Add ability to specify custom ICS (#41)

Author: stefanv

example/test_calendar.yaml

@@ -54,3 +54,9 @@ events:
         # seconds, minutes, hours, days, weeks, months, years
         years: 1
       until: 2030-04-22
+
+  # Event with custom RRULE
+  - summary: Another day
+    begin: 2021-04-22
+    ics: |
+      RRULE:FREQ=YEARLY;UNTIL=20280422T000000

tests/test_events.py

@@ -126,3 +126,19 @@ def test_event_with_duration():
     assert "DURATION:PT30M" in event_str
     assert "DTEND" not in event_str
     assert "DTSTART" in event_str
+
+
+def test_event_with_custom_ics():
+    event = event_from_yaml(
+        parse_yaml(
+            """
+            summary: Earth Day
+            begin: 2021-04-22
+            url: https://earthday.org
+            ics: |
+              RRULE:FREQ=YEARLY;UNTIL=20280422T000000
+            """
+        )
+    )
+    event_str = event.serialize()
+    assert "RRULE:FREQ=YEARLY;UNTIL=20280422T000000" in event_str

yaml2ics.py

@@ -35,6 +35,8 @@ def strfexception(exdate):
 def event_from_yaml(event_yaml: dict, tz: datetime.tzinfo = None) -> ics.Event:
     d = event_yaml
     repeat = d.pop("repeat", None)
+    ics_custom = d.pop("ics", None)
+
     if "timezone" in d:
         tz = gettz(d.pop("timezone"))
 
@@ -121,6 +123,17 @@ def event_from_yaml(event_yaml: dict, tz: datetime.tzinfo = None) -> ics.Event:
     event.dtstamp = datetime.datetime.utcnow().replace(tzinfo=dateutil.tz.UTC)
     if tz and event.floating and not event.all_day:
         event.replace_timezone(tz)
+
+    if ics_custom:
+        for line in ics_custom.split("\n"):
+            if ":" not in line:
+                raise RuntimeError(
+                    f"Invalid custom ICS (expected `fieldname:value`):\n  {line}"
+                )
+
+            ruletype, content = line.split(":", maxsplit=1)
+            event.extra.append(ics.ContentLine(name=ruletype, value=content))
+
     return event