// events.js:182
// throw er; // Unhandled 'error' event
// TypeError: callback.apply is not a function


exports.statsPage = (req, res) => {
  async.parallel({
    esldata: function(callback) {
        JobListing.find({ tags: { $in: esl} })
        .exec(callback)
    },
    remotedata: function(callback) {
        JobListing.find({location: {
          $in: ['Remote', 'remote', 'Remote,Remote']} })
          .exec(callback)
    },
    languagedata: function(callback) {
      JobListing.find({ tags : 'english' }, { tags : 'spanish' }, { tags : 'french' }, { tags : 'german' }, { tags : 'mandarin' }, { tags : 'italian' }, { tags : 'swedish' }, { tags : 'portuguese' }, { tags : 'arabic' })
        .exec(callback)
  },
  programmingdata: function(callback) {
    JobListing.find({ tags : 'programming' }, { tags : 'computer science' })
      .exec(callback)
  },
  naturaldata: function(callback) {
    JobListing.find({ tags : 'physics' }, {tags:'chemistry' }, {tags: 'mathematics'})
      .exec(callback)
  },
  naturaldata: function(callback) {
    JobListing.find({ tags : 'physics' }, {tags:'chemistry' }, {tags: 'mathematics'})
      .exec(callback)
  },
  socialdata: function(callback) {
    JobListing.find({ tags : 'history' }, { tags : 'politics' })
      .exec(callback)
  },
  musicdata: function(callback) {
    JobListing.find({ tags : 'music' }, { tags : 'art' })
      .exec(callback)
  },
  writerdata: function(callback) {
    JobListing.find({ tags : 'writer' } )
      .exec(callback)
  },
  }, function(err, listings) {
    if (err) { return next(err); } // Error in API usage.

    // Successful, so render.
    res.render('statistics',
    { esldata: listings.esldata.length, remotedata: listings.remotedata.length,
      languagedata: listings.languagedata.length, programmingdata: listings.programmingdata.length,
      naturaldata: listings.naturaldata.length, socialdata: listings.socialdata.length,
      musicdata: listings.musicdata.length, writerdata: listings.writerdata.length   });
  });
};