BusinessLayer

   public class BusinessLayerArcht
   {
      /// <summary>
      /// list of categories
      /// </summary>
      private List<CategoriesCtrlDto> _categories;

      /// <summary>
      /// call to urlstorage class
      /// </summary>
      private UrlStorage store = UrlStorage.instance;

      /// <summary>
      /// public constructor
      /// </summary>
      public BusinessLayerArcht() {
      }

      /// <summary>
      /// Load categories
      /// </summary>
      public void Load() {
         _categories = store.readXMLtoLIST();
      }

      /// <summary>
      /// browse the category and get the matched name
      /// </summary>
      /// <param name="name"></param>
      /// <returns></returns>
      private CategoriesCtrlDto GetCategWithName(string name) {
         CategoriesCtrlDto categ = null;

         foreach ( CategoriesCtrlDto ct in _categories ) {
            if ( ct.Name == name ) {
               categ = ct;
               break;
            }
         }

         return categ;
      }

      /// <summary>
      /// add link function, it has lists to sent to data layer for insert process
      /// </summary>
      /// <param name="source"></param>
      /// <param name="Categ"></param>
      /// <param name="lks"></param>
      /// <returns></returns>
      public bool add_link( string link_name, string link_url, string link_descr, string category_name ) {

         //bool if_exist = false;
         bool added_successfully = false;

         if ( string.IsNullOrEmpty( link_name ) )
            throw new ArgumentNullException( "add_link link_name BL" );
         if ( string.IsNullOrEmpty( category_name ) )
            throw new ArgumentNullException( "add_link category_name BL" );
         if ( string.IsNullOrEmpty( link_url ) )
            throw new ArgumentNullException( "add_link link_url BL" );
         if ( string.IsNullOrEmpty( link_descr ) )
            throw new ArgumentNullException( "add_link link_descr BL" );

         CategoriesCtrlDto categ = GetCategWithName(category_name);

         if(categ != null)
         {
            if ( categ.LinkExists( link_url ) ) {
               throw new ArgumentOutOfRangeException( "add link BL" );
            } else {
               List<LinksCtrlDto> lists = categ.AddLink( link_url, link_name, link_descr );
               _categories.Add( categ );

               added_successfully = store.add_link(category_name,link_url,link_name,link_descr);
            }
         }
         else
         {
            throw new ArgumentNullException( "find category BL" );
         }

         return added_successfully;
      }


      /// <summary>
      /// add a category and create a list of category and send to DL for insert process
      /// </summary>
      /// <param name="source"></param>
      /// <param name="category_name"></param>
      /// <returns></returns>
      public bool add_category( string category_name ) {

         //bool if_exist = false;
         bool added_successfully = false;

         if ( string.IsNullOrEmpty( category_name ) )
            throw new ArgumentNullException( "add_category link_descr BL" );

         CategoriesCtrlDto categ = GetCategWithName( category_name );

         if ( categ != null ) {
            throw new ArgumentOutOfRangeException( "add_category BL" );
         } else {
            _categories.Add( new CategoriesCtrlDto( category_name, null ) );
            added_successfully = store.add_category( category_name );
         }

         return added_successfully;
      }


      /// <summary>
      /// Delete a link and add to a list to be passed to DL for deletion process
      /// after if the deletion process returns true then we can remove that link from the list
      /// </summary>
      /// <param name="source"></param>
      /// <param name="link_url"></param>
      /// <param name="category_name"></param>
      /// <returns></returns>
      public bool delete_link(string link_url, string category_name) {

         bool removed_successfully = false;


         if ( string.IsNullOrEmpty( link_url ) )
            throw new ArgumentNullException( "delete_link link_url BL" );
         if ( string.IsNullOrEmpty( category_name ) )
            throw new ArgumentNullException( "delete_link link_url BL" );

         CategoriesCtrlDto categ = GetCategWithName( category_name );

         if ( categ != null ) {
            if ( categ.LinkExists( link_url ) ) {
               removed_successfully = store.delete_link( category_name, link_url );
               categ.DeleteLink( link_url );
            }
         } else {
            throw new ArgumentNullException( "delete_link BL" );
         }

            return removed_successfully;
      }


      /// <summary>
      /// delete a category (if it exists) and send parameter to DL
      /// for deletion process
      /// </summary>
      /// <param name="source"></param>
      /// <param name="category_name"></param>
      /// <returns></returns>
      public bool delete_category( string category_name ) {
         //bool if_exist = false;
         bool removed_successfully = false;

         if ( string.IsNullOrEmpty( category_name ) )
            throw new ArgumentNullException( "remove_category cat_name BL" );

         CategoriesCtrlDto categ = GetCategWithName( category_name );

         if ( categ == null ) {
            throw new ArgumentOutOfRangeException( "remove_category BL" );
         } else {
            removed_successfully = store.delete_category( category_name );
            _categories.Remove( categ );
         }

         return removed_successfully;
      }


      /// <summary>
      /// set List as readonly collection
      /// </summary>
      public ReadOnlyCollection<CategoriesCtrlDto> Categories {
         get {
            if ( this._categories == null )
               throw new ArgumentNullException( "ReadonlyCategory BL Exception" );
            else
            return _categories.AsReadOnly();
         }

      }
   }