/* This is an generic payload parser example.
** The code find the payload variable and parse it if exists.
**
** IMPORTANT: In most case, you will only need to edit the parsePayload function.
**
** Testing:
** You can do manual tests to this parse by using the Device Emulator. Copy and Paste the following code:
** [{ "variable": "payload", "value": "0109611395" }]
**
** The ignore_vars variable in this code should be used to ignore variables
** from the device that you don't want.
*/
// Add ignorable variables in this array.
const ignore_vars = [];

function toTagoFormat(object_item, serie, prefix = '') {
  const result = [];
  for (const key in object_item) {
    if (ignore_vars.includes(key) || object_item[key] === null) continue;

    if (typeof object_item[key] === 'object') {
      result.push({
        variable: object_item[key].variable || `${prefix}${key}`,
        value: object_item[key].value,
        serie: object_item[key].serie || serie,
        metadata: object_item[key].metadata,
        location: object_item[key].location,
        unit: object_item[key].unit,
      });
    } else {
      result.push({
        variable: `${prefix}${key}`,
        value: object_item[key],
        serie,
      });
    }
  }

  return result;
}

/**
 * This is the main function to parse the payload. Everything else doesn't require your attention.
 * @param {String} payload_raw 
 * @returns {Object} containing key and value to TagoIO
 */
function parsePayload(payload_raw) {
  const buffer = Buffer.from(payload_raw, 'hex');

  const lat = buffer.readInt32BE(3) * 0.000001;
  const lng = buffer.readInt32BE(7) * 0.000001;

  const data =  {
    gps_fix: Number((buffer.readUInt8(1) / 64).toFixed()),
    report_type: Number((buffer.readUInt8(1) % 64).toFixed()),
    battery_capacity: { value: buffer.readUInt8(2), unit: '%' },
    location: {
      value: `${lat},${lng}`,
      location: { lat, lng },
    },
    latitude: lat,
    longitude: lng,
  };

  return data;
}


// Remove unwanted variables.
payload = payload.filter(x => !ignore_vars.includes(x.variable));

// Payload is an environment variable. Is where what is being inserted to your device comes in.
// Payload always is an array of objects. [ { variable, value...}, {variable, value...} ...]
const payload_raw = payload.find(x => ['payload', 'payload_raw', 'data'].includes(x.variable));
if (payload_raw) {
  // Get a unique serie for the incoming data.
  const { value, serie } = payload_raw;

  // Parse the payload_raw to JSON format (it comes in a String format)
  if (value) {
    payload = payload.concat(toTagoFormat(parsePayload(value), serie));
  }
}