added python calendar feed generator

1 files changed, 79 insertions, 0 deletions

diff --git a/main.py b/main.py
new file mode 100644
index 0000000..cb870c9
--- /dev/null
+++ b/main.py
@@ -0,0 +1,79 @@
+from datetime import datetime, timedelta, time
+from dateutil.relativedelta import relativedelta
+import urllib2
+
+import json
+import logging
+import sys
+import copy
+
+from dateutil.rrule import rrulestr
+import icalendar
+
+def fetch_calendar(logger):
+    """Fetches the calendar events and returns a icalendar.Calendar instance.
+    """
+    response = urllib2.urlopen(CALENDARIUM_IMPORT_URL)
+    logger.debug('Fetched calendar from %s' % CALENDARIUM_IMPORT_URL)
+    return icalendar.Calendar.from_ical(response.read())
+
+def get_events(calendar, after, before):
+    """Yields all events in calendar as dictionary.
+
+    Only events after (including) after will be shown. Recurring events
+    til before (inclusively) will be shown.
+    """
+    for event in calendar.walk('vevent'):
+        event_fields = [
+                # dest, src, default
+                ('name', 'summary', 'unknown Event'),
+                ('description', 'description', ''),
+        ]
+        event_info = {}
+        for fieldinfo in event_fields:
+            try:
+                event_info[fieldinfo[0]] = event[fieldinfo[1]].format().encode("utf-8")
+                event_info[fieldinfo[0]] = event_info[fieldinfo[0]].decode("string-escape")
+            except KeyError:
+                event_info[fieldinfo[0]] = fieldinfo[2]
+        start = icalendar.vDDDTypes.from_ical(event['dtstart'].to_ical())
+        end = icalendar.vDDDTypes.from_ical(event['dtend'].to_ical())
+        if not isinstance(start, datetime):
+            start = datetime.combine(start, time())
+        if not isinstance(end, datetime):
+            end = datetime.combine(end, time())
+
+        if 'rrule' in event:
+            rrule = rrulestr(event['rrule'].to_ical(), dtstart=start)
+            duration = end - start
+            for occurence in rrule.between(after, before, True):
+                event_info['start'] = occurence
+                event_info['end'] = occurence + duration
+                yield copy.deepcopy(event_info)
+        else:
+            if start >= after:
+                event_info['start'] = start
+                event_info['end'] = end
+                yield event_info
+
+class DatetimeEncoder(json.JSONEncoder):
+    def default(self, obj):
+        if isinstance(obj, datetime):
+            return obj.isoformat()
+        return json.JSONEncoder.default(self,obj)
+
+CALENDARIUM_IMPORT_URL = 'https://sublab.org:5232/calendars/events'
+if __name__ == '__main__':
+    logging.basicConfig(stream=sys.stderr, level=logging.DEBUG)
+    logger = logging.getLogger('calendar_feed')
+    calendar = fetch_calendar(logger)
+    now = datetime.now()
+    after = now - relativedelta(days=1)
+    before = now + relativedelta(months=+2)
+
+    events = []
+    for event in get_events(calendar, after, before):
+        event['start'] = event['start'].isoformat()
+        event['end'] = event['end'].isoformat()
+        events.append(event)
+    print json.dumps(events)