Workaround no next on deleting current message

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

@@ -129,6 +129,7 @@ public class FragmentMessages extends FragmentBase {
     private AdapterMessage.ViewType viewType;
     private SelectionTracker<Long> selectionTracker = null;
 
+    private Long last_next = null;
     private int autoCloseCount = 0;
     private boolean autoExpand = true;
     private Map<String, List<Long>> values = new HashMap<>();
@@ -291,6 +292,8 @@ public class FragmentMessages extends FragmentBase {
 
                     @Override
                     public void onNext(boolean exists, Long id) {
+                        if (id != null)
+                            last_next = id;
                         bottom_navigation.getMenu().findItem(R.id.action_next).setIntent(new Intent().putExtra("id", id));
                         bottom_navigation.getMenu().findItem(R.id.action_next).setEnabled(id != null);
                     }
@@ -2080,8 +2083,16 @@ public class FragmentMessages extends FragmentBase {
         if (autoclose)
             finish();
         else if (autonext) {
+            if (last_next != null) {
+                Log.i("Navigating to last next=" + last_next);
+                navigate(last_next);
+                return;
+            }
+
             ViewModelMessages model = ViewModelProviders.of(getActivity()).get(ViewModelMessages.class);
             model.observePrevNext(getViewLifecycleOwner(), thread, new ViewModelMessages.IPrevNext() {
+                private boolean once = false;
+
                 @Override
                 public void onPrevious(boolean exists, Long id) {
                     // Do nothing
@@ -2089,6 +2100,10 @@ public class FragmentMessages extends FragmentBase {
 
                 @Override
                 public void onNext(boolean exists, Long id) {
+                    if (once)
+                        return;
+                    once = true;
+
                     if (id != null)
                         navigate(id);
                     if (!exists)
@@ -2110,6 +2125,11 @@ public class FragmentMessages extends FragmentBase {
 
             @Override
             protected void onExecuted(Bundle args, EntityMessage message) {
+                if (message == null) {
+                    finish();
+                    return;
+                }
+
                 LocalBroadcastManager lbm = LocalBroadcastManager.getInstance(getContext());
                 lbm.sendBroadcast(
                         new Intent(ActivityView.ACTION_VIEW_THREAD)

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

@@ -77,42 +77,62 @@ public class ViewModelMessages extends ViewModel {
 
     void observePrevNext(LifecycleOwner owner, final String thread, final IPrevNext intf) {
         LiveData<PagedList<TupleMessageEx>> list = messages.get(false);
-        if (list == null)
+        if (list == null) {
+            Log.w("Observe previous/next without list");
             return;
+        }
 
+        Log.i("Observe previous/next thread=" + thread);
         list.observe(owner, new Observer<PagedList<TupleMessageEx>>() {
             @Override
-            public void onChanged(PagedList<TupleMessageEx> list) {
-                boolean load = false;
-                for (int pos = 0; pos < list.size(); pos++) {
-                    TupleMessageEx item = list.get(pos);
+            public void onChanged(PagedList<TupleMessageEx> messages) {
+                Log.i("Observe previous/next thread=" + thread + " messages=" + messages.size());
+
+                for (int pos = 0; pos < messages.size(); pos++) {
+                    TupleMessageEx item = messages.get(pos);
                     if (item != null && thread.equals(item.thread)) {
+                        boolean load = false;
+
                         if (pos - 1 >= 0) {
-                            TupleMessageEx next = list.get(pos - 1);
+                            TupleMessageEx next = messages.get(pos - 1);
                             if (next == null)
                                 load = true;
-                            intf.onNext(true, next == null ? null : next.id);
+                            reportNext(intf, true, next == null ? null : next.id);
                         } else
-                            intf.onNext(false, null);
+                            reportNext(intf, false, null);
 
-                        if (pos + 1 < list.size()) {
-                            TupleMessageEx prev = list.get(pos + 1);
+                        if (pos + 1 < messages.size()) {
+                            TupleMessageEx prev = messages.get(pos + 1);
                             if (prev == null)
                                 load = true;
-                            intf.onPrevious(true, prev == null ? null : prev.id);
+                            reportPrevious(intf, true, prev == null ? null : prev.id);
                         } else
-                            intf.onPrevious(false, null);
+                            reportPrevious(intf, false, null);
 
                         if (load)
-                            list.loadAround(pos);
+                            messages.loadAround(pos);
 
-                        break;
+                        return;
                     }
                 }
+
+                Log.w("Observe previous/next gone thread=" + thread);
+                reportNext(intf, false, null);
+                reportPrevious(intf, false, null);
             }
         });
     }
 
+    private void reportPrevious(IPrevNext intf, boolean exists, Long id) {
+        Log.i("Previous exists=" + exists + " id=" + id);
+        intf.onPrevious(exists, id);
+    }
+
+    private void reportNext(IPrevNext intf, boolean exists, Long id) {
+        Log.i("Next exists=" + exists + " id=" + id);
+        intf.onNext(exists, id);
+    }
+
     interface IPrevNext {
         void onPrevious(boolean exists, Long id);