Add DTSTAMP and UID values to meeting instances

The iCalendar spec expects a meeting vEvent to include a datetime stamp
and a unique ID for each instance. This adds these values to the
generated output.

Minor cleanup also included since I was touching code around them and
noticed little nits.

Change-Id: I4753571850665a2f28a6799b84ead4c31a275cc7
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>

.gitignore

@@ -5,6 +5,7 @@
 
 # Packages
 *.egg
+*.eggs
 *.egg-info
 dist
 build

tox.ini

@@ -7,6 +7,7 @@ install_command = pip install -U {opts} {packages}
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 commands = python setup.py testr --slowest --testr-args='{posargs}'
+usedevelop = true
 
 [testenv:pep8]
 basepython = python3

yaml2ical/ical.py

@@ -11,10 +11,11 @@
 # under the License.
 
 import datetime
-import icalendar
 import logging
 import os
 import os.path
+
+import icalendar
 import pytz
 
 
@@ -108,9 +109,19 @@ class Yaml2IcalCalendar(icalendar.Calendar):
                 for skip_date in sch.skip_dates:
                     event.add('exdate', skip_date.date)
                     # NOTE(tonyb): If this is a skipped meeting add a
-                    # non-recurring event with an obvisous summary.
+                    # non-recurring event with an obvious summary.
                     self.add_schedule(meeting, sch, exdate=skip_date)
 
+            # Add update timestamp and unique ID for the event.
+            # Note: we need a way to uniquely identify the meeting, even if its
+            # details are modified. We don't really have much to go on to do
+            # that, so best effort just use the project name and date.
+            event.add('dtstamp', meeting.last_update)
+            start_date = exdate.date if exdate else next_meeting_date
+            event.add('uid', '%s-%s' % (
+                      meeting.project.replace(' ', '').lower(),
+                      datetime.datetime.strftime(start_date, '%Y%m%d')))
+
             # add event to calendar
             self.add_component(event)
 

yaml2ical/meeting.py

@@ -15,6 +15,7 @@ from io import StringIO
 import os
 import os.path
 import pytz
+import subprocess
 import yaml
 
 
@@ -201,10 +202,16 @@ class Meeting(object):
             s = Schedule(self, sch)
             self.schedules.append(s)
 
+        # Set a default last update time
+        self.last_update = datetime.datetime.utcnow()
+
     @classmethod
     def fromfile(cls, yaml_file):
-        f = open(yaml_file, 'r')
+        with open(yaml_file, 'r') as f:
-        return cls(f)
+            meeting = cls(f)
+
+        meeting.last_update = _get_update_time(yaml_file)
+        return meeting
 
     @classmethod
     def fromstring(cls, yaml_string):
@@ -212,6 +219,26 @@ class Meeting(object):
         return cls(s)
 
 
+def _get_update_time(src_file):
+    """Attempts to figure out the last time the file was updated.
+
+    If the file is under source control, this will try to find the last time it
+    was updated. If that is not possible, it will fallback to using the last
+    time the local file was modified.
+    """
+    try:
+        last_updated = subprocess.check_output(
+            [
+                'git', 'log', '-n1', '--format=%ad',
+                '--date=format:%Y-%m-%d %H:%M:%S',
+                '--', src_file,
+            ]
+        ).decode('utf-8').strip()
+        return datetime.datetime.strptime(last_updated, '%Y-%m-%d %H:%M:%S')
+    except (subprocess.CalledProcessError, ValueError):
+        return datetime.datetime.fromtimestamp(os.path.getmtime(src_file))
+
+
 def load_meetings(yaml_source):
     """Build YAML object and load meeting data