// Javascript, ES6

const checkIfCanGetOpinion = timeStamps => {
  var statistics = {
    threeDaysInRow: false,
    sessions: 0
  };
  // Create array of dates
  var datesArray = [];
  timeStamps.forEach(stamp => {
    const stampToUTC = stamp.replace(" ", "T") + "Z";
    const date = new Date(stampToUTC);
    datesArray.push(date);
  });
  // Transform dates into number of days
  const dayInMiliseconds = 24 * 60 * 60 * 1000;
  var datesToDays = datesArray.map(key => {
    return Date.parse(key) / dayInMiliseconds;
  });
  // above datesToDays array looks more or less like this: [17235.123123, 17235.123123, 17236.123123, 17236.123123, 17237.123123, 17237.123123]
  const firstDay = datesToDays[0];
  var daysInRow = datesToDays.map(day => {
    return Math.floor(day) - Math.floor(firstDay);
  });
  // remove duplicates
  daysInRow = daysInRow.filter(function(elem, pos, arr) {
    return arr.indexOf(elem) == pos;
  });
  // daysInRow array should be [0, 1, 2]
  if (daysInRow.join(",") === "0,1,2") {
    statistics.threeDaysInRow = true;
  } else {
    return false;
  }
  var sessionTimesInMiliseconds = datesArray.map(date => {
    return Date.parse(date);
  });
  // Substract the time of the previous session from this session to get time gaps between sessions
  var timeGapsBetweenSessions = [];
  const minGapLengthInMiliseconds = 30 * 60 * 1000;
  for (let i = 0; i < sessionTimesInMiliseconds.length - 1; i++) {
    var gap = sessionTimesInMiliseconds[i + 1] - sessionTimesInMiliseconds[i];
    timeGapsBetweenSessions.push(gap);
  }
  statistics.sessions += 1; // first session is already checked
  timeGapsBetweenSessions.forEach(gap => {
    if (gap >= minGapLengthInMiliseconds) statistics.sessions += 1;
  });
  if (statistics.threeDaysInRow === true && statistics.sessions >= 6) {
    return true;
  } else {
    return false;
  }
};