Take table or appointment bookings in WhatsApp

from clickruntime import on_event, credentials, http, state, notify

PHONE_NUMBER_ID = "123456789012345"

def send(to, body, rows=None):
    msg = {"type": "text", "text": {"body": body}} if not rows else {"type": "interactive", "interactive": {
        "type": "list", "body": {"text": body}, "action": {"button": "Pick a time",
        "sections": [{"title": "Free slots", "rows": [{"id": r, "title": r} for r in rows[:10]]}]}}}
    http.post(f"https://graph.facebook.com/v21.0/{PHONE_NUMBER_ID}/messages",
              headers={"Authorization": f"Bearer {credentials.secret('WHATSAPP_TOKEN')}"},
              json={"messaging_product": "whatsapp", "to": to, **msg})

@on_event
def handle(event):
    value = event.json["entry"][0]["changes"][0]["value"]
    if "messages" not in value:
        return {"skipped": True}
    m = value["messages"][0]
    slots = state.get("free_slots") or []  # e.g. ["Fri 19:00", "Fri 19:30", ...]
    picked = m.get("interactive", {}).get("list_reply", {}).get("id")
    if picked in slots:
        slots.remove(picked)
        state.set("free_slots", slots)
        send(m["from"], f"Booked for {picked}. See you then!")
        notify.email_me(f"Reservation: {picked}", f"From +{m['from']} ({value['contacts'][0]['profile']['name']})")
        return {"booked": picked}
    send(m["from"], "Hi! Which time would you like?", slots) if slots else send(m["from"], "Sorry, we're fully booked.")
    return {"offered": len(slots)}