignKey(Employee, models.CASCADE, related_name="rel_target_set")
    source = models.ForeignKey(Employee, models.CASCADE, related_name="rel_source_set")


class Ingredient(models.Model):
    iname = models.CharField(max_length=20, unique=True)

    class Meta:
        ordering = ("iname",)


class Recipe(models.Model):
    rname = models.CharField(max_length=20, unique=True)
    ingredients = models.ManyToManyField(
        Ingredient,
        through="RecipeIngredient",
        related_name="recipes",
    )

    class Meta:
        ordering = ("rname",)


class RecipeIngredient(models.Model):
    ingredient = models.ForeignKey(Ingredient, models.CASCADE, to_field="iname")
    recipe = models.ForeignKey(Recipe, models.CASCADE, to_field="rname")