[NTPSnippets] Show all downloads on the NTP (3/3): Downloads provider.

chrome/browser/ntp_snippets/download_suggestions_provider.h

+// 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.
+
+#ifndef CHROME_BROWSER_NTP_SNIPPETS_DOWNLOAD_SUGGESTIONS_PROVIDER_H_
+#define CHROME_BROWSER_NTP_SNIPPETS_DOWNLOAD_SUGGESTIONS_PROVIDER_H_
+
+#include <set>
+#include <string>
+#include <vector>
+
+#include "base/callback_forward.h"
+#include "base/memory/ptr_util.h"
+#include "base/memory/weak_ptr.h"
+#include "components/ntp_snippets/category.h"
+#include "components/ntp_snippets/category_factory.h"
+#include "components/ntp_snippets/category_status.h"
+#include "components/ntp_snippets/content_suggestion.h"
+#include "components/ntp_snippets/content_suggestions_provider.h"
+#include "components/ntp_snippets/offline_pages/offline_page_proxy.h"
+#include "content/public/browser/download_manager.h"
+
+class PrefRegistrySimple;
+class PrefService;
+
+namespace gfx {
+class Image;
+}
+
+namespace offline_pages {
+struct OfflinePageItem;
+}
+
+// Provides download content suggestions from the offline pages model (obtaining
+// the data through OfflinePageProxy) and the download manager (obtaining the
+// data through DownloadManager and each DownloadItem). Offline page related
+// downloads are referred to as offline page downloads, while the remaining
+// downloads (e.g. images, music, books) are called asset downloads.
+class DownloadSuggestionsProvider
+    : public ntp_snippets::ContentSuggestionsProvider,
+      public ntp_snippets::OfflinePageProxy::Observer,
+      public content::DownloadManager::Observer,
+      public content::DownloadItem::Observer {
+ public:
+  DownloadSuggestionsProvider(
+      ContentSuggestionsProvider::Observer* observer,
+      ntp_snippets::CategoryFactory* category_factory,
+      scoped_refptr<ntp_snippets::OfflinePageProxy> offline_page_proxy,
+      content::DownloadManager* download_manager,
+      PrefService* pref_service,
+      bool download_manager_ui_enabled);
+  ~DownloadSuggestionsProvider() override;
+
+  // ContentSuggestionsProvider implementation.
+  ntp_snippets::CategoryStatus GetCategoryStatus(
+      ntp_snippets::Category category) override;
+  ntp_snippets::CategoryInfo GetCategoryInfo(
+      ntp_snippets::Category category) override;
+  void DismissSuggestion(
+      const ntp_snippets::ContentSuggestion::ID& suggestion_id) override;
+  void FetchSuggestionImage(
+      const ntp_snippets::ContentSuggestion::ID& suggestion_id,
+      const ImageFetchedCallback& callback) override;
+  void ClearHistory(
+      base::Time begin,
+      base::Time end,
+      const base::Callback<bool(const GURL& url)>& filter) override;
+  void ClearCachedSuggestions(ntp_snippets::Category category) override;
+  void GetDismissedSuggestionsForDebugging(
+      ntp_snippets::Category category,
+      const DismissedSuggestionsCallback& callback) override;
+  void ClearDismissedSuggestionsForDebugging(
+      ntp_snippets::Category category) override;
+
+  static void RegisterProfilePrefs(PrefRegistrySimple* registry);
+
+ private:
+  friend class DownloadSuggestionsProviderTest;
+
+  void GetAllPagesCallbackForGetDismissedSuggestions(
+      const DismissedSuggestionsCallback& callback,
+      const std::vector<offline_pages::OfflinePageItem>& offline_pages) const;
+
+  // OfflinePageProxy::Observer implementation.
+  void OfflinePageModelChanged(
+      const std::vector<offline_pages::OfflinePageItem>& offline_pages)
+      override;
+  void OfflinePageDeleted(int64_t offline_id,
+                          const offline_pages::ClientId& client_id) override;
+
+  // content::DownloadManager::Observer implementation.
+  void OnDownloadCreated(content::DownloadManager* manager,
+                         content::DownloadItem* item) override;
+  void ManagerGoingDown(content::DownloadManager* manager) override;
+
+  // content::DownloadItem::Observer implementation.
+  void OnDownloadUpdated(content::DownloadItem* item) override;
+  void OnDownloadOpened(content::DownloadItem* item) override;
+  void OnDownloadRemoved(content::DownloadItem* item) override;
+  void OnDownloadDestroyed(content::DownloadItem* item) override;
+
+  // Updates the |category_status_| of the |provided_category_| and notifies the
+  // |observer_|, if necessary.
+  void NotifyStatusChanged(ntp_snippets::CategoryStatus new_status);
+
+  // Requests all offline pages and after asynchronously obtaining the result,
+  // prunes dismissed IDs and caches some most recent items. If |notify| is
+  // true, notifies |ContentSuggestionsProvider::Observer| about them.
+  void AsynchronouslyFetchOfflinePagesDownloads(bool notify);
+
+  // Retrieves all asset downloads, prunes dismissed IDs and caches some most
+  // recent items, but does not notify |ContentSuggestionsProvider::Observer|
+  // about them.
+  void FetchAssetsDownloads();
+
+  // Retrieves both offline page and asset downloads, updates the internal cache
+  // and notifies |ContentSuggestionsProvider::Observer|.
+  void AsynchronouslyFetchAllDownloadsAndSubmitSuggestions();
+
+  // Takes |kMaxSuggestionsCount| the most recent cached suggestions and
+  // notifies |ContentSuggestionsProvider::Observer| about them.
+  void SubmitContentSuggestions();
+
+  // Converts an OfflinePageItem to a ContentSuggestion for the
+  // |provided_category_|.
+  ntp_snippets::ContentSuggestion ConvertOfflinePage(
+      const offline_pages::OfflinePageItem& offline_page) const;
+
+  // Converts DownloadItem to a ContentSuggestion for the |provided_category_|.
+  ntp_snippets::ContentSuggestion ConvertDownloadItem(
+      const content::DownloadItem& download_item) const;
+
+  // Adds |item| to the internal asset download cache if all of the following
+  // holds:
+  // - the download is completed;
+  // - its suggestion has not been dismissed;
+  // - there are less than |kMaxSuggestionsCount| items cached or the oldest
+  //     cached item is older than the current item (the oldest item is removed
+  //     then);
+  // - the item is not present in the cache yet.
+  // Returns |true| if the item has been added.
+  bool CacheAssetDownloadIfNeeded(const content::DownloadItem* item);
+
+  // Removes item corresponding to |suggestion_id| either from offline pages or
+  // asset download cache (depends on the |suggestion_id|). Returns |false| if
+  // there is no corresponding item in the cache and so nothing has been
+  // removed.
+  bool RemoveSuggestionFromCacheIfPresent(
+      const ntp_snippets::ContentSuggestion::ID& suggestion_id);
+
+  // Removes item corresponding to |suggestion_id| from cache and fetches all
+  // corresponding downloads to update the cache if there may be any not in
+  // cache.
+  void RemoveSuggestionFromCacheAndRetrieveMoreIfNeeded(
+      const ntp_snippets::ContentSuggestion::ID& suggestion_id);
+
+  // Processes a list of offline pages (assuming that these are all the offline
+  // pages that currently exist), prunes dismissed IDs and updates internal
+  // cache. If |notify| is true, notifies
+  // |ContentSuggestionsProvider::Observer|.
+  void UpdateOfflinePagesCache(
+      bool notify,
+      const std::vector<offline_pages::OfflinePageItem>& all_offline_pages);
+
+  // Fires the |OnSuggestionInvalidated| event for the suggestion corresponding
+  // to the given |id_within_category| and clears it from the dismissed IDs
+  // list, if necessary.
+  void InvalidateSuggestion(const std::string& id_within_category);
+
+  // Reads dismissed IDs related to asset downloads from prefs.
+  std::set<std::string> ReadAssetDismissedIDsFromPrefs() const;
+
+  // Writes |dismissed_ids| into prefs for asset downloads.
+  void StoreAssetDismissedIDsToPrefs(
+      const std::set<std::string>& dismissed_ids);
+
+  // Reads dismissed IDs related to offline page downloads from prefs.
+  std::set<std::string> ReadOfflinePageDismissedIDsFromPrefs() const;
+
+  // Writes |dismissed_ids| into prefs for offline page downloads.
+  void StoreOfflinePageDismissedIDsToPrefs(
+      const std::set<std::string>& dismissed_ids);
+
+  // Reads from prefs dismissed IDs related to either offline page or asset
+  // downloads (given by |for_offline_page_downloads|).
+  std::set<std::string> ReadDismissedIDsFromPrefs(
+      bool for_offline_page_downloads) const;
+
+  // Writes |dismissed_ids| into prefs for either offline page or asset
+  // downloads (given by |for_offline_page_downloads|).
+  void StoreDismissedIDsToPrefs(bool for_offline_page_downloads,
+                                const std::set<std::string>& dismissed_ids);
+
+  void UnregisterDownloadItemObservers();
+
+  ntp_snippets::CategoryStatus category_status_;
+  const ntp_snippets::Category provided_category_;
+  scoped_refptr<ntp_snippets::OfflinePageProxy> offline_page_proxy_;
+  content::DownloadManager* download_manager_;
+
+  PrefService* pref_service_;
+
+  // Cached offline page downloads. If there are not enough asset downloads, all
+  // of these could be shown (they are the most recently visited, not dismissed
+  // and not invalidated). Order is undefined. If the model has less than
+  // |kMaxSuggestionsCount| offline pages, then all of them which satisfy the
+  // criteria above are cached, otherwise only |kMaxSuggestionsCount|.
+  std::vector<offline_pages::OfflinePageItem> cached_offline_page_downloads_;
+  // Cached asset downloads. If there are not enough offline page downloads, all
+  // of these could be shown (they are the most recently downloaded, not
+  // dismissed and not invalidated). Order is undefined. If the model has less
+  // than |kMaxSuggestionsCount| asset downloads, then all of them which satisfy
+  // the criteria above are cached, otherwise only |kMaxSuggestionsCount|.
+  std::vector<const content::DownloadItem*> cached_asset_downloads_;
+
+  // Whether the Download Manager UI is enabled, in which case the More button
+  // for the Downloads section can redirect there.
+  const bool download_manager_ui_enabled_;
+
+  base::WeakPtrFactory<DownloadSuggestionsProvider> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(DownloadSuggestionsProvider);
+};
+
+#endif  // CHROME_BROWSER_NTP_SNIPPETS_DOWNLOAD_SUGGESTIONS_PROVIDER_H_