Implemented calendar synchronization

Signed-off-by: Jim Martens <github@2martens.de>

src/twomartens/calendarsync/calendarsync.py

@@ -15,11 +15,54 @@
 #   limitations under the License.
 
 """calendarsync.calendarsync: provides entry point main()"""
+import argparse
+import datetime
+from os.path import isdir
+
+import pkg_resources
+from ics import Calendar
+from urllib.request import urlopen
+from urllib.parse import urlparse, ParseResult
 
 
 def main() -> None:
     """
     Main entry point.
     """
-    pass
-
+    parser = argparse.ArgumentParser(
+        description="Synchronizes jekyll event collection with remote calendar",
+    )
+    parser.add_argument('calendar_url', help='URL to the remote calendar ICS location')
+    parser.add_argument('event_collection_path', help='Path to event collection directory')
+    args = parser.parse_args()
+    
+    # handling exceptions
+    parsed_url: ParseResult = urlparse(args.calendar_url)
+    if parsed_url.netloc == '' or parsed_url.scheme == '':
+        raise ValueError('calendar_url: The given calendar url is not a proper URL.')
+    if not isdir(args.event_collection_path):
+        raise ValueError('event_collection_path: The given event collection path is not a directory.')
+    
+    calendar = Calendar(urlopen(args.calendar_url).read().decode('utf-8'))
+    template_filename = pkg_resources.resource_filename(
+        __package__,
+        'event_template.markdown'
+    )
+    with open(template_filename, 'r', encoding='utf-8') as template:
+        template_content = template.read()
+    for event in calendar.events:
+        event_content = template_content.replace('<name>', event.name)
+        created: datetime.datetime = event.created
+        created_str = created.isoformat(sep=' ')
+        event_content = event_content.replace('<date>', created_str)
+        begin: datetime.datetime = event.begin
+        begin_str = begin.isoformat(sep=' ')
+        event_content = event_content.replace('<begin>', begin_str)
+        end: datetime.datetime = event.end
+        end_str = end.isoformat(sep=' ')
+        event_content = event_content.replace('<end>', end_str)
+        event_content = event_content.replace('<location>', event.location)
+        
+        event_filename = begin.date().isoformat() + '-' + event.name.replace(' ', '_') + '.markdown'
+        with open(args.event_collection_path + event_filename, 'w', encoding='utf-8', newline='\n') as event_file:
+            event_file.write(event_content)

src/twomartens/calendarsync/event_template.markdown

@@ -0,0 +1,8 @@
+---
+layout: event
+title:  <name>
+date: <date>
+start_date: <begin>
+end_date: <end>
+location: <location>
+---