SharpVectors - SVG# Reloaded: An Introduction

// <developer>kevin@kevlindev.com</developer>
// <completed>100</completed>

using System;
using System.Collections;
using System.Collections.Generic;

namespace SharpVectors.Dom.Svg
{
	/// <summary>
	/// Base class for all SVG*List-derived classes.
    /// Note we're using <see cref="List{T}"/> (as opposed to deriving from) to hide unneeded <see cref="List{T}"/> methods
	/// Note that a CLR uint is equivalent to an IDL ulong, so uint is used for all index values
	/// </summary>
	public abstract class SvgList<T> : IEnumerable<T>
	{
        #region Private Fields

        private static Hashtable itemOwnerMap;
        protected List<T> items;

        #endregion

        #region Constructor

        /// <summary>
        /// SvgList constructor
        /// </summary>
		protected SvgList()
		{
            itemOwnerMap = new Hashtable();
			items = new List<T>();
		}

        #endregion

        #region ISvgList Interface
        /// <summary>
        /// NumberOfItems
        /// </summary>
        public uint NumberOfItems
        {
            get { return (uint) items.Count; }
        }

        /// <summary>
        /// Clear
        /// </summary>
        public void Clear()
        {
            // Note that we cannot use List<T>'s Clear method since we need to
            // remove all items from the itemOwnerMap
            while ( items.Count > 0 ) 
                RemoveItem(0);
        }

        /// <summary>
        /// Initialize
        /// </summary>
        /// <param name="newItem"></param>
        /// <returns></returns>
        public T Initialize(T newItem)
        {
            Clear();
            return AppendItem(newItem);
        }

        /// <summary>
        /// GetItem
        /// </summary>
        /// <param name="index"></param>
        /// <returns></returns>
        public T GetItem(uint index)
        {
            if ( index < 0 || items.Count <= index )
                throw new DomException(DomExceptionType.IndexSizeErr);

            return items[(int) index];
        }

        /// <summary>
        /// InsertItemBefore
        /// </summary>
        /// <param name="newItem"></param>
        /// <param name="index"></param>
        /// <returns></returns>
        public T InsertItemBefore(T newItem, uint index)
        {
            if ( index < 0 || items.Count <= index )
                throw new DomException(DomExceptionType.IndexSizeErr);

            // cache cast
            int i = (int) index;

            // if newItem exists in a list, remove it from that list
            if ( SvgList<T>.itemOwnerMap.ContainsKey(newItem) )
                ((SvgList<T>)SvgList<T>.itemOwnerMap[newItem]).RemoveItem(newItem);

            // insert item into this list
            items.Insert(i, newItem);

            // update the itemOwnerMap to associate newItem with this list
            SvgList<T>.itemOwnerMap[newItem] = this;

            return items[i];
        }

        /// <summary>
        /// ReplaceItem
        /// </summary>
        /// <param name="newItem"></param>
        /// <param name="index"></param>
        /// <returns></returns>
        public T ReplaceItem(T newItem, uint index)
        {
            if ( index < 0 || items.Count <= index )
                throw new DomException(DomExceptionType.IndexSizeErr);

            // cache cast
            int i = (int) index;

            // if newItem exists in a list, remove it from that list
            if (SvgList<T>.itemOwnerMap.ContainsKey(newItem))
                ((SvgList<T>)SvgList<T>.itemOwnerMap[newItem]).RemoveItem(newItem);

            // remove oldItem from itemOwnerMap
            SvgList<T>.itemOwnerMap.Remove(items[i]);

            // update the itemOwnerMap to associate newItem with this list
            SvgList<T>.itemOwnerMap[newItem] = this;

            // store newItem and return
            return items[i] = newItem;
        }

        /// <summary>
        /// RemoveItem
        /// </summary>
        /// <param name="index"></param>
        /// <returns></returns>
        public T RemoveItem(uint index)
        {
            if ( index < 0 || items.Count <= index )
                throw new DomException(DomExceptionType.IndexSizeErr);

            // cache cast
            int i = (int) index;

            // save removed item so we can return it
            T result = items[i];

            // item is longer associated with this list, so remove item from itemOwnerMap
            SvgList<T>.itemOwnerMap.Remove(result);

            // remove item from this list
            items.RemoveAt(i);

            // return removed item
            return result;
        }

        /// <summary>
        /// AppendItem
        /// </summary>
        /// <param name="newItem"></param>
        /// <returns></returns>
        public T AppendItem(T newItem)
        {
            // if item exists in a list, remove it from that list
            if (SvgList<T>.itemOwnerMap.ContainsKey(newItem))
                ((SvgList<T>)SvgList<T>.itemOwnerMap[newItem]).RemoveItem(newItem);

            // update the itemOwnerMap to associate newItem with this list
            SvgList<T>.itemOwnerMap[newItem] = this;

            // add item and return
            items.Add(newItem);
            return newItem;
        }
        #endregion

        #region IEnumerable Interface

        public IEnumerator<T> GetEnumerator() 
        {
            return items.GetEnumerator();
            //return new SvgListEnumerator(this);
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return items.GetEnumerator();
        }

        #endregion

        #region Support Methods
        /// <summary>
        /// RemoveItem - used to remove an item by value as opposed to by position
        /// </summary>
        /// <param name="item"></param>
        private void RemoveItem(T item)
        {
            int index = items.IndexOf(item);
            if (index >= 0)
            {
                RemoveItem((uint)index);
            }

            //for ( int i = 0; i < items.Count; i++ )
            //{
            //    if ( items[i] == item )
            //    {
            //        RemoveItem((uint) i);
            //        break;
            //    }
            //}
        }
        #endregion
    }
}