signalk-provider-vor1415/lib/index.js

This provider takes the VOR2014/2015 JSON stream and transforms it into Signal K vessel information

var debug        = require('debug')('provider-vor1415')
  , Readable     = require('stream').Readable
  , util         = require('util')
  , _            = require('lodash')
  , request      = require('request-promise')
;

function Race(url, opts) {
  if(!(this instanceof Race)) {
    return new Race(opts);
  }

  if(!url) {
    throw new Error("Please provide JSON URL");
  }

  this.url = url;
  this.options = opts || {};

  if(!this.options.interval) {
    this.options.interval = (30 * 60) * 1000; // 30 minutes
  }

  if(!this.options.stream) {
    this.options.stream = {};
  }

  this.options.stream.objectMode = true;
  Readable.call(this, this.options.stream);

  this._lastDownload  = -1;
  this._lastData      = null;
  this._codes         = {};
  this._vessels       = {};

  setInterval(this.__check.bind(this), 1000);
}

util.inherits(Race, Readable);
module.exports = Race;

Race.prototype._read = function(size) {};

Race.prototype.__check = function() {
  debug("Checking when we last downloaded a VOR update");

  if(this._lastData !== null && this._lastDownload > 0 && (Date.now() - this._lastDownload) < this.options.interval) {
    debug("Data is (quite) recent, idling.\n");
    return;
  }

  debug("Data is not recent, getting ready to download a new copy.\n");
  this.__fetch();
};

Race.prototype.__fetch = function() {
  if(this._lastData === null) {
    this._lastData = {};
  }

  this._lastDownload = Date.now();

  request
    .get(this.url)
    .then(this.__handleData.bind(this))
    .catch(this.__handleError.bind(this))
  ;
};

Race.prototype.__handleData = function(data) {
  if(_.isString(data)) {
    data = JSON.parse(data);
  }

  if(!_.isEqual(this._lastData, data)) {
    this._lastData = data;
    this.__reduce();
  }

  this._lastDownload = Date.now();
};

Race.prototype.__handleError = function(err) {
  debug("ERROR");
  debug(err);
};

Race.prototype.__reduce = function() {
  if(!this.__isValid()) {
    return;
  }

  var data    = this._lastData;
  var fields  = data.data.fields;
  var tracks  = data.data.trackslatest;
  var self    = this;

  _.each(data.codes, function(vessel) {
    self._codes[vessel.code.toUpperCase()] = {
      color: ('#' + vessel.color).toUpperCase(),
      name: vessel.name,
      uuid: 'VOR0' + vessel.code
    };
  });

  _.each(tracks, function(track) {
    var obj = {};

    for(var i in fields) {
      obj[fields[i]] = track[i];
    }

    obj.vessel = self._codes[obj.code.toUpperCase()];
    obj.uuid = obj.vessel.uuid;

    self._vessels[obj.code] = obj;
  })

  this.__generateDeltas();
};

Race.prototype.__generateUpdate = function(path, vessel, key, type) {
  type = type || 'string';
  var val;

  switch(type) {
    case 'float':
      val = parseFloat(vessel[key]);
    break;

    default: 
      val = String(vessel[key]);
    break;
  }

  if(typeof vessel[key] === "undefined") {
    if(type === 'float') {
      val = 0.0;
    } else {
      val = "";
    }
  }

  if(val === null || typeof val === 'undefined' || val === "null" || val === "NULL") {
    if(type === 'float') {
      val = 0.0;
    } else {
      val = "";
    }
  }

  return {
    path: path,
    value: val
  };
};

Race.prototype.__generateDeltas = function() {
  // return debug(JSON.stringify(this._vessels, null, 2));

  /*
  "TBRU": {
    "code": "TBRU",
    "reportdate": "2014-12-11 12:55:00",
    "timeoffix": "2014-12-11 12:55:00",
    "status": "RAC",
    "latitude": "24.38333",
    "longitude": "58.14517",
    "dtf": "00321.50",
    "dtlc": "+00000",
    "legstanding": "1",
    "twentyfourhourrun": "515.0",
    "legprogress": 94,
    "dul": "00000.00",
    "boatheadingtrue": "315",
    "smg": "04.3",
    "seatemperature": 27.545454545455,
    "truwindspeedavg": "3",
    "speedthrowater": "6",
    "truewindspeedmax": "4",
    "truewinddirection": "42",
    "latestspeedthrowater": "4",
    "vessel": {
      "color": "#AED13F",
      "name": "Team Brunel",
      "uuid": "VOR-TBRU"
    },
    "uuid": "VOR-TBRU"
  }
  */  

  var self = this;
  var legLength = parseFloat(this._lastData.leglength);

  _.each(this._vessels, function(vessel) {
    var delta = {
      context: 'vessels.' + vessel.uuid,
      updates: []
    };

    delta.updates.push({
      path: 'name', 
      value: vessel.vessel.name
    });

    delta.updates.push({
      path: 'uuid', 
      value: vessel.uuid
    });

    delta.updates.push({
      path: 'navigation.state',
      value: self.__getStatus(vessel.status)
    });

    if((legLength - parseFloat(vessel.dtf)) !== null) {
      delta.updates.push({
        path: 'navigation.logTrip',
        value: legLength - parseFloat(vessel.dtf)
      });
    }

    delta.updates.push(self.__generateUpdate('navigation.position.longitude', vessel, 'longitude', 'float'));
    delta.updates.push(self.__generateUpdate('navigation.position.latitude', vessel, 'longitude', 'float'));
    delta.updates.push(self.__generateUpdate('navigation.headingTrue', vessel, 'boatheadingtrue', 'float'));
    delta.updates.push(self.__generateUpdate('navigation.speedThroughWater', vessel, 'speedthrowater', 'float'));

    delta.updates.push(self.__generateUpdate('environment.wind.directionTrue', vessel, 'truewinddirection', 'float'));
    delta.updates.push(self.__generateUpdate('environment.wind.speedTrue', vessel, 'truewindspeedavg', 'float'));
    delta.updates.push(self.__generateUpdate('environment.waterTemp', vessel, 'seatemperature', 'float'));

    self.push(delta);
  });
};

Race.prototype.__getStatus = function(status) {
  status = status.toUpperCase();

  if(status === "RAC") {
    return "Under way sailing";
  } else if(status === "SUS") {
    return "Aground";
  } else {
    return "Not defined";
  }
}

Race.prototype.__isValid = function() {
  if(this._lastData === null) {
    return false;
  }

  if(!_.isObject(this._lastData.codes)) {
    return false;
  }

  if(!_.isObject(this._lastData.data)) {
    return false;
  }

  if(!_.isObject(this._lastData.data.fields)) {
    return false;
  }

  if(!_.isArray(this._lastData.data.fields)) {
    return false;
  }

  if(!_.isArray(this._lastData.data.trackslatest)) {
    return false;
  }

  return true;
};