text: // Copyright (c) 2012 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 CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SERVICE_H_
  #define CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SERVICE_H_
  
  #include <string>
  
  #include "base/compiler_specific.h"
  #include "base/gtest_prod_util.h"
  #include "base/memory/scoped_ptr.h"
  #include "base/metrics/field_trial.h"
  #include "base/time.h"
  #include "chrome/browser/metrics/proto/study.pb.h"
  #include "chrome/browser/metrics/proto/trials_seed.pb.h"
  #include "chrome/browser/metrics/variations/variations_request_scheduler.h"
  #include "chrome/browser/web_resource/resource_request_allowed_notifier.h"
  #include "chrome/common/chrome_version_info.h"
  #include "googleurl/src/gurl.h"
  #include "net/url_request/url_fetcher_delegate.h"
  
  #if defined(OS_WIN)
  #include "chrome/browser/metrics/variations/variations_registry_syncer_win.h"
  #endif
  
  class PrefService;
  class PrefRegistrySimple;
  
  namespace chrome_variations {
  
  // Used to setup field trials based on stored variations seed data, and fetch
  // new seed data from the variations server.
  class VariationsService
      : public net::URLFetcherDelegate,
        public ResourceRequestAllowedNotifier::Observer {
   public:
    virtual ~VariationsService();
  
    // Creates field trials based on Variations Seed loaded from local prefs. If
    // there is a problem loading the seed data, all trials specified by the seed
    // may not be created.
    bool CreateTrialsFromSeed();
  
    // Calls FetchVariationsSeed once and repeats this periodically. See
    // implementation for details on the period. Must be called after
    // |CreateTrialsFromSeed|.
    void StartRepeatedVariationsSeedFetch();
  
    // Returns the variations server URL, which can vary if a command-line flag is
    // set and/or the variations restrict pref is set in |local_prefs|. Declared
    // static for test purposes.
    static GURL GetVariationsServerURL(PrefService* local_prefs);
  
  #if defined(OS_WIN)
    // Starts syncing Google Update Variation IDs with the registry.
    void StartGoogleUpdateRegistrySync();
  #endif
  
    // Exposed for testing.
    void SetCreateTrialsFromSeedCalledForTesting(bool called);
  
    // Exposed for testing.
    static std::string GetDefaultVariationsServerURLForTesting();
  
    // Register Variations related prefs in Local State.
    static void RegisterPrefs(PrefRegistrySimple* registry);
  
    // Factory method for creating a VariationsService.
    static VariationsService* Create(PrefService* local_state);
  
   protected:
    // Starts the fetching process once, where |OnURLFetchComplete| is called with
    // the response.
    virtual void DoActualFetch();
  
    // This constructor exists for injecting a mock notifier. It is meant for
    // testing only. This instance will take ownership of |notifier|.
    VariationsService(ResourceRequestAllowedNotifier* notifier,
                      PrefService* local_state);
  
   private:
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyChannel);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyLocale);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyPlatform);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyVersion);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyVersionWildcards);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyStartDate);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, DoNotFetchIfOffline);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, DoNotFetchIfOnlineToOnline);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, FetchOnReconnect);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, IsStudyExpired);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, LoadSeed);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, StoreSeed);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, ValidateStudy);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, SeedStoredWhenOKStatus);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, SeedNotStoredWhenNonOKStatus);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, ForceGroupWithFlag1);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, ForceGroupWithFlag2);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, ForceFirstGroupWithFlag);
    FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, DontChooseGroupWithFlag);
  
    // Creates the VariationsService with the given |local_state| prefs service.
    // Use the |Create| factory method to create a VariationsService.
    explicit VariationsService(PrefService* local_state);
  
    // Checks if prerequisites for fetching the Variations seed are met, and if
    // so, performs the actual fetch using |DoActualFetch|.
    void FetchVariationsSeed();
  
    // net::URLFetcherDelegate implementation:
    virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE;
  
    // ResourceRequestAllowedNotifier::Observer implementation:
    virtual void OnResourceRequestsAllowed() OVERRIDE;
  
    // Store the given seed data to the given local prefs. Note that |seed_data|
    // is assumed to be the raw serialized protobuf data stored in a string. It
    // will be Base64Encoded for storage. If the string is invalid or the encoding
    // fails, the |local_prefs| is left as is and the function returns false.
    bool StoreSeedData(const std::string& seed_data,
                       const base::Time& seed_date,
                       PrefService* local_prefs);
  
    // Returns whether |study| should be disabled according to its restriction
    // parameters. Uses |version_info| for min / max version checks,
    // |reference_date| for the start date check and |channel| for channel
    // checks.
    static bool ShouldAddStudy(const Study& study,
                               const chrome::VersionInfo& version_info,
                               const base::Time& reference_date,
                               chrome::VersionInfo::Channel channel);
  
    // Checks whether a study is applicable for the given |channel| per |filter|.
    static bool CheckStudyChannel(const Study_Filter& filter,
                                  chrome::VersionInfo::Channel channel);
  
    // Checks whether a study is applicable for the given |locale| per |filter|.
    static bool CheckStudyLocale(const chrome_variations::Study_Filter& filter,
                                 const std::string& locale);
  
    // Checks whether a study is applicable for the given |platform| per |filter|.
    static bool CheckStudyPlatform(const Study_Filter& filter,
                                   chrome_variations::Study_Platform platform);
  
    // Checks whether a study is applicable for the given version per |filter|.
    static bool CheckStudyVersion(const Study_Filter& filter,
                                  const std::string& version_string);
  
    // Checks whether a study is applicable for the given date/time per |filter|.
    static bool CheckStudyStartDate(const Study_Filter& filter,
                                    const base::Time& date_time);
  
    // Checks whether |study| is expired using the given date/time.
    static bool IsStudyExpired(const Study& study,
                               const base::Time& date_time);
  
    // Validates the sanity of |study| and computes the total probability.
    static bool ValidateStudyAndComputeTotalProbability(
        const Study& study,
        base::FieldTrial::Probability* total_probability);
  
    // Loads the Variations seed data from the given local prefs into |seed|. If
    // there is a problem with loading, the pref value is cleared and false is
    // returned. If successful, |seed| will contain the loaded data and true is
    // returned.
    bool LoadTrialsSeedFromPref(PrefService* local_prefs, TrialsSeed* seed);
  
    // Creates and registers a field trial from the |study| data. Disables the
    // trial if IsStudyExpired(study, reference_date) is true.
    void CreateTrialFromStudy(const Study& study,
                              const base::Time& reference_date);
  
    // Record the time of the most recent successful fetch.
    void RecordLastFetchTime();
  
    // The pref service used to store persist the variations seed.
    PrefService* local_state_;
  
    // Contains the scheduler instance that handles timing for requests to the
    // server. Initially NULL and instantiated when the initial fetch is
    // requested.
    scoped_ptr<VariationsRequestScheduler> request_scheduler_;
  
    // Contains the current seed request. Will only have a value while a request
    // is pending, and will be reset by |OnURLFetchComplete|.
    scoped_ptr<net::URLFetcher> pending_seed_request_;
  
    // The URL to use for querying the Variations server.
    GURL variations_server_url_;
  
    // Cached serial number from the most recently fetched Variations seed.
    std::string variations_serial_number_;
  
    // Tracks whether |CreateTrialsFromSeed| has been called, to ensure that
    // it gets called prior to |StartRepeatedVariationsSeedFetch|.
    bool create_trials_from_seed_called_;
  
    // Tracks whether the initial request to the variations server had completed.
    bool initial_request_completed_;
  
    // Helper class used to tell this service if it's allowed to make network
    // resource requests.
    scoped_ptr<ResourceRequestAllowedNotifier> resource_request_allowed_notifier_;
  
    // The start time of the last seed request. This is used to measure the
    // latency of seed requests. Initially zero.
    base::TimeTicks last_request_started_time_;
  
  #if defined(OS_WIN)
    // Helper that handles synchronizing Variations with the Registry.
    VariationsRegistrySyncer registry_syncer_;
  #endif
  };
  
  }  // namespace chrome_variations
  
  #endif  // CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SERVICE_H_
  