'use strict';  

/* exported Timer, addMixin, ObserverSubjectMixin, DebugMixin */

(function(exports) {

  function addMixin(destination, source) {
    for (var k in source) {
      if (source.hasOwnProperty(k) && !(k in destination)) {
        destination[k] = source[k];
      }
    }
    return destination;
  }

  var DebugMixin = {
    DEBUG: true,

    debug: function(msg, obj) {
      if(!this.DEBUG) {
        return;
      }

      var str = (this._id) ? ('[' + this._id + '] ' + msg) : msg;
      if(obj) {
        str += '|' + JSON.stringify(obj);
      }
      console.log(str);
    }
  };

  var ObserverSubjectMixin = {
      _notify: function mlv_notify(data) {
        if(this._observers && Array.isArray(this._observers)) {
          this._observers.forEach((obs) => obs.onEvent(this._id, data));
        }
      },

      addListener: function mlv_addListener(observer) {
        if('onEvent' in observer) {
          if(!this._observers) {
            this._observers = [];
          }
          this._observers.push(observer);
        }
      },

      removeListener: function mlv_removeListener(observer) {
        if(!this._observers || !Array.isArray(this._observers)) {
          return;
        }

        var idx = this._observers.indexOf(observer);
        if(idx !== -1) {
          this._observers.splice(idx, 1);
        }
      },
  };

  var Timer = function() {
    this._startTime = new Date();
  };

  Timer.prototype = {
    _startTime: null,

    getElapsedTime: function getElapsedTime() {
      var endTime = new Date();
      return endTime.getTime() - this._startTime.getTime();
    },

    reset: function reset() {
      this._startTime = new Date();
    }
  };

  exports.addMixin = addMixin;
  exports.DebugMixin = DebugMixin;
  exports.ObserverSubjectMixin = ObserverSubjectMixin;
  exports.Timer = Timer;

}((typeof exports === 'undefined') ? window : exports));