Block focus time on busy days

from google.oauth2.credentials import Credentials
from googleapiclient.discovery import build
from datetime import datetime, timedelta, time
from zoneinfo import ZoneInfo
from clickruntime import on_trigger, credentials

TZ = ZoneInfo("America/New_York")

@on_trigger
def run(event):
    cal = build("calendar", "v3", credentials=Credentials(credentials.connection("google", "work")), cache_discovery=False)
    day = datetime.now(TZ).date() + timedelta(days=1)
    start, end = datetime.combine(day, time(9), TZ), datetime.combine(day, time(18), TZ)
    items = [e for e in cal.events().list(calendarId="primary", timeMin=start.isoformat(), timeMax=end.isoformat(),
                                          singleEvents=True, orderBy="startTime").execute()["items"] if "dateTime" in e["start"]]
    spans = [(datetime.fromisoformat(e["start"]["dateTime"]), datetime.fromisoformat(e["end"]["dateTime"])) for e in items]
    if sum((b - a).total_seconds() for a, b in spans) <= 4 * 3600:
        return {"blocked": False}
    cursor = start
    for a, b in spans + [(end, end)]:
        if a - cursor >= timedelta(hours=2):
            cal.events().insert(calendarId="primary", body={
                "summary": "Focus", "transparency": "opaque",
                "start": {"dateTime": cursor.isoformat()}, "end": {"dateTime": (cursor + timedelta(hours=2)).isoformat()},
            }).execute()
            return {"blocked": True, "at": cursor.isoformat()}
        cursor = max(cursor, b)
    return {"blocked": False, "reason": "no 2-hour gap"}