/** Decoder **/
var payloadStr = decodeToString(payload);
var data = JSON.parse(payloadStr);
var deviceType = 'Gas Valve';
var res = _base64ToArrayBuffer(data.data);

if (res.length < 6)
    return null;

var dateTime = GetCurrentDateTime();
var serial = GetSerial(res[3], res[4], res[5]);
var valveModel = GetModel(res[2]);
var stsValve = GetStsValve(res[2]);
var stsValveCode = GetStsValveCode(res[2]);
var deviceName = serial;

var low_bat = GetFlagError(res[1], 1);
var motion_detect = GetFlagError(res[1], 2);
var magnet_detect = GetFlagError(res[1], 3);
var tamper_detect = GetFlagError(res[1], 4);
var power_on = GetFlagError(res[1], 5);
var power_bat = GetFlagError(res[1], 6);
var err_time = GetFlagError(res[1], 7);
var cfg_done = GetFlagError(res[1], 8);

var result = {
    deviceName: deviceName,
    deviceType: deviceType,
    attributes: {
        integrationName: metadata['integrationName'],
    },
    telemetry: {
        NAME_DEV: "Gas Shutoff Valve LoRaWAN 'Smartico V-LR'",
        REAL_TIME: dateTime,
        SERIAL: serial,
        VALVE_MODEL: valveModel,
        STS_VALVE: stsValve,
        STS_VALVE_CODE: stsValveCode,

        FLG_LOW_BAT: low_bat,
        FLG_MOTION_DETECT: motion_detect,
        FLG_MAGNET_DETECT: magnet_detect,
        FLG_TAMPER_DETECT: tamper_detect,
        FLG_POWER_ON: power_on,
        FLG_POWER_BAT: power_bat,
        FLG_ERR_TIME: err_time,
        FLG_CFG_DONE: cfg_done
    }
};

/** Helper functions **/

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

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

function _base64ToArrayBuffer(base64) {
    var binary_string = atob(base64);
    var len = binary_string.length;
    var bytes = new Uint8Array(len);

    for (var i = 0; i < len; i++) {
        bytes[i] = binary_string.charCodeAt(i);
    }
    return bytes;
}

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;

    return date + '.' + month + '.' + year + ' ' + hour + ':' + min + ':' + sec;
}

function GetSerial(byte1, byte2, byte3) {
    var value1 = parseInt(byte1, 10).toString(16);
    while (value1.length < 2) value1 = '0' + value1;

    var value2 = parseInt(byte2, 10).toString(16);
    while (value2.length < 2) value2 = '0' + value2;

    var value3 = parseInt(byte3, 10).toString(16);
    while (value3.length < 2) value3 = '0' + value3;

    var value = value1 + value2 + value3;
    var res = parseInt(value, 16).toString();

    while (res.length < 7) res = '0' + res;

    return res;
}

function GetModel(byte1) {
    var value = parseInt(byte1, 10).toString(2);
    while (value.length < 8) value = '0' + value;

    var val = value[0] + value[1];
    var res = parseInt(val, 2);

    if (res == 0) return "Gas";
    if (res == 1) return "Water";
    return "Undefined";
}

function GetStsValve(byte1) {
    var value = parseInt(byte1, 10).toString(2);
    while (value.length < 8) value = '0' + value;

    var val = value[5] + value[6] + value[7];
    var res = parseInt(val, 2);

    if (res == 0) return "Undefined";
    if (res == 1) return "Close";
    if (res == 2) return "Ready to open";
    if (res == 3) return "Open";
    return "Error";
}

function GetStsValveCode(byte1) {
    var value = parseInt(byte1, 10).toString(2);
    while (value.length < 8) value = '0' + value;

    var val = value[5] + value[6] + value[7];
    return parseInt(val, 2);
}

function GetFlagError(byte1, num) {
    var value = parseInt(byte1, 10).toString(2);
    while (value.length < 8) value = '0' + value;

    if (num == 1) return Number(value[7]);
    if (num == 2) return Number(value[6]);
    if (num == 3) return Number(value[5]);
    if (num == 4) return Number(value[4]);
    if (num == 5) return Number(value[3]);
    if (num == 6) return Number(value[2]);
    if (num == 7) return Number(value[1]);
    if (num == 8) return Number(value[0]);

    return null;
}

return result;