Adds pre-defined values for public tickets

This commit adds three new settings that allow the operator to
pre-define the `queue`, `priority` and `due_date` fields for public
tickets. If one of these settings are present the corresponding input
field is hidden from the form.

The settings are the following:

    HELPDESK_PUBLIC_TICKET_QUEUE = 'website'
    HELPDESK_PUBLIC_TICKET_PRIORITY = 2
    HELPDESK_PUBLIC_TICKET_DUE_DATE = ''

If the due date is set to the empty string, no due date is saved in the
ticket (analogously to the form). The other settings should be
self-explanatory.

helpdesk/forms.py

@@ -368,6 +368,14 @@ class PublicTicketForm(AbstractTicketForm):
         Add any (non-staff) custom fields that are defined to the form
         """
         super(PublicTicketForm, self).__init__(*args, **kwargs)
+
+        if hasattr(settings, 'HELPDESK_PUBLIC_TICKET_QUEUE'):
+            self.fields['queue'].widget = forms.HiddenInput()
+        if hasattr(settings, 'HELPDESK_PUBLIC_TICKET_PRIORITY'):
+            self.fields['priority'].widget = forms.HiddenInput()
+        if hasattr(settings, 'HELPDESK_PUBLIC_TICKET_DUE_DATE'):
+            self.fields['due_date'].widget = forms.HiddenInput()
+
         self._add_form_custom_fields(False)
 
     def save(self):

helpdesk/views/public.py

@@ -8,10 +8,11 @@ views/public.py - All public facing views, eg non-staff (no authentication
 """
 from django.core.exceptions import ObjectDoesNotExist
 from django.core.urlresolvers import reverse
-from django.http import HttpResponseRedirect
+from django.http import HttpResponseRedirect, HttpResponse
 from django.shortcuts import render
 from django.utils.http import urlquote
 from django.utils.translation import ugettext as _
+from django.conf import settings
 
 from helpdesk import settings as helpdesk_settings
 from helpdesk.decorators import protect_view
@@ -58,6 +59,19 @@ def homepage(request):
         except Queue.DoesNotExist:
             queue = None
         initial_data = {}
+
+        # add pre-defined data for public ticket
+        if hasattr(settings, 'HELPDESK_PUBLIC_TICKET_QUEUE'):
+            # get the requested queue; return an error if queue not found
+            try:
+                queue = Queue.objects.get(slug=settings.HELPDESK_PUBLIC_TICKET_QUEUE)
+            except Queue.DoesNotExist:
+                return HttpResponse(status=500)
+        if hasattr(settings, 'HELPDESK_PUBLIC_TICKET_PRIORITY'):
+            initial_data['priority'] = settings.HELPDESK_PUBLIC_TICKET_PRIORITY
+        if hasattr(settings, 'HELPDESK_PUBLIC_TICKET_DUE_DATE'):
+            initial_data['due_date'] = settings.HELPDESK_PUBLIC_TICKET_DUE_DATE
+
         if queue:
             initial_data['queue'] = queue.id