Optimize folder processing

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

@@ -142,18 +142,6 @@ public class AdapterFolder extends RecyclerView.Adapter<AdapterFolder.ViewHolder
         }
 
         private void bindTo(final TupleFolderEx folder) {
-            boolean hidden = false;
-
-            int level = 0;
-            TupleFolderEx parent = folder.parent_ref;
-            while (parent != null) {
-                level++;
-                if (parent.collapsed)
-                    hidden = true;
-                parent = parent.parent_ref;
-            }
-
-            view.setVisibility(hidden ? View.GONE : View.VISIBLE);
             view.setActivated(folder.tbc != null || folder.tbd != null);
             view.setAlpha(disabledIds.contains(folder.id) ? Helper.LOW_LIGHT : 1.0f);
 
@@ -195,13 +183,14 @@ public class AdapterFolder extends RecyclerView.Adapter<AdapterFolder.ViewHolder
             }
 
             ViewGroup.LayoutParams lp = vwLevel.getLayoutParams();
-            lp.width = (account < 0 ? 1 : level) * dp12;
+            lp.width = (account < 0 ? 1 : folder.indentation) * dp12;
             vwLevel.setLayoutParams(lp);
 
             ivExpander.setImageLevel(folder.collapsed ? 1 /* more */ : 0 /* less */);
             ivExpander.setVisibility(account < 0
                     ? View.GONE
-                    : folder.child_refs.size() > 0 ? View.VISIBLE : View.INVISIBLE);
+                    : folder.child_refs != null && folder.child_refs.size() > 0
+                    ? View.VISIBLE : View.INVISIBLE);
 
             if (listener == null) {
                 ivNotify.setVisibility(folder.notify ? View.VISIBLE : View.GONE);
@@ -210,10 +199,10 @@ public class AdapterFolder extends RecyclerView.Adapter<AdapterFolder.ViewHolder
 
             if (folder.unseen > 0)
                 tvName.setText(context.getString(R.string.title_name_count,
-                        folder.getDisplayName(context, parent),
+                        folder.getDisplayName(context, folder.parent_ref == null ? null : folder.parent_ref),
                         nf.format(folder.unseen)));
             else
-                tvName.setText(folder.getDisplayName(context, parent));
+                tvName.setText(folder.getDisplayName(context, folder.parent_ref == null ? null : folder.parent_ref));
 
             tvName.setTypeface(folder.unseen > 0 ? Typeface.DEFAULT_BOLD : Typeface.DEFAULT);
             tvName.setTextColor(folder.unseen > 0 ? colorUnread : textColorSecondary);
@@ -715,6 +704,7 @@ public class AdapterFolder extends RecyclerView.Adapter<AdapterFolder.ViewHolder
         }
 
         TupleFolderEx root = new TupleFolderEx();
+        root.name = "[root]";
         root.child_refs = parents;
         for (TupleFolderEx parent : parents)
             parent.parent_ref = root;
@@ -728,7 +718,7 @@ public class AdapterFolder extends RecyclerView.Adapter<AdapterFolder.ViewHolder
             }
         }
 
-        List<TupleFolderEx> hierarchical = getHierchical(parents);
+        List<TupleFolderEx> hierarchical = getHierchical(parents, 0);
 
         DiffUtil.DiffResult diff = DiffUtil.calculateDiff(new DiffCallback(items, hierarchical), false);
 
@@ -758,13 +748,14 @@ public class AdapterFolder extends RecyclerView.Adapter<AdapterFolder.ViewHolder
         diff.dispatchUpdatesTo(this);
     }
 
-    List<TupleFolderEx> getHierchical(List<TupleFolderEx> parents) {
+    List<TupleFolderEx> getHierchical(List<TupleFolderEx> parents, int indentation) {
         List<TupleFolderEx> result = new ArrayList<>();
 
         for (TupleFolderEx parent : parents) {
+            parent.indentation = indentation;
             result.add(parent);
-            if (parent.child_refs != null)
-                result.addAll(getHierchical(parent.child_refs));
+            if (!parent.collapsed && parent.child_refs != null)
+                result.addAll(getHierchical(parent.child_refs, indentation + 1));
         }
 
         return result;

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

@@ -44,6 +44,9 @@ public class TupleFolderEx extends EntityFolder implements Serializable {
     public int unseen;
     public int executing;
 
+    @Ignore
+    int indentation;
+
     @Ignore
     TupleFolderEx parent_ref;