functions.js

/*****************************************
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.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');
}