// Décodeur LoRaWAN officiel : Milesight AM103-LoRaWAN Indoor Air Quality Sensor (3 in 1) (Milesight)
// Source : https://github.com/TheThingsNetwork/lorawan-devices/blob/master/vendor/milesight-iot/am103.js
// The Things Network Device Repository, fichier publié par le constructeur, distribué sans modification.
// Format : decodeUplink(input) (TTN v3 / ChirpStack v4). Hébergé par smartbuildings.fr.


function decodeUplink(input) {
  var res = Decoder(input.bytes, input.fPort);
  if (res.error) {
    return {
      errors: [res.error],
    };
  }
  return {
    data: res,
  };
}

/**
 * Payload Decoder for The Things Network
 * 
 * Copyright 2021 Milesight IoT
 * 
 * @product AM104 / AM107
 */
function Decoder(bytes, port) {
  var decoded = {};

  for (var i = 0; i < bytes.length;) {
    var channel_id = bytes[i++];
    var channel_type = bytes[i++];
    // BATTERY
    if (channel_id === 0x01 && channel_type === 0x75) {
      decoded.battery = bytes[i];
      i += 1;
    }
    // TEMPERATURE
    else if (channel_id === 0x03 && channel_type === 0x67) {
      // ℃
      decoded.temperature = readInt16LE(bytes.slice(i, i + 2)) / 10;
      i += 2;

      // ℉
      // decoded.temperature = readInt16LE(bytes.slice(i, i + 2)) / 10 * 1.8 + 32;
      // i +=2;
    }
    // HUMIDITY
    else if (channel_id === 0x04 && channel_type === 0x68) {
      decoded.humidity = bytes[i] / 2;
      i += 1;
    }
    // PIR
    else if (channel_id === 0x05 && channel_type === 0x6A) {
      decoded.activity = readUInt16LE(bytes.slice(i, i + 2));
      i += 2;
    }
    // LIGHT
    else if (channel_id === 0x06 && channel_type === 0x65) {
      decoded.illumination = readUInt16LE(bytes.slice(i, i + 2));
      decoded.infrared_and_visible = readUInt16LE(bytes.slice(i + 2, i + 4));
      decoded.infrared = readUInt16LE(bytes.slice(i + 4, i + 6));
      i += 6;
    }
    // CO2
    else if (channel_id === 0x07 && channel_type === 0x7D) {
      decoded.co2 = readUInt16LE(bytes.slice(i, i + 2));
      i += 2;
    }
    // TVOC
    else if (channel_id === 0x08 && channel_type === 0x7D) {
      decoded.tvoc = readUInt16LE(bytes.slice(i, i + 2));
      i += 2;
    }
    // PRESSURE
    else if (channel_id === 0x09 && channel_type === 0x73) {
      decoded.pressure = readUInt16LE(bytes.slice(i, i + 2)) / 10;
      i += 2;
    } else {
      break;
    }
  }

  return decoded;
}

/* ******************************************
* bytes to number
********************************************/
function readUInt16LE(bytes) {
  var value = (bytes[1] << 8) + bytes[0];
  return value & 0xffff;
}

function readInt16LE(bytes) {
  var ref = readUInt16LE(bytes);
  return ref > 0x7fff ? ref - 0x10000 : ref;
}