Fix broken --load-local option

src/Application.vala

@@ -201,6 +201,16 @@ public class AppCenter.App : Gtk.Application {
             return;
         }
 
+        if (local_path != null) {
+            var file = File.new_for_commandline_arg (local_path);
+
+            try {
+                local_package = AppCenterCore.FlatpakBackend.get_default ().add_local_component_file (file);
+            } catch (Error e) {
+                warning ("Failed to load local AppStream XML file: %s", e.message);
+            }
+        }
+
         if (active_window == null) {
             // Force a Flatpak cache refresh when the window is created, so we get new apps
             update_manager.update_cache.begin (true);

src/Core/FlatpakBackend.vala

@@ -1948,6 +1948,41 @@ public class AppCenterCore.FlatpakBackend : Object {
         return job.result.get_boolean ();
     }
 
+    public Package? add_local_component_file (File file) throws Error {
+        var metadata = new AppStream.Metadata ();
+        try {
+            metadata.parse_file (file, AppStream.FormatKind.XML);
+        } catch (Error e) {
+            throw e;
+        }
+
+        var component = metadata.get_component ();
+        if (component == null) {
+            return null;
+        }
+
+        string name = _("%s (local)").printf (component.get_name ());
+        string id = "%s%s".printf (component.get_id (), Package.LOCAL_ID_SUFFIX);
+
+        component.set_name (name, null);
+        component.set_id (id);
+        component.set_origin (Package.APPCENTER_PACKAGE_ORIGIN);
+
+        var component_box = new AppStream.ComponentBox.simple ();
+        try {
+            component_box.add (component);
+        } catch (Error e) {
+            throw e;
+        }
+
+        user_appstream_pool.add_components (component_box);
+
+        var package = new AppCenterCore.FlatpakPackage (user_installation, component);
+        package_list[id] = package;
+
+        return package;
+    }
+
     private static GLib.Once<FlatpakBackend> instance;
     public static unowned FlatpakBackend get_default () {
         return instance.once (() => { return new FlatpakBackend (); });