Clear upcoming station tracks when steering, and re-fetch two

src/libtomahawk/playlist/dynamic/GeneratorInterface.h

@@ -102,6 +102,10 @@ public:
      *  If this generator doesn't support this (and returns false for
      * \c onDemandSteerable) this will be null. The generator is responsible
      *  for reacting to changes in the widget.
+     *
+     * Steering widgets may emit a \c steeringChanged() signal, which will cause the model to toss any
+     *  upcoming tracks and re-fetch them.
+     *
      */
     virtual QWidget* steeringWidget() { return 0; }
 

src/libtomahawk/playlist/dynamic/echonest/EchonestSteerer.cpp

@@ -218,6 +218,8 @@ EchonestSteerer::applySteering()
         }
     }
 
+    emit steeringChanged();
+
     resetSteering( true );
 }
 

src/libtomahawk/playlist/dynamic/echonest/EchonestSteerer.h

@@ -57,6 +57,9 @@ signals:
     void reset();
 
     void resized();
+
+    // interface to DynamicWidget
+    void steeringChanged();
 private slots:
     void changed();
 

src/libtomahawk/playlist/dynamic/widgets/DynamicWidget.cpp

@@ -324,6 +324,8 @@ DynamicWidget::startStation()
         m_steering = m_playlist->generator()->steeringWidget();
         Q_ASSERT( m_steering );
 
+        connect( m_steering, SIGNAL( steeringChanged() ), this, SLOT( steeringChanged() ) );
+
         int x = ( width() / 2 ) - ( m_steering->size().width() / 2 );
         int y = height() - m_steering->size().height() - 40; // padding
 
@@ -394,6 +396,25 @@ DynamicWidget::controlChanged( const Tomahawk::dyncontrol_ptr& control )
     emit descriptionChanged( m_playlist->generator()->sentenceSummary() );
 }
 
+void
+DynamicWidget::steeringChanged()
+{
+    // When steering changes, toss all the tracks that are upcoming, and re-fetch.
+    QModelIndex cur = m_view->currentIndex();
+    const int upcoming = m_view->proxyModel()->rowCount( QModelIndex() ) - 1 - cur.row();
+    tDebug() << "Removing tracks after current in station, found" << upcoming;
+
+    QModelIndexList toRemove;
+    for ( int i = cur.row() + 1; i < m_view->proxyModel()->rowCount( QModelIndex() ); i++ )
+    {
+        toRemove << m_view->proxyModel()->index( i, 0, QModelIndex() );
+    }
+
+    m_view->proxyModel()->removeIndexes( toRemove );
+
+    m_playlist->generator()->fetchNext();
+}
+
 
 void
 DynamicWidget::showPreview()

src/libtomahawk/playlist/dynamic/widgets/DynamicWidget.h

@@ -103,6 +103,7 @@ private slots:
 
     void controlsChanged( bool added );
     void controlChanged( const Tomahawk::dyncontrol_ptr& control );
+    void steeringChanged();
     void showPreview();
 
     void layoutFloatingWidgets();