// Copyright 2024 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_USER_EDUCATION_RECENT_SESSION_TRACKER_H_
#define CHROME_BROWSER_USER_EDUCATION_RECENT_SESSION_TRACKER_H_

#include <optional>

#include "base/callback_list.h"
#include "base/functional/callback_forward.h"
#include "base/memory/raw_ref.h"
#include "base/time/time.h"
#include "chrome/browser/user_education/browser_user_education_storage_service.h"
#include "components/user_education/common/session/user_education_session_manager.h"
#include "components/user_education/common/user_education_storage_service.h"

// Tracks recent sessions by the current user on this device.
// Used to help understand usage across populations and to provide additional
// input for user education experience triggers.
//
// Data is stored in `RecentSessionDataStorageService`, which is typically part
// of `BrowserUserEducationStorageService`.
class RecentSessionTracker {
 public:
  static constexpr int kMaxRecentSessionRecords = 30;
  static constexpr base::TimeDelta kMaxRecentSessionRetention = base::Days(30);

  // Callback that provides updated recent session data to observers.
  using RecentSessionsUpdatedCallback =
      base::RepeatingCallback<void(const RecentSessionData&)>;

  RecentSessionTracker(
      user_education::UserEducationSessionProvider& session_provider,
      user_education::UserEducationStorageService& feature_promo_storage,
      RecentSessionDataStorageService& recent_session_storage);
  RecentSessionTracker(const RecentSessionTracker&) = delete;
  void operator=(const RecentSessionTracker&) = delete;
  ~RecentSessionTracker();

  // Add a callback that observes when recent sessions have been updated.
  // Will be called immediately if there has already been an update since the
  // current application started.
  base::CallbackListSubscription AddRecentSessionsUpdatedCallback(
      RecentSessionsUpdatedCallback callback);

  const std::optional<RecentSessionData>& recent_session_data_for_testing()
      const {
    return recent_session_data_;
  }

 private:
  // Called when a new User Education session starts.
  void OnSessionStart();

  const base::CallbackListSubscription subscription_;
  const raw_ref<user_education::UserEducationStorageService>
      feature_promo_storage_;
  const raw_ref<RecentSessionDataStorageService> recent_session_storage_;
  base::RepeatingCallbackList<RecentSessionsUpdatedCallback::RunType>
      recent_sessions_updated_callback_;

  // Cache this data so that observers have access to it.
  std::optional<RecentSessionData> recent_session_data_;
};

#endif  // CHROME_BROWSER_USER_EDUCATION_RECENT_SESSION_TRACKER_H_