Post new Squarespace orders to Slack

from datetime import datetime, timezone
from clickruntime import on_trigger, credentials, http, state, notify, report_fetched

@on_trigger
def run(event):
    now = datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")
    since = state.get("checked_at") or now
    resp = http.get("https://api.squarespace.com/1.0/commerce/orders",
                    params={"modifiedAfter": since, "modifiedBefore": now},
                    headers={"Authorization": f"Bearer {credentials.secret('SQUARESPACE_API_KEY')}",
                             "User-Agent": "ClickRuntime"})
    resp.raise_for_status()
    seen = set(state.get("seen") or [])
    orders = [o for o in resp.json()["result"] if o["id"] not in seen]
    report_fetched(len(orders))
    if not orders:
        return {"new": 0}
    for o in orders:
        items = ", ".join(f"{i['quantity']}× {i['productName']}" for i in o["lineItems"])
        b = o["billingAddress"]
        notify.slack(f"Order #{o['orderNumber']}: {b['firstName']} {b['lastName']}\n{items}\n"
                     f"Total: {o['grandTotal']['currency']} {o['grandTotal']['value']}", channel="#shop-orders")
    state.set("seen", (list(seen) + [o["id"] for o in orders])[-500:])
    state.set("checked_at", now)
    return {"new": len(orders)}