Send polite Gmail reminders for overdue QuickBooks invoices

import base64
from datetime import date
from email.message import EmailMessage
from google.oauth2.credentials import Credentials
from googleapiclient.discovery import build
from clickruntime import on_trigger, credentials, http, state, notify, ai
API = "https://quickbooks.api.intuit.com/v3/company/1234567890"  # your QuickBooks company id

def qb(method, path, **kw):
    r = http.request(method, API + path, params={"minorversion": 73, **kw.pop("params", {})}, **kw, headers={"Accept": "application/json", "Authorization": "Bearer " + credentials.connection("quickbooks", "company")})
    return r.raise_for_status() or r.json()

@on_trigger
def run(event):
    today = date.today()
    invoices = qb("GET", "/query", params={"query": f"select * from Invoice where Balance > '0' and DueDate < '{today}'"})["QueryResponse"].get("Invoice", [])
    last = state.get("last") or {}
    gmail, sent = build("gmail", "v1", credentials=Credentials(credentials.connection("google", "work")), cache_discovery=False), []
    for inv in invoices:
        days = (today - date.fromisoformat(inv["DueDate"])).days
        if not inv.get("BillEmail") or (today - date.fromisoformat(last.get(inv["Id"], "2000-01-01"))).days < 7:
            continue
        tone = "friendly" if days < 14 else "neutral" if days < 30 else "firm but polite"
        facts = f"Invoice {inv['DocNumber']} for ${inv['Balance']:,.2f} was due {inv['DueDate']} ({days} days ago)."
        try:
            body = ai.generate(f"Write a short {tone} payment reminder email body to {inv['CustomerRef']['name']}. {facts}", max_output_tokens=200).text
        except ai.AIError:
            body = f"Hello,\n\nA quick reminder: {facts} Please let us know when we can expect payment.\n\nThanks"
        msg = EmailMessage()
        msg["To"], msg["Subject"] = inv["BillEmail"]["Address"], f"Reminder: invoice {inv['DocNumber']}"
        msg.set_content(body)
        gmail.users().messages().send(userId="me", body={"raw": base64.urlsafe_b64encode(msg.as_bytes()).decode()}).execute()
        last[inv["Id"]] = str(today)
        sent.append(f"{inv['CustomerRef']['name']} #{inv['DocNumber']}: ${inv['Balance']:,.2f}, {days} days")
    if sent:
        notify.email_me(f"Sent {len(sent)} payment reminders", "\n".join(sent))
    state.set("last", last)
    return {"reminded": len(sent)}