package.json

{
  "name": "pairer",
  "version": "1.0.0",
  "description": "a pairer for CW",
  "main": "pairer.js",
  "scripts": {
    "start": "node ./pairer.js"
  },
  "author": "Jack Thibaut",
  "license": "MIT",
  "bin": "./pairer.js"
}

pairer.js

#!/usr/bin/env node

const fs = require('fs')
const promisify = require('util').promisify
const readline = require('readline')
const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
})
rl.pause()
const read = promisify(fs.readFile)
const write = promisify(fs.writeFile)

const ask = (question) => new Promise((resolve, reject) => {
  rl.resume()
  rl.question(question, answer => {
    rl.pause()
    return resolve(answer)
  })
})

const pairs = async ([a, b, input = './students.json', output = './previous.json']) => {
  const { seniors, juniors } = await read(input)
    .then(res => JSON.parse(res.toString('utf-8')))
    .catch(() => ({seniors: false, juniors: false}))

  if (!seniors && !juniors) {
    const answer = await ask('No student file was found, do you want to create a new one? (Y/N) ')
    if (answer === 'Y') {
      const fileName = await ask('student file name: (\'students.json\') ')
        .then(res => res || 'students.json')
      const group1 = await ask('how many students in first group? ')
      const group1Name = await ask('name of the first group? ')
      const group1Arr = []
      for (let i = 0; i < group1; i++) {
        const student = await ask('student name: ')
        group1Arr.push(student)
      }

      const group2 = await ask('how many students in second group? ')
      const group2Name = await ask('name of the second group? ')

      const group2Arr = []
      for (let i = 0; i < group2; i++) {
        const student = await ask('student name: ')
        group2Arr.push(student)
      }
      await write(`./${fileName}`, JSON.stringify({
        [group1Name]: group1Arr,
        [group2Name]: group2Arr
      }))
      return pairs([0, 0, `./${fileName}`])
    } else {
      process.exit(0)
    }
  }

  const division = juniors.length > seniors.length
    ? juniors.length / seniors.length
    : seniors.length / juniors.length
  const color = juniors.length > seniors.length
    ? '\x1b[32m'
    : '\x1b[33m'
  const iteratee = juniors.length > seniors.length
    ? seniors
    : juniors
  const opposite = juniors.length > seniors.length
    ? juniors
    : seniors


  const previous = await read(output)
    .then(res => JSON.parse(res))
    .catch(() => iteratee.reduce((acc, el) => {
      acc[el] = []
      return acc
    }, {}))

  const matched = new Set()

  const newPairs = shuffle(iteratee).reduce((acc, el) => {
    const matches = opposite.reduce((curr,pot) => {
      if (!matched.has(pot) && curr.length < division && !previous[el].includes(pot)) {
        curr.push(pot)
        matched.add(pot)
      }
      return curr
    }, [])
    acc[el] = matches
    previous[el].push(...matches)
    return acc
  }, {})

  write(output, JSON.stringify(previous))

  const single = Object.keys(newPairs).find(el => newPairs[el].length < division)

  let loggingFormat = newPairs

  if (single) {
    const pairedIt = shuffle(Object.keys(newPairs)).reduce((acc, el) => !acc && el !== single ? el : acc, '')
    loggingFormat = Object.keys(newPairs).reduce((acc, el) => {
      return el !== pairedIt && el !== single
        ? {...acc, [el] : newPairs[el]}
        : acc
    } ,{[`${pairedIt} & ${single}`]: newPairs[pairedIt]})
  }

  console.log('=============================================')
  console.log('=              PAIRS FOR TODAY              =')
  console.log('=============================================')
  Object.keys(loggingFormat).forEach(el => {
    console.log(pad(`${color}${el}\x1b[0m: ${loggingFormat[el]}`, 51))
  })
  console.log('=============================================')
  rl.close()
}


const pad = (str, length) => {
  const padding = (length - str.length) / 2
  let borders = '='
  for (let i = 0; i < padding; i++) {
    borders += ' '
  }
  return `${borders}${str}${padding%1 ? borders.slice(1) + '=' : borders.slice(1) + ' ='}`
}

const shuffle = (a) => {
  for (let i = a.length - 1; i > 0; i--) {
      const j = Math.floor(Math.random() * (i + 1));
      [a[i], a[j]] = [a[j], a[i]];
  }
  return a;
}

pairs(process.argv)