roundtablelizor/app.js

const TESTS_LIST = ['Charles', 'Baruch','Frédéric', 'John', 'Dan',
                    'Linus', 'Nina', 'Mikhaïl', 'Russel', 'Françoise',
                    'Albert', 'Beth', 'Erykah', 'Aretha', 'Lucio',
                    'Bartleby','Zach','Patti','Aesop','Vernon']

const NOBODY = '***NOBODY';

function groupSizeChanged(val){
  let nbParticipants = document.getElementsByClassName('participant').length;
  let meetsPerRound = val - 1;
  let maxRounds = Math.floor(nbParticipants / meetsPerRound);

  document.getElementById('nbRounds').max = maxRounds

}

var participants;

function loadParticipantsFileChooser(){
  document.getElementById('filechooser').click()
}
function loadTest(){
  addParticipants(TESTS_LIST)
}

function loadParticipantsFromFile(file){

  let reader = new FileReader();
  let contents = reader.readAsText(file);
  reader.onload = function(event) {
    let contents = reader.result;
    let lines = contents.split('\n');
    addParticipants(lines)
  };

}

function addParticipants(list){
  list.forEach(function(item) {
      if(item.trim() !== '')
        addParticipant(item)
  });
}

function addParticipant(name){
    var newInput = document.createElement('input');
    newInput.setAttribute('class','participant');
    newInput.setAttribute('placeholder','participant');
    if(name)
      newInput.value = name;
    document.getElementById('participants').appendChild(newInput)

    //outch...
    document.getElementById('nbPerGroup').disabled = false;
    document.getElementById('nbRounds').disabled = false;
    document.getElementById('btn-do-it').disabled = false;
}

function russellize(){


  let k = document.getElementById('nbPerGroup').value
  let nbRounds = document.getElementById('nbRounds').value
  let nbGroups = Math.ceil(participants.length / k)
  let rounds = new Array()

  let missingParticipants = nbGroups * k - participants.length
  for(let n = 0; n < missingParticipants; n++)
      participants.push(NOBODY + n);

  let availablesPerParticipants = new Map()

  participants.forEach(function (p) {
    availablesPerParticipants.set(p,participants.slice().filter(el => el !== p))
  });

  for(let i = 1; i <= nbRounds; i++){
    let round = new Array()
    let availables = participants.slice()
    for(let j = 0; j < nbGroups ; j++){
        let currentGroup = new Array()
        let toTest = availables.slice()
        while(currentGroup.length < k){
          let random = Math.floor(Math.random()*toTest.length)
          let randomParticipant = toTest[random]
          let ok = true
          toTest.splice(random, 1);
          // console.log(randomParticipant + '/' + random)
          currentGroup.forEach(function (p) {
              if(availablesPerParticipants.get(p).indexOf(randomParticipant)<0){
                ok = false
                return
              }
          })

          if(!ok && toTest.length === 0){
             return false
           }

          if(ok){
            let randomEq = availables.indexOf(randomParticipant)
            availables.splice(randomEq, 1);
            // console.log(availables)
            currentGroup.forEach(function (p) {
              let l = availablesPerParticipants.get(p)
              let index = l.indexOf(randomParticipant)
              l.splice(index,1)
            })
            currentGroup.push(randomParticipant)
          }
        }
        round.push(currentGroup)
    }
    rounds.push(round)
  }

  return rounds
}


function run(){
    doIt()
}

function doIt(){

  participants = new Array()

  var inputs = document.getElementsByClassName('participant')
  for(var i = 0; i < inputs.length; i++){
      participants.push(inputs[i].value)
  }

  let rounds = false
  let attempts = 0
  while(!rounds){
    attempts ++
    rounds = russellize()
  }
  console.log(rounds)
  console.log("Attempts = " + attempts)
  let stats = new Map()
  participants.forEach(function (p) {
    let l = new Array()
    stats.set(p,l)
    rounds.forEach(function (round) {
      round.forEach(function (group) {
         if(group.indexOf(p)>=0){
            group.forEach(function (p2) {
              if(p !== p2){
                l.push(p2)
              }
            })
         }
      })
    })
  })

  document.getElementById('rounds').innerHTML=''
  let view = renderRounds(rounds)
  document.getElementById('rounds').appendChild(view)
}

function renderRounds(rounds){
  let x = 1
  let roundsBlock = document.createElement('div')
  rounds.forEach(function (round) {
    let roundBlockWrap = document.createElement('div')
    let roundBlock = document.createElement('div')
    let roundTitle = document.createElement('h2')
    let roundTitleText = document.createTextNode('Round ' + x)
    roundTitle.appendChild(roundTitleText)
    roundBlockWrap.appendChild(roundTitle)
    roundBlock.classList.add('round')
    let y = 1
    round.forEach(function (group) {
      let groupBlock = document.createElement('div')
      let groupTitle = document.createElement('h4')
      let groupTitleText = document.createTextNode('Group ' + y)
      groupTitle.append(groupTitleText)
      groupBlock.append(groupTitle)
      roundBlock.append(groupBlock)
      let list = document.createElement('ul')
      groupBlock.appendChild(list)
      groupBlock.classList.add('group')
      group.forEach(function (p) {
          let emptySlot = p.indexOf(NOBODY) >= 0
          let item = document.createElement('li')
          if(emptySlot)
              item.classList='empty-slot'
          let pTxt = emptySlot ? '' : p;
          item.appendChild(document.createTextNode(pTxt))
          list.appendChild(item)
      })
      y ++
    })
    x++
    roundBlockWrap.append(roundBlock)
    roundsBlock.appendChild(roundBlockWrap)
  })
  return roundsBlock
}