class CustomUserManager(BaseUserManager):
    def create_user(self, email, password=None, **extra_fields):
        if not email:
            raise ValueError('Users must have a valid e-mail address')

        user = self.model(email=self.normalize_email(email),
                          username=extra_fields.get('username'),
                         )
        user.set_password(password)
        user.save(using=self._db)

        return user

    def create_superuser(self, email, password=None, **extra_fields):
        user = self.create_user(email, password, **extra_fields)
        user.is_admin = True
        user.is_staff = True
        user.save(using=self._db)

        return user


class CustomUser(AbstractBaseUser):
    username = models.CharField(max_length=50, null=True, blank=True, default='')
    email = models.EmailField(unique=True)
    is_admin = models.BooleanField(default=False)
    is_staff = models.BooleanField(default=False)

    USERNAME_FIELD = 'email'

    objects = CustomUserManager()

    def __unicode__(self):
        return self.email

    def has_perm(self, perm, obj=None):
        return True

    def has_module_perms(self, app_label):
        return True

    def get_full_name(self):
        return self.email

    def get_short_name(self):
        return self.email


class Post(models.Model):
    title = models.CharField(max_length=200)
    text = models.TextField()
    publisher = models.ForeignKey(CustomUser, related_name='posts')

    def __unicode__(self):
        return self.title