//
// (C) Copyright 2003-2023 by Autodesk, Inc.
//
// Permission to use, copy, modify, and distribute this software in
// object code form for any purpose and without fee is hereby granted,
// provided that the above copyright notice appears in all copies and
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// DOES NOT WARRANT THAT THE OPERATION OF THE PROGRAM WILL BE
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// Software - Restricted Rights) and DFAR 252.227-7013(c)(1)(ii)
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//
using System;
using System.Windows.Forms;
using System.Collections;

using Autodesk.Revit;
using Autodesk.Revit.DB;
using Autodesk.Revit.UI;

using TaskDialog = Autodesk.Revit.UI.TaskDialog;

namespace Revit.SDK.Samples.DeleteObject.CS
{
    /// <summary>
    /// Delete the elements that were selected
    /// </summary>
    [Autodesk.Revit.Attributes.Transaction(Autodesk.Revit.Attributes.TransactionMode.Manual)]
    [Autodesk.Revit.Attributes.Regeneration(Autodesk.Revit.Attributes.RegenerationOption.Manual)]
    [Autodesk.Revit.Attributes.Journaling(Autodesk.Revit.Attributes.JournalingMode.NoCommandData)]
    public class Command : Autodesk.Revit.UI.IExternalCommand
    {
        ///<summary>
        /// Implement this method as an external command for Revit.
        /// </summary>
        /// <param name="commandData">An object that is passed to the external application 
        /// which contains data related to the command, 
        /// such as the application object and active view.</param>
        /// <param name="message">A message that can be set by the external application 
        /// which will be displayed if a failure or cancellation is returned by 
        /// the external command.</param>
        /// <param name="elements">A set of elements to which the external application 
        /// can add elements that are to be highlighted in case of failure or cancellation.</param>
        /// <returns>Return the status of the external command. 
        /// A result of Succeeded means that the API external method functioned as expected. 
        /// Cancelled can be used to signify that the user cancelled the external operation 
        /// at some point. Failure should be returned if the application is unable to proceed with 
        /// the operation.</returns>
        public Autodesk.Revit.UI.Result Execute(
            Autodesk.Revit.UI.ExternalCommandData commandData,
            ref string message, Autodesk.Revit.DB.ElementSet elements)
        {
            Autodesk.Revit.UI.UIApplication revit = commandData.Application;
            Transaction trans = new Transaction(revit.ActiveUIDocument.Document, "Revit.SDK.Samples.DeleteObject");
            trans.Start();
            ElementSet collection = new ElementSet();
            foreach (ElementId elementId in revit.ActiveUIDocument.Selection.GetElementIds())
            {
               collection.Insert(revit.ActiveUIDocument.Document.GetElement(elementId));
            }
            // check user selection
            if (collection.Size < 1)
            {
                message = "Please select object(s) before delete.";
                trans.RollBack();
                return Autodesk.Revit.UI.Result.Cancelled;
            }

            bool error = true;
            try
            {
                error = true;

                // delete selection
                IEnumerator e = collection.GetEnumerator();
                bool MoreValue = e.MoveNext();
                while (MoreValue)
                {
                    Element component = e.Current as Element;
                    revit.ActiveUIDocument.Document.Delete(component.Id);
                    MoreValue = e.MoveNext();
                }

                error = false;
            }
            catch
            {
                // if revit threw an exception, try to catch it
                foreach (Element c in collection)
                {
                    elements.Insert(c);
                }
                message = "object(s) can't be deleted.";
                trans.RollBack();
                return Autodesk.Revit.UI.Result.Failed;
            }
            finally
            {
                // if revit threw an exception, display error and return failed
                if (error)
                {
                    TaskDialog.Show("Error", "Delete failed.");
                }
            }
            trans.Commit();
            return Autodesk.Revit.UI.Result.Succeeded;
        }
    }
}