// Copyright 2018 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_CHROME_FEATURE_LIST_CREATOR_H_
#define CHROME_BROWSER_METRICS_CHROME_FEATURE_LIST_CREATOR_H_

#include <memory>
#include <string>

#include "base/feature_list.h"
#include "base/memory/raw_ptr.h"
#include "base/no_destructor.h"
#include "base/types/pass_key.h"
#include "build/build_config.h"
#include "chrome/browser/chrome_browser_field_trials.h"
#include "chrome/browser/policy/chrome_browser_policy_connector.h"
#include "components/metrics_services_manager/metrics_services_manager.h"
#include "components/prefs/pref_service.h"

namespace ash {
class ChromeBrowserMainPartsAsh;
}  // namespace ash

namespace installer {
class InitialPreferences;
}  // namespace installer

namespace network_time {
class NetworkTimeTracker;
}  // namespace network_time

class ChromeMetricsServicesManagerClient;

// The ChromeFeatureListCreator creates the FeatureList and classes required for
// setting up field trials, e.g. VariationsService, MetricsServicesManager etc.
// before the full browser loop starts. The |local_state| is instantiated, and
// its ownership will be taken by BrowserProcessImpl when the full browser
// starts. Note: On ChromeOS, this class depends on BrowserPolicyConnectorAsh
// whose behavior depends on DBusThreadManager being initialized.
class ChromeFeatureListCreator {
 public:
  // The instance of ChromeFeatureListCreator gets constructed on first access
  // through this API and is never destroyed. This construction is generally a
  // no-op until CreateFeatureList() is called.
  static ChromeFeatureListCreator* GetInstance();

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

  ~ChromeFeatureListCreator();

  // Initializes all necessary parameters to create the feature list and calls
  // base::FeatureList::SetInstance() to set the global instance.
  void CreateFeatureList();

  // Sets the application locale and verifies (via a CHECK) that it matches
  // what was used when creating field trials.
  void SetApplicationLocale(const std::string& locale);

  // Gets the MetricsServicesManagerClient* used in this class.
  metrics_services_manager::MetricsServicesManagerClient*
  GetMetricsServicesManagerClient();

  // Passes ownership of the |local_state_| to the caller.
  std::unique_ptr<PrefService> TakePrefService();

  // Passes ownership of the |metrics_services_manager_| to the caller.
  std::unique_ptr<metrics_services_manager::MetricsServicesManager>
  TakeMetricsServicesManager();

  // Passes ownership of the |browser_policy_connector_| to the caller.
  std::unique_ptr<policy::ChromeBrowserPolicyConnector>
  TakeChromeBrowserPolicyConnector();

  // Passes ownership of the |network_time_tracker_| to the caller.
  std::unique_ptr<network_time::NetworkTimeTracker> TakeNetworkTimeTracker();

#if !BUILDFLAG(IS_ANDROID) && !BUILDFLAG(IS_CHROMEOS)
  std::unique_ptr<installer::InitialPreferences> TakeInitialPrefs();
#endif

  PrefService* local_state() { return local_state_.get(); }
  policy::ChromeBrowserPolicyConnector* browser_policy_connector() {
    return browser_policy_connector_.get();
  }
  network_time::NetworkTimeTracker* network_time_tracker() {
    CHECK(network_time_tracker_);
    return network_time_tracker_.get();
  }
  const std::string& actual_locale() { return actual_locale_; }

  ChromeBrowserFieldTrials* browser_field_trials() {
    return browser_field_trials_.get();
  }

#if BUILDFLAG(IS_CHROMEOS)
  // Get the FeatureList::Accessor, clearing immediately -- this must only be
  // used by ChromeBrowserMainPartsAsh.
  std::unique_ptr<base::FeatureList::Accessor> GetAndClearFeatureListAccessor(
      base::PassKey<ash::ChromeBrowserMainPartsAsh> key) {
    return std::move(cros_feature_list_accessor_);
  }
#endif  // BUILDFLAG(IS_CHROMEOS)

 private:
  friend class base::NoDestructor<ChromeFeatureListCreator>;

  ChromeFeatureListCreator();

  void CreatePrefService();
  void ConvertFlagsToSwitches();
  void CreateNetworkTimeTracker();

  // Sets up the field trials and related initialization. Call only after
  // about:flags have been converted to switches.
  void SetUpFieldTrials();

  void CreateMetricsServices();

  // Imports variations initial preference any preferences (to local state)
  // needed for first run. This is always called and early outs if not
  // first-run.
  void SetupInitialPrefs();

  // Must be destroyed after |local_state_|.
  std::unique_ptr<policy::ChromeBrowserPolicyConnector>
      browser_policy_connector_;

  // If TakePrefService() is called, the caller will take the ownership
  // of this variable. Stop using this variable afterwards.
  std::unique_ptr<PrefService> local_state_;

  // The locale used by the application. It is set when initializing the
  // ResouceBundle.
  std::string actual_locale_;

  // This is owned by |metrics_services_manager_| but we need to expose it.
  raw_ptr<ChromeMetricsServicesManagerClient, AcrossTasksDanglingUntriaged>
      metrics_services_manager_client_;

  std::unique_ptr<network_time::NetworkTimeTracker> network_time_tracker_;

  std::unique_ptr<metrics_services_manager::MetricsServicesManager>
      metrics_services_manager_;

  std::unique_ptr<ChromeBrowserFieldTrials> browser_field_trials_;

#if !BUILDFLAG(IS_ANDROID) && !BUILDFLAG(IS_CHROMEOS)
  std::unique_ptr<installer::InitialPreferences> installer_initial_prefs_;
#endif

#if BUILDFLAG(IS_CHROMEOS)
  // On ChromeOS, the platform needs to be able to access the
  // FeatureList::Accessor. On other platforms, this API should not be used.
  std::unique_ptr<base::FeatureList::Accessor> cros_feature_list_accessor_;
#endif  // BUILDFLAG(IS_CHROMEOS)
};

#endif  // CHROME_BROWSER_METRICS_CHROME_FEATURE_LIST_CREATOR_H_