[partition] Move BootLoaderModel convenience functions

- These were hidden inside PartitionPage, but are useful elsewhere.

src/modules/partition/core/BootLoaderModel.cpp

@@ -23,9 +23,13 @@
 #include "core/PartitionInfo.h"
 #include "core/KPMHelpers.h"
 
+#include "utils/Logger.h"
+
 // KPMcore
 #include <kpmcore/core/device.h>
 
+#include <QComboBox>
+
 static QStandardItem*
 createBootLoaderItem( const QString& description, const QString& path, bool isPartition )
 {
@@ -148,3 +152,48 @@ BootLoaderModel::data( const QModelIndex& index, int role ) const
     }
     return QStandardItemModel::data( index, role );
 }
+
+namespace Calamares
+{
+int
+findBootloader( const QAbstractItemModel* model, const QString& path )
+{
+    for ( int i = 0; i < model->rowCount(); ++i)
+    {
+        const auto index = model->index( i, 0, QModelIndex() );
+        if ( !index.isValid() )
+            continue;
+        QVariant var = model->data( index, BootLoaderModel::BootLoaderPathRole );
+        if ( var.isValid() && var.toString() == path )
+            return i;
+    }
+
+    return -1;
+}
+
+void
+restoreSelectedBootLoader( QComboBox& combo, const QString& path )
+{
+    const auto* model = combo.model();
+    if ( model->rowCount() < 1 )
+    {
+        cDebug() << "No items in BootLoaderModel";
+        return;
+    }
+
+    int r = -1;
+    if ( path.isEmpty() )
+    {
+        combo.setCurrentIndex( 0 );
+    }
+    else if ( (r = findBootloader( model, path )) >= 0 )
+    {
+        combo.setCurrentIndex( r );
+    }
+    else
+    {
+        combo.setCurrentIndex( 0 );
+    }
+}
+
+}  // namespace