Announce new Paddle subscribers in Slack

from clickruntime import on_event, credentials, http, notify

import hashlib, hmac

def paddle_signed(event):
    parts = dict(p.split("=", 1) for p in event.header("Paddle-Signature").split(";"))
    expected = hmac.new(credentials.secret("PADDLE_WEBHOOK_SECRET").encode(),
                        f"{parts['ts']}:{event.body}".encode(), hashlib.sha256).hexdigest()
    return hmac.compare_digest(expected, parts["h1"])

@on_event
def handle(event):
    if not paddle_signed(event):
        return {"posted": False, "reason": "bad signature"}
    body = event.json
    if body["event_type"] != "subscription.created":
        return {"posted": False}
    sub = body["data"]
    customer = http.get(f"https://api.paddle.com/customers/{sub['customer_id']}",
                        headers={"Authorization": f"Bearer {credentials.secret('PADDLE_API_KEY')}"}).json()["data"]
    price = sub["items"][0]["price"]
    amount = int(price["unit_price"]["amount"]) / 100
    notify.slack(f"🎉 New subscription: {customer['email']} on *{price['description']}*, "
                 f"{price['unit_price']['currency_code']} {amount:,.2f}/{price['billing_cycle']['interval']}",
                 channel="#revenue")
    return {"subscription": sub["id"]}