"""
This is the webhook server that interfaces with Google's WebSub (formerly pubsubhubbub) server. This is its own server, so it can live on a different host than the frontend.
"""

#TODO: fold update-websub.py into this?

import time
import sqlite3
from flask import Flask, request
from urllib.parse import parse_qs

from common import *

app = Flask(__name__)

@app.route('/websub/v1/<int:timestamp>/<nonce>/<subject>/<sig>', methods=["GET"])
def websub(timestamp, nonce, subject, sig):
    mode = request.args.get('hub.mode', '')
    topic = request.args.get('hub.topic', '')
    challenge = request.args.get('hub.challenge', '')
    until = int(request.args.get('hub.lease_seconds', '0'))

    channel_id = parse_qs(topic.split('?')[1]).get('channel_id', [''])[0]  # TODO: support playlists # XXX: can raise indexerror
    if not channel_id:
        return '', 400

    if time.time() - timestamp > int(cf['websub']['lease']):
        return '', 400
    # TODO: implement hmac check: return '',400 unless hmac_sha1_hex("$timestamp/$nonce", $HMACKEY) eq $sig

    if mode != "subscribe":
        return '', 200
        # Note: channels are not purged from the websub dbtable.

    with sqlite3.connect(cf['global']['database']) as conn:
        c = conn.cursor()
        c.execute("""
		INSERT OR REPLACE INTO websub (channel_id, subscribed_until)
                           VALUES (?, datetime(?, 'unixepoch'))
        """, (channel_id, time.time()+until))
    return challenge, 200

@app.route('/websub/v1/<int:timestamp>/<nonce>/<subject>/<sig>', methods=["POST"])
def websub_post(timestamp, nonce, subject, sig):
	# TODO: implement hmac check: return '',400 unless hmac_sha1_hex("$timestamp/$nonce", $HMACKEY) eq $sig
	# todo: # say 400 and exit unless hmac_sha1_hex($body, $HMACKEY) eq $ENV{X-Hub-Signature }

    with sqlite3.connect(cf['global']['database']) as conn:
        c = conn.cursor()
        ok = update_channel(conn, request.data)
        if not ok:
            with open('/tmp/websub-subscriptions.err', 'a') as f:
                f.write(f"<!-- {time.ctime()} ({int(time.time())}) -->\n{xmlfeed}\n")
    return '', 200

if __name__ == '__main__':
    app.run(debug=True)