Connected.Components/Components/DropZone/DynamicDropItem.razor.cs

// Copyright (c) MudBlazor 2021
// MudBlazor licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using Connected.Annotations;
using Connected.Utilities;
using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Components.Web;

namespace Connected.Components;

public partial class DynamicDropItem<T> : UIComponent
{
   private bool _dragOperationIsInProgress = false;

   [CascadingParameter]
   protected DropContainer<T> Container { get; set; }

   /// <summary>
   /// The zone identifier of the corresponding drop zone
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.DropZone.Behavior)]
   public string ZoneIdentifier { get; set; }

   /// <summary>
   /// the data item that is represneted by this item
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.DropZone.Behavior)]
   public T Item { get; set; }

   /// <summary>
   /// Child content of component
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.DropZone.Appearance)]
   public RenderFragment ChildContent { get; set; }

   /// <summary>
   /// An additional class that is applied to this element when a drag operation is in progress
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.DropZone.DraggingClass)]
   public string DraggingClass { get; set; }

   /// <summary>
   /// An event callback set fires, when a drag operation has been started
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.DropZone.Behavior)]
   public EventCallback<T> OnDragStarted { get; set; }

   /// <summary>
   /// An event callback set fires, when a drag operation has been eneded. This included also a cancelled transaction
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.DropZone.Behavior)]
   public EventCallback<T> OnDragEnded { get; set; }

   /// <summary>
   /// When true, the item can't be dragged. defaults to false
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.DropZone.Disabled)]
   public bool Disabled { get; set; } = false;

   /// <summary>
   /// The class that is applied when disabled <see cref="Disabled"/> is set to true
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.DropZone.Disabled)]
   public string DisabledClass { get; set; }

   [Parameter]
   [Category(CategoryTypes.DropZone.Sorting)]
   public int Index { get; set; } = -1;

   [Parameter]
   [Category(CategoryTypes.DropZone.Sorting)]
   public bool HideContent { get; set; }

   #region Event handling and callbacks

   private async Task DragStarted()
   {
      if (Container == null) { return; }

      _dragOperationIsInProgress = true;
      Container.StartTransaction(Item, ZoneIdentifier ?? string.Empty, Index, OnDroppedSucceeded, OnDroppedCanceled);
      await OnDragStarted.InvokeAsync();
   }

   private async Task OnDroppedSucceeded()
   {
      _dragOperationIsInProgress = false;

      await OnDragEnded.InvokeAsync(Item);
      StateHasChanged();
   }

   private async Task OnDroppedCanceled()
   {
      _dragOperationIsInProgress = false;

      await OnDragEnded.InvokeAsync(Item);
      StateHasChanged();
   }

   private async Task DragEnded(DragEventArgs e)
   {
      if (_dragOperationIsInProgress == true)
      {
         _dragOperationIsInProgress = false;
         await Container?.CancelTransaction();
      }
      else
      {
         await OnDragEnded.InvokeAsync(Item);
      }
   }

   private void HandleDragEnter()
   {
      if (Container == null || Container.TransactionInProgress() == false) { return; }

      Container.UpdateTransactionIndex(Index);
   }

   private void HandleDragLeave()
   {
   }

   #endregion

   protected string Classname =>
   new CssBuilder("mud-drop-item")
       .AddClass(DraggingClass, _dragOperationIsInProgress == true)
       .AddClass(DisabledClass, Disabled == true)
       .AddClass(Class)
       .Build();

}