Blazorise Gantt: Editing

@code {
    private DateOnly selectedDate = DateOnly.FromDateTime( DateTime.Today );

    private List<TaskItem> tasks = CreateTasks();

    private static List<TaskItem> CreateTasks()
    {
        var baseDate = DateTime.Today.AddDays( -2 );

        var result = new List<TaskItem>
        {
            new() { Id = "1", Title = "Marketing campaign", Start = baseDate, End = baseDate.AddDays( 15 ), Progress = 45d },
            new() { Id = "2", ParentId = "1", Title = "Research", Start = baseDate, End = baseDate.AddDays( 4 ), Progress = 100d },
            new() { Id = "3", ParentId = "1", Title = "Creative", Start = baseDate.AddDays( 4 ), End = baseDate.AddDays( 9 ), Progress = 70d },
            new() { Id = "4", ParentId = "1", Title = "Distribution", Start = baseDate.AddDays( 9 ), End = baseDate.AddDays( 15 ), Progress = 20d },
        };

        foreach ( var item in result )
        {
            item.Duration = Math.Max( 1, (int)Math.Ceiling( ( item.End - item.Start ).TotalDays ) );
        }

        return result;
    }

    private bool AllowCommand( GanttCommandContext<TaskItem> context )
    {
        if ( context.CommandType == GanttCommandType.Delete && context.Item?.ParentId is null )
            return false;

        return true;
    }

    public class TaskItem
    {
        public string Id { get; set; }

        public string ParentId { get; set; }

        public string Title { get; set; }

        public DateTime Start { get; set; }

        public DateTime End { get; set; }

        public int Duration { get; set; }

        public double Progress { get; set; }
    }
}

@code {
    private DateOnly selectedDate = DateOnly.FromDateTime( DateTime.Today );
    private List<TaskItem> tasks = CreateTasks();
    private bool editorVisible;
    private string editorModeTitle = "Edit task";
    private string editorTitle;
    private string editorParentId;
    private string editorTargetId;
    private TaskItem editorDraft;
    private string lastAction = "None";
    private int nextId = 100;

    private Task OnNewItemClicked( GanttCommandContext<TaskItem> context )
        => OpenEditor( context.Item, null, null, "Create task" );

    private Task OnAddChildItemClicked( GanttCommandContext<TaskItem> context )
        => OpenEditor( context.Item, context.ParentItem, null, $"Create child for {context.ParentItem?.Title}" );

    private Task OnEditItemClicked( GanttItemClickedEventArgs<TaskItem> context )
        => OpenEditor( context.Item, null, context.Item?.Id, $"Edit {context.Item?.Title}" );

    private Task OnDeleteItemClicked( GanttItemClickedEventArgs<TaskItem> context )
    {
        if ( context?.Item?.Id is null )
            return Task.CompletedTask;

        RemoveTaskWithChildren( tasks, context.Item.Id );
        lastAction = $"Deleted {context.Item.Title}";

        return Task.CompletedTask;
    }

    private Task OpenEditor( TaskItem item, TaskItem parentItem, string targetId, string modeTitle )
    {
        editorDraft = item?.Clone() ?? new TaskItem();
        editorParentId = parentItem?.Id;
        editorTargetId = targetId;
        editorTitle = editorDraft.Title ?? string.Empty;
        editorModeTitle = modeTitle;
        editorVisible = true;

        return Task.CompletedTask;
    }

    private Task CloseEditor()
    {
        editorVisible = false;
        editorDraft = null;
        editorParentId = null;
        editorTargetId = null;
        editorTitle = string.Empty;

        return Task.CompletedTask;
    }

    private Task SaveEditor()
    {
        if ( editorDraft is null )
            return Task.CompletedTask;

        editorDraft.Title = string.IsNullOrWhiteSpace( editorTitle )
            ? "Untitled task"
            : editorTitle.Trim();

        if ( string.IsNullOrEmpty( editorTargetId ) )
        {
            editorDraft.Id ??= $"task-{nextId++}";
            editorDraft.ParentId = editorParentId;
            tasks.Add( editorDraft.Clone() );
            lastAction = editorParentId is null
                ? $"Created {editorDraft.Title}"
                : $"Created child {editorDraft.Title}";
        }
        else
        {
            var existingTask = tasks.FirstOrDefault( x => x.Id == editorTargetId );

            if ( existingTask is not null )
            {
                existingTask.Title = editorDraft.Title;
                lastAction = $"Updated {existingTask.Title}";
            }
        }

        return CloseEditor();
    }

    private static void RemoveTaskWithChildren( List<TaskItem> list, string itemId )
    {
        var idsToDelete = new HashSet<string>( StringComparer.Ordinal ) { itemId };
        var changed = true;

        while ( changed )
        {
            changed = false;

            foreach ( var task in list )
            {
                if ( task.ParentId is not null && idsToDelete.Contains( task.ParentId ) && idsToDelete.Add( task.Id ) )
                    changed = true;
            }
        }

        list.RemoveAll( x => idsToDelete.Contains( x.Id ) );
    }

    private static List<TaskItem> CreateTasks()
    {
        var baseDate = DateTime.Today.AddDays( -2 );

        return new List<TaskItem>
        {
            new() { Id = "1", Title = "Website redesign", Start = baseDate, End = baseDate.AddDays( 14 ), Duration = 14 },
            new() { Id = "2", ParentId = "1", Title = "Discovery", Start = baseDate, End = baseDate.AddDays( 4 ), Duration = 4 },
            new() { Id = "3", ParentId = "1", Title = "Implementation", Start = baseDate.AddDays( 4 ), End = baseDate.AddDays( 12 ), Duration = 8 },
            new() { Id = "4", ParentId = "1", Title = "Launch", Start = baseDate.AddDays( 12 ), End = baseDate.AddDays( 14 ), Duration = 2 },
        };
    }

    public class TaskItem
    {
        public string Id { get; set; }

        public string ParentId { get; set; }

        public string Title { get; set; }

        public DateTime Start { get; set; }

        public DateTime End { get; set; }

        public int Duration { get; set; }

        public TaskItem Clone()
        {
            return new TaskItem
            {
                Id = Id,
                ParentId = ParentId,
                Title = Title,
                Start = Start,
                End = End,
                Duration = Duration,
            };
        }
    }
}