add events to Google Calendar from a Sheets spreadsheet

sync.py

# WARNING: deletes all events in specified time range (line 53)
# see https://docs.google.com/spreadsheets/d/1Iwd2qV-xbHgyDU2YKQr7UedLvYhVsEmxciuPsk5rLA0/ for example spreadsheet layout
# there should be a credentials.json file in your working directory: see https://developers.google.com/calendar/api/quickstart/python#authorize_credentials_for_a_desktop_application
# also, properly setup your project's authorization screen to include both required scopes.
# code based on https://github.com/googleworkspace/python-samples/blob/main/calendar/quickstart/quickstart.py (and sheets equivalent)

from __future__ import print_function

import os.path
from google.auth.transport.requests import Request
from google.oauth2.credentials import Credentials
from google_auth_oauthlib.flow import InstalledAppFlow
from googleapiclient.discovery import build
from googleapiclient.errors import HttpError
import datetime

SCOPES = ['https://www.googleapis.com/auth/spreadsheets', 'https://www.googleapis.com/auth/calendar']
spreadsheetID=''
calendarID=''

def main():

    creds = None

    if os.path.exists('token.json'):
        creds = Credentials.from_authorized_user_file('token.json', SCOPES)
    if not creds or not creds.valid:
        if creds and creds.expired and creds.refresh_token:
            creds.refresh(Request())
        else:
            flow = InstalledAppFlow.from_client_secrets_file(
                'credentials.json', SCOPES)
            creds = flow.run_local_server(port=0)
        with open('token.json', 'w') as token:
            token.write(creds.to_json())

    try:
        sheet = build('sheets', 'v4', credentials=creds).spreadsheets()
        calendar = build('calendar', 'v3', credentials=creds)
        
        def getValues(range):
            result = sheet.values().get(spreadsheetId=spreadsheetID,
                                    range=range).execute()
            values = result.get('values', [])
            return values

        subjects = [["Discrete", getValues("A2:B24")], ["Python", getValues("C2:D27")], 
        ["Econ", getValues("E2:F33")], ["Analysis", getValues("G2:H40")], ["CS", getValues("I2:J45")]]

        events_result = calendar.events().list(calendarId=calendarID, timeMin=datetime.datetime.strptime(subjects[0][1][0][0], "%m/%d/%Y").isoformat() + 'Z', timeMax=datetime.datetime.strptime(subjects[4][1][43][0], "%m/%d/%Y").isoformat() + 'Z').execute()
        events = events_result.get('items', [])
        for event in events:
            calendar.events().delete(calendarId=calendarID, eventId=event['id']).execute()
        
        for i in range(len(subjects)):
            for j in range(len(subjects[i][1])):
                calendar.events().insert(calendarId=calendarID, body={
                    'summary': subjects[i][0],
                    'description': subjects[i][1][j][1],
                    'start': {
                        'date': datetime.datetime.strptime(subjects[i][1][j][0], "%m/%d/%Y").strftime("%Y-%m-%d")
                        },
                    'end': {
                        'date': datetime.datetime.strptime(subjects[i][1][j][0], "%m/%d/%Y").strftime("%Y-%m-%d")
                        },
                }).execute()

    except HttpError as err:
        print(err)

if __name__ == '__main__':
    main()