import datetime

from django.db import models

class Country(models.Model):

    # Table Column Fields

    name = models.CharField(max_length=50)

    def __str__(self):

        return self.name

class Person(models.Model):

    # Table Column Fields

    name = models.CharField(max_length=128)

    person_country_id = models.IntegerField()

    # Relation Fields

    person_country = models.ForeignObject(

        Country,

        from_fields=["person_country_id"],

        to_fields=["id"],

        on_delete=models.CASCADE,

    )

    friends = models.ManyToManyField("self", through="Friendship", symmetrical=False)

    class Meta:

        ordering = ("name",)

    def __str__(self):

        return self.name

class Group(models.Model):

    # Table Column Fields

    name = models.CharField(max_length=128)

    group_country = models.ForeignKey(Country, models.CASCADE)

    members = models.ManyToManyField(

        Person, related_name="groups", through="Membership"

    )

    class Meta:

        ordering = ("name",)

    def __str__(self):

        return self.name

class Membership(models.Model):

    # Table Column Fields

    membership_country = models.ForeignKey(Country, models.CASCADE)

    date_joined = models.DateTimeField(default=datetime.datetime.now)

    invite_reason = models.CharField(max_length=64, null=True)

    person_id = models.IntegerField()

    group_id = models.IntegerField(blank=True, null=True)

    # Relation Fields

    person = models.ForeignObject(

        Person,

        from_fields=["person_id", "membership_country"],

        to_fields=["id", "person_country_id"],

        on_delete=models.CASCADE,

    )

    group = models.ForeignObject(

        Group,

        from_fields=["group_id", "membership_country"],

        to_fields=["id", "group_country"],

        on_delete=models.CASCADE,

    )

    class Meta:

        ordering = ("date_joined", "invite_reason")

    def __str__(self):

        group_name = self.group.name if self.group_id else "NULL"

        return "%s is a member of %s" % (self.person.name, group_name)

class Friendship(models.Model):

    # Table Column Fields

    from_friend_country = models.ForeignKey(

        Country, models.CASCADE, related_name="from_friend_country"

    )

    from_friend_id = models.IntegerField()

    to_friend_country_id = models.IntegerField()

    to_friend_id = models.IntegerField()

    # Relation Fields

    from_friend = models.ForeignObject(

        Person,

        on_delete=models.CASCADE,

        from_fields=["from_friend_country", "from_friend_id"],

        to_fields=["person_country_id", "id"],

        related_name="from_friend",

    )

    to_friend_country = models.ForeignObject(

        Country,

        from_fields=["to_friend_country_id"],

        to_fields=["id"],

        related_name="to_friend_country",

        on_delete=models.CASCADE,

    )

    to_friend = models.ForeignObject(

        Person,

        from_fields=["to_friend_country_id", "to_friend_id"],

        to_fields=["person_country_id", "id"],

        related_name="to_friend",

        on_delete=models.CASCADE,

    )