📰 Keep Suggestion sections in declaration order

chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/NewTabPageAdapter.java

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.ntp.cards;
 
 import android.graphics.Canvas;
 import android.support.v4.view.ViewCompat;
 import android.support.v7.widget.RecyclerView;
 import android.support.v7.widget.RecyclerView.Adapter;
@@ skipping 14 matching lines @@
 import org.chromium.chrome.browser.ntp.snippets.CategoryStatus.CategoryStatusEnum;
 import org.chromium.chrome.browser.ntp.snippets.SectionHeader;
 import org.chromium.chrome.browser.ntp.snippets.SectionHeaderViewHolder;
 import org.chromium.chrome.browser.ntp.snippets.SnippetArticle;
 import org.chromium.chrome.browser.ntp.snippets.SnippetArticleViewHolder;
 import org.chromium.chrome.browser.ntp.snippets.SnippetsBridge;
 import org.chromium.chrome.browser.ntp.snippets.SuggestionsSource;
 
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.TreeMap;
 
 /**
  * A class that handles merging above the fold elements and below the fold cards into an adapter
  * that will be used to back the NTP RecyclerView. The first element in the adapter should always be
  * the above-the-fold view (containing the logo, search box, and most visited tiles) and subsequent
  * elements will be the cards shown to the user
  */
 public class NewTabPageAdapter extends Adapter<NewTabPageViewHolder>
         implements SuggestionsSource.Observer {
     private static final String TAG = "Ntp";
 
     private final NewTabPageManager mNewTabPageManager;
     private final View mAboveTheFoldView;
     private SuggestionsSource mSuggestionsSource;
     private final UiConfig mUiConfig;
     private final ItemTouchCallbacks mItemTouchCallbacks = new ItemTouchCallbacks();
     private NewTabPageRecyclerView mRecyclerView;
 
     /**
      * List of all item groups (which can themselves contain multiple items. When flattened, this
      * will be a list of all items the adapter exposes.
      */
     private final List<ItemGroup> mGroups = new ArrayList<>();
     private final AboveTheFoldItem mAboveTheFold = new AboveTheFoldItem();
     private final SpacingItem mBottomSpacer = new SpacingItem();
 
     /** Maps suggestion categories to sections, with stable iteration ordering. */
-    private final Map<Integer, SuggestionsSection> mSections = new TreeMap<>();
+    private final Map<Integer, SuggestionsSection> mSections = new LinkedHashMap<>();
 
     private class ItemTouchCallbacks extends ItemTouchHelper.Callback {
         @Override
         public void onSwiped(ViewHolder viewHolder, int direction) {
             mRecyclerView.onItemDismissStarted(viewHolder.itemView);
 
             NewTabPageAdapter.this.dismissItem(viewHolder);
         }
 
         @Override
@@ skipping 62 matching lines @@
         for (int category : categories) {
             int categoryStatus = suggestionsSource.getCategoryStatus(category);
             assert categoryStatus != CategoryStatus.NOT_PROVIDED;
             if (categoryStatus == CategoryStatus.LOADING_ERROR
                     || categoryStatus == CategoryStatus.CATEGORY_EXPLICITLY_DISABLED)
                 continue;
 
             List<SnippetArticle> suggestions =
                     suggestionsSource.getSuggestionsForCategory(category);
             suggestionsPerCategory[i++] = suggestions.size();
+
+            // Create the new section.
+            SuggestionsCategoryInfo info = mSuggestionsSource.getCategoryInfo(category);
+            if (suggestions.isEmpty() && !info.showIfEmpty()) continue;
+            mSections.put(category, new SuggestionsSection(category, info, this));
+
+            // Add the new suggestions.
             setSuggestions(category, suggestions, categoryStatus);
         }
         // |mNewTabPageManager| is null in some tests.
         if (mNewTabPageManager != null) {
             mNewTabPageManager.trackSnippetsPageImpression(categories, suggestionsPerCategory);
         }
         suggestionsSource.setObserver(this);
         updateGroups();
     }
 
     /** Returns callbacks to configure the interactions with the RecyclerView's items. */
     public ItemTouchHelper.Callback getItemTouchCallbacks() {
         return mItemTouchCallbacks;
     }
 
     @Override
     public void onNewSuggestions(@CategoryInt int category) {
+        // We never want to add suggestions from unknown categories.
+        if (!mSections.containsKey(category)) return;
+
         // We never want to refresh the suggestions if we already have some content.
-        if (mSections.containsKey(category) && mSections.get(category).hasSuggestions()) return;
+        if (mSections.get(category).hasSuggestions()) return;
 
         // The status may have changed while the suggestions were loading, perhaps they should not
         // be displayed any more.
         @CategoryStatusEnum
         int status = mSuggestionsSource.getCategoryStatus(category);
         if (!SnippetsBridge.isCategoryEnabled(status)) {
             Log.w(TAG, "Received suggestions for a disabled category (id=%d, status=%d)", category,
                     status);
             return;
         }
@@ skipping 132 matching lines @@
         // Count the number of suggestions before this category.
         int globalPositionOffset = 0;
         for (Map.Entry<Integer, SuggestionsSection> entry : mSections.entrySet()) {
             if (entry.getKey() == category) break;
             globalPositionOffset += entry.getValue().getSuggestionsCount();
         }
         // Assign global indices to the new suggestions.
         for (SnippetArticle suggestion : suggestions) {
             suggestion.mGlobalPosition = globalPositionOffset + suggestion.mPosition;
         }
-        // Add the new suggestions.
-        if (!mSections.containsKey(category)) {
-            SuggestionsCategoryInfo info = mSuggestionsSource.getCategoryInfo(category);
-            if (suggestions.isEmpty() && !info.showIfEmpty()) return;
-
-            mSections.put(category, new SuggestionsSection(category, info, this));
-        }
 
         mSections.get(category).setSuggestions(suggestions, status);
     }
 
     private void updateGroups() {
         mGroups.clear();
         mGroups.add(mAboveTheFold);
         // TODO(treib,bauerb): Preserve the order of categories we got from getCategories.
         mGroups.addAll(mSections.values());
         if (!mSections.isEmpty()) {
@@ skipping 65 matching lines @@
     ItemGroup getGroup(int itemPosition) {
         int itemsSkipped = 0;
         for (ItemGroup group : mGroups) {
             List<NewTabPageItem> items = group.getItems();
             itemsSkipped += items.size();
             if (itemPosition < itemsSkipped) return group;
         }
         return null;
     }
 
+    @VisibleForTesting
+    List<ItemGroup> getGroups() {
+        return Collections.unmodifiableList(mGroups);
+    }
+
     private int getGroupPositionOffset(ItemGroup group) {
         int positionOffset = 0;
         for (ItemGroup candidateGroup : mGroups) {
             if (candidateGroup == group) return positionOffset;
             positionOffset += candidateGroup.getItems().size();
         }
         return RecyclerView.NO_POSITION;
     }
 }