detect calendar email responses for evolution filter

gistfile1.txt

#!/usr/bin/python3
"""
detect calendar email responses for evolution filter
returns Unix code 1 if is a calendar answer
Martin Monperrus
Oct 2023
"""
from datetime import datetime, timedelta
import json
import itertools
import os.path
import time
import ics
import base64
import binascii
import sys
from email import message_from_bytes

def action_if_calendar_reply_found():
  sys.exit(2)

mime_message = message_from_bytes(sys.stdin.buffer.read())
contenttype = mime_message.get_content_type()
#print(contenttype)
if "text/calendar" in contenttype.lower() and "method=reply" in contenttype.lower():
    action_if_calendar_reply_found()
if mime_message.get_content_type() == "multipart/alternative" or mime_message.get_content_type() ==  "multipart/mixed":
  for part in mime_message.get_payload():
    #try:
      #print(part.get_content_type())
      if part.get_content_type() == "text/calendar" or part.get_content_type() == "application/ics" :
        contenttype= [x for x in part._headers if x[0].lower()=="content-type"][0][1]
        encoding= [x for x in part._headers if x[0].lower()=="content-transfer-encoding"][0][1]
        calendar_data = part.get_payload()
        if encoding.lower() == 'base64':
          calendar_data = base64.b64decode(calendar_data).decode('utf-8')
        #print(dir(part))
        #print(calendar_data.decode('utf-8'))
        
        # some MUAs add method=REPLY, that's good!
        if "method=REPLY".lower() in contenttype.lower():            
          print("multipart/method=REPLY")
          action_if_calendar_reply_found()
        else:
          # but some MUAs don't 
          calendar = ics.Calendar(calendar_data)
          event = [x for x in calendar.events][0]
          #print(calendar.method.lower())
          if calendar.method.lower() == "REPLY".lower():
            #print(calendar_data.decode('utf-8'))
            print("multipart/calendar.method.lower()")
            action_if_calendar_reply_found()
            
            
      #except Exception as e:         print(e)