(function () {
    'use strict';

    /**************************************************
     * Linked list node class
     *
     * Internal private class to represent a node within
     * a linked list.  Each node has a 'data' property and
     * a pointer the previous node and the next node in the list.
     *
     * Since the 'Node' function is not assigned to
     * module.exports it is not visible outside of this
     * file, therefore, it is private to the LinkedList
     * class.
     *
     ***************************************************/

    /**
     * Creates a node object with a data property and pointer
     * to the next node
     *
     * @constructor
     * @param {object|number|string} data The data to initialize with the node
     */
    function Node(data) {
        this.data = data || null;
        this.next = null;
        this.prev = null;
    }

    /* Functions attached to the Node prototype.  All node instances will
     * share these methods, meaning there will NOT be copies made for each
     * instance.  This will be a huge memory savings since there will likely
     * be a large number of individual nodes.
     */
    Node.prototype = {

        /**
         * Returns whether or not the node has a pointer to the next node
         *
         * @returns {boolean} true if there is a next node; false otherwise
         */
        hasNext: function() {
            return (this.next !== null);
        },

        /**
         * Returns whether or not the node has a pointer to the previous node
         *
         * @returns {boolean} true if there is a previous node; false otherwise
         */
        hasPrev: function() {
            return (this.prev !== null);
        },

        /**
         * Returns the data of the the node
         *
         * @returns {object|string|number} the data of the node
         */
        getData: function() {
            return this.data;
        },

        /**
         * Returns a string represenation of the node.  If the data is an
         * object, it returns the JSON.stringify version of the object.
         * Otherwise, it simply returns the data
         *
         * @return {string} the string represenation of the node data
         */
        toString: function() {
            if (typeof this.data === 'object') {
                return JSON.stringify(this.data);
            } else {
                return String(this.data);
            }
        }
    };

    module.exports = Node;

}());