Discord backstage invite webapp for PyConline AU 2020

discord_inviter.py

from flask import Flask, redirect
import requests
from hmac import compare_digest as constant_time_compare
from walter.config import Config
import waitress

app = Flask(__name__)


with Config("PyCon AU", "Discord inviter") as config:
    DISCORD_MAIN_CHANNEL = config("DISCORD_MAIN_CHANNEL")
    DISCORD_BOT_TOKEN = config("DISCORD_BOT_TOKEN")
    PRETIX_ORGANIZER = config("PRETIX_ORGANIZER")
    PRETIX_EVENT = config("PRETIX_EVENT")
    PRETIX_CHECKIN_LIST = config("PRETIX_CHECKIN_LIST")
    PRETIX_SECRET = config("PRETIX_SECRET")
    PRETIX_QUESTION_ID = config("PRETIX_QUESTION_ID", cast=int)
    DEBUG = config("DEBUG", cast=bool, default=False)
    PORT = config("PORT", cast=int, default=8000)


@app.route("/<secret>")
def hello_world(secret):
    res = requests.post(
        f"https://discord.com/api/v6/channels/{DISCORD_MAIN_CHANNEL}/invites",
        json={"max_uses": 1, "unique": True},
        headers={"Authorization": f"Bot {DISCORD_BOT_TOKEN}",},
    )
    res.raise_for_status()
    invite_code = res.json()["code"]
    success = False
    try:
        ticket = requests.post(
            f"https://pretix.eu/api/v1/organizers/{PRETIX_ORGANIZER}/events/{PRETIX_EVENT}/checkinlists/{PRETIX_CHECKIN_LIST}/positions/{secret}/redeem/",
            json={"answers": {str(PRETIX_QUESTION_ID): invite_code},},
            headers={"Authorization": f"Token {PRETIX_SECRET}"},
        )
        if ticket.status_code == 201:
            success = True
            return redirect(f"https://discord.gg/{invite_code}")
        elif (
            ticket.status_code == 400 and ticket.json()["reason"] == "already_redeemed"
        ):
            old_invite_code = next(
                x["answer"]
                for x in ticket.json()["position"]["answers"]
                if x["question"] == PRETIX_QUESTION_ID
            )
            return redirect(f"https://discord.gg/{old_invite_code}")
        else:
            ticket.raise_for_status()
    finally:
        if not success:
            requests.delete(
                f"https://discord.com/api/v6/invites/{invite_code}",
                headers={"Authorization": f"Bot {DISCORD_BOT_TOKEN}",},
            ).raise_for_status()


if __name__ == "__main__":
    if DEBUG:
        app.run(debug=DEBUG, port=PORT)
    else:
        waitress.serve(app, listen=f"0.0.0.0:{PORT}")