content_script.js

var data = {};
var last = {};
var players = [];

chrome.storage.sync.get({
  numTurns: 10,
  showAllChanges: false,
  useCountDown: false
}, function(items) {
  NUM_TURNS = items.numTurns;
  SHOW_ALL_CHANGES = items.showAllChanges;
  USE_COUNTDOWN = items.useCountDown;
});

addedCityLabel = false
addedTurnCounter = false

// mode: https://stackoverflow.com/a/3783970
function mode(array) {
  var freq = {};
  var max = 0;
  var result = null;
  for(var v in array) {
    freq[array[v]] = (freq[array[v]] || 0) + 1;
    if(freq[array[v]] > max) {
      max = freq[array[v]];
      result = array[v];
    }
  }
  return result;
}

function inGame(){
  return document.getElementById("game-leaderboard");
}

function getNextIncrease(){
  var turnCounter = document.getElementById('turn-counter');
  var currentTurn = parseInt(turnCounter.textContent.split(' ')[1]);
  if(USE_COUNTDOWN){
    var turnsLeft = 25 - (currentTurn % 25);
  } else {
    var turnsLeft = 25 - (currentTurn % 25) + parseInt(currentTurn);
  }
  ;
  return " Next Increase: " + turnsLeft;
}

function getArmy(player){
  var leaderboard = document.getElementById('game-leaderboard');
  var player_cell = leaderboard.querySelectorAll('.leaderboard-name.' + player);
  return parseInt(player_cell[0].nextSibling.innerHTML);
}

function updateCities(player, cities){
  var leaderboard = document.getElementById('game-leaderboard');
  var cities_cell = leaderboard.querySelectorAll('.cities-' + player);
  var player_row = cities_cell[0].parentElement;

  // Add flash if cities increase to > 0 or SHOW_ALL_CHANGES set
  if ((SHOW_ALL_CHANGES && parseInt(cities_cell[0].innerHTML) !== cities)
      || (cities_cell[0].innerHTML == "0" && cities > 0)) {
    setTimeout(function(row, cl) { row.className = cl; },
      1000, player_row, player_row.className);
    player_row.className += " flash " + player;
  }
  cities_cell[0].innerHTML = cities;
}

function turn(){
  var leaderboard = document.getElementById('game-leaderboard');
  var turnCounter = document.getElementById('turn-counter');

  // Initialise columns
  if(!addedCityLabel){
    leaderboard.rows[0].insertCell(leaderboard.rows[0].cells.length).innerHTML = "Cities";
    var table_length = leaderboard.rows[0].cells.length;

    for (var i = 0, row; row = leaderboard.rows[i + 1]; i ++){
      var player_color = row.children[table_length - 4].classList[1];
      var x = row.insertCell(table_length - 1);
      x.innerHTML = "0";
      x.className = "cities-" + player_color;

      // Store player data
      players.push(player_color);
      data[players[i]] = new Array();
      last[players[i]] = new Array();
    }
    addedCityLabel = true;
  }

  // add Turn Counter
  if(!addedTurnCounter) {
    var nextIncrease = document.createElement('div');
    nextIncrease.id = "nextIncreaseCounter";
    turnCounter.appendChild(nextIncrease);

    addedTurnCounter = true;
  }
  var nextIncreaseCounter = document.getElementById('nextIncreaseCounter');
  nextIncreaseCounter.textContent = getNextIncrease();

  // Update city counts
  for(var i = 0; i < players.length; i++) {
    var player = players[i];
    var current_army = getArmy(player);

    // Save army count
    last[player].push(current_army);

    // Check change in army
    if(last[player].length > 1) {
      var army_change = current_army - last[player][last[player].length - 2];

      // Save army change
      if (army_change > 0) {
        data[player].push(army_change);

        // Calculate number of cities
        if(data[player].length >= NUM_TURNS) {
          var guess_cities = mode(data[player].slice(data[player].length - NUM_TURNS));
          updateCities(player, guess_cities - 1);
        }
      }
    }
  }
}

turnInterval = setInterval(function() {
  if (inGame()){
    turn();
  } else {
    addedCityLabel = false
    addedTurnCounter = false
    data = {};
    last = {};
    players = [];
  }
}, 500);