class UserManager(BaseUserManager):

    def _create_user(self, username, email, password, is_staff, is_superuser, **extra_fields):
        now = timezone.now()
        if not username:
            raise ValueError(_('The given username must be set'))
        if not email:
            raise ValueError(_('The given email must be set'))
        email = self.normalize_email(email)
        user = self.model(
            username=username, email=email,
            is_staff=is_staff, is_active=False,
            is_superuser=is_superuser, last_login=now,
            date_joined=now, **extra_fields
        )
        user.set_password(password)
        user.save(using=self._db)
        return user

    def create_user(self, username, email, password=None, **extra_fields):
        return self._create_user(username, email, password, False, False, **extra_fields)

    def create_superuser(self, username, email, password, **extra_fields):
        user=self._create_user(username, email, password, True, True, **extra_fields)
        user.is_active=True
        user.save(using=self._db)
        return user

class User(AbstractBaseUser, PermissionsMixin):
    # Standard fields
    username = models.CharField(_('username'), max_length=30, unique=True,
        help_text=_('Required. 30 characters or fewer. Letters, numbers and @/./+/-/_ characters'),
        validators=[
        validators.RegexValidator(re.compile('^[w.@+-]+$'), _('Enter a valid username.'), _('invalid'))
    ])
    first_name = models.CharField(_('first name'), max_length=30, blank=True, null=True)
    last_name = models.CharField(_('last name'), max_length=30, blank=True, null=True)
    email = models.EmailField(_('email address'), max_length=255)
    is_staff = models.BooleanField(_('staff status'), default=False,
        help_text=_('Designates whether the user can log into this admin site.'))
    is_active = models.BooleanField(_('active'), default=True,
        help_text=_('Designates whether this user should be treated as active. Unselect this instead of deleting accounts.'))
    date_joined = models.DateTimeField(_('date joined'), default=timezone.now)

    # Custom fields
    is_publisher = models.BooleanField(_('publisher status'), default=False)

    # User manager
    objects = UserManager()

    USERNAME_FIELD = 'username'
    REQUIRED_FIELDS = ['email']

    class Meta:
        verbose_name = _('user')
        verbose_name_plural = _('users')

    def get_full_name(self):
        full_name = '%s %s' % (self.first_name, self.last_name)
        return full_name.strip()

    def get_short_name(self):
        return self.first_name

    def email_user(self, subject, message, from_email=None):
        send_mail(subject, message, from_email, [self.email])