/** Decoder **/
var payloadStr = decodeToString(payload);
var data = JSON.parse(payloadStr);
var deviceName =  data.deviceName;
var deviceType = 'Gas Meter';
var dateTime=GetCurrentDateTime();
var res1 = _base64ToArrayBuffer(data.data);
var gasValue = GetGasMeterValue(res1);
var temp = GetTempValue(res1);

var flg_low_bat = FLG_LOW_BAT(res1);
var flg_motion_detect = FLG_MOTION_DETECT(res1);
var flg_magnet_detect = FLG_MAGNET_DETECT(res1);
var flg_tamper_detect = FLG_TAMPER_DETECT(res1);
var sts_valve = STS_VALVE(res1);
var flg_err_ovr = FLG_ERR_OVR(res1);
var flg_err_reverse = FLG_ERR_REVERSE(res1);
var flg_err_sensor = FLG_ERR_SENSOR(res1);
var flg_err_gas = FLG_ERR_GAS(res1);
var flg_power_on = FLG_POWER_ON(res1);
var flg_err_time = FLG_ERR_TIME(res1);
var flg_lock = FLG_LOCK(res1);
var flg_cfg_done = FLG_CFG_DONE(res1);

var result = {
   deviceName: deviceName,
   deviceType: deviceType,
   attributes: {
       integrationName: metadata['integrationName'],
   },
   telemetry: {
       gasMeter: gasValue,
       temperature: temp,
       REAL_TIME: dateTime,
       SN: data.deviceName,
       FLG_LOW_BAT: flg_low_bat,
       FLG_MOTION_DETECT: flg_motion_detect,
       FLG_MAGNET_DETECT: flg_magnet_detect,
       FLG_TAMPER_DETECT: flg_tamper_detect,
       STS_VALVE: sts_valve,
       FLG_ERR_OVR: flg_err_ovr,
       FLG_ERR_REVERSE: flg_err_reverse,
       FLG_ERR_SENSOR: flg_err_sensor,
       FLG_ERR_GAS: flg_err_gas,
       FLG_ERR_TIME: flg_err_time,
       FLG_POWER_ON: flg_power_on,
       FLG_LOCK: flg_lock,
       FLG_CFG_DONE: flg_cfg_done
   }
};

/** Helper functions **/

function decodeToString(payload) {
   return String.fromCharCode.apply(String, payload);
}

function decodeToJson(payload) {
   var str = decodeToString(payload);
   var data = JSON.parse(str);
   return data;
}

function GetCurrentDateTime(){
    var a=new Date();
    var year = a.getFullYear().toString();
  var month = (a.getMonth()+1).toString();
  if(month.length==1) month="0"+month;
  var date = a.getDate().toString();
  if(date.length==1) date="0"+date;
  var hour = a.getHours().toString();
  if(hour.length==1) hour="0"+hour;
  var min = a.getMinutes().toString();
  if(min.length==1) min="0"+min;
  var sec = a.getSeconds().toString();
  if(sec.length==1) sec="0"+sec;
  var time = date + '.' + month + '.' + year + ' ' + hour + ':' + min + ':' + sec ;
  return time;
}

function _base64ToArrayBuffer(base64) {
    var binary_string = atob(base64);
    var len = binary_string.length;
    var bytes = new Uint8Array(len);
    var str="";
    for (var i = 0; i < len; i++) {
        bytes[i] = binary_string.charCodeAt(i);
    }
    return bytes;
}

function GetGasMeterValue(arr) {
    var bytes = arr;
    var value = 0;
    for (var j = 7; j < 11; j++) {
    value = (value << 8) | bytes[j];}
    return value/1000;
}

function GetTempValue(arr) {
    var bytes = arr;
    var value = "0";
    var value1 = parseInt(bytes[11],10).toString(16);
    if(value1.length==1) value1="0"+value1;
    var value2 = parseInt(bytes[12],10).toString(16);
    if(value2.length==1) value2="0"+value2;
    value=value1+value2;
    if(value.toLowerCase()=="ffff")
         return null;
    value = parseInt(value, 16).toString(10);
    value = (value << 16)>>16;
    return value/100;
}

function FLG_LOW_BAT(arr) {
    var value = parseInt(arr[2], 10).toString(2);
    while(value.length<8){
    value='0'+value;}
    return Number(value[7]);
}

function FLG_MOTION_DETECT(arr) {
    var value = parseInt(arr[2], 10).toString(2);
    while(value.length<8){
    value='0'+value;}
    return Number(value[6]);
}

function FLG_MAGNET_DETECT(arr) {
    var value = parseInt(arr[2], 10).toString(2);
    while(value.length<8){
    value='0'+value;}
    return Number(value[5]);
}

function FLG_TAMPER_DETECT(arr) {
    var value = parseInt(arr[2], 10).toString(2);
    while(value.length<8){
    value='0'+value;}
    return Number(value[4]);
}

function STS_VALVE(arr) {
    var value = parseInt(arr[2], 10).toString(2);
    while(value.length<8){
    value='0'+value;}
    var str = value[1]+value[2]+value[3];
    var res = parseInt(str, 2).toString(10);
    return Number(res);
}

function FLG_ERR_OVR(arr) {
    var value = parseInt(arr[2], 10).toString(2);
    while(value.length<8){
    value='0'+value;}
    return Number(value[0]);
}

function FLG_ERR_REVERSE(arr) {
    var value = parseInt(arr[1], 10).toString(2);
    while(value.length<8){
    value='0'+value;}
    return Number(value[7]);
}

function FLG_ERR_SENSOR(arr) {
    var value = parseInt(arr[1], 10).toString(2);
    while(value.length<8){
    value='0'+value;}
    return Number(value[6]);
}

function FLG_ERR_GAS(arr) {
    var value = parseInt(arr[1], 10).toString(2);
    while(value.length<8){
    value='0'+value;}
    return Number(value[5]);
}

function FLG_ERR_TIME(arr) {
    var value = parseInt(arr[1], 10).toString(2);
    while(value.length<8){
    value='0'+value;}
    return Number(value[4]);
}

function FLG_POWER_ON(arr) {
    var value = parseInt(arr[1], 10).toString(2);
    while(value.length<8){
    value='0'+value;}
    return Number(value[2]);
}

function FLG_LOCK(arr) {
    var value = parseInt(arr[1], 10).toString(2);
    while(value.length<8){
    value='0'+value;}
    return Number(value[1]);
}

function FLG_CFG_DONE(arr) {
    var value = parseInt(arr[1], 10).toString(2);
    while(value.length<8){
    value='0'+value;}
    return Number(value[0]);
}

return result;