from django.db import models

class Author(models.Model):

    name = models.CharField(max_length=100)

    age = models.IntegerField()

    friends = models.ManyToManyField("self", blank=True)

    rating = models.FloatField(null=True)

    def __str__(self):

        return self.name

class Publisher(models.Model):

    name = models.CharField(max_length=255)

    num_awards = models.IntegerField()

    duration = models.DurationField(blank=True, null=True)

    def __str__(self):

        return self.name

class Book(models.Model):

    isbn = models.CharField(max_length=9)

    name = models.CharField(max_length=255)

    pages = models.IntegerField()

    rating = models.FloatField()

    price = models.DecimalField(decimal_places=2, max_digits=6)

    authors = models.ManyToManyField(Author)

    contact = models.ForeignKey(Author, models.CASCADE, related_name="book_contact_set")

    publisher = models.ForeignKey(Publisher, models.CASCADE)

    pubdate = models.DateField()

    def __str__(self):

        return self.name

class Store(models.Model):

    name = models.CharField(max_length=255)

    books = models.ManyToManyField(Book)

    original_opening = models.DateTimeField()

    friday_night_closing = models.TimeField()

    def __str__(self):

        return self.name