from django import forms
from django.contrib.auth.forms import AuthenticationForm

GROUP = (
    ('', '--------------'),
    ('red_server'),
    ('blue_server'),
)

class LoginForm(AuthenticationForm):
    group = forms.ChoiceField(choices=GROUP, required=True,
                              help_text="Choose one of the groups to login." )
    field_order = ['group', 'username', 'password']

from django.contrib.auth.models import User
from django.conf import settings

def client_for(username, password=None, group=None):
    """
    Get a connection for the given user.
    """

    auth_server = settings.AUTH_SERVER[group]
    # here goes the server authentication code

class UnixBackend(object):
"""
Authenticate the given user as a Unix account on a remote host.
"""

def authenticate(self, username=None, password=None):
    try:
        client_for(username, password, group)
    except paramiko.AuthenticationException:
        return None
    try:
        user = User.objects.get(username=username)
    except User.DoesNotExist:
        # Create a new user if the user does not exist yet
        user = User(username=username)
        user.is_staff = False
        user.is_active = True
        user.save()
    return user

def get_user(self, user_id):
    try:
        return User.objects.get(pk=user_id)
    except User.DoesNotExist:
        return None