Add bookmark provider for content suggestions

components/ntp_snippets/bookmarks/bookmark_suggestions_provider.cc

Index: components/ntp_snippets/bookmarks/bookmark_suggestions_provider.cc
diff --git a/components/ntp_snippets/bookmarks/bookmark_suggestions_provider.cc b/components/ntp_snippets/bookmarks/bookmark_suggestions_provider.cc
new file mode 100644
index 0000000000000000000000000000000000000000..25b18e3d3421b0e69f400cddd2a8ce0afc1c93f4
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+++ b/components/ntp_snippets/bookmarks/bookmark_suggestions_provider.cc
@@ -0,0 +1,167 @@
+// 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.
+
+#include "components/ntp_snippets/bookmarks/bookmark_suggestions_provider.h"
+
+#include <utility>
+#include <vector>
+
+#include "base/strings/utf_string_conversions.h"
+#include "components/bookmarks/browser/bookmark_model.h"
+#include "components/ntp_snippets/bookmarks/bookmark_last_visit_utils.h"
+#include "components/ntp_snippets/content_suggestion.h"
+
+using bookmarks::BookmarkModel;
+using bookmarks::BookmarkNode;
+
+namespace {
+const int kMaxBookmarks = 10;
+const int kMaxBookmarkAgeInDays = 42;
+
+base::Time GetThresholdTime() {
+  return base::Time::Now() - base::TimeDelta::FromDays(kMaxBookmarkAgeInDays);
+}
+
+}  // namespace
+
+namespace ntp_snippets {
+
+BookmarkSuggestionsProvider::BookmarkSuggestionsProvider(
+    bookmarks::BookmarkModel* bookmark_model)
+    : ContentSuggestionsProvider({ContentSuggestionsCategory::BOOKMARKS}),
+      category_status_(ContentSuggestionsCategoryStatus::AVAILABLE_LOADING),
+      observer_(nullptr),
+      bookmark_model_(bookmark_model),
+      fetch_requested_(false),
+      end_of_list_last_visit_date_(GetThresholdTime()) {
+  bookmark_model_->AddObserver(this);
+}
+
+BookmarkSuggestionsProvider::~BookmarkSuggestionsProvider() {}
+
+// Inherited from KeyedService.
+void BookmarkSuggestionsProvider::Shutdown() {
+  bookmark_model_->RemoveObserver(this);
+  category_status_ = ContentSuggestionsCategoryStatus::NOT_PROVIDED;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Private methods
+
+void BookmarkSuggestionsProvider::SetObserver(
+    ContentSuggestionsProvider::Observer* observer) {
+  observer_ = observer;
+  if (observer)
+    FetchBookmarks();
+}
+
+ContentSuggestionsCategoryStatus BookmarkSuggestionsProvider::GetCategoryStatus(
+    ContentSuggestionsCategory category) {
+  return category_status_;
+}
+
+void BookmarkSuggestionsProvider::DismissSuggestion(
+    const std::string& suggestion_id) {
+  // TODO(jkrcal): Implement blacklisting bookmarks until they are next visited.
+  // Then also implement ClearDismissedSuggestionsForDebugging.
+}
+
+void BookmarkSuggestionsProvider::FetchSuggestionImage(
+    const std::string& suggestion_id,
+    const ImageFetchedCallback& callback) {
+  callback.Run(suggestion_id, gfx::Image());
+}
+
+void BookmarkSuggestionsProvider::ClearCachedSuggestionsForDebugging() {
+  // Ignored.
+}
+
+void BookmarkSuggestionsProvider::ClearDismissedSuggestionsForDebugging() {
+  // TODO(jkrcal): Implement when discarded suggestions are supported.
+}
+
+void BookmarkSuggestionsProvider::BookmarkModelLoaded(
+    bookmarks::BookmarkModel* model,
+    bool ids_reassigned) {
+  DCHECK_EQ(bookmark_model_, model);
+  if (fetch_requested_) {
+    fetch_requested_ = false;
+    FetchBookmarksInternal();
+  }
+}
+
+void BookmarkSuggestionsProvider::OnWillChangeBookmarkMetaInfo(
+    BookmarkModel* model,
+    const BookmarkNode* node) {
+  // Store the last visit date of the node that is about to change.
+  node_to_change_last_visit_date_ = GetLastVisitDateForBookmark(node);
+}
+
+void BookmarkSuggestionsProvider::BookmarkMetaInfoChanged(
+    BookmarkModel* model,
+    const BookmarkNode* node) {
+  base::Time time = GetLastVisitDateForBookmark(node);
+  if (time == node_to_change_last_visit_date_ ||
+      time < end_of_list_last_visit_date_)
+    return;
+
+  // Last visit date of a node has changed (and is relevant for the list), we
+  // should update the suggestions.
+  FetchBookmarks();
+}
+
+void BookmarkSuggestionsProvider::FetchBookmarksInternal() {
+  DCHECK(bookmark_model_->loaded());
+
+  NotifyStatusChanged(ContentSuggestionsCategoryStatus::AVAILABLE);
+  if (!observer_)
+    return;
+
+  std::vector<const BookmarkNode*> bookmarks = GetRecentlyVisitedBookmarks(
+      bookmark_model_, kMaxBookmarks, GetThresholdTime());
+
+  std::vector<ContentSuggestion> suggestions;
+  for (const BookmarkNode* bookmark : bookmarks) {
+    ContentSuggestion suggestion(
+        MakeUniqueID(ContentSuggestionsCategory::BOOKMARKS,
+                     bookmark->url().spec()),
+        bookmark->url());
+
+    // TODO(jkrcal): keep it in UTF16 when ContentSuggestion title adapts to it.
+    suggestion.set_title(base::UTF16ToUTF8(bookmark->GetTitle()));
+    suggestion.set_snippet_text(std::string());
+    suggestion.set_publish_date(GetLastVisitDateForBookmark(bookmark));
+    suggestion.set_publisher_name(bookmark->url().host());
+    suggestions.emplace_back(std::move(suggestion));
+  }
+
+  if (suggestions.empty())
+    end_of_list_last_visit_date_ = GetThresholdTime();
+  else
+    end_of_list_last_visit_date_ = suggestions.back().publish_date();
+
+  observer_->OnNewSuggestions(ContentSuggestionsCategory::BOOKMARKS,
+                              std::move(suggestions));
+}
+
+void BookmarkSuggestionsProvider::FetchBookmarks() {
+  if (bookmark_model_->loaded())
+    FetchBookmarksInternal();
+  else
+    fetch_requested_ = true;
+}
+
+void BookmarkSuggestionsProvider::NotifyStatusChanged(
+    ContentSuggestionsCategoryStatus new_status) {
+  if (category_status_ == new_status)
+    return;
+  category_status_ = new_status;
+
+  if (!observer_)
+    return;
+  observer_->OnCategoryStatusChanged(ContentSuggestionsCategory::BOOKMARKS,
+                                     new_status);
+}
+
+}  // namespace ntp_snippets