Limit the number of Most Visited lines to two

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/strings/sys_string_conversions.h"
 #include "base/time/time.h"
 #include "components/strings/grit/components_strings.h"
 #import "ios/chrome/browser/ui/collection_view/cells/collection_view_item+collection_view_controller.h"
 #import "ios/chrome/browser/ui/collection_view/cells/collection_view_text_item.h"
 #import "ios/chrome/browser/ui/collection_view/collection_view_controller.h"
 #import "ios/chrome/browser/ui/collection_view/collection_view_model.h"
 #import "ios/chrome/browser/ui/content_suggestions/cells/content_suggestions_footer_item.h"
 #import "ios/chrome/browser/ui/content_suggestions/cells/content_suggestions_text_item.h"
 #import "ios/chrome/browser/ui/content_suggestions/cells/suggested_content.h"
+#import "ios/chrome/browser/ui/content_suggestions/content_suggestions_collection_utils.h"
 #import "ios/chrome/browser/ui/content_suggestions/content_suggestions_data_sink.h"
 #import "ios/chrome/browser/ui/content_suggestions/content_suggestions_data_source.h"
 #import "ios/chrome/browser/ui/content_suggestions/content_suggestions_image_fetcher.h"
 #import "ios/chrome/browser/ui/content_suggestions/content_suggestions_view_controller.h"
 #import "ios/chrome/browser/ui/content_suggestions/identifier/content_suggestion_identifier.h"
 #import "ios/chrome/browser/ui/content_suggestions/identifier/content_suggestions_section_information.h"
 #import "ios/chrome/browser/ui/favicon/favicon_attributes.h"
 #include "ui/base/l10n/l10n_util.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
@@ skipping 65 matching lines @@
     case ContentSuggestionsSectionReadingList:
       return SectionIdentifierReadingList;
     case ContentSuggestionsSectionMostVisited:
       return SectionIdentifierMostVisited;
 
     case ContentSuggestionsSectionUnknown:
       return SectionIdentifierDefault;
   }
 }
 
+const CGFloat kNumberOfMostVisitedLines = 2;
+
 }  // namespace
 
 @interface ContentSuggestionsCollectionUpdater ()<ContentSuggestionsDataSink,
                                                   SuggestedContentDelegate>
 
 @property(nonatomic, weak) id<ContentSuggestionsDataSource> dataSource;
 @property(nonatomic, strong)
     NSMutableDictionary<NSNumber*, ContentSuggestionsSectionInformation*>*
         sectionInfoBySectionIdentifier;
+// Width of the collection. Upon size change, it reflects the new size.
+@property(nonatomic, assign) CGFloat collectionWidth;
 
 @end
 
 @implementation ContentSuggestionsCollectionUpdater
 
 @synthesize collectionViewController = _collectionViewController;
 @synthesize dataSource = _dataSource;
 @synthesize sectionInfoBySectionIdentifier = _sectionInfoBySectionIdentifier;
+@synthesize collectionWidth = _collectionWidth;
 
 - (instancetype)initWithDataSource:
     (id<ContentSuggestionsDataSource>)dataSource {
   self = [super init];
   if (self) {
     _dataSource = dataSource;
     _dataSource.dataSink = self;
   }
   return self;
 }
 
 #pragma mark - Properties
 
 - (void)setCollectionViewController:
     (ContentSuggestionsViewController*)collectionViewController {
   _collectionViewController = collectionViewController;
+  self.collectionWidth =
+      collectionViewController.collectionView.bounds.size.width;
 
   [self reloadAllData];
 }
 
 #pragma mark - ContentSuggestionsDataSink
 
 - (void)dataAvailableForSection:
     (ContentSuggestionsSectionInformation*)sectionInfo {
   SectionIdentifier sectionIdentifier = SectionIdentifierForInfo(sectionInfo);
 
@@ skipping 116 matching lines @@
   NSArray<CSCollectionViewItem*>* existingItems =
       [model itemsInSectionWithIdentifier:sectionIdentifier];
   if (existingItems.count > 0 && existingItems[0].type == ItemTypeEmpty) {
     [model removeItemWithType:ItemTypeEmpty
         fromSectionWithIdentifier:sectionIdentifier];
     emptyItemRemoved = YES;
   }
 
   [suggestions enumerateObjectsUsingBlock:^(CSCollectionViewItem* item,
                                             NSUInteger index, BOOL* stop) {
+    NSInteger section = [model sectionForSectionIdentifier:sectionIdentifier];
+    if ([self isMostVisitedSection:section] &&
+        [model numberOfItemsInSection:section] >=
+            [self mostVisitedPlaceCount]) {
+      return;
+    }
     ItemType type = ItemTypeForInfo(sectionInfo);
     item.type = type;
     NSIndexPath* addedIndexPath =
         [self addItem:item toSectionWithIdentifier:sectionIdentifier];
     [self fetchFaviconForItem:item];
     item.delegate = self;
 
     if (!emptyItemRemoved || index > 0) {
       [indexPaths addObject:addedIndexPath];
     } else {
@@ skipping 58 matching lines @@
   CSCollectionViewItem* item = [self emptyItemForSectionInfo:sectionInfo];
   return [self addItem:item toSectionWithIdentifier:sectionIdentifier];
 }
 
 - (BOOL)isMostVisitedSection:(NSInteger)section {
   return
       [self.collectionViewController.collectionViewModel
           sectionIdentifierForSection:section] == SectionIdentifierMostVisited;
 }
 
+- (void)updateMostVisitedForSize:(CGSize)size {
+  self.collectionWidth = size.width;
+
+  CSCollectionViewModel* model =
+      self.collectionViewController.collectionViewModel;
+  if (![model hasSectionForSectionIdentifier:SectionIdentifierMostVisited])
+    return;
+
+  NSInteger mostVisitedSection =
+      [model sectionForSectionIdentifier:SectionIdentifierMostVisited];
+  ContentSuggestionsSectionInformation* mostVisitedSectionInfo =
+      self.sectionInfoBySectionIdentifier[@(SectionIdentifierMostVisited)];
+  NSArray<CSCollectionViewItem*>* mostVisited =
+      [self.dataSource itemsForSectionInfo:mostVisitedSectionInfo];
+  NSInteger newCount = MIN([self mostVisitedPlaceCount],
+                           static_cast<NSInteger>(mostVisited.count));
+  NSInteger currentCount = [model numberOfItemsInSection:mostVisitedSection];
+
+  if (currentCount == newCount)
+    return;
+
+  // If the animations are enabled, the items are added then the rotation
+  // animation is triggered, creating a weird sequenced animation.
+  [UIView setAnimationsEnabled:NO];
+  if (currentCount > newCount) {
+    for (NSInteger i = newCount; i < currentCount; i++) {
+      NSIndexPath* itemToRemove =
+          [NSIndexPath indexPathForItem:newCount inSection:mostVisitedSection];
+      [self.collectionViewController dismissEntryAtIndexPath:itemToRemove];
+    }
+  } else {
+    NSMutableArray* itemsToBeAdded = [NSMutableArray array];
+    for (NSInteger i = currentCount; i < newCount; i++) {
+      [itemsToBeAdded addObject:mostVisited[i]];
+    }
+    [self.collectionViewController addSuggestions:itemsToBeAdded
+                                    toSectionInfo:mostVisitedSectionInfo];
+  }
+  [UIView setAnimationsEnabled:YES];
+}
+
 #pragma mark - SuggestedContentDelegate
 
 - (void)loadImageForSuggestedItem:(CSCollectionViewItem*)suggestedItem {
   __weak ContentSuggestionsCollectionUpdater* weakSelf = self;
   __weak CSCollectionViewItem* weakItem = suggestedItem;
 
   void (^imageFetchedCallback)(UIImage*) = ^(UIImage* image) {
     ContentSuggestionsCollectionUpdater* strongSelf = weakSelf;
     CSCollectionViewItem* strongItem = weakItem;
     if (!strongSelf || !strongItem) {
@@ skipping 165 matching lines @@
     toSectionWithIdentifier:(NSInteger)sectionIdentifier {
   CSCollectionViewModel* model =
       self.collectionViewController.collectionViewModel;
   NSInteger section = [model sectionForSectionIdentifier:sectionIdentifier];
   NSInteger itemNumber = [model numberOfItemsInSection:section];
   [model addItem:item toSectionWithIdentifier:sectionIdentifier];
 
   return [NSIndexPath indexPathForItem:itemNumber inSection:section];
 }
 
+// Returns the maximum number of Most Visited tiles to be displayed in the
+// collection.
+- (NSInteger)mostVisitedPlaceCount {
+  return content_suggestions::numberOfTilesForWidth(self.collectionWidth) *
+         kNumberOfMostVisitedLines;
+}
+
 @end