Extracted some pages to their own assembly and finished the artifact display page code

OpenArchival.Blazor.FileViewer/FileViewerFactory.cs

@@ -0,0 +1,38 @@
+namespace OpenArchival.Blazor.FileViewer;
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+
+public static class FileViewerFactory
+{
+    private static Dictionary<string, Type> _extensionMapping = [];
+
+    static FileViewerFactory() {
+        // Image types taken from https://developer.mozilla.org/en-US/docs/Web/Media/Guides/Formats/Image_types
+        RegisterViewerComponent<ImageViewer>([".apng", ".png", ".avif", ".gif", ".jpg", ".jpeg", ".jfif", ".pjpeg", ".pjp", ".svg", ".webp"]);
+    }
+
+    public static void RegisterViewerComponent<ComponentType>(IEnumerable<string> extensions) where ComponentType : IFileViewer
+    {
+        foreach (var extension in extensions)
+        {
+            _extensionMapping.Add(extension, typeof(ComponentType));
+        }
+    }
+
+    public static Type GetViewerComponent(string filename)
+    {
+        if (_extensionMapping.TryGetValue(Path.GetExtension(filename).ToLowerInvariant(), out var componentType)) 
+        {
+            return componentType;
+        } 
+        else
+        {
+            return typeof(UnsupportedFileViewer);
+        }
+    }
+}