Developing Next Generation Smart Clients using .NET 2.0 working with Existing .NET 1.1 SOA-based XML Web Services

using System;
using System.Xml.Serialization;
using System.Collections;
using System.Runtime.Serialization;

namespace SmartInstitute.ObjectModel
{
	public delegate void CollectionAddHandler( CollectionBase collection, ItemBase item );

	public delegate void CollectionRemoveHandler( CollectionBase collection, ItemBase item );

	public delegate void CollectionClearHandler( CollectionBase collection );

	public delegate void CollectionAddRangeHandler(CollectionBase collection);

	public delegate void CollectionRefreshHandler( CollectionBase collection );


	/// <summary>
	/// Base class for all collection type classes
	/// </summary>
	[Serializable]
	public abstract class CollectionBase : System.Collections.CollectionBase
	{
		public event ItemChangeHandler OnItemChange;
		public event ItemDetachHandler OnItemDetach;
		public event ItemShowHandler OnItemShow;
		public event ItemSelectHandler OnItemSelect;
		public event ItemUndoStateHandler OnItemUndo;
		public event ItemRedoStateHandler OnItemRedo;
		public event ItemBeginUpdateHandler OnItemBeginUpdate;
		public event ItemEndUpdateHandler OnItemEndUpdate;

		public event CollectionAddHandler OnItemCollectionAdd;
		public event CollectionRemoveHandler OnItemCollectionRemove;
		public event CollectionClearHandler OnItemCollectionClear;
		public event SelectionChangeHandler OnItemCollectionSelectionChanged;
		public event CollectionAddRangeHandler OnAddRange;
		public event CollectionRefreshHandler OnRefresh;

		private bool _IsDirty = false;

		/// <summary>
		/// The parent reference must be ignored in serialization because
		/// it creates circular reference and XmlSerializer cannot serialize it.
		/// </summary>
		[XmlIgnore]
		[NonSerialized]
		private WeakReference _Parent;

		[XmlIgnore]
		public object Parent
		{
			get
			{
				if( _Parent.IsAlive )
				{
					return _Parent.Target;
				}
				else
				{
					return null;
				}
			}
			set
			{
				_Parent = new WeakReference( value );
			}
		}

		public bool IsDirty
		{
			get
			{
				return _IsDirty;
			}
			set
			{
				_IsDirty = value;
			}
		}

		protected CollectionBase( object parent )
		{
			this.Parent = parent;
		}

		protected virtual void AddRange(Array items)
		{
			foreach (ItemBase item in items)
			{
				this.Add(item);
			}

			if (null != OnAddRange)
				OnAddRange(this);
		}

		/// <summary>
		/// Add new item to the collection
		/// </summary>
		/// <param name="item"></param>
		protected virtual int Add( ItemBase item )
		{
			// Attach to events in order to listen to events for individual item
			// events are propagated to the parent
			this.ListenChildItem( item );
			
			if( null == item.Parent )
				item.Parent = this;

			this.IsDirty = true;
			int result = List.Add( item );

			if( null != OnItemCollectionAdd )
			{
				OnItemCollectionAdd( this, item );
			}

			return result;
		}

		protected virtual void Remove( ItemBase item )
		{
			if( List.Contains( item ) )
			{
				this.IsDirty = true;

				List.Remove( item );

				if( null != OnItemCollectionRemove )
				{
					OnItemCollectionRemove( this, item );
				}
			}
		}

		new public void RemoveAt(int index)
		{
			ItemBase item = this[index];
			this.Remove(item);
		}

		new public void Clear( )
		{	
			// remove from last
			while( List.Count > 0 )
			{
				this.IsDirty = true;

				ItemBase item = this[ List.Count - 1 ];
				this.Remove( item );
			}

			if( null != OnItemCollectionClear )
			{
				OnItemCollectionClear( this );
			}

		}

		protected ItemBase this[ int index ]
		{
			get
			{
				return (ItemBase) List[ index ];
			}
			set
			{
				List[ index ] = value;
			}
		}

		/// <summary>
		/// Copy all items from this instance of collection to the specified instance		
		/// </summary>
		/// <param name="col"></param>
		/// <param name="index"></param>
		public void CopyTo( CollectionBase col, int index )
		{
			foreach (ItemBase item in base.InnerList)
			{
				col.Add(item);
			}
		}

		public void Refresh()
		{
			if (null != OnRefresh)
				OnRefresh( this );
		}

		#region Child Item event handling

		private void item_OnShow( ItemBase item )
		{
			if( null != OnItemShow )
			{
				OnItemShow( item );
			}
		}

		/// <summary>
		/// Propagate item change event
		/// </summary>
		/// <param name="item"></param>
		private void item_OnChange( ItemBase item, string changeType )
		{
			if( null != OnItemChange )
			{
				OnItemChange( item, changeType );
			}
		}

		/// <summary>
		/// Propagate item detach event
		/// </summary>
		/// <param name="item"></param>
		private void item_OnDetach( ItemBase item )
		{
			// TODO: need to remove event listener
			if( null != OnItemDetach )
			{
				OnItemDetach( item );
			}
		}

		
		// ----------------------- Child Item event handling --------------------

		protected void ListenChildItem( ItemBase item )
		{
			item.OnChange += new ItemChangeHandler( item_OnChange );
			item.OnDetach += new ItemDetachHandler( item_OnDetach );
			item.OnSelect += new ItemSelectHandler(item_OnSelect);
			item.OnShow += new ItemShowHandler( item_OnShow );

			item.OnBeginUpdate += new ItemBeginUpdateHandler(item_OnBeginUpdate);
			item.OnEndUpdate += new ItemEndUpdateHandler(item_OnEndUpdate);
			item.OnUndoState += new ItemUndoStateHandler(item_OnUndoState);
			item.OnRedoState += new ItemRedoStateHandler(item_OnRedoState);

			item.OnCollectionAdd += new CollectionAddHandler(item_OnCollectionAdd);
			item.OnCollectionClear += new CollectionClearHandler(item_OnCollectionClear);
			item.OnCollectionRemove += new CollectionRemoveHandler(item_OnCollectionRemove);
			item.OnSelectionChanged += new SelectionChangeHandler(item_OnSelectionChanged);
		}

		#endregion

		#region Event Handlers 

		private void item_OnSelect(ItemBase item)
		{
			if( null != OnItemSelect )
				OnItemSelect( item );
		}

		private void item_OnCollectionAdd(CollectionBase collection, ItemBase item)
		{
			if( null != OnItemCollectionAdd )			
				OnItemCollectionAdd( collection, item );
		}

		private void item_OnCollectionClear(CollectionBase collection)
		{
			if( null != OnItemCollectionClear )
				OnItemCollectionClear( collection );
		}

		private void item_OnCollectionRemove(CollectionBase collection, ItemBase item)
		{
			if( null != OnItemCollectionRemove )
				OnItemCollectionRemove( collection, item );
		}

		private void item_OnSelectionChanged(CollectionBase collection, ItemBase item)
		{
			if( null != OnItemCollectionSelectionChanged )
				OnItemCollectionSelectionChanged( collection, item );
		}

		private void item_OnBeginUpdate(ItemBase item, string name)
		{
			if( null != OnItemBeginUpdate )
				OnItemBeginUpdate( item, name );
		}

		private void item_OnUndoState(ItemBase item)
		{
			if( null != OnItemUndo )
				OnItemUndo( item );
		}

		private void item_OnRedoState(ItemBase item)
		{
			if( null != OnItemRedo )
				OnItemRedo( item );
		}

		private void item_OnEndUpdate(ItemBase item)
		{
			if( null != OnItemEndUpdate )
				OnItemEndUpdate( item );
		}

		#endregion

	}

}