from django.contrib.auth import authenticate, login
from django.contrib.syndication.views import Feed
from django.http import HttpResponse
import base64

class HTTPAuthFeed(Feed):
    basic_auth_realm = 'My Page'
    
    def __call__(self, request, *args, **kwargs):
        # HTTP auth check inspired by http://djangosnippets.org/snippets/243/
        if request.user.is_authenticated():
            # already logged in
            return super(HTTPAuthFeed, self).__call__(request, *args, **kwargs)
    
        # check HTTP auth credentials
        if 'HTTP_AUTHORIZATION' in request.META:
            auth = request.META['HTTP_AUTHORIZATION'].split()
            if len(auth) == 2:
                # only basic auth is supported
                if auth[0].lower() == "basic":
                    uname, passwd = base64.b64decode(auth[1]).split(':')
                    user = authenticate(username=uname, password=passwd)
                    if user is not None:
                        if user.is_active:
                            login(request, user)
                            request.user = user
                            return super(HTTPAuthFeed, self).__call__(request, *args, **kwargs)
        
        # missing auth header or failed authentication results in 401
        response = HttpResponse()
        response.status_code = 401
        response['WWW-Authenticate'] = 'Basic realm="%s"' % self.basic_auth_realm
        return response