window.DED = window.DED || {};
DED.util = DED.util || {};
DED.util.Observer = function() {
  this.fns = [];
}
DED.util.Observer.prototype = {
  subscribe: function(fn) {
    this.fns.push(fn);
  },
  unsubscribe: function(fn) {
    this.fns = this.fns.filter(
      function(el) {
        if ( el !== fn ) {
          return el;
        }
      }
    );
  },
  fire: function(o) {
    this.fns.forEach(
      function(el) {
        el(o);
      }
    );
  }
};

DED.Queue = function() {

 // Queued requests.
  this.queue = [];

  // Observable Objects that can notify the client of interesting moments
  // on each DED.Queue instance.
  this.onComplete = new DED.util.Observer;
  this.onFailure = new DED.util.Observer;
  this.onFlush = new DED.util.Observer;

  // Core properties that set up a frontend queueing system.
  this.retryCount = 3;
  this.currentRetry = 0;
  this.paused = false;
  this.timeout = 5000;
  this.conn = {};
  this.timer = {};
}

DED.Queue.method('flush',function() {
    if (!this.queue.length > 0) {
      return;
    }
    if (this.paused) {
      this.paused = false;
      return;
    }
    var that = this;
    this.currentRetry++;
    var abort = function() {
      that.conn.abort();
      if (that.currentRetry == that.retryCount) {
        that.onFailure.fire();
        that.currentRetry = 0;
      } else {
        that.flush();
      }
    };
    this.timer = window.setTimeout(abort, this.timeout);
    var callback = function(o) {
      window.clearTimeout(that.timer);
      that.currentRetry = 0;
      that.queue.shift();
      that.onFlush.fire(o.responseXML);
      if (that.queue.length == 0) {
        that.onComplete.fire();

return;
      }
      // recursive call to flush
      that.flush();
    };
    this.conn = asyncRequest(
      this.queue[0]['method'],
      this.queue[0]['uri'],
      callback,
      this.queue[0]['params']
    );
  }).method('setRetryCount', function(count) {
    this.retryCount = count;

  }).method('setTimeout', function(time) {
    this.timeout = time;

  }).method('add', function(o) {
    this.queue.push(o);
  
  }).method('pause', function() {
    this.paused = true;
  
  }).method('dequeue', function() {
    this.queue.pop();
  
  }).method('clear', function() {
    this.queue = [];
  });