// Decode decodes an array of bytes into an object.
//  - fPort contains the LoRaWAN fPort number
//  - bytes is an array of bytes, e.g. [225, 230, 255, 0]
//  - variables contains the device variables e.g. {"calibration": "3.5"}
// The function must return an object, e.g. {"temperature": 22.5}
function Decode(fPort, bytes, variables) {

  // Hilfsfunktion: 16-Bit signed Big Endian lesen
  function readInt16BE(b0, b1) {
    var val = (b0 << 8) | b1;
    if (val & 0x8000) val = val - 0x10000;
    return val;
  }

  if (bytes.length < 7) {
    return { error: "invalid payload length" };
  }

  var d = {};

  d.heating    = readInt16BE(bytes[0], bytes[1]) / 100.0;
  d.heatingFloor = readInt16BE(bytes[2], bytes[3]) / 100.0;
  d.airHumidity  = readInt16BE(bytes[4], bytes[5]) / 100.0;
  d.switch       = bytes[6];

  if (bytes.length >= 15) {
    d.relayOnTime = (bytes[7] << 16) | (bytes[8] << 8) | bytes[9];
    d.uptime      = (bytes[10] << 16) | (bytes[11] << 8) | bytes[12];
    d.loadWatts   = (bytes[13] << 8) | bytes[14];
  }

  return d;
}