Collections Manager

I wanted to work with a Singleton Pattern and have a class that can be moved from project to project without having to do much modification in work.  I have come up with a collections manager that keeps track of what players have collected inside of a given level.  The code looks like the following:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Collections;

using UPC = System.Type;



namespace NinjaRoyale.Collections

{

    /**

     * Keeps track of all the collections collected inside of the game for any given player

     *

     * UPC - Universal Product Code, Finds out what kind of Collectible an object is

     *

     * Author - Mavin Martin

     * Date   - 11/21/2012

     */

    public class CollectionsManager

    {

        private static CollectionsManager instance = null;



        Dictionary<Entity, Dictionary<UPC, int>> ownerStash;





        /**

         * ===== CollectionsManager =====

         *

         * Uses Singleton Pattern to guarantee only one Collection Manager

         */

        private CollectionsManager()

        {

            ownerStash = new Dictionary<Entity, Dictionary<UPC, int>>();

        }



        /**

         * AddCollectable - Add's Collectable to the player

         *

         * PARAMS

         *  owner - Independent object owning the collectible

         *  item  - Item owned by owner

         */

        public void AddCollectable(Entity owner, Collectible item)

        {

            Dictionary<UPC, int> stash;

            if (!ownerStash.TryGetValue(owner, out stash))

                stash = initiateStash(owner);



            addItemToStash(stash, item);

        }



        /**

         * getStashItems - Get's the stash items owned by a certain owner

         *

         * PARAMS

         *  owner - Independent object owning the stash

         *

         * RETURN

         *  Dictionary<UPC, int> - Stash of items as linked list

         */

        public Dictionary<UPC, int> getStashItems(Entity owner)

        {

            Dictionary<UPC, int> stash;

            if (!ownerStash.TryGetValue(owner, out stash))

                stash = initiateStash(owner);



            return stash;

        }



        /**

         * RemoveCollectible - Removes Collectible from the player. 

         *

         * If you are getting rid of all items for an owner, please call RemoveOwner instead.

         *

         * PARAMS

         *  owner - Independent object owning items

         *  item  - Item belonging to the owner

         */

        public void RemoveCollectible(Entity owner, Collectible item)

        {

            Dictionary<UPC, int> stash;

            ownerStash.TryGetValue(owner, out stash);

            UPC upc = getUPC(item);

            stash.Remove(upc);

        }



        /**

         * RemoveOwner - Removes an owner from the Collections Manager.

         *

         * IMPORTANT NOTE: Owner does not need to add themselves.  This happens immediately when adding collectible

         *

         * PARAMS

         *  owner - the Entity that will own the collectible

         */

        public void RemoveOwner(Entity owner)

        {

            ownerStash.Remove(owner);

        }



        /**

         * addItemToStash - Add's item to the stash for a given player

         *

         * PARAMS

         *  stash - Linked List of items in the stash

         *  item  - Item to be added to the stash

         */

        private void addItemToStash(Dictionary<UPC, int> stash, Collectible item)

        {

            int count = 0;

            UPC upc = getUPC(item);

            if (!stash.TryGetValue(upc, out count))

                initiateItem(stash, item);



            stash[upc] += 1;

        }



        /**

         * initiateItem - Initiates item in a given stash

         *

         * PARAMS

         *  stash - Linked List of items in the stash

         *  item  - Item to be added to the stash

         */

        private void initiateItem(Dictionary<UPC, int> stash, Collectible item)

        {

            UPC upc = getUPC(item);

            stash.Add(upc, 0);

        }



        /**

         * getUPC - Get's the UPC of a specific Collectible

         *

         * RETURN

         *  UPC - Type of item being worked with

         */

        public static UPC getUPC(Collectible item)

        {

            return item.GetType();

        }



        /**

         * initiateStash - Registers an owner inside of the Collections Manager

         *

         * PARAMS

         *  owner - The independent object owning a stash

         * 

         * RETURN

         *  Dictionary<UPC, int> - Stash for a given player

         */

        private Dictionary<UPC, int> initiateStash(Entity owner)

        {

            Dictionary<UPC, int> stash = new Dictionary<UPC, int>();

            ownerStash.Add(owner, stash);



            return stash;

        }



        /**

         * GetInstance - Grabs Collection Manager Instance

         *

         * GUARANTEED SINGLETON

         *

         * RETURN

         *  CollectionsManager - Instance of the Collections Manager

         */

        public static CollectionsManager GetInstance()

        {

            if (instance == null)

            {

                instance = new CollectionsManager();

            }



            return instance;

        }

    }

}