import Meetings from '/imports/api/meetings';
import Logger from '/imports/startup/server/logger';
import { check } from 'meteor/check';

const SELECT_RANDOM_USER_ENABLED = Meteor.settings.public.selectRandomUser.enabled;

const SELECT_RANDOM_USER_COUNTDOWN = Meteor.settings.public.selectRandomUser.countdown;

//Time intervals in milliseconds
//for iteration in animation
let intervals = [0, 200, 450, 750, 1100, 1500];

//Used to togle to the first value of intervals to
//differenciare whether this function has been called
let updateIndicator = true;

//A finction that toggles
//the first interval on each call
function toggleIndicator(){
  if(updateIndicator){
    intervals[0] = 1;
  } else {
    intervals[0] = 0;
  }
  updateIndicator = !updateIndicator;
}

//All possible combinations of 3 elements
//to to speed up randomizing
const optionsFor3 = [ 
  [0, 1, 2],
  [0, 2, 1],
  [1, 2, 0],
  [1, 0, 2],
  [2, 0, 1],
  [2, 1, 0]
];

export default function updateRandomUser(meetingId, userIds, choice, requesterId) {
  check(meetingId, String);
  check(userIds, Array);
  check(choice, Number);
  check(requesterId, String);

  let userList = [];

  const selector = {
    meetingId,
  };

  toggleIndicator();

  const numberOfUsers = userIds.length;

  const chosenUser = userIds[choice];

  if (choice < 0) { // no viewer
    userList = [[requesterId,intervals[0]], [requesterId,0], [requesterId,0], [requesterId,0], [requesterId,0], [requesterId,0]];
  } 
  
  else if (numberOfUsers == 1) { //If user is only one, obviously it is the chosen one
    userList = [[userIds[0],intervals[0]], [userIds[0],0], [userIds[0],0], [userIds[0],0], [userIds[0],0], [userIds[0],0]];
  } 
  
  else if(!SELECT_RANDOM_USER_COUNTDOWN) { //If animation is disabled, we only care about the chosen one
    userList = [[chosenUser,intervals[0]], [chosenUser,0], [chosenUser,0], [chosenUser,0], [chosenUser,0], [chosenUser,0]];
  } 
  
  else if(numberOfUsers == 2){ // If there are only two users, we can just chow them in turns
    const IDs = userIds.slice();
    IDs.splice(choice, 1);
    userList = [[IDs[0],intervals[0]], [chosenUser,intervals[1]], [IDs[0],intervals[2]], [chosenUser,intervals[3]], [IDs[0],intervals[4]], [chosenUser,intervals[5]]];
  } 
  
  else if(numberOfUsers == 3){ //If there are 3 users, the number of combinations is small, so we'll use that
    const option = Math.floor(Math.random() * 6);
    const order = optionsFor3[option];
    userList = [[userIds[order[0]],intervals[0]], [userIds[order[1]],intervals[1]], [userIds[order[2]],intervals[2]], [userIds[order[0]],intervals[3]], [userIds[order[1]],intervals[4]], [chosenUser,intervals[5]]];
  } 
  
  else { // We generate 5 users randomly, just for animation, and last one is the chosen one
    const itrations = intervals.length -1;
    let IDs = userIds.slice();
    for(i = 0; i < itrations; i++ ){
      if(IDs == 0) { // we used up all the options 
        IDs = userIds.slice(); //start over
        let userId = IDs.splice(0, 1);
        if(userList[userList.length] == [userId, intervals[i]]){ //If we start over with the one we finnished, change it
          IDs.push(userId);
          userId = IDs.splice(0, 1)
        }
        userList.push([userId, intervals[i]]);
      } else {
        const userId = IDs.splice(Math.floor(Math.random() * IDs.length), 1);
        userList.push([userId, intervals[i]]);
      } 
    }
    userList.push([chosenUser, intervals[itrations + 1]]);
  }

  const modifier = {
    $set: {
      randomlySelectedUser: userList,
    },
  };

  try {
    const { insertedId } = Meetings.upsert(selector, modifier);
    if (insertedId) {
      Logger.info(`Set randomly selected userId and interval = ${userList} by requesterId=${requesterId} in meeitingId=${meetingId}`);
    }
  } catch (err) {
    Logger.error(`Setting randomly selected userId and interval = ${userList} by requesterId=${requesterId} in meetingId=${meetingId}`);
  }
}