Add PdfFileDropZone for interactive PDF uploads

Replaced static upload message in `CreateEnvelopeWizardPopup.razor` with a new `PdfFileDropZone` component to enhance user experience. The component supports drag-and-drop functionality, file selection, and dynamic states (e.g., disabled, drag-active).

Introduced `PdfFileDropZone.razor` with customizable parameters such as `Disabled`, `HasDocument`, `UploadText`, and `DragDropHintText`. Added event handling for drag-and-drop interactions and file selection.

Updated `sender-page.css` to include styles for the new component, ensuring seamless integration with the existing layout. Adjusted styles for hover effects, drag-active state, and disabled state.

These changes improve usability and make PDF uploads more intuitive.

EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Components/Sender/CreateEnvelopeWizardPopup.razor

@@ -245,9 +245,11 @@
                     }
                     else
                     {
-                        <div class="sender-create-wizard__empty-list">
-                            @L("SenderWizard_DocumentRequiredHint", "Bitte laden Sie ein PDF-Dokument hoch, um fortzufahren.")
-                        </div>
+                        <PdfFileDropZone Disabled="@IsActionLocked"
+                                         HasDocument="false"
+                                         UploadText='@L("SenderWizard_DocumentRequiredHint", "Bitte laden Sie ein PDF-Dokument hoch, um fortzufahren.")'
+                                         DragDropHintText='@L("SenderWizard_DragDropPdfHint", "Oder ziehen Sie die PDF-Datei hierher.")'
+                                         FileSelected="OnDocumentSelectedAsync" />
                     }
                 </div>
             }

EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Components/Sender/PdfFileDropZone.razor

@@ -0,0 +1,104 @@
+@using Microsoft.AspNetCore.Components.Forms
+
+<div class="sender-pdf-dropzone @DropZoneClass">
+    <div class="sender-pdf-dropzone__content">
+        <div class="sender-pdf-dropzone__title">@CurrentActionText</div>
+        @if (!string.IsNullOrWhiteSpace(DragDropHintText))
+        {
+            <div class="sender-pdf-dropzone__hint">@DragDropHintText</div>
+        }
+    </div>
+
+    <InputFile OnChange="OnFileSelectedAsync"
+               accept="@Accept"
+               disabled="@Disabled"
+               @ondragenter="OnDragEnter"
+               @ondragleave="OnDragLeave"
+               @ondragover="OnDragOver"
+               @ondrop="OnDrop"
+               class="sender-pdf-dropzone__input" />
+</div>
+
+@code {
+    [Parameter]
+    public bool Disabled { get; set; }
+
+    [Parameter]
+    public bool HasDocument { get; set; }
+
+    [Parameter]
+    public string Accept { get; set; } = ".pdf";
+
+    [Parameter]
+    public string UploadText { get; set; } = "PDF hochladen";
+
+    [Parameter]
+    public string ReplaceText { get; set; } = "PDF ersetzen";
+
+    [Parameter]
+    public string DragDropHintText { get; set; } = "Datei hierhin ziehen oder klicken";
+
+    [Parameter]
+    public EventCallback<InputFileChangeEventArgs> FileSelected { get; set; }
+
+    private int _dragDepth;
+    private bool _isDragActive;
+
+    private string CurrentActionText => HasDocument ? ReplaceText : UploadText;
+
+    private string DropZoneClass
+    {
+        get
+        {
+            if (Disabled)
+                return "sender-pdf-dropzone--disabled";
+
+            return _isDragActive ? "sender-pdf-dropzone--drag-active" : string.Empty;
+        }
+    }
+
+    private void OnDragEnter(DragEventArgs _)
+    {
+        if (Disabled)
+            return;
+
+        _dragDepth++;
+        _isDragActive = true;
+    }
+
+    private void OnDragLeave(DragEventArgs _)
+    {
+        if (Disabled)
+            return;
+
+        _dragDepth = Math.Max(0, _dragDepth - 1);
+        if (_dragDepth == 0)
+            _isDragActive = false;
+    }
+
+    private void OnDragOver(DragEventArgs _)
+    {
+        if (Disabled)
+            return;
+
+        _isDragActive = true;
+    }
+
+    private void OnDrop(DragEventArgs _)
+    {
+        _dragDepth = 0;
+        _isDragActive = false;
+    }
+
+    private async Task OnFileSelectedAsync(InputFileChangeEventArgs args)
+    {
+        _dragDepth = 0;
+        _isDragActive = false;
+
+        if (Disabled)
+            return;
+
+        if (FileSelected.HasDelegate)
+            await FileSelected.InvokeAsync(args);
+    }
+}

EnvelopeGenerator.Server/EnvelopeGenerator.Server/wwwroot/css/sender-page.css

@@ -1466,6 +1466,66 @@
     display: none;
 }
 
+.sender-pdf-dropzone {
+    position: relative;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    min-height: 92px;
+    border: 1px dashed rgba(100, 116, 139, 0.5);
+    border-radius: 8px;
+    background: rgba(248, 250, 252, 0.9);
+    color: #334155;
+    cursor: pointer;
+    transition: border-color 120ms ease, background-color 120ms ease, box-shadow 120ms ease;
+}
+
+.sender-pdf-dropzone:hover {
+    border-color: rgba(126, 34, 206, 0.45);
+    background: rgba(241, 245, 249, 0.95);
+}
+
+.sender-pdf-dropzone--drag-active {
+    border-color: rgba(16, 185, 129, 0.75);
+    background: linear-gradient(180deg, rgba(16, 185, 129, 0.14), rgba(16, 185, 129, 0.08));
+    box-shadow: 0 0 0 3px rgba(16, 185, 129, 0.16);
+}
+
+.sender-pdf-dropzone--disabled {
+    opacity: 0.55;
+    cursor: not-allowed;
+}
+
+.sender-pdf-dropzone__content {
+    text-align: center;
+    display: grid;
+    gap: 0.2rem;
+    padding: 0.75rem 0.9rem;
+}
+
+.sender-pdf-dropzone__title {
+    font-size: 0.86rem;
+    font-weight: 700;
+}
+
+.sender-pdf-dropzone__hint {
+    font-size: 0.78rem;
+    color: #64748b;
+}
+
+.sender-pdf-dropzone__input {
+    position: absolute;
+    inset: 0;
+    width: 100%;
+    height: 100%;
+    opacity: 0;
+    cursor: pointer;
+}
+
+.sender-pdf-dropzone--disabled .sender-pdf-dropzone__input {
+    cursor: not-allowed;
+}
+
 .sender-create-wizard__document-meta {
     border: 1px solid rgba(16, 185, 129, 0.3);
     border-radius: 8px;
@@ -1524,6 +1584,10 @@
         width: 100%;
     }
 
+    .sender-pdf-dropzone {
+        width: 100%;
+    }
+
     .sender-create-wizard__upload-btn {
         width: 100%;
     }