// Copyright 2015 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_EXTENSIONS_API_SETTINGS_PRIVATE_SETTINGS_PRIVATE_EVENT_ROUTER_H_
#define CHROME_BROWSER_EXTENSIONS_API_SETTINGS_PRIVATE_SETTINGS_PRIVATE_EVENT_ROUTER_H_

#include <memory>

#include "base/macros.h"
#include "chrome/browser/chromeos/settings/cros_settings.h"
#include "chrome/browser/extensions/api/settings_private/prefs_util.h"
#include "components/keyed_service/core/keyed_service.h"
#include "components/prefs/pref_change_registrar.h"
#include "extensions/browser/event_router.h"

namespace content {
class BrowserContext;
}

namespace extensions {

class SettingsPrivateDelegate;

// This is an event router that will observe listeners to pref changes on the
// appropriate pref service(s) and notify listeners on the JavaScript
// settingsPrivate API.
class SettingsPrivateEventRouter : public KeyedService,
                                   public EventRouter::Observer {
 public:
  static SettingsPrivateEventRouter* Create(
      content::BrowserContext* browser_context);
  ~SettingsPrivateEventRouter() override;

 protected:
  explicit SettingsPrivateEventRouter(content::BrowserContext* context);

  // KeyedService overrides:
  void Shutdown() override;

  // EventRouter::Observer overrides:
  void OnListenerAdded(const EventListenerInfo& details) override;
  void OnListenerRemoved(const EventListenerInfo& details) override;

  // This registrar monitors for user prefs changes.
  PrefChangeRegistrar user_prefs_registrar_;

  // This registrar monitors for local state changes.
  PrefChangeRegistrar local_state_registrar_;

 private:
  // Decide if we should listen for pref changes or not. If there are any
  // JavaScript listeners registered for the onPrefsChanged event, then we
  // want to register for change notification from the PrefChangeRegistrar.
  // Otherwise, we want to unregister and not be listening for pref changes.
  void StartOrStopListeningForPrefsChanges();

  void OnPreferenceChanged(const std::string& pref_name);

  PrefChangeRegistrar* FindRegistrarForPref(const std::string& pref_name);

  using SubscriptionMap =
      std::map<std::string,
               std::unique_ptr<chromeos::CrosSettings::ObserverSubscription>>;
  SubscriptionMap cros_settings_subscription_map_;

  content::BrowserContext* context_;
  bool listening_;

  std::unique_ptr<PrefsUtil> prefs_util_;

  DISALLOW_COPY_AND_ASSIGN(SettingsPrivateEventRouter);
};

}  // namespace extensions

#endif  // CHROME_BROWSER_EXTENSIONS_API_SETTINGS_PRIVATE_SETTINGS_PRIVATE_EVENT_ROUTER_H_