// From midnight forward.
const resetArray = [
  { occupancy: 32, receivedTime: 1515614058833 },
  { occupancy: 50, receivedTime: 1515614127933 }
];

let occupancy = 0;
let ins = 0;
let outs = 0;

function kpiFilter(messages) {
  messages.forEach((message, i) => {
    const nextMessage = messages[i + 1] || message;

    let reset;

    resetArray.forEach(resetRecord => {
      if (
        resetRecord.receivedTime >= message.receivedTime &&
        resetRecord.receivedTime <= nextMessage.receivedTime
      ) {
        reset = resetRecord;
      }
    });

    // A reset record is found close to these dates.
    if (reset) {
      // Add the current message's ins/outs first (looks the same as below)
      if (message.action === 'IN') {
        ins++;
      } else if (message.action === 'OUT') {
        outs++;
      }

      const offset = reset.occupancy - occupancy;

      // Now do the reset calculation
      if (offset > 0) {
        ins += offset;
      } else {
        outs += offset;
      }

      occupancy = ins - outs;
    } else {
      if (message.action === 'IN') {
        ins++;
      } else if (message.action === 'OUT') {
        outs++;
      }
      occupancy = ins - outs;
    }
  });

  console.log('INS: ', ins);
  console.log('OUTS: ', outs);
  console.log('OCCUPANCY: ', occupancy);

  return {
    deploymentId: messages[0].deploymentId,
    occupancy: occupancy,
    availability: 200 - occupancy,
    turnover: ins / 200,
    utilization: occupancy / 200
  };
}