level-majority.js

const co = require('co');
const fs = require('fs');

require('../../app/models/topic');
require('../../app/models/level');
const User = require('../../app/models/user');

function extractLevelMajority(topicsArray) {

  let beginner = 0;
  let basic = 0;
  let medium = 0;
  let expert = 0;

  topicsArray.forEach(topic => {
    if ((topic.levelId || {}).label === 'beginner') {
      beginner += 1;
    } else if ((topic.levelId || {}).label === 'basic') {
      basic += 1;
    } else if ((topic.levelId || {}).label === 'medium') {
      medium += 1;
    } else if ((topic.levelId || {}).label === 'expert') {
      expert += 1;
    }
  })

  if (beginner > basic && beginner > medium && beginner > expert) {
    return 'beginner';
  } else if (basic > beginner && basic > medium &&  basic > expert) {
    return 'basic';
  } else if (medium > beginner && medium > basic && medium > expert) {
    return 'medium';
  } else if (expert > beginner && expert > medium && expert > basic) {
    return 'expert';
  }
  return 'no-majority';
}

module.exports = function() {
  co(function*() {

    yield new Promise((resolve, reject) => {
      let counter = 0;
      const majorityMap = {};

      const query = {
        topics: { $exists: true},
        'onboardingSteps.0': 'revision',
      }

        const uCursor = User.find(query, 'topics.levelId')
          .populate('topics.levelId', 'label')
          // .populate('topics.topicId', 'name')
          .limit(40000)
          .lean()
          .cursor();


        uCursor.eachAsync(user => {

          const majorLabel = extractLevelMajority(user.topics);

          if(!majorityMap[majorLabel]) {
            majorityMap[majorLabel] = {
              count: 0,
              ratio: 0,
            }
          }

          majorityMap[majorLabel].count += 1;
          // majorityMap[majorLabel].ratio = majorityMap[majorLabel].count / totalUsers * 100;

          counter += 1;
          console.log('at', counter, 'out of ~180k')
        })

        .then(() => {
          // calculate ratio
          Object.keys(majorityMap).forEach(m => {
            majorityMap[m].ratio = majorityMap[m].count / counter * 100;
          })
          majorityMap.total = counter;
          console.log('done');
          fs.writeFile('level-majority.json', JSON.stringify(majorityMap, null, 2), err => {
            if (err) console.log('something wrong happened', err);
            console.log('done writing to file');
            process.exit(0);
          })
          console.log(majorityMap)
          resolve();
        })

        .catch(err => {
          console.log(err);
          reject();
          process.exit(0);
        });

      })
    })


};