from django.contrib.redirects.models import Redirect
from django import http
from django.conf import settings
import re

class RegExRedirectFallbackMiddleware(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()
        
        
        redirects = Redirect.objects.filter(site__id__exact=settings.SITE_ID)
        for r in redirects:
            try:
                old_path = re.compile(r.old_path, re.IGNORECASE)
            except re.error:
                # old_path does not compile into regex, ignore it and move on to the next one
                continue
                
            if re.match(r.old_path, path):
                new_path = r.new_path.replace('$', '\\')
                replaced_path = re.sub(old_path, new_path, path)
                return http.HttpResponsePermanentRedirect(replaced_path)
            
        # Return the response.
        return response