from django.http import HttpResponsePermanentRedirect
from django.conf import settings


PAGE_VAR = getattr(settings, 'PAGE_VAR', 'page')


class FixFirstPaginatedPage(object):
    def process_request(self, request):
        if request.method == 'GET':
            try:
                page = int(request.GET[PAGE_VAR])
            except (KeyError, ValueError, TypeError):
                return None
            if page == 1:
                params = request.GET.copy()
                del(params[PAGE_VAR])
                path = request.path
                if params:
                    path += '?' + params.urlencode()
                return HttpResponsePermanentRedirect(path)