apollo/services/poll.js

const plex = require("./plex");
const logger = require("./logging")
const config = require("../config/configuration");

const lastPlaying = {};
const lastScrobbleTimes = {};

async function poll() {
  const now = Date.now();
  const playing = [];

  try {
    const data = await plex.getCurrentlyPlaying();
    playing.push.apply(playing, data);
  } catch (ex) {
    logger.error(ex, "Could not fetch currently playing data from Plex.");
    return;
  }

  for (let current of playing) {
    const previous = lastPlaying[current.sessionKey];
    lastPlaying[current.sessionKey] = current;
    if (previous == null) {
      logger.info(current, "A new session has started.");
      continue;
    }

    if (checkIfCanScrobble(current, previous, now)) {
      logger.info(previous, "Scrobble");
      lastScrobbleTimes[previous.mediaKey] = now;
    }
  }

  // Scrobble then remove lingering sessions
  for (let key in lastPlaying) {
    if (!playing.some(p => p.sessionKey == key)) {
      const track = lastPlaying[key];
      if (checkIfCanScrobble(null, track, now)) {
        logger.info(track, "Scrobble");
        lastScrobbleTimes[track.mediaKey] = now;
      }
      delete lastPlaying[key];
      logger.debug("Deleted old session.", key);
    }
  }
}

function applyFilter(track, filters) {
  if (!filters)
    return;

  for (let filter of filters) {
    if (filter.library && !filter.library.some(l => l == track.library))
      continue;
    if (filter.ip && !filter.ip.some(l => l == track.ip))
      continue;
    if (filter.deviceId && !filter.deviceId.some(l => l == track.deviceId))
      continue;
    if (filter.platform && !filter.platform.some(l => l == track.platform))
      continue;
    if (filter.product && !filter.product.some(l => l == track.product))
      continue;
    return true;
  }
  return false;
}

function checkIfCanScrobble(current, previous, now) {
  if (!previous)
    return;

  let filters = [];
  if (previous.source == 'plex')
    filters = config.scrobble.plex.filters;

  if (!applyFilter(previous, filters)) {
    logger.debug(previous, 'No filters got triggered. Ignoring.');
    return false;
  }

  const scrobbleDuration = isInt(config.scrobble.minimum.duration) ? Number(config.scrobble.minimum.duration) : 30;
  const scrobblePercent = isInt(config.scrobble.minimum.percent) ? Number(config.scrobble.minimum.percent) : 30;

  if (previous) {
    const newPlayback = current == null || current.playtime < previous.playtime;
    const canBeScrobbled = previous.playtime > scrobbleDuration * 1000 || previous.playtime / previous.duration > scrobblePercent;

    if (newPlayback && canBeScrobbled) {
      const sameSong = current != null && current.mediaKey == previous.mediaKey;
      const lastTime = lastScrobbleTimes[previous.mediaKey];
      return !sameSong || !lastTime || now - lastTime > scrobbleDuration;
    }
  }
  return false;
}

function isInt(value) {
  return !isNaN(value) &&
    parseInt(Number(value)) == value &&
    !isNaN(parseInt(value, 10));
}

module.exports = poll;