Get a Slack reminder before each meeting

from google.oauth2.credentials import Credentials
from googleapiclient.discovery import build
from datetime import datetime, timedelta, timezone
from clickruntime import on_trigger, report_fetched, credentials, state, notify

@on_trigger
def run(event):
    cal = build("calendar", "v3", credentials=Credentials(credentials.connection("google", "work")), cache_discovery=False)
    now = datetime.now(timezone.utc)
    items = cal.events().list(calendarId="primary", timeMin=now.isoformat(), timeMax=(now + timedelta(minutes=15)).isoformat(),
                              singleEvents=True, orderBy="startTime").execute()["items"]
    reminded = set(state.get("reminded") or [])
    due = [e for e in items if "dateTime" in e["start"] and e["id"] not in reminded]
    report_fetched(len(due))
    if not due:
        return {"summary": "Nothing coming up"}
    for e in due:
        people = ", ".join(a.get("displayName", a["email"]) for a in e.get("attendees", []) if not a.get("self"))
        notify.slack(f"In 10 minutes: {e.get('summary')}\nWith: {people or 'just you'}\n{e.get('hangoutLink', '')}",
                     channel="#my-reminders")
        reminded.add(e["id"])
    state.set("reminded", sorted(reminded)[-200:])
    return {"reminded": len(due)}