from django.contrib.redirects.models import Redirect

from django import http

from django.conf import settings

class RedirectFallbackMiddleware(object):

    def process_response(self, request, response):

        if response.status_code != 404:

            return response # No need to check for a redirect for non-404 responses.

        path = request.get_full_path()

        try:

            r = Redirect.objects.get(site__id__exact=settings.SITE_ID, old_path=path)

        except Redirect.DoesNotExist:

            r = None

        if r is None and settings.APPEND_SLASH:

            # Try removing the trailing slash.

            try:

                r = Redirect.objects.get(site__id__exact=settings.SITE_ID,

                    old_path=path[:path.rfind('/')]+path[path.rfind('/')+1:])

            except Redirect.DoesNotExist:

                pass

        if r is not None:

            if r.new_path == '':

                return http.HttpResponseGone()

            return http.HttpResponsePermanentRedirect(r.new_path)

        # No redirect was found. Return the response.

        return response