/**
 * Licensed Materials - Property of IBM IBM Cognos Products: Modeling UI (C)
 * Copyright IBM Corp. 2016, 2018 US Government Users Restricted Rights - Use,
 * duplication or disclosure restricted by GSA ADP Schedule Contract with IBM
 * Corp.
 */
define([
	'bi/commons/ui/core/Class'
], function(Class) {

	var Queue = Class.extend({
		init: function() {
			this._nextOut = 0;
			this._lastIn = 0;
			this._q = {};
		},

		/**
		 * Place a new item in the queue
		 * @param {Object} Object to be placed in the queue
		 */
		enqueue: function(data) {
			this._q[this._lastIn] = data;
			this._lastIn++;
		},

		/**
		 * Remove the next element from the queue, if one exists
		 * @returns {Object} Object at the head of the queue
		 */
		dequeue: function() {
			var data;

			if (this.size() > 0) {
				data = this._q[this._nextOut];
				delete this._q[this._nextOut];
				this._nextOut++;
			}

			return data;
		},

		/**
		 * Get the number of elements in the queue
		 * @returns {Number} Size of the queue
		 */
		size: function() {
			return this._lastIn - this._nextOut;
		},

		/**
		 * Returns true if the queue is empty (size === 0)
		 * @returns {Boolean} True if queue is empty
		 */
		isEmpty: function() {
			return this.size() <= 0;
		}
	});

	return Queue;
});