#!/bin/sh
''':'
. "`dirname "$0"`/../../venv/bin/activate"
exec python "$0" "$@"
':'''

import sys
import time
import secrets
import sqlite3
import requests

from common import *

feed_param = {
    'channel': 'channel_id',
    'playlist': 'playlist_id',
}

def pull_subscriptions(verbose=1, force_all=False, limit=-1):
    """
    Crawls youtube channels' RSS feeds and stores found videos in the database.
    verbose: 0: completely silent; 1: warn on errors; 2: log all accessed feeds
    force_all: fetch all known channels. otherwise only those not crawled in 24h
    limit: limit number of processed feeds
    """
    with sqlite3.connect(cf['global']['database']) as conn:
        c = conn.cursor()
        c.execute("""
            SELECT DISTINCT s.channel_id, type
              FROM subscriptions AS s LEFT JOIN crawler AS c
                ON s.channel_id = c.channel_id
             WHERE ? OR IFNULL(crawled_at,0) < datetime('now', '-1 day')
          ORDER BY crawled_at
             LIMIT ?
        """, (force_all,limit))
        results = c.fetchall()

        if verbose >= 2 and not len(results):
            sys.stderr.write(f'no feeds to update.\n')

        for i,(feed_id, feed_type) in enumerate(results):
            if i: time.sleep(60)
            pull_feed(feed_id, feed_type, conn, verbose)

def pull_feed(feed_id, feed_type, conn, verbose):
    c = conn.cursor()

    if verbose >= 2:
        sys.stderr.write(f'fetching {feed_id}\n')

    xmlfeed = fetch_xml(feed_param[feed_type], feed_id)
    if not xmlfeed:
        if verbose:
            sys.stderr.write(f'FETCH FAILED: {feed_id}\n')
        return False

    try:
        update_channel(conn, xmlfeed)
    except:
        if verbose:
            sys.stderr.write(f'STORE FAILED: {feed_id}\n')
        # writing failed, so we store the feed in a file for later analysis.
        with open('/tmp/pull-subscriptions.err', 'ab') as f:
            f.write(f"<!-- {time.ctime()} ({int(time.time())}) -->\n"
                    .encode('ascii'))
            f.write(xmlfeed + b"\n")
        return False

    # update crawled_at timestamp:
    c.execute("""
    INSERT OR REPLACE INTO crawler (channel_id)
                    VALUES (?)
    """, (feed_id,))

    conn.commit()
    return True


def update_subscriptions(verbose=1, force_all=False, limit=-1):
    """
    Refreshes the websub (pubsubhubhub) subscription requests for youtube feeds.
    verbose: 0: completely silent; 1: warn on errors; 2: log all accessed feeds
    limit: limit number of processed feeds
    """
    with sqlite3.connect(cf['global']['database']) as conn:
        c = conn.cursor()
        c.execute("""
            SELECT DISTINCT s.channel_id, type
              FROM subscriptions AS s LEFT JOIN websub AS w
                ON s.channel_id = w.channel_id
             WHERE ? OR IFNULL(subscribed_until,0) < datetime('now','+12 hours')
          ORDER BY subscribed_until
             LIMIT ?
        """, (force_all,limit))
        results = c.fetchall()

        if verbose >= 2 and not len(results):
            sys.stderr.write(f'no feeds to update.\n')

        for i,(feed_id, feed_type) in enumerate(results):
            if i: time.sleep(60)
            update_feed(feed_id, feed_type, verbose)

def update_feed(feed_id, feed_type, verbose):
    webhook = cf['websub']['public_uri']
    lease = cf['websub']['lease']
    hmackey = cf['websub']['hmac_key']

    if verbose >= 2:
        sys.stderr.write(f'updating {feed_id}\n')

    feed_type = feed_param[feed_type]
    version, timestamp = "v1", int(time.time())
    nonce = secrets.token_urlsafe(16)
    sig = websub_url_hmac(hmackey, feed_id, timestamp, nonce)
    r = requests.post("https://pubsubhubbub.appspot.com/subscribe", {
        "hub.callback":      f"{webhook}/websub/{version}/{timestamp}/" + \
                             f"{nonce}/{feed_id}/{sig}",
        "hub.topic":         f"https://www.youtube.com/xml/feeds/videos.xml" + \
                             f"?{feed_type}={feed_id}",
        "hub.verify":        "async",
        "hub.mode":          "subscribe",
        "hub.lease_seconds": lease,
        "hub.secret":        hmackey,
    })
    if not r.ok:
        if verbose:
            sys.stderr.write(f'FAILED {feed_id}: {r.text}\n')
        return False

    return True


if __name__ == '__main__':
    if len(sys.argv) < 2 or sys.argv[1] not in ['pull','websub']:
        sys.stderr.write(
            f'Usage: YT_CONFIG=... {sys.argv[0]} pull [-f] [-1] [-v|-vv]\n'
            f'       YT_CONFIG=... {sys.argv[0]} websub [-f] [-1] [-v|-vv]\n'
            f'-f: force even if still up-to-date-ish\n'
            f'-v: report errors\n'
            f'-vv: report accessed feeds\n'
            f'-1: limit to one feed (for testing it works)\n')
        sys.exit(1)

    verbosity = 2 if '-vv' in sys.argv else 1 if '-v' in sys.argv else 0
    limit = 1 if '-1' in sys.argv else -1
    force = '-f' in sys.argv

    if 'pull' in sys.argv:
        pull_subscriptions(verbosity, force, limit)
    elif 'websub' in sys.argv:
        update_subscriptions(verbosity, force, limit)