Expand only one message at a time

app/src/main/java/eu/faircode/email/FragmentMessages.java

@@ -1196,6 +1196,7 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
         public void setValue(String name, long id, boolean enabled) {
             if (!values.containsKey(name))
                 values.put(name, new ArrayList<Long>());
+
             if (enabled) {
                 if (!values.get(name).contains(id))
                     values.get(name).add(id);
@@ -1203,6 +1204,19 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
                 values.get(name).remove(id);
 
             if ("expanded".equals(name)) {
+                // Collapse other messages
+                SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getContext());
+                boolean expand_one = prefs.getBoolean("expand_one", false);
+                if (expand_one) {
+                    for (Long other : new ArrayList<>(values.get(name)))
+                        if (!other.equals(id)) {
+                            values.get(name).remove(other);
+                            int pos = adapter.getPositionForKey(other);
+                            if (pos != RecyclerView.NO_POSITION)
+                                adapter.notifyItemChanged(pos);
+                        }
+                }
+
                 updateExpanded();
                 if (enabled)
                     handleExpand(id);

app/src/main/java/eu/faircode/email/FragmentOptionsBehavior.java

@@ -47,6 +47,7 @@ public class FragmentOptionsBehavior extends FragmentBase implements SharedPrefe
     private SwitchCompat swDoubleTap;
     private SwitchCompat swExpandRead;
     private SwitchCompat swAutoExpand;
+    private SwitchCompat swExpandOne;
     private SwitchCompat swAutoClose;
     private Spinner spOnClose;
     private SwitchCompat swCollapse;
@@ -56,7 +57,7 @@ public class FragmentOptionsBehavior extends FragmentBase implements SharedPrefe
     private SwitchCompat swDisableTracking;
 
     private final static String[] RESET_OPTIONS = new String[]{
-            "pull", "autoscroll", "swipenav", "swipe_reversed", "doubletap", "expand_read", "autoexpand", "autoclose", "onclose",
+            "pull", "autoscroll", "swipenav", "swipe_reversed", "doubletap", "expand_read", "autoexpand", "expand_one", "autoclose", "onclose",
             "collapse", "autoread", "automove", "discard_delete", "disable_tracking"
     };
 
@@ -77,6 +78,7 @@ public class FragmentOptionsBehavior extends FragmentBase implements SharedPrefe
         swDoubleTap = view.findViewById(R.id.swDoubleTap);
         swExpandRead = view.findViewById(R.id.swExpandRead);
         swAutoExpand = view.findViewById(R.id.swAutoExpand);
+        swExpandOne = view.findViewById(R.id.swExpandOne);
         swAutoClose = view.findViewById(R.id.swAutoClose);
         spOnClose = view.findViewById(R.id.spOnClose);
         swCollapse = view.findViewById(R.id.swCollapse);
@@ -141,6 +143,13 @@ public class FragmentOptionsBehavior extends FragmentBase implements SharedPrefe
             }
         });
 
+        swExpandOne.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
+            @Override
+            public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
+                prefs.edit().putBoolean("expand_one", checked).apply();
+            }
+        });
+
         swAutoClose.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
@@ -255,6 +264,7 @@ public class FragmentOptionsBehavior extends FragmentBase implements SharedPrefe
         swDoubleTap.setChecked(prefs.getBoolean("doubletap", false));
         swExpandRead.setChecked(prefs.getBoolean("expand_read", true));
         swAutoExpand.setChecked(prefs.getBoolean("autoexpand", true));
+        swExpandOne.setChecked(prefs.getBoolean("expand_one", false));
         swAutoClose.setChecked(prefs.getBoolean("autoclose", true));
 
         String onClose = prefs.getString("onclose", "");

app/src/main/res/layout/fragment_options_behavior.xml

@@ -105,6 +105,17 @@
             app:layout_constraintStart_toStartOf="parent"
             app:layout_constraintTop_toBottomOf="@id/swAutoExpand" />
 
+        <androidx.appcompat.widget.SwitchCompat
+            android:id="@+id/swExpandOne"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="12dp"
+            android:text="@string/title_advanced_expand_one"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/tvAutoExpandHint"
+            app:switchPadding="12dp" />
+
         <androidx.appcompat.widget.SwitchCompat
             android:id="@+id/swCollapse"
             android:layout_width="0dp"
@@ -113,7 +124,7 @@
             android:text="@string/title_advanced_collapse"
             app:layout_constraintEnd_toEndOf="parent"
             app:layout_constraintStart_toStartOf="parent"
-            app:layout_constraintTop_toBottomOf="@id/tvAutoExpandHint"
+            app:layout_constraintTop_toBottomOf="@id/swExpandOne"
             app:switchPadding="12dp" />
 
         <TextView

app/src/main/res/values/strings.xml

@@ -267,6 +267,7 @@
     <string name="title_advanced_double_tap">Double tap to mark message read/unread</string>
     <string name="title_advanced_expand_read">Mark messages read on expanding</string>
     <string name="title_advanced_autoexpand">Automatically expand messages</string>
+    <string name="title_advanced_expand_one">Expand only one message at a time</string>
     <string name="title_advanced_collapse">Collapse messages in conversations on \'back\'</string>
     <string name="title_advanced_autoclose">Automatically close conversations</string>
     <string name="title_advanced_onclose">On closing a conversation</string>