wrapper the altitude state

StateWrapper.js

var Emitter = require('events').EventEmitter;
var util = require('util');

function StateWrapper(client) {
    Emitter.call(this);

    this._state = {
        altitude: 0
    };

    this._handle = null;
    this._client = client;

    this._watch();
}

util.inherits(StateWrapper, Emitter);

StateWrapper.prototype._watch = function() {
    var that = this;

    this._client.on('navdata', function(data) {
        if (!data) return;
        if (!data.demo) return;

        that._state.altitude = data.demo.altitude;
        that.emit('altitude', data.demo.altitude);
    });
};

StateWrapper.prototype.gotoAltitude = function(altitude, callback) {
    var that = this;

    var direction = null;
    if (altitude < this._state.altitude) {
        this._client.down(0.1);
        direction = 'down';
    } else {
        this._client.up(0.1);
        direction = 'up';
    }

    var handle = setInterval(function() {
        if ((direction == 'up' && that._state.altitude > altitude) || (direction == 'down' && that._state.altitude < altitude)) {
            that._client.stop();
            clearInterval(handle);
            callback();
        }
    }, 100);
};

module.exports = StateWrapper;