[netinstall] Implement `local` loading of packages

- For a static list of selectable packages (e.g. what you might otherwise
  use file:/// for with a static file on the ISO) you can now stick the
  list in the config file itself, simplifying some setups.
- Also saves faffing about with network.

SEE #1319

src/modules/netinstall/NetInstallPage.cpp

@@ -154,6 +154,14 @@ NetInstallPage::dataIsHere()
     ui->groupswidget->header()->setSectionResizeMode( 0, QHeaderView::ResizeToContents );
     ui->groupswidget->header()->setSectionResizeMode( 1, QHeaderView::Stretch );
 
+    expandGroups();
+
+    emit checkReady( true );
+}
+
+void
+NetInstallPage::expandGroups()
+{
     // Go backwards because expanding a group may cause rows to appear below it
     for ( int i = m_groups->rowCount() - 1; i >= 0; --i )
     {
@@ -163,8 +171,6 @@ NetInstallPage::dataIsHere()
             ui->groupswidget->setExpanded( index, true );
         }
     }
-
-    emit checkReady( true );
 }
 
 PackageTreeItem::List
@@ -203,6 +209,23 @@ NetInstallPage::loadGroupList( const QString& confUrl )
     }
 }
 
+void
+NetInstallPage::loadGroupList( const QVariantList& l )
+{
+    // This short-cuts through loading and just uses the data,
+    // containing cruft from dataIsHere() and readGroups().
+    m_groups = new PackageModel( l );
+    retranslate();  // For changed model
+    ui->groupswidget->setModel( m_groups );
+    ui->groupswidget->header()->setSectionResizeMode( 0, QHeaderView::ResizeToContents );
+    ui->groupswidget->header()->setSectionResizeMode( 1, QHeaderView::Stretch );
+
+    expandGroups();
+
+    emit checkReady( true );
+}
+
+
 void
 NetInstallPage::setRequired( bool b )
 {

src/modules/netinstall/NetInstallPage.h

@@ -64,6 +64,8 @@ public:
      * displaying the page.
      */
     void loadGroupList( const QString& url );
+    /// @brief Retrieve pre-processed and fetched group data
+    void loadGroupList( const QVariantList& l );
 
     // Sets the "required" state of netinstall data. Influences whether
     // corrupt or unavailable data causes checkReady() to be emitted
@@ -90,6 +92,13 @@ private:
     // of this module to know the format expected of the YAML files.
     bool readGroups( const QByteArray& yamlData );
 
+    /** @brief Expand entries that should be pre-expanded
+     *
+     * Follows the *expanded* key / the startExpanded field in the
+     * group entries of the model. Call this after filling up the model.
+     */
+    void expandGroups();
+
     Ui::Page_NetInst* ui;
 
     std::unique_ptr< CalamaresUtils::Locale::TranslatedString > m_title;  // Above the treeview

src/modules/netinstall/NetInstallViewStep.cpp

@@ -209,7 +209,15 @@ NetInstallViewStep::setConfigurationMap( const QVariantMap& configurationMap )
         // Keep putting groupsUrl into the global storage,
         // even though it's no longer used for in-module data-passing.
         Calamares::JobQueue::instance()->globalStorage()->insert( "groupsUrl", groupsUrl );
-        m_widget->loadGroupList( groupsUrl );
+        if ( groupsUrl == QStringLiteral( "local" ) )
+        {
+            QVariantList l = configurationMap.value( "groups" ).toList();
+            m_widget->loadGroupList( l );
+        }
+        else
+        {
+            m_widget->loadGroupList( groupsUrl );
+        }
     }
 
     bool bogus = false;