// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROME_BROWSER_METRICS_DESKTOP_SESSION_DURATION_AUDIBLE_CONTENTS_TRACKER_H_
#define CHROME_BROWSER_METRICS_DESKTOP_SESSION_DURATION_AUDIBLE_CONTENTS_TRACKER_H_

#include <set>

#include "base/memory/raw_ptr.h"
#include "base/scoped_observation.h"
#include "chrome/browser/ui/browser_window/public/browser_collection_observer.h"
#include "chrome/browser/ui/tabs/tab_strip_model_observer.h"

class GlobalBrowserCollection;

namespace metrics {

// BrowserCollectionObserver / TabStripModelObserver used for tracking audio
// status.
// TODO(chrisha): Migrate this entire thing to use RecentlyAudibleHelper
// notifications rather then TabStripModel notifications.
// https://crbug.com/41390955
class AudibleContentsTracker : public BrowserCollectionObserver,
                               public TabStripModelObserver {
 public:
  // Interface for an observer of the AudibleContentsTracker. The only client
  // of this class is the DesktopSessionDurationTracker, but an observer
  // interface has been created for ease of testing.
  class Observer {
   public:
    Observer() = default;

    Observer(const Observer&) = delete;
    Observer& operator=(const Observer&) = delete;

    virtual ~Observer() = default;

    // Invoked when a first audio source starts playing after a period of no
    // audio sources.
    virtual void OnAudioStart() = 0;

    // Invoked when all audio sources stop playing.
    virtual void OnAudioEnd() = 0;
  };

  // Creates an audible contents tracker that dispatches its messages to the
  // provided |observer|.
  explicit AudibleContentsTracker(Observer* observer);

  AudibleContentsTracker(const AudibleContentsTracker&) = delete;
  AudibleContentsTracker& operator=(const AudibleContentsTracker&) = delete;

  ~AudibleContentsTracker() override;

 private:
  // BrowserCollectionObserver:
  void OnBrowserCreated(BrowserWindowInterface* browser) override;

  // TabStripModelObserver:
  void OnTabStripModelChanged(
      TabStripModel* tab_strip_model,
      const TabStripModelChange& change,
      const TabStripSelectionChange& selection) override;
  void OnTabChangedAt(tabs::TabInterface* tab,
                      TabChangeType change_type) override;

  // Used for managing audible_contents_, and invoking OnAudioStart and
  // OnAudioEnd callbacks.
  void AddAudibleWebContents(content::WebContents* web_contents);
  void RemoveAudibleWebContents(content::WebContents* web_contents);

  raw_ptr<Observer> observer_;

  // The set of WebContents that are currently playing audio.
  std::set<raw_ptr<content::WebContents, SetExperimental>> audible_contents_;

  // TODO(crbug.com/495682308): remove when the AudibleContentsTracker is no
  // longer outliving the GlobalBrowserCollection it observes.
  base::ScopedObservation<GlobalBrowserCollection,
                          BrowserCollectionObserver>::LeakedDanglingUntriaged
      browser_collection_observation_{this};
};

}  // namespace metrics

#endif  // CHROME_BROWSER_METRICS_DESKTOP_SESSION_DURATION_AUDIBLE_CONTENTS_TRACKER_H_