text: // Copyright 2018 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 COMPONENTS_NTP_TILES_CUSTOM_LINKS_MANAGER_IMPL_H_
  #define COMPONENTS_NTP_TILES_CUSTOM_LINKS_MANAGER_IMPL_H_
  
  #include <utility>
  #include <vector>
  
  #include "base/macros.h"
  #include "base/memory/weak_ptr.h"
  #include "base/optional.h"
  #include "base/scoped_observation.h"
  #include "components/history/core/browser/history_service.h"
  #include "components/history/core/browser/history_service_observer.h"
  #include "components/ntp_tiles/custom_links_manager.h"
  #include "components/ntp_tiles/custom_links_store.h"
  #include "components/ntp_tiles/ntp_tile.h"
  #include "components/prefs/pref_change_registrar.h"
  
  class PrefService;
  
  namespace user_prefs {
  class PrefRegistrySyncable;
  }  // namespace user_prefs
  
  namespace ntp_tiles {
  
  // Non-test implementation of the CustomLinksManager interface.
  class CustomLinksManagerImpl : public CustomLinksManager,
                                 public history::HistoryServiceObserver {
   public:
    // Restores the previous state of |current_links_| from prefs.
    CustomLinksManagerImpl(PrefService* prefs,
                           // Can be nullptr in unittests.
                           history::HistoryService* history_service);
  
    ~CustomLinksManagerImpl() override;
  
    // CustomLinksManager implementation.
    bool Initialize(const NTPTilesVector& tiles) override;
    void Uninitialize() override;
    bool IsInitialized() const override;
  
    const std::vector<Link>& GetLinks() const override;
  
    bool AddLink(const GURL& url, const std::u16string& title) override;
    bool UpdateLink(const GURL& url,
                    const GURL& new_url,
                    const std::u16string& new_title) override;
    bool ReorderLink(const GURL& url, size_t new_pos) override;
    bool DeleteLink(const GURL& url) override;
    bool UndoAction() override;
  
    base::CallbackListSubscription RegisterCallbackForOnChanged(
        base::RepeatingClosure callback) override;
  
    // Register preferences used by this class.
    static void RegisterProfilePrefs(
        user_prefs::PrefRegistrySyncable* user_prefs);
  
   private:
    void ClearLinks();
  
    // Stores the current list to the profile's preferences. Does not notify
    // |OnPreferenceChanged|.
    void StoreLinks();
  
    // Returns an iterator into |custom_links_|.
    std::vector<Link>::iterator FindLinkWithUrl(const GURL& url);
  
    // history::HistoryServiceObserver implementation.
    // Deletes any Most Visited links whose URL is in |deletion_info|. Clears
    // |previous_links_|. Does not delete entries expired by HistoryService.
    void OnURLsDeleted(history::HistoryService* history_service,
                       const history::DeletionInfo& deletion_info) override;
    void HistoryServiceBeingDeleted(
        history::HistoryService* history_service) override;
  
    // Called when the current list of links and/or initialization state in
    // PrefService is modified. Saves the new set of links in |current_links_|
    // and notifies |closure_list_|.
    void OnPreferenceChanged();
  
    PrefService* const prefs_;
    CustomLinksStore store_;
    std::vector<Link> current_links_;
    // The state of the current list of links before the last action was
    // performed.
    base::Optional<std::vector<Link>> previous_links_;
  
    // List of closures to be invoked when custom links are updated by outside
    // sources.
    base::RepeatingClosureList closure_list_;
  
    // Observer for the HistoryService.
    base::ScopedObservation<history::HistoryService,
                            history::HistoryServiceObserver>
        history_service_observation_{this};
  
    // Observer for Chrome sync changes to |prefs::kCustomLinksList| and
    // |prefs::kCustomLinksInitialized|.
    PrefChangeRegistrar pref_change_registrar_;
    // Used to ignore notifications from |pref_change_registrar_| that we trigger
    // ourselves when updating the preferences.
    bool updating_preferences_ = false;
  
    base::WeakPtrFactory<CustomLinksManagerImpl> weak_ptr_factory_{this};
  
    DISALLOW_COPY_AND_ASSIGN(CustomLinksManagerImpl);
  };
  
  }  // namespace ntp_tiles
  
  #endif  // COMPONENTS_NTP_TILES_CUSTOM_LINKS_MANAGER_IMPL_H_
  