feat: Pull years out of ICS file

.gitignore

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+ICS files

README.md

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+This is a fork of https://github.com/druths/icssplitter
+
+# Getting dates present in an ICS file
+You may need to break apart an ICS file so that you can upload it to a cloud-based system, but you may not know which years you have calendar events for. To solve this, I modified icssplitter and added ics_info.py. This will split out a list of years that you can then feed into icssplitter.
+
+Basic usage for this tool is:
+
+	python ics_info.py my_big_file.ics.
+
+In case the original project gets removed, here is the README for icssplitter.
+
 # Let's split those ICS files...
 ics files allow us to move calendar events between calendaring systems (e.g.,
 Google and Exchange).  The problem is that they get big... and cloud-based

ics_info.py

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+"""
+A handy script for extracting all event years from an ICS file.
+Works well for determining what values to pass to https://github.com/druths/icssplitter/
+
+@author Dan Getz (@quizwedge)
+"""
+
+import argparse
+import re
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser()
+    parser.add_argument('input_file', help='the input ICS file')
+
+    args = parser.parse_args()
+
+    print(f'Extracting years from {args.input_file}')
+
+    created_pattern = re.compile('^DTSTART')
+
+    in_fname = args.input_file
+
+    infh = open(in_fname, 'r')
+
+    # parsing constants
+    BEGIN_EVENT = 'BEGIN:VEVENT'
+    END_EVENT = 'END:VEVENT'
+
+    in_preamble = True
+    in_event = False
+    events = set()
+
+    for line in infh:
+        if in_preamble and line.startswith(BEGIN_EVENT):
+            in_preamble = False
+
+        if not in_preamble:
+            if line.startswith(BEGIN_EVENT):
+                in_event = True
+
+            if in_event:
+                if created_pattern.match(line):
+                    last_value = line.split(':')[-1][:4]
+                    events.add(last_value)
+
+            if line.startswith(END_EVENT):
+                in_event = False
+
+    print(sorted(events))