from django.conf import settings
from django.http import HttpResponse
import hashlib

class BasicAuthMiddleware():
	def process_request(self, request):
		basic_auth_enabled = getattr(settings, 'BASIC_AUTH_ENABLED', False)
		expected_username = getattr(settings, 'BASIC_AUTH_USERNAME', None)
		expected_password = getattr(settings, 'BASIC_AUTH_PASSWORD', None)
		realm = getattr(settings, 'BASIC_AUTH_REALM', 'Restricted access')
		if not (basic_auth_enabled and expected_username and expected_password):
			return None

		if request.META.has_key('HTTP_AUTHORIZATION'):
			username, password = self.basic_authenticate(request.META['HTTP_AUTHORIZATION'])
			if (username == expected_username and hashlib.sha1(password).hexdigest() == expected_password):
				return None

		response =  HttpResponse('<h1>Authorization Required</h1>')
		response['WWW-Authenticate'] = 'Basic realm="%s"' % realm
		response.status_code = 401
		return response

	def basic_authenticate(self, authentication):
		# Taken from paste.auth
		(authmeth, auth) = authentication.split(' ',1)
		if 'basic' != authmeth.lower():
			return (None, None)
		auth = auth.strip().decode('base64')
		username, password = auth.split(':',1)
		return (username, password)