// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COMPONENTS_OPTIMIZATION_GUIDE_CORE_HINTS_HINTS_MANAGER_H_
#define COMPONENTS_OPTIMIZATION_GUIDE_CORE_HINTS_HINTS_MANAGER_H_

#include <memory>
#include <optional>
#include <string>
#include <vector>

#include "base/containers/flat_map.h"
#include "base/containers/flat_set.h"
#include "base/containers/lru_cache.h"
#include "base/feature_list.h"
#include "base/functional/callback_forward.h"
#include "base/gtest_prod_util.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/weak_ptr.h"
#include "base/sequence_checker.h"
#include "base/task/sequenced_task_runner.h"
#include "base/time/clock.h"
#include "base/timer/timer.h"
#include "components/optimization_guide/core/filters/hints_component_info.h"
#include "components/optimization_guide/core/filters/optimization_hints_component_observer.h"
#include "components/optimization_guide/core/hints/hints_fetcher.h"
#include "components/optimization_guide/core/hints/insertion_ordered_set.h"
#include "components/optimization_guide/core/hints/optimization_guide_decision.h"
#include "components/optimization_guide/core/hints/push_notification_manager.h"
#include "components/optimization_guide/core/optimization_guide_features.h"
#include "components/optimization_guide/proto/hints.pb.h"

class OptimizationGuideLogger;
class OptimizationGuideNavigationData;
class OptimizationGuideTestAppInterfaceWrapper;
class PrefService;

namespace network {
class SharedURLLoaderFactory;
}  // namespace network

namespace signin {
class IdentityManager;
}  // namespace signin

namespace optimization_guide {
class HintCache;
class HintsFetcherFactory;
class OptimizationFilter;
class OptimizationGuideStore;
class OptimizationMetadata;
enum class OptimizationTypeDecision;
class StoreUpdateData;
class TabUrlProvider;
class TopHostProvider;

// Whether batch updates are enabled for active tabs and top hosts.
// TODO: crbug.com/421924837 - This only exists to allow tests to exercise this
// behavior on platforms where it is disabled. Fix tests and remove this.
BASE_DECLARE_FEATURE(kHintsBatchUpdateForActiveTabsAndTopHosts);

// The max number of concurrent fetches to the remote Optimization Guide
// Service that should be allowed for batch updates.
inline constexpr size_t kMaxConcurrentBatchUpdateFetches = 20;

// The max number of concurrent fetches to the remote Optimization Guide
// Service that should be allowed for navigations
// TODO: crbug.com/421924837 - This is only a param because some tests are
// hardcoded to a assume a value that doesn't match the real one. Fix that and
// remove this.
BASE_DECLARE_FEATURE_PARAM(size_t, kHintsMaxConcurrentNavigationFetches);

extern const char kOptimizationGuideServiceGetHintsDefaultURL[];
// The local histogram used to record that the component hints are stored in
// the cache and are ready for use.
extern const char kLoadedHintLocalHistogramString[];

class HintsManager : public OptimizationHintsComponentObserver,
                     public PushNotificationManager::Delegate {
 public:
  HintsManager(
      bool is_off_the_record,
      const std::string& application_locale,
      PrefService* pref_service,
      base::WeakPtr<OptimizationGuideStore> hint_store,
      TopHostProvider* top_host_provider,
      TabUrlProvider* tab_url_provider,
      scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory,
      std::unique_ptr<PushNotificationManager> push_notification_manager,
      signin::IdentityManager* identity_manager,
      OptimizationGuideLogger* optimization_guide_logger);

  ~HintsManager() override;

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

  // Unhooks the observer to |optimization_guide_service_|.
  void Shutdown();

  // Returns the OptimizationGuideDecision from |optimization_type_decision|.
  static OptimizationGuideDecision
  GetOptimizationGuideDecisionFromOptimizationTypeDecision(
      OptimizationTypeDecision optimization_type_decision);

  // OptimizationHintsComponentObserver implementation:
  void OnHintsComponentAvailable(const HintsComponentInfo& info) override;

  // |next_update_closure| is called the next time OnHintsComponentAvailable()
  // is called and the corresponding hints have been updated.
  void ListenForNextUpdateForTesting(base::OnceClosure next_update_closure);

  // Registers the optimization types that have the potential for hints to be
  // called by consumers of the Optimization Guide.
  void RegisterOptimizationTypes(
      const std::vector<proto::OptimizationType>& optimization_types);

  // Returns the optimization types that are registered.
  base::flat_set<proto::OptimizationType> registered_optimization_types()
      const {
    return registered_optimization_types_;
  }

  // Returns whether there is an optimization allowlist loaded for
  // |optimization_type|.
  bool HasLoadedOptimizationAllowlist(
      proto::OptimizationType optimization_type);
  // Returns whether there is an optimization blocklist loaded for
  // |optimization_type|.
  bool HasLoadedOptimizationBlocklist(
      proto::OptimizationType optimization_type);

  // Returns the OptimizationTypeDecision based on the given parameters.
  // |optimization_metadata| will be populated, if applicable.
  OptimizationTypeDecision CanApplyOptimization(
      const GURL& navigation_url,
      proto::OptimizationType optimization_type,
      OptimizationMetadata* optimization_metadata);

  // Returns the OptimizationTypeDecision based on the given parameters.
  // |optimization_metadata| will be populated, if applicable. The decision will
  // be computed on |url_keyed_hint| or |host_keyed_hint| if possible.
  // |skip_cache| will be used to determine if the decision is unknown.
  OptimizationTypeDecision CanApplyOptimization(
      bool is_on_demand_request,
      const GURL& url,
      proto::OptimizationType optimization_type,
      const proto::Hint* url_keyed_hint,
      const proto::Hint* host_keyed_hint,
      bool skip_cache,
      OptimizationMetadata* optimization_metadata);

  // Invokes |callback| with the decision for the URL contained in |url| and
  // |optimization_type|, when sufficient information has been collected to
  // make the decision.
  virtual void CanApplyOptimization(
      const GURL& url,
      optimization_guide::proto::OptimizationType optimization_type,
      optimization_guide::OptimizationGuideDecisionCallback callback);

  // Invokes |callback| with the decision for |navigation_url| and
  // |optimization_type|, when sufficient information has been collected by
  // |this| to make the decision. Virtual for testing.
  virtual void CanApplyOptimizationAsync(
      const GURL& navigation_url,
      proto::OptimizationType optimization_type,
      OptimizationGuideDecisionCallback callback);

  // Invokes |callback| with the decision for all types contained in
  // |optimization_types| for each URL contained in |urls|, when sufficient
  // information has been collected to make decisions. If information is not
  // available for all URLs, the remote Optimization Guide Service will be
  // contacted to fetch information for those URLs using |request_context|.
  void CanApplyOptimizationOnDemand(
      const std::vector<GURL>& urls,
      const base::flat_set<proto::OptimizationType>& optimization_types,
      proto::RequestContext request_context,
      OnDemandOptimizationGuideDecisionRepeatingCallback callback,
      std::optional<proto::RequestContextMetadata> request_context_metadata);

  // Clears all fetched hints from |hint_cache_|.
  void ClearFetchedHints();

  // Clears the host-keyed fetched hints from |hint_cache_|, both the persisted
  // and in memory ones.
  void ClearHostKeyedHints();

  // Overrides |hints_fetcher_factory| for testing.
  void SetHintsFetcherFactoryForTesting(
      std::unique_ptr<HintsFetcherFactory> hints_fetcher_factory);

  // Overrides |clock_| for testing.
  void SetClockForTesting(const base::Clock* clock);

  // Notifies |this| that a navigation with |navigation_data| started.
  // |callback| is run when the request has finished regardless of whether there
  // was actually a hint for that load or not. The callback can be used as a
  // signal for tests.
  void OnNavigationStartOrRedirect(
      OptimizationGuideNavigationData* navigation_data,
      base::OnceClosure callback);

  // Notifies |this| that a navigation with redirect chain
  // |navigation_redirect_chain| has finished.
  void OnNavigationFinish(const std::vector<GURL>& navigation_redirect_chain);

  // Notifies |this| that deferred startup has occurred. This enables |this|
  // to execute background tasks while minimizing the risk of regressing
  // metrics such as jank.
  void OnDeferredStartup();

  // Fetch the hints for the given URLs with the provided |request_context|.
  void FetchHintsForURLs(const std::vector<GURL>& target_urls,
                         proto::RequestContext request_context);

  // PushNotificationManager::Delegate:
  void RemoveFetchedEntriesByHintKeys(
      base::OnceClosure on_success,
      proto::KeyRepresentation key_representation,
      const base::flat_set<std::string>& hint_keys) override;

  // Returns true if |this| is allowed to fetch hints at the navigation time for
  // |url|.
  bool IsAllowedToFetchNavigationHints(const GURL& url);

  // Returns the hint cache for |this|.
  HintCache* hint_cache();

  // Returns the persistent store for |this|.
  base::WeakPtr<OptimizationGuideStore> hint_store();

  // Returns the push notification manager for |this|. May be nullptr;
  PushNotificationManager* push_notification_manager();

  // Add hints to the cache with the provided metadata. For testing only.
  void AddHintForTesting(const GURL& url,
                         proto::OptimizationType optimization_type,
                         const std::optional<OptimizationMetadata>& metadata);

  // Add hints to the cache for the provided optimization types. For testing
  // only.
  void AddHintWithMultipleOptimizationsForTesting(
      const GURL& url,
      const std::vector<optimization_guide::proto::OptimizationType>&
          optimization_types);

  // Add hints to the cache for the provided optimization types and metadata.
  // For testing only.
  void AddHintWithMultipleOptimizationsForTesting(
      const GURL& url,
      const std::vector<
          std::pair<optimization_guide::proto::OptimizationType,
                    std::optional<optimization_guide::OptimizationMetadata>>>&
          optimization_types_and_metadata);

  // Add hints to be returned for on-demand hints requests.
  void AddOnDemandHintForTesting(
      const GURL& url,
      proto::OptimizationType optimization_type,
      const OptimizationGuideDecisionWithMetadata& decision);

 private:
  friend class ::OptimizationGuideTestAppInterfaceWrapper;
  friend class HintsManagerTest;

  FRIEND_TEST_ALL_PREFIXES(HintsManagerFetchingTest, BatchUpdateFetcherCleanup);
  FRIEND_TEST_ALL_PREFIXES(
      HintsManagerFetchingTest,
      PageInsightsHubContextRequestContextMetadataPihSentGetHintsRequest);
  FRIEND_TEST_ALL_PREFIXES(
      HintsManagerFetchingTest,
      PageInsightsHubContextNotSentRequestContextMetadataPihSentGetHintsRequest);
  FRIEND_TEST_ALL_PREFIXES(
      HintsManagerFetchingTest,
      PageInsightsHubContextRequestContextMetadataNotPihSentGetHintsRequest);
  FRIEND_TEST_ALL_PREFIXES(
      HintsManagerFetchingTest,
      PageInsightsHubContextRequestContextMetadataPihNotSentGetHintsRequest);

  // Processes the optimization filters contained in the hints component.
  void ProcessOptimizationFilters(
      const google::protobuf::RepeatedPtrField<proto::OptimizationFilter>&
          allowlist_optimization_filters,
      const google::protobuf::RepeatedPtrField<proto::OptimizationFilter>&
          blocklist_optimization_filters);

  // Process a set of optimization filters.
  //
  // |is_allowlist| will be used to ensure that the filters are either uses as
  // allowlists or blocklists.
  void ProcessOptimizationFilterSet(const google::protobuf::RepeatedPtrField<
                                        proto::OptimizationFilter>& filters,
                                    bool is_allowlist);

  // Callback run after the hint cache is fully initialized. At this point,
  // the HintsManager is ready to process hints.
  void OnHintCacheInitialized();

  // Updates the cache with the latest hints sent by the Component Updater.
  void UpdateComponentHints(base::OnceClosure update_closure,
                            std::unique_ptr<StoreUpdateData> update_data,
                            std::unique_ptr<proto::Configuration> config);

  // Called when the hints have been fully updated with the latest hints from
  // the Component Updater. This is used as a signal during tests.
  void OnComponentHintsUpdated(base::OnceClosure update_closure,
                               bool hints_updated);

  // Initiates fetching of hints - either immediately over via a timer.
  void InitiateHintsFetchScheduling();

  // Returns the URLs that are currently in the active tab model that do not
  // have a hint available in |hint_cache_|.
  const std::vector<GURL> GetActiveTabURLsToRefresh();

  // Schedules |active_tabs_hints_fetch_timer_| to fire based on the last time a
  // fetch attempt was made.
  void ScheduleActiveTabsHintsFetch();

  bool HasPersonalizableTypesRegistered();

  // Called to make a request to fetch hints from the remote Optimization Guide
  // Service. Used to fetch hints for origins frequently visited by the user and
  // URLs open in the active tab model.
  void FetchHintsForActiveTabs();

  // Called when the hints for active tabs have been fetched from the remote
  // Optimization Guide Service and are ready for parsing. This is used when
  // fetching hints in batch mode.
  void OnHintsForActiveTabsFetched(
      const base::flat_set<std::string>& hosts_fetched,
      const base::flat_set<GURL>& urls_fetched,
      std::optional<std::unique_ptr<proto::GetHintsResponse>>
          get_hints_response);

  // Called when the batch update hints have been fetched from the remote
  // Optimization Guide Service and are ready for parsing. This is used when
  // fetching hints on demand or from SRP.
  void OnBatchUpdateHintsFetched(
      int32_t request_id,
      proto::RequestContext request_context,
      const base::flat_set<std::string>& hosts_fetched,
      const base::flat_set<GURL>& urls_fetched,
      const base::flat_set<GURL>& urls_for_callback,
      const base::flat_set<proto::OptimizationType>& optimization_types,
      OnDemandOptimizationGuideDecisionRepeatingCallback callback,
      std::optional<std::unique_ptr<proto::GetHintsResponse>>
          get_hints_response);

  // Called when information is ready such that we can invoke any callbacks that
  // require returning decisions to consumer features.
  //
  // TODO(crbug.com/40208585): Clean this up when we clean up some of the
  // existing interfaces.
  void OnBatchUpdateHintsStored(
      const base::flat_set<GURL>& urls_fetched,
      const base::flat_set<proto::OptimizationType>& optimization_types,
      OnDemandOptimizationGuideDecisionRepeatingCallback callback);

  // Creates a hints fetcher and stores it in |batch_update_hints_fetchers_| and
  // returns the request ID associated with the fetch. It is expected to call
  // `CleanUpBatchUpdateHintsFetcher` with the returned request ID once the
  // fetch has finished.
  std::pair<int32_t, HintsFetcher*> CreateAndTrackBatchUpdateHintsFetcher();

  // Called to inform |this| that the batch fetcher with |request_id| is no
  // longer needed removes the request from |batch_update_hints_fetchers_|
  void CleanUpBatchUpdateHintsFetcher(int32_t request_id);

  // Fetch batch hints for all `hosts` and `urls` for the `optimization_types`
  // with the `request_context`. `access_token` can be empty which indicates no
  // auth is specified.
  void FetchOptimizationGuideServiceBatchHints(
      const InsertionOrderedSet<std::string>& hosts,
      const InsertionOrderedSet<GURL>& urls,
      const base::flat_set<optimization_guide::proto::OptimizationType>&
          optimization_types,
      optimization_guide::proto::RequestContext request_context,
      OnDemandOptimizationGuideDecisionRepeatingCallback callback,
      std::optional<proto::RequestContextMetadata> request_context_metadata,
      const std::string& access_token);

  // Returns decisions for |url| and |optimization_types| based on what's cached
  // locally.
  base::flat_map<proto::OptimizationType, OptimizationGuideDecisionWithMetadata>
  GetDecisionsWithCachedInformationForURLAndOptimizationTypes(
      const GURL& url,
      const base::flat_set<proto::OptimizationType>& optimization_types);

  // Invokes |callback| for |url| and |optimization_types| based on what is
  // cached on device.
  void InvokeOnDemandHintsCallbackForURL(
      const GURL& url,
      const base::flat_set<proto::OptimizationType>& optimization_types,
      OnDemandOptimizationGuideDecisionRepeatingCallback callback);

  // Invokes |callback| for |requested_urls| and |optimization_types| based on
  // what is contained in |response|.
  void ProcessAndInvokeOnDemandHintsCallbacks(
      std::unique_ptr<proto::GetHintsResponse> response,
      const base::flat_set<GURL> requested_urls,
      const base::flat_set<proto::OptimizationType> optimization_types,
      OnDemandOptimizationGuideDecisionRepeatingCallback callback);

  // Called when the hints for a navigation have been fetched from the remote
  // Optimization Guide Service and are ready for parsing. This is used when
  // fetching hints in real-time. |navigation_url| is the URL associated with
  // the navigation handle that initiated the fetch.
  // |page_navigation_urls_requested| contains the URLs that were requested  by
  // |this| to be fetched. |page_navigation_hosts_requested| contains the hosts
  // that were requested by |this| to be fetched.
  void OnPageNavigationHintsFetched(
      base::WeakPtr<OptimizationGuideNavigationData> navigation_data_weak_ptr,
      const std::optional<GURL>& navigation_url,
      const base::flat_set<GURL>& page_navigation_urls_requested,
      const base::flat_set<std::string>& page_navigation_hosts_requested,
      std::optional<std::unique_ptr<proto::GetHintsResponse>>
          get_hints_response);

  // Called when the fetched hints have been stored in |hint_cache| and are
  // ready to be used. This is used when hints were fetched in batch mode.
  void OnFetchedActiveTabsHintsStored();

  // Called when the fetched hints have been stored in |hint_cache| and are
  // ready to be used. This is used when hints were fetched in real-time.
  // |navigation_url| is the URL associated with the navigation handle that
  // initiated the fetch. |page_navigation_hosts_requested| contains the hosts
  // whose hints should be loaded into memory when invoked.
  void OnFetchedPageNavigationHintsStored(
      base::WeakPtr<OptimizationGuideNavigationData> navigation_data_weak_ptr,
      const std::optional<GURL>& navigation_url,
      const base::flat_set<std::string>& page_navigation_hosts_requested);

  // Returns true if there is a fetch currently in-flight for |navigation_url|.
  bool IsHintBeingFetchedForNavigation(const GURL& navigation_url);

  // Cleans up the hints fetcher for |navigation_url|, if applicable.
  void CleanUpFetcherForNavigation(const GURL& navigation_url);

  // Returns the time when a hints fetch request was last attempted.
  base::Time GetLastHintsFetchAttemptTime() const;

  // Sets the time when a hints fetch was last attempted to |last_attempt_time|.
  void SetLastHintsFetchAttemptTime(base::Time last_attempt_time);

  // Called when the request to load a hint has completed.
  void OnHintLoaded(base::OnceClosure callback,
                    const proto::Hint* loaded_hint) const;

  // Loads the hint if available for navigation to |url|.
  // |callback| is run when the request has finished regardless of whether there
  // was actually a hint for that load or not. The callback can be used as a
  // signal for tests.
  void LoadHintForURL(const GURL& url, base::OnceClosure callback);

  // Loads the hint for |host| if available.
  // |callback| is run when the request has finished regardless of whether there
  // was actually a hint for that |host| or not. The callback can be used as a
  // signal for tests.
  void LoadHintForHost(const std::string& host, base::OnceClosure callback);

  // Returns whether there is an optimization type to fetch for. Will return
  // false if no optimization types are registered or if all registered
  // optimization types are covered by optimization filters.
  bool HasOptimizationTypeToFetchFor();

  // Creates a hints fetch for navigation represented by |navigation_data|, if
  // it is allowed. The fetch will include the host and URL of the
  // |navigation_data| if the associated hints for each are not already in the
  // cache.
  void MaybeFetchHintsForNavigation(
      base::WeakPtr<OptimizationGuideNavigationData> navigation_data_weak_ptr,
      const std::string& access_token);

  // If an entry for |navigation_url| is contained in |registered_callbacks_|,
  // it will load the hint for |navigation_url|'s host and upon completion, will
  // invoke the registered callbacks for |navigation_url|.
  void PrepareToInvokeRegisteredCallbacks(const GURL& navigation_url);

  // Invokes the registered callbacks for |navigation_url|, if applicable.
  void OnReadyToInvokeRegisteredCallbacks(const GURL& navigation_url);

  // Whether all information was available to make a decision for
  // |navigation_url| and |optimization type}.
  bool HasAllInformationForDecisionAvailable(
      const GURL& navigation_url,
      proto::OptimizationType optimization_type);

  HintsFetcherFactory* GetHintsFetcherFactory();

  // Returns the number of batch update hints fetches initiated.
  //
  // Exposed here for testing.
  int32_t num_batch_update_hints_fetches_initiated() const {
    return batch_update_hints_fetcher_request_id_;
  }

  // Returns the current active tabs batch update hints fetcher.
  //
  // Exposed here for testing.
  HintsFetcher* active_tabs_batch_update_hints_fetcher() const {
    return active_tabs_batch_update_hints_fetcher_.get();
  }

  // The logger that plumbs the debug logs to the optimization guide
  // internals page. Not owned. Guaranteed to outlive |this|, since the logger
  // and |this| are owned by the optimization guide keyed service.
  raw_ptr<OptimizationGuideLogger> optimization_guide_logger_;

  // The information of the latest component delivered by
  // |optimization_guide_service_|.
  std::optional<HintsComponentInfo> hints_component_info_;

  // The component version that failed to process in the last session, if
  // applicable.
  const std::optional<base::Version> failed_component_version_;

  // The version of the component that is currently being processed.
  std::optional<base::Version> currently_processing_component_version_;

  // The set of optimization types that have been registered with the hints
  // manager.
  //
  // Should only be read and modified on the UI thread.
  base::flat_set<proto::OptimizationType> registered_optimization_types_;

  // The set of optimization types that the component specified by
  // |component_info_| has optimization filters for.
  base::flat_set<proto::OptimizationType> optimization_types_with_filter_;

  // A map from optimization type to the host filter that holds the allowlist
  // for that type.
  base::flat_map<proto::OptimizationType, std::unique_ptr<OptimizationFilter>>
      allowlist_optimization_filters_;

  // A map from optimization type to the host filter that holds the blocklist
  // for that type.
  base::flat_map<proto::OptimizationType, std::unique_ptr<OptimizationFilter>>
      blocklist_optimization_filters_;

  // A map from URL to a map of callbacks keyed by their optimization type.
  base::flat_map<GURL,
                 base::flat_map<proto::OptimizationType,
                                std::vector<OptimizationGuideDecisionCallback>>>
      registered_callbacks_;

  // Whether |this| was created for an off the record profile.
  const bool is_off_the_record_;

  // The current applcation locale of Chrome.
  const std::string application_locale_;

  // A reference to the PrefService for this profile. Not owned.
  raw_ptr<PrefService> pref_service_ = nullptr;

  // The hint cache that holds both hints received from the component and
  // fetched from the remote Optimization Guide Service.
  std::unique_ptr<HintCache> hint_cache_;

  // For testing only. Stores hints to be returned for on-demand hint requests.
  base::flat_map<GURL,
                 base::flat_map<proto::OptimizationType,
                                OptimizationGuideDecisionWithMetadata>>
      on_demand_hints_for_testing_;

  // The fetcher that handles making requests for hints for active tabs from
  // the remote Optimization Guide Service.
  std::unique_ptr<HintsFetcher> active_tabs_batch_update_hints_fetcher_;

  // A map from request ID to the fetcher that handles making requests for hints
  // for multiple hosts from the remote Optimization Guide Service.
  base::LRUCache<int32_t, std::unique_ptr<HintsFetcher>>
      batch_update_hints_fetchers_;
  int32_t batch_update_hints_fetcher_request_id_ = 0;

  // A cache keyed by navigation URL to the fetcher making a request for a hint
  // for that URL and/or host to the remote Optimization Guide Service that
  // keeps track of when an entry has been placed in the cache.
  base::LRUCache<GURL, std::unique_ptr<HintsFetcher>>
      page_navigation_hints_fetchers_;

  // The factory used to create hints fetchers. It is mostly used to create
  // new fetchers for use under the page navigation context, but will also be
  // used to create the initial fetcher for the batch update context.
  std::unique_ptr<HintsFetcherFactory> hints_fetcher_factory_;

  // The top host provider that can be queried. Not owned.
  raw_ptr<TopHostProvider> top_host_provider_ = nullptr;

  // The tab URL provider that can be queried. Not owned.
  raw_ptr<TabUrlProvider> tab_url_provider_ = nullptr;

  // The timer used to schedule fetching hints from the remote Optimization
  // Guide Service.
  base::OneShotTimer active_tabs_hints_fetch_timer_;

  // The class that handles push notification processing and informs |this| of
  // what to do through the implemented Delegate above.
  std::unique_ptr<PushNotificationManager> push_notification_manager_;

  // Unowned IdentityManager for fetching access tokens. Could be null for
  // incognito profiles.
  const raw_ptr<signin::IdentityManager> identity_manager_;

  // The clock used to schedule fetching from the remote Optimization Guide
  // Service.
  raw_ptr<const base::Clock> clock_;

  // Whether fetched hints should be cleared when the store is initialized
  // because a new optimization type was registered.
  bool should_clear_hints_for_new_type_ = false;

  // Used in testing to subscribe to an update event in this class.
  base::OnceClosure next_update_closure_;

  // Background thread where hints processing should be performed.
  //
  // Warning: This must be the last object, so it is destroyed (and flushed)
  // first. This will prevent use-after-free issues where the background thread
  // would access other member variables after they have been destroyed.
  scoped_refptr<base::SequencedTaskRunner> background_task_runner_;

  // Requests contexts for which personalized metadata should be enabled.
  const features::RequestContextSet allowed_contexts_for_personalized_metadata_;

  // Optimization types for which proactive personalization is enabled.
  const features::OptimizationTypeSet
      allowed_optimization_types_for_proactive_personalization_;

  SEQUENCE_CHECKER(sequence_checker_);

  // Used to get |weak_ptr_| to self.
  base::WeakPtrFactory<HintsManager> weak_ptr_factory_{this};

  // Wrapper that immediately invokes HintsFetcher for the purposes of fetching
  // hints for urls.
  void FetchHintsForURLsInternal(
      const InsertionOrderedSet<std::string>& target_hosts,
      const InsertionOrderedSet<GURL>& target_urls,
      optimization_guide::proto::RequestContext request_context,
      const std::string& access_token);

  // Wrapper that immediately invokes HintsFetcher for the purposes of fetching
  // hints for active tabs.
  void FetchHintsForActiveTabsInternal(
      const std::vector<std::string>& top_hosts,
      const std::vector<GURL>& active_tab_urls_to_refresh,
      optimization_guide::proto::RequestContext request_context,
      HintsFetchedCallback hints_fetched_callback,
      const std::string& access_token);
};

// Overrides the Hints Protobuf that would come from the component updater. If
// the value of this switch is invalid, regular hint processing is used.
// The value of this switch should be a base64 encoding of a binary
// Configuration message, found in optimization_guide's hints.proto. Providing a
// valid value to this switch causes Chrome startup to block on hints parsing.
inline constexpr char kHintsProtoOverrideSwitch[] =
    "optimization_guide_hints_override";

// Overrides the hints fetch scheduling and delay, causing a hints fetch
// immediately on start up using the TopHostProvider. This is meant for testing.
inline constexpr char kFetchHintsOverrideTimerSwitch[] =
    "optimization-guide-fetch-hints-override-timer";

// Purges the store of all hints before loading any new hints on start up.
inline constexpr char kPurgeHintsStoreSwitch[] =
    "purge-optimization-guide-store";

// Disables fetching of hints in real-time at the time of navigation start.
// Meant for testing only.
inline constexpr char
    kDisableFetchingHintsAtNavigationStartForTestingSwitch[] =
        "disable-fetching-hints-at-navigation-start";

// Attempts to parse a base64 encoded Optimization Guide Configuration proto
// from the command line. If no proto is given or if it is encoded incorrectly,
// nullptr is returned.
std::unique_ptr<proto::Configuration>
ParseComponentConfigFromCommandLine();

}  // namespace optimization_guide

#endif  // COMPONENTS_OPTIMIZATION_GUIDE_CORE_HINTS_HINTS_MANAGER_H_