// Copyright 2014 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 CONTENT_BROWSER_BATTERY_STATUS_BATTERY_STATUS_SERVICE_H_
#define CONTENT_BROWSER_BATTERY_STATUS_BATTERY_STATUS_SERVICE_H_

#include "base/callback_list.h"
#include "base/memory/singleton.h"
#include "content/common/content_export.h"
#include "third_party/WebKit/public/platform/WebBatteryStatus.h"

namespace content {
class BatteryStatusManager;

class CONTENT_EXPORT BatteryStatusService {
 public:
  typedef base::Callback<void(const blink::WebBatteryStatus&)>
      BatteryUpdateCallback;
  typedef base::CallbackList<void(const blink::WebBatteryStatus&)>
      BatteryUpdateCallbackList;
  typedef BatteryUpdateCallbackList::Subscription BatteryUpdateSubscription;

  // Returns the BatteryStatusService singleton.
  static BatteryStatusService* GetInstance();

  // Adds a callback to receive battery status updates.
  // Must be called on the I/O thread.
  scoped_ptr<BatteryUpdateSubscription> AddCallback(
      const BatteryUpdateCallback& callback);

  // Gracefully clean-up.
  void Shutdown();

  // Injects a custom battery status manager for testing purposes.
  // This class takes ownership of the injected object.
  void SetBatteryManagerForTesting(BatteryStatusManager* test_battery_manager);

  // Returns callback to invoke when battery is changed. Used for testing.
  const BatteryUpdateCallback& GetUpdateCallbackForTesting() const;

 private:
  friend struct DefaultSingletonTraits<BatteryStatusService>;

  BatteryStatusService();
  virtual ~BatteryStatusService();

  // Updates current battery status and sends new status to interested
  // render processes. Can be called on any thread via a callback.
  void UpdateBatteryStatus(const blink::WebBatteryStatus& status);
  void NotifyConsumers(const blink::WebBatteryStatus& status);
  void ConsumersChanged();

  scoped_ptr<BatteryStatusManager> battery_fetcher_;
  BatteryUpdateCallbackList callback_list_;
  BatteryUpdateCallback update_callback_;
  blink::WebBatteryStatus status_;
  bool status_updated_;
  bool is_shutdown_;

  DISALLOW_COPY_AND_ASSIGN(BatteryStatusService);
};

}  // namespace content

#endif  // CONTENT_BROWSER_BATTERY_STATUS_BATTERY_STATUS_SERVICE_H_