Text appointment reminders and follow-ups from a sheet

from google.oauth2.credentials import Credentials
from googleapiclient.discovery import build
from twilio.rest import Client
from datetime import datetime, timedelta
from clickruntime import on_trigger, credentials, http

SHEET_ID = "your-spreadsheet-id"
FROM = "+15005550006"

def sms(to, body):
    return Client(credentials.secret("TWILIO_ACCOUNT_SID"), credentials.secret("TWILIO_AUTH_TOKEN")).messages.create(to=to, from_=FROM, body=body)
sheets = lambda: build("sheets", "v4", credentials=Credentials(credentials.connection("google", "work")), cache_discovery=False).spreadsheets().values()

@on_trigger
def run(event):
    rows = sheets().get(spreadsheetId=SHEET_ID, range="Appointments!A2:E").execute().get("values", [])
    now, sent = datetime.now(), 0
    for i, r in enumerate(rows, start=2):
        name, phone, when, reminded, followed = (r + [""] * 5)[:5]
        try:
            at = datetime.fromisoformat(when)
        except ValueError:
            continue
        if not reminded and now < at <= now + timedelta(hours=24):
            sms(phone, f"Hi {name}, a reminder of your appointment on {at:%a %d %b at %H:%M}. Reply if you need to change it.")
            col, sent = "D", sent + 1
        elif not followed and at + timedelta(hours=2) <= now < at + timedelta(hours=26):
            sms(phone, f"Thanks for coming in today, {name}. Book your next visit any time by replying to this text.")
            col, sent = "E", sent + 1
        else:
            continue
        sheets().update(spreadsheetId=SHEET_ID, range=f"Appointments!{col}{i}", valueInputOption="RAW", body={"values": [["sent"]]}).execute()
    return {"sent": sent}