gps-tracking-ext/lib/functions.js

Let you work with some GPS trackers that connects through tcp.

/*****************************************
 FUNCTIONS
 ******************************************/
exports.rad = function (x) {
  return x * Math.PI / 180;
};

/*
 @param p1: {lat:X,lng:Y}
 @param p2: {lat:X,lng:Y}
 */
exports.get_distance = function (p1, p2) {
  var R = 6378137; // Earth’s mean radius in meter
  var dLat = exports.rad(p2.lat - p1.lat);
  var dLong = exports.rad(p2.lng - p1.lng);
  var a = Math.sin(dLat / 2) * Math.sin(dLat / 2) +
    Math.cos(exports.rad(p1.lat)) * Math.cos(exports.rad(p2.lat)) *
    Math.sin(dLong / 2) * Math.sin(dLong / 2);
  var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
  var d = R * c;
  return d; // returns the distance in meter
};

exports.send = function (socket, msg) {
  socket.write(msg);
  //console.log('Sending to ' + socket.name + ': ' + msg);
};

exports.bufferToHexString = function (buffer) {
  var str = '';
  for (var i = 0; i < buffer.length; i++) {
    if (buffer[i] < 16) {
      str += '0';
    }
    str += buffer[i].toString(16);
  }
  return str;
}

exports.parse_data = function (data) {
  data = data.replace(/(\r\n|\n|\r)/gm, ''); //Remove 3 type of break lines
  var cmd_start = data.indexOf('B'); //al the incomming messages has a cmd starting with 'B'
  if (cmd_start > 13) throw 'Device ID is longer than 12 chars!';
  var parts = {
    'start': data.substr(0, 1),
    'device_id': data.substring(1, cmd_start),
    'cmd': data.substr(cmd_start, 4),
    'data': data.substring(cmd_start + 4, data.length - 1),
    'finish': data.substr(data.length - 1, 1)
  };
  return parts;
};

exports.parse_gps_data = function (str) {
  var data = {
    'date': str.substr(0, 6),
    'availability': str.substr(6, 1),
    'latitude': gps_minute_to_decimal(parseFloat(str.substr(7, 9))),
    'latitude_i': str.substr(16, 1),
    'longitude': gps_minute_to_decimal(parseFloat(str.substr(17, 9))),
    'longitude_i': str.substr(27, 1),
    'speed': str.substr(28, 5),
    'time': str.substr(33, 6),
    'orientation': str.substr(39, 6),
    'io_state': str.substr(45, 8),
    'mile_post': str.substr(53, 1),
    'mile_data': parseInt(str.substr(54, 8), 16)
  };
  return data;
};

exports.send_to = function (socket, cmd, data) {
  if (typeof (socket.device_id) == 'undefined') throw 'The socket is not paired with a device_id yet';
  var str = gps_format.start;
  str += socket.device_id + gps_format.separator + cmd;
  if (typeof (data) != 'undefined') str += gps_format.separator + data;
  str += gps_format.end;
  send(socket, str);
  //Example: (<DEVICE_ID>|<CMD>|<DATA>) - separator: | ,start: (, end: )
};

exports.minute_to_decimal = function (pos, pos_i) {
  if (typeof (pos_i) === 'undefined') pos_i = 'N';
  var dg = parseInt(pos / 100);
  var minutes = pos - (dg * 100);
  var res = (minutes / 60) + dg;
  return (pos_i.toUpperCase() === 'S' || pos_i.toUpperCase() === 'W') ? res * -1 : res;
};

// Send a message to all clients
exports.broadcast = function (message, sender) {
  clients.forEach(function (client) {
    if (client === sender) return;
    client.write(message);
  });
  process.stdout.write(message + '\n');
};

exports.data_to_hex_array = function (data) {
  var arr = [];
  for (var i = 0; i < data.length; i++)arr.push(data[i].toString(16));
  return arr;
};

/* RETRUN AN INTEGER FROM A HEX CHAR OR integer */
exports.hex_to_int = function (hex_char) {
  return parseInt(hex_char, 16);
};

exports.sum_hex_array = function (hex_array) {
  var sum = 0;
  for (var i in hex_array) sum += exports.hex_to_int(hex_array[i]);
  return sum;
};

exports.hex_array_to_hex_str = function (hex_array) {
  var str = '';
  for (var i in hex_array) {
    var char;
    if (typeof (hex_array[i]) === 'number') char = hex_array[i].toString(16);
    else char = hex_array[i].toString();
    str += exports.str_pad(char, 2, '0');
  }
  return str;
};

exports.str_pad = function (input, length, string) {
  string = string || '0';
  input = input + '';
  return input.length >= length ? input : new Array(length - input.length + 1).join(string) + input;
};

exports.crc_itu_get_verification = function (hex_data) {
  var crc16 = require('crc-itu').crc16;
  if (typeof (hex_data) === 'String') str = hex_data;
  else str = exports.hex_array_to_hex_str(hex_data);
  return crc16(str, 'hex');
};

exports.hex_gps_time = function (hex) {
  return '20' + parseInt(hex.substr(0, 2), 16) + '-' + parseInt(hex.substr(2, 2), 16) + '-' + parseInt(hex.substr(4, 2), 16) + ' ' + parseInt(hex.substr(6, 2), 16) + ':' + parseInt(hex.substr(8, 2), 16) + ':' + parseInt(hex.substr(10, 2), 16)
}