firebase-ios-sdk/FirebaseRemoteConfig/Sources/FIRRemoteConfig.m

/*
 * Copyright 2019 Google
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#import "FirebaseRemoteConfig/Sources/Public/FirebaseRemoteConfig/FIRRemoteConfig.h"

#import "FirebaseABTesting/Sources/Private/FirebaseABTestingInternal.h"
#import "FirebaseCore/Sources/Private/FirebaseCoreInternal.h"
#import "FirebaseRemoteConfig/Sources/FIRRemoteConfigComponent.h"
#import "FirebaseRemoteConfig/Sources/Private/FIRRemoteConfig_Private.h"
#import "FirebaseRemoteConfig/Sources/Private/RCNConfigFetch.h"
#import "FirebaseRemoteConfig/Sources/Private/RCNConfigSettings.h"
#import "FirebaseRemoteConfig/Sources/RCNConfigConstants.h"
#import "FirebaseRemoteConfig/Sources/RCNConfigContent.h"
#import "FirebaseRemoteConfig/Sources/RCNConfigDBManager.h"
#import "FirebaseRemoteConfig/Sources/RCNConfigExperiment.h"
#import "FirebaseRemoteConfig/Sources/RCNConfigValue_Internal.h"
#import "FirebaseRemoteConfig/Sources/RCNDevice.h"
#import "FirebaseRemoteConfig/Sources/RCNPersonalization.h"

/// Remote Config Error Domain.
/// TODO: Rename according to obj-c style for constants.
NSString *const FIRRemoteConfigErrorDomain = @"com.google.remoteconfig.ErrorDomain";
/// Remote Config Error Info End Time Seconds;
NSString *const FIRRemoteConfigThrottledEndTimeInSecondsKey = @"error_throttled_end_time_seconds";
/// Minimum required time interval between fetch requests made to the backend.
static NSString *const kRemoteConfigMinimumFetchIntervalKey = @"_rcn_minimum_fetch_interval";
/// Timeout value for waiting on a fetch response.
static NSString *const kRemoteConfigFetchTimeoutKey = @"_rcn_fetch_timeout";

/// Listener for the get methods.
typedef void (^FIRRemoteConfigListener)(NSString *_Nonnull, NSDictionary *_Nonnull);

@implementation FIRRemoteConfigSettings

- (instancetype)init {
  self = [super init];
  if (self) {
    _minimumFetchInterval = RCNDefaultMinimumFetchInterval;
    _fetchTimeout = RCNHTTPDefaultConnectionTimeout;
  }
  return self;
}

@end

@implementation FIRRemoteConfig {
  /// All the config content.
  RCNConfigContent *_configContent;
  RCNConfigDBManager *_DBManager;
  RCNConfigSettings *_settings;
  RCNConfigFetch *_configFetch;
  RCNConfigExperiment *_configExperiment;
  dispatch_queue_t _queue;
  NSString *_appName;
  NSMutableArray *_listeners;
}

static NSMutableDictionary<NSString *, NSMutableDictionary<NSString *, FIRRemoteConfig *> *>
    *RCInstances;

+ (nonnull FIRRemoteConfig *)remoteConfigWithApp:(FIRApp *_Nonnull)firebaseApp {
  return [FIRRemoteConfig remoteConfigWithFIRNamespace:FIRNamespaceGoogleMobilePlatform
                                                   app:firebaseApp];
}

+ (nonnull FIRRemoteConfig *)remoteConfigWithFIRNamespace:(NSString *_Nonnull)firebaseNamespace {
  if (![FIRApp isDefaultAppConfigured]) {
    FIRLogError(kFIRLoggerRemoteConfig, @"I-RCN000047",
                @"FIRApp not configured. Please make sure you have called [FIRApp configure]");
    // TODO: Maybe throw an exception here? That'd be a breaking change though, but at this point
    // RC can't work as expected.
  }

  return [FIRRemoteConfig remoteConfigWithFIRNamespace:firebaseNamespace app:[FIRApp defaultApp]];
}

+ (nonnull FIRRemoteConfig *)remoteConfigWithFIRNamespace:(NSString *_Nonnull)firebaseNamespace
                                                      app:(FIRApp *_Nonnull)firebaseApp {
  // Use the provider to generate and return instances of FIRRemoteConfig for this specific app and
  // namespace. This will ensure the app is configured before Remote Config can return an instance.
  id<FIRRemoteConfigProvider> provider =
      FIR_COMPONENT(FIRRemoteConfigProvider, firebaseApp.container);
  return [provider remoteConfigForNamespace:firebaseNamespace];
}

+ (FIRRemoteConfig *)remoteConfig {
  // If the default app is not configured at this point, warn the developer.
  if (![FIRApp isDefaultAppConfigured]) {
    FIRLogError(kFIRLoggerRemoteConfig, @"I-RCN000047",
                @"FIRApp not configured. Please make sure you have called [FIRApp configure]");
    // TODO: Maybe throw an exception here? That'd be a breaking change though, but at this point
    // RC can't work as expected.
  }

  return [FIRRemoteConfig remoteConfigWithFIRNamespace:FIRNamespaceGoogleMobilePlatform
                                                   app:[FIRApp defaultApp]];
}

/// Singleton instance of serial queue for queuing all incoming RC calls.
+ (dispatch_queue_t)sharedRemoteConfigSerialQueue {
  static dispatch_once_t onceToken;
  static dispatch_queue_t sharedRemoteConfigQueue;
  dispatch_once(&onceToken, ^{
    sharedRemoteConfigQueue =
        dispatch_queue_create(RCNRemoteConfigQueueLabel, DISPATCH_QUEUE_SERIAL);
  });
  return sharedRemoteConfigQueue;
}

/// Designated initializer
- (instancetype)initWithAppName:(NSString *)appName
                     FIROptions:(FIROptions *)options
                      namespace:(NSString *)FIRNamespace
                      DBManager:(RCNConfigDBManager *)DBManager
                  configContent:(RCNConfigContent *)configContent
                      analytics:(nullable id<FIRAnalyticsInterop>)analytics {
  self = [super init];
  if (self) {
    _appName = appName;
    _DBManager = DBManager;
    // The fully qualified Firebase namespace is namespace:firappname.
    _FIRNamespace = [NSString stringWithFormat:@"%@:%@", FIRNamespace, appName];

    // Initialize RCConfigContent if not already.
    _configContent = configContent;
    _settings = [[RCNConfigSettings alloc] initWithDatabaseManager:_DBManager
                                                         namespace:_FIRNamespace
                                                   firebaseAppName:appName
                                                       googleAppID:options.googleAppID];

    FIRExperimentController *experimentController = [FIRExperimentController sharedInstance];
    _configExperiment = [[RCNConfigExperiment alloc] initWithDBManager:_DBManager
                                                  experimentController:experimentController];
    /// Serial queue for read and write lock.
    _queue = [FIRRemoteConfig sharedRemoteConfigSerialQueue];

    // Initialize with default config settings.
    [self setDefaultConfigSettings];
    _configFetch = [[RCNConfigFetch alloc] initWithContent:_configContent
                                                 DBManager:_DBManager
                                                  settings:_settings
                                                 analytics:analytics
                                                experiment:_configExperiment
                                                     queue:_queue
                                                 namespace:_FIRNamespace
                                                   options:options];

    [_settings loadConfigFromMetadataTable];

    if (analytics) {
      _listeners = [[NSMutableArray alloc] init];
      RCNPersonalization *personalization =
          [[RCNPersonalization alloc] initWithAnalytics:analytics];
      [self addListener:^(NSString *key, NSDictionary *config) {
        [personalization logArmActive:key config:config];
      }];
    }
  }
  return self;
}

// Initialize with default config settings.
- (void)setDefaultConfigSettings {
  // Set the default config settings.
  self->_settings.fetchTimeout = RCNHTTPDefaultConnectionTimeout;
  self->_settings.minimumFetchInterval = RCNDefaultMinimumFetchInterval;
}

- (void)ensureInitializedWithCompletionHandler:
    (nonnull FIRRemoteConfigInitializationCompletion)completionHandler {
  __weak FIRRemoteConfig *weakSelf = self;
  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
    FIRRemoteConfig *strongSelf = weakSelf;
    if (!strongSelf) {
      return;
    }
    BOOL initializationSuccess = [self->_configContent initializationSuccessful];
    NSError *error = nil;
    if (!initializationSuccess) {
      error = [[NSError alloc]
          initWithDomain:FIRRemoteConfigErrorDomain
                    code:FIRRemoteConfigErrorInternalError
                userInfo:@{NSLocalizedDescriptionKey : @"Timed out waiting for database load."}];
    }
    completionHandler(error);
  });
}

/// Adds a listener that will be called whenever one of the get methods is called.
/// @param listener Function that takes in the parameter key and the config.
- (void)addListener:(nonnull FIRRemoteConfigListener)listener {
  @synchronized(_listeners) {
    [_listeners addObject:listener];
  }
}

- (void)callListeners:(NSString *)key config:(NSDictionary *)config {
  @synchronized(_listeners) {
    for (FIRRemoteConfigListener listener in _listeners) {
      dispatch_async(_queue, ^{
        listener(key, config);
      });
    }
  }
}

#pragma mark - fetch

- (void)fetchWithCompletionHandler:(FIRRemoteConfigFetchCompletion)completionHandler {
  dispatch_async(_queue, ^{
    [self fetchWithExpirationDuration:self->_settings.minimumFetchInterval
                    completionHandler:completionHandler];
  });
}

- (void)fetchWithExpirationDuration:(NSTimeInterval)expirationDuration
                  completionHandler:(FIRRemoteConfigFetchCompletion)completionHandler {
  FIRRemoteConfigFetchCompletion completionHandlerCopy = nil;
  if (completionHandler) {
    completionHandlerCopy = [completionHandler copy];
  }
  [_configFetch fetchConfigWithExpirationDuration:expirationDuration
                                completionHandler:completionHandlerCopy];
}

#pragma mark - fetchAndActivate

- (void)fetchAndActivateWithCompletionHandler:
    (FIRRemoteConfigFetchAndActivateCompletion)completionHandler {
  __weak FIRRemoteConfig *weakSelf = self;
  FIRRemoteConfigFetchCompletion fetchCompletion = ^(FIRRemoteConfigFetchStatus fetchStatus,
                                                     NSError *fetchError) {
    FIRRemoteConfig *strongSelf = weakSelf;
    if (!strongSelf) {
      return;
    }
    // Fetch completed. We are being called on the main queue.
    // If fetch is successful, try to activate the fetched config
    if (fetchStatus == FIRRemoteConfigFetchStatusSuccess && !fetchError) {
      [strongSelf
          activateFromFetchAndActivate:true
                        withCompletion:^(BOOL changed, NSError *_Nullable activateError) {
                          if (completionHandler) {
                            FIRRemoteConfigFetchAndActivateStatus status =
                                activateError
                                    ? FIRRemoteConfigFetchAndActivateStatusSuccessUsingPreFetchedData
                                    : FIRRemoteConfigFetchAndActivateStatusSuccessFetchedFromRemote;
                            dispatch_async(dispatch_get_main_queue(), ^{
                              completionHandler(status, nil);
                            });
                          }
                        }];
    } else if (completionHandler) {
      FIRRemoteConfigFetchAndActivateStatus status =
          fetchStatus == FIRRemoteConfigFetchStatusSuccess
              ? FIRRemoteConfigFetchAndActivateStatusSuccessUsingPreFetchedData
              : FIRRemoteConfigFetchAndActivateStatusError;
      dispatch_async(dispatch_get_main_queue(), ^{
        completionHandler(status, fetchError);
      });
    }
  };
  [self fetchWithCompletionHandler:fetchCompletion];
}

#pragma mark - apply

typedef void (^FIRRemoteConfigActivateChangeCompletion)(BOOL changed, NSError *_Nullable error);

- (void)activateWithCompletion:(FIRRemoteConfigActivateChangeCompletion)completion {
  [self activateFromFetchAndActivate:false withCompletion:completion];
}

- (void)activateFromFetchAndActivate:(BOOL)isFetchAndActivate
                      withCompletion:(FIRRemoteConfigActivateChangeCompletion)completion {
  __weak FIRRemoteConfig *weakSelf = self;
  void (^applyBlock)(void) = ^(void) {
    FIRRemoteConfig *strongSelf = weakSelf;
    if (!strongSelf) {
      NSError *error = [NSError errorWithDomain:FIRRemoteConfigErrorDomain
                                           code:FIRRemoteConfigErrorInternalError
                                       userInfo:@{@"ActivationFailureReason" : @"Internal Error."}];
      if (completion) {
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
          completion(NO, error);
        });
      }
      FIRLogError(kFIRLoggerRemoteConfig, @"I-RCN000068", @"Internal error activating config.");
      return;
    }
    // Check if the last fetched config has already been activated. Fetches with no data change are
    // ignored.
    if (strongSelf->_settings.lastETagUpdateTime == 0 ||
        strongSelf->_settings.lastETagUpdateTime <= strongSelf->_settings.lastApplyTimeInterval) {
      FIRLogDebug(kFIRLoggerRemoteConfig, @"I-RCN000069",
                  @"Most recently fetched config is already activated.");
      if (completion) {
        NSError *error =
            isFetchAndActivate
                ? [NSError errorWithDomain:FIRRemoteConfigErrorDomain
                                      code:FIRRemoteConfigErrorInternalError
                                  userInfo:@{
                                    @"ActivationFailureReason" :
                                        @"Most recently fetched config already activated"
                                  }]
                : nil;
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
          completion(NO, error);
        });
      }
      return;
    }
    [strongSelf->_configContent copyFromDictionary:self->_configContent.fetchedConfig
                                          toSource:RCNDBSourceActive
                                      forNamespace:self->_FIRNamespace];
    strongSelf->_settings.lastApplyTimeInterval = [[NSDate date] timeIntervalSince1970];
    FIRLogDebug(kFIRLoggerRemoteConfig, @"I-RCN000069", @"Config activated.");
    [strongSelf->_configContent activatePersonalization];
    [strongSelf->_configExperiment updateExperimentsWithHandler:^(NSError *_Nullable error) {
      if (completion) {
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
          completion(YES, nil);
        });
      }
    }];
  };
  dispatch_async(_queue, applyBlock);
}

#pragma mark - helpers
- (NSString *)fullyQualifiedNamespace:(NSString *)namespace {
  // If this is already a fully qualified namespace, return.
  if ([namespace rangeOfString:@":"].location != NSNotFound) {
    return namespace;
  }
  NSString *fullyQualifiedNamespace = [NSString stringWithFormat:@"%@:%@", namespace, _appName];
  return fullyQualifiedNamespace;
}

#pragma mark - Get Config Result

- (FIRRemoteConfigValue *)objectForKeyedSubscript:(NSString *)key {
  return [self configValueForKey:key];
}

- (FIRRemoteConfigValue *)configValueForKey:(NSString *)key {
  if (!key) {
    return [[FIRRemoteConfigValue alloc] initWithData:[NSData data]
                                               source:FIRRemoteConfigSourceStatic];
  }
  NSString *FQNamespace = [self fullyQualifiedNamespace:_FIRNamespace];
  __block FIRRemoteConfigValue *value;
  dispatch_sync(_queue, ^{
    value = self->_configContent.activeConfig[FQNamespace][key];
    if (value) {
      if (value.source != FIRRemoteConfigSourceRemote) {
        FIRLogError(kFIRLoggerRemoteConfig, @"I-RCN000001",
                    @"Key %@ should come from source:%zd instead coming from source: %zd.", key,
                    (long)FIRRemoteConfigSourceRemote, (long)value.source);
      }
      [self callListeners:key
                   config:[self->_configContent getConfigAndMetadataForNamespace:FQNamespace]];
      return;
    }
    value = self->_configContent.defaultConfig[FQNamespace][key];
    if (value) {
      return;
    }

    value = [[FIRRemoteConfigValue alloc] initWithData:[NSData data]
                                                source:FIRRemoteConfigSourceStatic];
  });
  return value;
}

- (FIRRemoteConfigValue *)configValueForKey:(NSString *)key source:(FIRRemoteConfigSource)source {
  if (!key) {
    return [[FIRRemoteConfigValue alloc] initWithData:[NSData data]
                                               source:FIRRemoteConfigSourceStatic];
  }
  NSString *FQNamespace = [self fullyQualifiedNamespace:_FIRNamespace];

  __block FIRRemoteConfigValue *value;
  dispatch_sync(_queue, ^{
    if (source == FIRRemoteConfigSourceRemote) {
      value = self->_configContent.activeConfig[FQNamespace][key];
    } else if (source == FIRRemoteConfigSourceDefault) {
      value = self->_configContent.defaultConfig[FQNamespace][key];
    } else {
      value = [[FIRRemoteConfigValue alloc] initWithData:[NSData data]
                                                  source:FIRRemoteConfigSourceStatic];
    }
  });
  return value;
}

- (NSUInteger)countByEnumeratingWithState:(NSFastEnumerationState *)state
                                  objects:(id __unsafe_unretained[])stackbuf
                                    count:(NSUInteger)len {
  __block NSUInteger localValue;
  dispatch_sync(_queue, ^{
    localValue =
        [self->_configContent.activeConfig[self->_FIRNamespace] countByEnumeratingWithState:state
                                                                                    objects:stackbuf
                                                                                      count:len];
  });
  return localValue;
}

#pragma mark - Properties

/// Last fetch completion time.
- (NSDate *)lastFetchTime {
  __block NSDate *fetchTime;
  dispatch_sync(_queue, ^{
    NSTimeInterval lastFetchTime = self->_settings.lastFetchTimeInterval;
    fetchTime = [NSDate dateWithTimeIntervalSince1970:lastFetchTime];
  });
  return fetchTime;
}

- (FIRRemoteConfigFetchStatus)lastFetchStatus {
  __block FIRRemoteConfigFetchStatus currentStatus;
  dispatch_sync(_queue, ^{
    currentStatus = self->_settings.lastFetchStatus;
  });
  return currentStatus;
}

- (NSArray *)allKeysFromSource:(FIRRemoteConfigSource)source {
  __block NSArray *keys = [[NSArray alloc] init];
  dispatch_sync(_queue, ^{
    NSString *FQNamespace = [self fullyQualifiedNamespace:self->_FIRNamespace];
    switch (source) {
      case FIRRemoteConfigSourceDefault:
        if (self->_configContent.defaultConfig[FQNamespace]) {
          keys = [[self->_configContent.defaultConfig[FQNamespace] allKeys] copy];
        }
        break;
      case FIRRemoteConfigSourceRemote:
        if (self->_configContent.activeConfig[FQNamespace]) {
          keys = [[self->_configContent.activeConfig[FQNamespace] allKeys] copy];
        }
        break;
      default:
        break;
    }
  });
  return keys;
}

- (nonnull NSSet *)keysWithPrefix:(nullable NSString *)prefix {
  __block NSMutableSet *keys = [[NSMutableSet alloc] init];
  dispatch_sync(_queue, ^{
    NSString *FQNamespace = [self fullyQualifiedNamespace:self->_FIRNamespace];
    if (self->_configContent.activeConfig[FQNamespace]) {
      NSArray *allKeys = [self->_configContent.activeConfig[FQNamespace] allKeys];
      if (!prefix.length) {
        keys = [NSMutableSet setWithArray:allKeys];
      } else {
        for (NSString *key in allKeys) {
          if ([key hasPrefix:prefix]) {
            [keys addObject:key];
          }
        }
      }
    }
  });
  return [keys copy];
}

#pragma mark - Defaults

- (void)setDefaults:(NSDictionary<NSString *, NSObject *> *)defaultConfig {
  NSString *FQNamespace = [self fullyQualifiedNamespace:_FIRNamespace];
  NSDictionary *defaultConfigCopy = [[NSDictionary alloc] init];
  if (defaultConfig) {
    defaultConfigCopy = [defaultConfig copy];
  }
  void (^setDefaultsBlock)(void) = ^(void) {
    NSDictionary *namespaceToDefaults = @{FQNamespace : defaultConfigCopy};
    [self->_configContent copyFromDictionary:namespaceToDefaults
                                    toSource:RCNDBSourceDefault
                                forNamespace:FQNamespace];
    self->_settings.lastSetDefaultsTimeInterval = [[NSDate date] timeIntervalSince1970];
  };
  dispatch_async(_queue, setDefaultsBlock);
}

- (FIRRemoteConfigValue *)defaultValueForKey:(NSString *)key {
  NSString *FQNamespace = [self fullyQualifiedNamespace:_FIRNamespace];
  __block FIRRemoteConfigValue *value;
  dispatch_sync(_queue, ^{
    NSDictionary *defaultConfig = self->_configContent.defaultConfig;
    value = defaultConfig[FQNamespace][key];
    if (value) {
      if (value.source != FIRRemoteConfigSourceDefault) {
        FIRLogError(kFIRLoggerRemoteConfig, @"I-RCN000002",
                    @"Key %@ should come from source:%zd instead coming from source: %zd", key,
                    (long)FIRRemoteConfigSourceDefault, (long)value.source);
      }
    }
  });
  return value;
}

- (void)setDefaultsFromPlistFileName:(nullable NSString *)fileName {
  if (!fileName || fileName.length == 0) {
    FIRLogWarning(kFIRLoggerRemoteConfig, @"I-RCN000037",
                  @"The plist file '%@' could not be found by Remote Config.", fileName);
    return;
  }
  NSArray *bundles = @[ [NSBundle mainBundle], [NSBundle bundleForClass:[self class]] ];

  for (NSBundle *bundle in bundles) {
    NSString *plistFile = [bundle pathForResource:fileName ofType:@"plist"];
    // Use the first one we find.
    if (plistFile) {
      NSDictionary *defaultConfig = [[NSDictionary alloc] initWithContentsOfFile:plistFile];
      if (defaultConfig) {
        [self setDefaults:defaultConfig];
      }
      return;
    }
  }
  FIRLogWarning(kFIRLoggerRemoteConfig, @"I-RCN000037",
                @"The plist file '%@' could not be found by Remote Config.", fileName);
}

#pragma mark - custom variables

- (FIRRemoteConfigSettings *)configSettings {
  __block NSTimeInterval minimumFetchInterval = RCNDefaultMinimumFetchInterval;
  __block NSTimeInterval fetchTimeout = RCNHTTPDefaultConnectionTimeout;
  dispatch_sync(_queue, ^{
    minimumFetchInterval = self->_settings.minimumFetchInterval;
    fetchTimeout = self->_settings.fetchTimeout;
  });
  FIRLogDebug(kFIRLoggerRemoteConfig, @"I-RCN000066",
              @"Successfully read configSettings. Minimum Fetch Interval:%f, "
              @"Fetch timeout: %f",
              minimumFetchInterval, fetchTimeout);
  FIRRemoteConfigSettings *settings = [[FIRRemoteConfigSettings alloc] init];
  settings.minimumFetchInterval = minimumFetchInterval;
  settings.fetchTimeout = fetchTimeout;
  /// The NSURLSession needs to be recreated whenever the fetch timeout may be updated.
  [_configFetch recreateNetworkSession];
  return settings;
}

- (void)setConfigSettings:(FIRRemoteConfigSettings *)configSettings {
  void (^setConfigSettingsBlock)(void) = ^(void) {
    if (!configSettings) {
      return;
    }

    self->_settings.minimumFetchInterval = configSettings.minimumFetchInterval;
    self->_settings.fetchTimeout = configSettings.fetchTimeout;
    /// The NSURLSession needs to be recreated whenever the fetch timeout may be updated.
    [self->_configFetch recreateNetworkSession];
    FIRLogDebug(kFIRLoggerRemoteConfig, @"I-RCN000067",
                @"Successfully set configSettings. Minimum Fetch Interval:%f, "
                @"Fetch timeout:%f",
                configSettings.minimumFetchInterval, configSettings.fetchTimeout);
  };
  dispatch_async(_queue, setConfigSettingsBlock);
}

@end