How to use

chunk

function

in

CollectionChain

/**
 * Parse a rank result from redis
 * @param  {array} rank In this format: [ 'foo', '39', 'bar', '13' ]
 * @return {object} In this format: [ { foo: 39 }, { bar: 13 } ]
 * @private
 */
const rankParser = rank => {
 return _.chain(rank)
  .chunk(2)
  .map(([key, count]) => ({ [key]: Number(count) }))
  .value();
}

/**
 * Parse & merge multiple rank results from redis.
 * @param  {array}  ranks In this format: [['foo', '39', 'bar', '13'], ['foo', '11']]
 * @return {object}       In this format: [{ foo: 50 }, { bar: 13 }]
 */
const createRankTotalParser = (direction, startingAt, limit) => ranks => {
 return _.chain(ranks)
  .flatten()
  .chunk(2)
  .reduce((acc, [key, count]) => _.tap(acc, acc => {
   acc[key] = (acc[key] || 0) + Number(count);
  }), { })
  .toPairs()
  .sortBy(([, count]) => direction === 'asc' ? count : -count)
  .drop(startingAt)
  .takeWhile((value, index) => limit <= 0 || index < limit)
  .map(([key, count]) => ({ [key]: count }))
  .value();
}