Remember previous sort method as a secondary ordering

android/uhabits-core/src/main/java/org/isoron/uhabits/core/models/Checkmark.java

@@ -31,6 +31,11 @@ import static org.isoron.uhabits.core.utils.StringUtils.defaultToStringStyle;
  * While repetitions simply record that the habit was performed at a given date,
  * a checkmark provides more information, such as whether a repetition was
  * expected at that day or not.
+ * </p>
+ * <p>
+ * Note that the priority comparator in
+ * {@link org.isoron.uhabits.core.models.memory.MemoryHabitList}
+ * relies on SKIP > YES_MANUAL > YES_AUTO > NO.
  * <p>
  * Checkmarks are computed automatically from the list of repetitions.
  */

android/uhabits-core/src/main/java/org/isoron/uhabits/core/models/HabitList.java

@@ -252,6 +252,6 @@ public abstract class HabitList implements Iterable<Habit>
         BY_SCORE_DESC,
         BY_PRIORITY_ASC,
         BY_PRIORITY_DESC,
-        BY_POSITION;
+        BY_POSITION
     }
 }

android/uhabits-core/src/main/java/org/isoron/uhabits/core/models/memory/MemoryHabitList.java

@@ -40,6 +40,9 @@ public class MemoryHabitList extends HabitList
     @NonNull
     private Order order = Order.BY_POSITION;
 
+    @NonNull
+    private Order previousOrder = Order.BY_POSITION;
+
     @Nullable
     private MemoryHabitList parent = null;
 
@@ -113,14 +116,27 @@ public class MemoryHabitList extends HabitList
     @Override
     public synchronized void setOrder(@NonNull Order order)
     {
+        this.previousOrder = this.order;
         this.order = order;
-        this.comparator = getComparatorByOrder(order);
+        this.comparator = getComposedComparatorByOrder(order, this.previousOrder);
         resort();
         getObservable().notifyListeners();
     }
 
-    private Comparator<Habit> getComparatorByOrder(Order order)
+    private Comparator<Habit> getComposedComparatorByOrder(Order firstOrder, Order secondOrder)
     {
+        return (h1, h2) -> {
+            int firstResult = getComparatorByOrder(firstOrder).compare(h1, h2);
+
+            if (firstResult != 0 || secondOrder == null) {
+                return firstResult;
+            }
+
+            return getComparatorByOrder(secondOrder).compare(h1, h2);
+        };
+    }
+
+    private Comparator<Habit> getComparatorByOrder(Order order) {
         Comparator<Habit> nameComparatorAsc =
                 (h1, h2) -> h1.getName().compareTo(h2.getName());
 

android/uhabits-core/src/main/java/org/isoron/uhabits/core/ui/screens/habits/list/ListHabitsMenuBehavior.java

@@ -128,10 +128,10 @@ public class ListHabitsMenuBehavior
     }
 
     public void onSortByPriority() {
-        if (adapter.getOrder() != HabitList.Order.BY_PRIORITY_DESC) {
-            adapter.setOrder(HabitList.Order.BY_PRIORITY_DESC);
-        } else {
+        if (adapter.getOrder() != HabitList.Order.BY_PRIORITY_ASC) {
             adapter.setOrder(HabitList.Order.BY_PRIORITY_ASC);
+        } else {
+            adapter.setOrder(HabitList.Order.BY_PRIORITY_DESC);
         }
     }
 

android/uhabits-core/src/test/java/org/isoron/uhabits/core/ui/screens/habits/list/ListHabitsMenuBehaviorTest.java

@@ -136,7 +136,7 @@ public class ListHabitsMenuBehaviorTest extends BaseUnitTest
     {
         behavior.onSortByPriority();
         verify(adapter).setOrder(orderCaptor.capture());
-        assertThat(orderCaptor.getValue(), equalTo(BY_PRIORITY_DESC));
+        assertThat(orderCaptor.getValue(), equalTo(BY_PRIORITY_ASC));
     }
 
     @Test