XPlorerBar : Part 2 - Adding design-time support to the WPF explorer bar control

#region [       Copyright © 2008, Zona-Tools, all rights reserved.       ]
/*
 * 
    This source code is licensed under the Code Project Open License (CPOL).
    Check out http://www.codeproject.com/info/cpol10.aspx for further details.
 * 
*/
#endregion


#region [       Using namespaces       ]

using Microsoft.Windows.Design.Model;

#endregion


namespace ZonaTools.XPlorerBar.VisualStudio.Design
{
    /// <summary>
    /// Provides utilities to manipulate items in a ModelItemCollection.
    /// </summary>
    internal static class ModelItemCollectionHelper
    {
        #region [       Gets item's parent nested items       ]

        //===========================================================================
        /// <summary>
        /// Retrieves the parent's nested items of a specific item.
        /// </summary>
        /// <param name="item">Item whose brothers and sisters are searched 
        /// for.</param>
        /// <param name="property">Name of the parent's property which enable the
        /// nested items retrieval.</param>
        /// <returns>Parent's nested items collection.</returns>
        //===========================================================================
        private static ModelItemCollection GetParentItemsCollection(ModelItem item, string property)
        {
            //Makes sure the item is valid
            if (item == null)
                return null;

            //Gets item's parent and makes sure it is valid
            ModelItem parentItem = item.Parent;
            if (parentItem == null)
                return null;

            //Returns the parent's items collection
            return parentItem.Properties[property].Collection;
        }

        #endregion


        #region [       Checks item position in the collection       ]

        //===========================================================================
        /// <summary>
        /// Checks if the specified item is the first child of its parent.
        /// </summary>
        /// <param name="item">Item to check.</param>
        /// <param name="property">Name of the parent's property which enable the
        /// nested items retrieval.</param>
        /// <returns><c>true</c> if the specified item is the first child of its
        /// parent; otherwise <c>false</c>.</returns>
        //===========================================================================
        internal static bool IsItFirstSection(ModelItem item, string property)
        {
            //Gets the parent items collection
            ModelItemCollection parentItemsCollection = 
                GetParentItemsCollection(item, property);

            //Makes sure the item and the parent items collection are valid
            if ((item == null) || (parentItemsCollection == null))
                return true;

            //Checks if item is the first child of its parent
            return (parentItemsCollection.IndexOf(item) == 0);
        }


        //===========================================================================
        /// <summary>
        /// Checks if the specified item is the last child of its parent.
        /// </summary>
        /// <param name="item">Item to check.</param>
        /// <param name="property">Name of the parent's property which enable the
        /// nested items retrieval.</param>
        /// <returns><c>true</c> if the specified item is the last child of its
        /// parent; otherwise <c>false</c>.</returns>
        //===========================================================================
        internal static bool IsItLastSection(ModelItem item, string property)
        {
            //Gets the parent items collection
            ModelItemCollection parentItemsCollection = 
                GetParentItemsCollection(item, property);

            //Makes sure the item and the parent items collection are valid
            if ((item == null) || (parentItemsCollection == null))
                return true;

            //Checks if item is the last item of its parent
            return (parentItemsCollection.IndexOf(item) == (parentItemsCollection.Count - 1));
        }

        #endregion


        #region [       Moves item in the collection       ]

        //===========================================================================
        /// <summary>
        /// Moves (up or down) the specified item in its parent container.
        /// </summary>
        /// <param name="item">The item to move.</param>
        /// <param name="moveUp"><c>true</c> if the item has to move up; otherwise
        /// <c>false</c>.</param>
        /// <param name="property">Name of the parent's property which enable the
        /// nested items retrieval.</param>
        //===========================================================================
        internal static void MoveItem(ModelItem item, bool moveUp, string property)
        {
            //Gets the parent items collection
            ModelItemCollection parentItemsCollection =
                ModelItemCollectionHelper.GetParentItemsCollection(item, property);

            //Makes sure the item and the parent items collection are valid
            if ((item == null) || (parentItemsCollection == null))
                return;

            //Gets the index of the specified item in the collection
            int index = parentItemsCollection.IndexOf(item);

            //Moves the item according to the value of the 'MoveUp' boolean
            if (moveUp)
                parentItemsCollection.Move(index, index - 1);
            else
                parentItemsCollection.Move(index, index + 1);
        }

        #endregion
    }
}