Added local RAG (#756)

Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

app/MindWork AI Studio/Components/SelectFile.razor.cs

@@ -3,6 +3,9 @@ using AIStudio.Tools.Services;
 
 using Microsoft.AspNetCore.Components;
 
+// This component has a parameter called File, which would shadow the file system's File class:
+using IOFile = System.IO.File;
+
 namespace AIStudio.Components;
 
 public partial class SelectFile : MSGComponentBase
@@ -28,6 +31,24 @@ public partial class SelectFile : MSGComponentBase
     [Parameter]
     public Func<string, string?> Validation { get; set; } = _ => null;
 
+    /// <summary>
+    /// When true, the file can also be chosen by dropping it onto this component.
+    /// </summary>
+    [Parameter]
+    public bool EnableDragDrop { get; set; }
+
+    /// <summary>
+    /// On which layer to register the drop area. Higher layers have priority over lower layers.
+    /// </summary>
+    [Parameter]
+    public int Layer { get; set; } = DropLayers.ROOT;
+
+    /// <summary>
+    /// Catch all documents that are hovered over the AI Studio window and not only over the drop zone.
+    /// </summary>
+    [Parameter]
+    public bool CatchAllDocuments { get; set; }
+
     [Inject]
     public RustService RustService { get; set; } = null!;
     
@@ -73,4 +94,46 @@ public partial class SelectFile : MSGComponentBase
             this.isFileDialogOpen = false;
         }
     }
+
+    /// <summary>
+    /// Takes the first dropped path which leads to a usable file.
+    /// </summary>
+    /// <remarks>
+    /// This component carries exactly one file, so a multi-selection cannot be honored as a whole.
+    /// A dropped folder is rejected instead of being read as "the first file inside it": the user
+    /// was asked for a file, and picking one for them would be a surprise.
+    /// </remarks>
+    /// <param name="paths">The dropped paths.</param>
+    private async Task PathsDropped(List<string> paths)
+    {
+        foreach (var path in paths)
+        {
+            if (!IOFile.Exists(path))
+                continue;
+
+            if (this.Filter is { Length: > 0 } && !FileTypes.IsAllowedPath(path, this.Filter))
+                continue;
+
+            this.Logger.LogInformation("The user dropped the file '{DroppedFilePath}'.", path);
+            this.InternalFileChanged(path);
+            return;
+        }
+
+        this.Logger.LogWarning("None of the {Count} dropped path(s) could be used as a file.", paths.Count);
+        await this.MessageBus.SendWarning(new(Icons.Material.Filled.Warning, this.GetDropWarning(paths)));
+    }
+
+    private string GetDropWarning(List<string> paths)
+    {
+        // Naming the actual mistake beats a generic "that did not work". Dropping a folder onto a
+        // file picker is the likeliest of them:
+        if (paths.Any(Directory.Exists))
+            return T("Please drop a file, not a folder.");
+
+        // The file exists, so the file type filter is what turned it down:
+        if (paths.Any(IOFile.Exists))
+            return T("Please drop a file with a supported file type.");
+
+        return T("The dropped file could not be accessed. Please choose it with the file chooser instead.");
+    }
 }