# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1418249960 -3600
# Node ID e7da6ceb1a9902d6d105b52cf073e0015b4cbc1e
# Parent  4a7f257f384674ad778b796fa1e5bd1087628eef
Added initial support for cancelling attendance, reorganising the handler code.

diff -r 4a7f257f3846 -r e7da6ceb1a99 imiptools/handlers/resource.py
--- a/imiptools/handlers/resource.py	Wed Dec 10 21:41:56 2014 +0100
+++ b/imiptools/handlers/resource.py	Wed Dec 10 23:19:20 2014 +0100
@@ -8,7 +8,85 @@
 from imiptools.handlers.common import CommonFreebusy
 from vCalendar import to_node
 
-class Event(Handler):
+class ResourceHandler(Handler):
+
+    "Handling mechanisms specific to resources."
+
+    def _record_and_respond(self, handle_for_attendee):
+
+        oa = self.require_organiser_and_attendees()
+        if not oa:
+            return None
+
+        organiser_item, attendees = oa
+
+        # Validate the organiser, ignoring spoofed requests.
+
+        if not self.validate_identities([organiser_item]):
+            return None
+
+        # Process each attendee separately.
+
+        calendar = []
+
+        for attendee, attendee_attr in attendees.items():
+
+            # Check for event using UID.
+
+            if not self.have_new_object(attendee, "VEVENT"):
+                continue
+
+            # Collect response objects produced when handling the request.
+
+            response = handle_for_attendee(attendee, attendee_attr)
+            if response:
+                calendar.append(response)
+
+        return calendar
+
+    def _schedule_for_attendee(self, attendee, attendee_attr):
+
+        # If newer than any old version, discard old details from the
+        # free/busy record and check for suitability.
+
+        periods = self.get_periods()
+        freebusy = self.store.get_freebusy(attendee) or []
+        scheduled = self.can_schedule(freebusy, periods)
+
+        attendee_attr["PARTSTAT"] = scheduled and "ACCEPTED" or "DECLINED"
+        if self.messenger and self.messenger.sender != get_address(attendee):
+            attendee_attr["SENT-BY"] = get_uri(self.messenger.sender)
+
+        # Make a version of the request with just this attendee.
+
+        self.details["ATTENDEE"] = [(attendee, attendee_attr)]
+
+        event = to_node({"VEVENT" : [(self.details, {})]})
+        self.store.set_event(attendee, self.uid, event)
+
+        # Only update free/busy details if the event is scheduled.
+
+        if scheduled:
+            self.update_freebusy(freebusy, attendee, periods)
+        else:
+            self.remove_from_freebusy(freebusy, attendee)
+
+        if self.publisher:
+            self.publisher.set_freebusy(attendee, freebusy)
+
+        return event
+
+    def _cancel_for_attendee(self, attendee, attendee_attr):
+
+        freebusy = self.store.get_freebusy(attendee) or []
+        self.remove_from_freebusy(freebusy, attendee)
+
+        if self.publisher:
+            self.publisher.set_freebusy(attendee, freebusy)
+
+        return None
+
+class Event(ResourceHandler):
 
     "An event handler."
 
@@ -16,7 +94,11 @@
         pass
 
     def cancel(self):
-        pass
+
+        "Cancel attendance for attendees."
+
+        self._record_and_respond(self._cancel_for_attendee)
+        return None
 
     def counter(self):
 
@@ -54,57 +136,13 @@
         No support for countering requests is implemented.
         """
 
-        oa = self.require_organiser_and_attendees()
-        if not oa:
-            return None
-
-        organiser_item, attendees = oa
-
-        # Validate the organiser, ignoring spoofed requests.
-
-        if not self.validate_identities([organiser_item]):
+        response = self._record_and_respond(self._schedule_for_attendee)
+        if response:
+            return "REPLY", to_part("REPLY", response)
+        else:
             return None
 
-        # Process each attendee separately.
-
-        calendar = []
-
-        for attendee, attendee_attr in attendees.items():
-
-            # Check for event using UID.
-
-            if not self.have_new_object(attendee, "VEVENT"):
-                continue
-
-            # If newer than any old version, discard old details from the
-            # free/busy record and check for suitability.
-
-            periods = self.get_periods()
-            freebusy = self.store.get_freebusy(attendee) or []
-            scheduled = self.can_schedule(freebusy, periods)
-
-            attendee_attr["PARTSTAT"] = scheduled and "ACCEPTED" or "DECLINED"
-            if self.messenger and self.messenger.sender != get_address(attendee):
-                attendee_attr["SENT-BY"] = get_uri(self.messenger.sender)
-            self.details["ATTENDEE"] = [(attendee, attendee_attr)]
-
-            event = to_node({"VEVENT" : [(self.details, {})]})
-            calendar.append(event)
-            self.store.set_event(attendee, self.uid, event)
-
-            # Only update free/busy details if the event is scheduled.
-
-            if scheduled:
-                self.update_freebusy(freebusy, attendee, periods)
-            else:
-                self.remove_from_freebusy(freebusy, attendee)
-
-            if self.publisher:
-                self.publisher.set_freebusy(attendee, freebusy)
-
-        return "REPLY", to_part("REPLY", calendar)
-
-class Freebusy(Handler, CommonFreebusy):
+class Freebusy(ResourceHandler, CommonFreebusy):
 
     "A free/busy handler."
 
@@ -119,7 +157,7 @@
 
     # request provided by CommonFreeBusy.request
 
-class Journal(Handler):
+class Journal(ResourceHandler):
 
     "A journal entry handler."
 
@@ -132,7 +170,7 @@
     def publish(self):
         pass
 
-class Todo(Handler):
+class Todo(ResourceHandler):
 
     "A to-do item handler."