import urlparse

from django.contrib import admin
from django.core.urlresolvers import reverse
from django.http import HttpResponseRedirect
from django.utils.translation import ugettext_lazy, ugettext as _
from django.utils.encoding import force_unicode

class MyModelAdmin(admin.ModelAdmin):
    
    def response_change(self, request, obj):
        """
        Determines the HttpResponse for the change_view stage.
        
        We are returning the user to a filtered changelist page
        from the change screen when the user presses save.
        This makes for more intutive editing of filtered objects
        since upon saving you will be redirected back to the filtered
        changelist page.
        
        Requires that in your admin/change_form.html you add a hidden
        form input named "_go_to_on_save" that you can populate with
        the value from request.META.HTTP_REFERER as below:
        {% block after_related_objects %}{% if request.META.HTTP_REFERER %}<input type="hidden" name="_go_to_on_save" value="{{ request.META.HTTP_REFERER }}" />{% endif %}{% endblock %}
        """
        opts = obj._meta

        msg = _('The %(name)s "%(obj)s" was changed successfully.') % {'name': force_unicode(opts.verbose_name), 'obj': force_unicode(obj)}
        
        if request.POST.has_key("_go_to_on_save") and urlparse.urlparse(request.POST['_go_to_on_save']).query\
                and request.get_host() in request.POST['_go_to_on_save']\
                and not (request.POST.has_key("_continue") or request.POST.has_key("_saveasnew") or\
                request.POST.has_key("_addanother")):
            self.message_user(request, msg)
            change_url = reverse('admin:%s_%s_changelist' % (self.model._meta.app_label, self.model._meta.module_name))
            potential_go_to_url = urlparse.urlparse(request.POST['_go_to_on_save'])
            if change_url == potential_go_to_url.path:
                query = urlparse.urlparse(request.POST['_go_to_on_save']).query
                return HttpResponseRedirect(change_url+'?'+query)
        
        return super(MyModelAdmin, self).response_change(request, obj)