// 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 COMPONENTS_OMNIBOX_BROWSER_OMNIBOX_EVENT_GLOBAL_TRACKER_H_
#define COMPONENTS_OMNIBOX_BROWSER_OMNIBOX_EVENT_GLOBAL_TRACKER_H_

#include <memory>

#include "base/callback_list.h"

namespace base {
template <typename T>
struct DefaultSingletonTraits;
}  // namespace base

struct OmniboxLog;

// Omnibox code tracks events on a per-user-context basis, but there are
// several clients who need to observe these events for all user contexts
// (e.g., all Profiles in the //chrome embedder).  This class serves as an
// intermediary to bridge the gap: omnibox code calls the
// OmniboxEventGlobalTracker singleton on an event of interest, and it then
// forwards the event to its registered observers.
class OmniboxEventGlobalTracker {
 public:
  using OnURLOpenedCallbackList =
      base::RepeatingCallbackList<void(OmniboxLog*)>;
  using OnURLOpenedCallback = OnURLOpenedCallbackList::CallbackType;

  // Returns the instance of OmniboxEventGlobalTracker.
  static OmniboxEventGlobalTracker* GetInstance();

  // Registers |cb| to be invoked when user open an URL from the omnibox.
  std::unique_ptr<OnURLOpenedCallbackList::Subscription> RegisterCallback(
      const OnURLOpenedCallback& cb);

  // Called to notify all registered callbacks that an URL was opened from
  // the omnibox.
  void OnURLOpened(OmniboxLog* log);

 private:
  friend struct base::DefaultSingletonTraits<OmniboxEventGlobalTracker>;

  OmniboxEventGlobalTracker();
  ~OmniboxEventGlobalTracker();
  OmniboxEventGlobalTracker(const OmniboxEventGlobalTracker&) = delete;
  OmniboxEventGlobalTracker& operator=(const OmniboxEventGlobalTracker&) =
      delete;

  OnURLOpenedCallbackList on_url_opened_callback_list_;
};

#endif  // COMPONENTS_OMNIBOX_BROWSER_OMNIBOX_EVENT_GLOBAL_TRACKER_H_