Fetch Suggestions by category

ios/chrome/browser/ui/content_suggestions/content_suggestions_collection_updater.mm

 // 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.
 
 #import "ios/chrome/browser/ui/content_suggestions/content_suggestions_collection_updater.h"
 
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
 #include "base/time/time.h"
 #import "ios/chrome/browser/ui/collection_view/collection_view_controller.h"
@@ skipping 105 matching lines @@
 
 - (void)setCollectionViewController:
     (ContentSuggestionsViewController*)collectionViewController {
   _collectionViewController = collectionViewController;
 
   [self reloadAllData];
 }
 
 #pragma mark - ContentSuggestionsDataSink
 
-- (void)dataAvailable {
-  [self reloadAllData];
+- (void)dataAvailableForSection:
+    (ContentSuggestionsSectionInformation*)sectionInfo {
+  SectionIdentifier sectionIdentifier = SectionIdentifierForInfo(sectionInfo);
+
+  CollectionViewModel* model =
+      self.collectionViewController.collectionViewModel;
+  if ([model hasSectionForSectionIdentifier:sectionIdentifier] &&
+      [model itemsInSectionWithIdentifier:sectionIdentifier].count > 0) {
+    // Do not dismiss the presented items.
+    return;
+  }
+
+  [self addSuggestions:[self.dataSource suggestionsForSection:sectionInfo]];
 }
 
 - (void)clearSuggestion:(ContentSuggestionIdentifier*)suggestionIdentifier {
   SectionIdentifier sectionIdentifier =
       SectionIdentifierForInfo(suggestionIdentifier.sectionInfo);
   if (![self.collectionViewController.collectionViewModel
           hasSectionForSectionIdentifier:sectionIdentifier]) {
     return;
   }
 
@@ skipping 14 matching lines @@
     return;
 
   NSIndexPath* indexPath = [self.collectionViewController.collectionViewModel
              indexPathForItem:correspondingItem
       inSectionWithIdentifier:sectionIdentifier];
   [self.collectionViewController dismissEntryAtIndexPath:indexPath];
 }
 
 - (void)reloadAllData {
   [self resetModels];
-  CollectionViewModel* model =
-      self.collectionViewController.collectionViewModel;
-
-  NSArray<ContentSuggestion*>* suggestions = [self.dataSource allSuggestions];
-
-  for (ContentSuggestion* suggestion in suggestions) {
-    NSInteger sectionIdentifier =
-        [self addSectionIfNeeded:suggestion.suggestionIdentifier.sectionInfo];
-    ContentSuggestionsArticleItem* articleItem =
-        [[ContentSuggestionsArticleItem alloc]
-            initWithType:ItemTypeForContentSuggestionType(suggestion.type)
-                   title:suggestion.title
-                subtitle:suggestion.text
-                delegate:self
-                     url:suggestion.url];
-
-    articleItem.publisher = suggestion.publisher;
-    articleItem.publishDate = suggestion.publishDate;
-
-    articleItem.suggestionIdentifier = suggestion.suggestionIdentifier;
-
-    [model addItem:articleItem toSectionWithIdentifier:sectionIdentifier];
-  }
-
-  if ([self.collectionViewController isViewLoaded]) {
-    [self.collectionViewController.collectionView reloadData];
-  }
+  [self addSuggestions:[self.dataSource allSuggestions]];
 }
 
 - (void)clearSection:(ContentSuggestionsSectionInformation*)sectionInfo {
   SectionIdentifier sectionIdentifier = SectionIdentifierForInfo(sectionInfo);
   NSInteger section = [self.collectionViewController.collectionViewModel
       sectionIdentifierForSection:sectionIdentifier];
 
   [self.collectionViewController dismissSection:section];
 }
 
@@ skipping 37 matching lines @@
          inSectionWithIdentifier:sectionIdentifier];
   };
 
   [self.dataSource.imageFetcher
       fetchImageForSuggestion:articleItem.suggestionIdentifier
                      callback:imageFetchedCallback];
 }
 
 #pragma mark - Private methods
 
+// Add the |suggestions| to the model and reload the data.
+- (void)addSuggestions:(NSArray<ContentSuggestion*>*)suggestions {
+  if (suggestions.count == 0) {
+    return;
+  }
+
+  CollectionViewModel* model =
+      self.collectionViewController.collectionViewModel;
+
+  for (ContentSuggestion* suggestion in suggestions) {
+    NSInteger sectionIdentifier =
+        [self addSectionIfNeeded:suggestion.suggestionIdentifier.sectionInfo];
+    ContentSuggestionsArticleItem* articleItem =
+        [[ContentSuggestionsArticleItem alloc]
+            initWithType:ItemTypeForContentSuggestionType(suggestion.type)
+                   title:suggestion.title
+                subtitle:suggestion.text
+                delegate:self
+                     url:suggestion.url];
+
+    articleItem.publisher = suggestion.publisher;
+    articleItem.publishDate = suggestion.publishDate;
+
+    articleItem.suggestionIdentifier = suggestion.suggestionIdentifier;
+
+    [model addItem:articleItem toSectionWithIdentifier:sectionIdentifier];
+  }
+
+  if ([self.collectionViewController isViewLoaded]) {
+    [self.collectionViewController.collectionView reloadData];
+  }
+}
+
 - (NSInteger)addSectionIfNeeded:
     (ContentSuggestionsSectionInformation*)sectionInformation {
   NSInteger sectionIdentifier = SectionIdentifierForInfo(sectionInformation);
 
   CollectionViewModel* model =
       self.collectionViewController.collectionViewModel;
   if (![model hasSectionForSectionIdentifier:sectionIdentifier]) {
     [model addSectionWithIdentifier:sectionIdentifier];
     self.sectionInfoBySectionIdentifier[@(sectionIdentifier)] =
         sectionInformation;
     [self.sectionInfoBySectionIdentifier setObject:sectionInformation
                                             forKey:@(sectionIdentifier)];
   }
   return sectionIdentifier;
 }
 
 - (void)resetModels {
   [self.collectionViewController loadModel];
   self.sectionInfoBySectionIdentifier = [[NSMutableDictionary alloc] init];
 }
 
 @end