Fix people header placement when only hub visible

Bug: 150166074
Test: atest, manual
Change-Id: If85b08731bad75096e14ea83a59fe6230c337313

packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationSectionsManager.java

@@ -332,6 +332,10 @@ public class NotificationSectionsManager implements StackScrollAlgorithm.Section
                 // Put it at the end of the list.
                 peopleHeaderTarget = lastNotifIndex;
             }
+            // Offset the target to account for the current position of the people header.
+            if (currentPeopleHeaderIdx != -1 && currentPeopleHeaderIdx < peopleHeaderTarget) {
+                peopleHeaderTarget--;
+            }
         }
 
         // Add headers in reverse order to preserve indices
@@ -459,6 +463,11 @@ public class NotificationSectionsManager implements StackScrollAlgorithm.Section
         return mPeopleHubView;
     }
 
+    @VisibleForTesting
+    void setPeopleHubVisible(boolean visible) {
+        mPeopleHubVisible = visible;
+    }
+
     private final ConfigurationListener mConfigurationListener = new ConfigurationListener() {
         @Override
         public void onLocaleListChanged() {

packages/SystemUI/tests/src/com/android/systemui/statusbar/notification/stack/NotificationSectionsManagerTest.java

@@ -315,6 +315,24 @@ public class NotificationSectionsManagerTest extends SysuiTestCase {
         verify(mNssl).changeViewPosition(mSectionsManager.getPeopleHeaderView(), 0);
     }
 
+    @Test
+    public void testPeopleFiltering_keepPeopleHeaderWhenSectionEmpty() {
+        mSectionsManager.setPeopleHubVisible(true);
+        enablePeopleFiltering();
+
+        setStackState(
+                ChildType.PEOPLE_HEADER,
+                ChildType.ALERTING_HEADER,
+                ChildType.ALERTING,
+                ChildType.GENTLE_HEADER,
+                ChildType.GENTLE
+        );
+        mSectionsManager.updateSectionBoundaries();
+
+        verify(mNssl, never()).removeView(mSectionsManager.getPeopleHeaderView());
+        verify(mNssl).changeViewPosition(mSectionsManager.getPeopleHeaderView(), 0);
+    }
+
     private void enablePeopleFiltering() {
         when(mSectionsFeatureManager.isFilteringEnabled()).thenReturn(true);
         when(mSectionsFeatureManager.getNumberOfBuckets()).thenReturn(4);