Add global data collection switch. (#1219)

* Addition of global data collection switch.
* Added Messaging conformance to data switch.
  Also formatted code.
* Move data collection flag internal until all SDKs conform to it.
* Formatting in response to code review.

2 files changed, 112 insertions, 1 deletions

diff --git a/Firebase/Core/FIRApp.m b/Firebase/Core/FIRApp.m
index 3d05f12..717da4e 100644
--- a/Firebase/Core/FIRApp.m
+++ b/Firebase/Core/FIRApp.m
@@ -46,6 +46,11 @@ NSString *const kFIRAppIsDefaultAppKey = @"FIRAppIsDefaultAppKey";
 NSString *const kFIRAppNameKey = @"FIRAppNameKey";
 NSString *const kFIRGoogleAppIDKey = @"FIRGoogleAppIDKey";
 
+NSString *const kFIRGlobalAppDataCollectionEnabledDefaultsKeyFormat =
+    @"/google/firebase/global_data_collection_enabled:%@";
+NSString *const kFIRGlobalAppDataCollectionEnabledPlistKey =
+    @"FirebaseAutomaticDataCollectionEnabled";
+
 NSString *const kFIRAppDiagnosticsNotification = @"FIRAppDiagnosticsNotification";
 
 NSString *const kFIRAppDiagnosticsConfigurationTypeKey = @"ConfigType";
@@ -227,6 +232,7 @@ static NSMutableDictionary *sLibraryVersions;
     if (sAllApps && sAllApps[self.name]) {
       FIRLogDebug(kFIRLoggerCore, @"I-COR000006", @"Deleting app named %@", self.name);
       [sAllApps removeObjectForKey:self.name];
+      [self clearDataCollectionSwitchFromUserDefaults];
       if ([self.name isEqualToString:kFIRDefaultAppName]) {
         sDefaultApp = nil;
       }
@@ -332,6 +338,30 @@ static NSMutableDictionary *sLibraryVersions;
   return [_options copy];
 }
 
+- (void)setAutomaticDataCollectionEnabled:(BOOL)automaticDataCollectionEnabled {
+  NSString *key =
+      [NSString stringWithFormat:kFIRGlobalAppDataCollectionEnabledDefaultsKeyFormat, self.name];
+  [[NSUserDefaults standardUserDefaults] setBool:automaticDataCollectionEnabled forKey:key];
+}
+
+- (BOOL)isAutomaticDataCollectionEnabled {
+  // Check if it's been manually set before in code, and use that as the higher priority value.
+  NSNumber *defaultsObject = [[self class] readDataCollectionSwitchFromUserDefaultsForApp:self];
+  if (defaultsObject) {
+    return [defaultsObject boolValue];
+  }
+
+  // Read the Info.plist to see if the flag is set. If it's not set, it should default to `YES`.
+  // As per the implementation of `readDataCollectionSwitchFromPlist`, it's a cached value and has
+  // no performance impact calling multiple times.
+  NSNumber *collectionEnabledPlistValue = [[self class] readDataCollectionSwitchFromPlist];
+  if (collectionEnabledPlistValue) {
+    return [collectionEnabledPlistValue boolValue];
+  }
+
+  return YES;
+}
+
 #pragma mark - private
 
 + (void)sendNotificationsToSDKs:(FIRApp *)app {
@@ -613,11 +643,64 @@ static NSMutableDictionary *sLibraryVersions;
 }
 
 // end App ID validation
-#pragma mark
+
+#pragma mark - Reading From Plist & User Defaults
+
+/**
+ * Clears the data collection switch from the standard NSUserDefaults for easier testing and
+ * readability.
+ */
+- (void)clearDataCollectionSwitchFromUserDefaults {
+  NSString *key =
+      [NSString stringWithFormat:kFIRGlobalAppDataCollectionEnabledDefaultsKeyFormat, self.name];
+  [[NSUserDefaults standardUserDefaults] removeObjectForKey:key];
+}
+
+/**
+ * Reads the data collection switch from the standard NSUserDefaults for easier testing and
+ * readability.
+ */
++ (nullable NSNumber *)readDataCollectionSwitchFromUserDefaultsForApp:(FIRApp *)app {
+  // Read the object in user defaults, and only return if it's an NSNumber.
+  NSString *key =
+      [NSString stringWithFormat:kFIRGlobalAppDataCollectionEnabledDefaultsKeyFormat, app.name];
+  id collectionEnabledDefaultsObject = [[NSUserDefaults standardUserDefaults] objectForKey:key];
+  if ([collectionEnabledDefaultsObject isKindOfClass:[NSNumber class]]) {
+    return collectionEnabledDefaultsObject;
+  }
+
+  return nil;
+}
+
+/**
+ * Reads the data collection switch from the Info.plist for easier testing and readability. Will
+ * only read once from the plist and return the cached value.
+ */
++ (nullable NSNumber *)readDataCollectionSwitchFromPlist {
+  static NSNumber *collectionEnabledPlistObject;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    // Read the data from the `Info.plist`, only assign it if it's there and an NSNumber.
+    id plistValue = [[NSBundle mainBundle]
+        objectForInfoDictionaryKey:kFIRGlobalAppDataCollectionEnabledPlistKey];
+    if (plistValue && [plistValue isKindOfClass:[NSNumber class]]) {
+      collectionEnabledPlistObject = (NSNumber *)plistValue;
+    }
+  });
+
+  return collectionEnabledPlistObject;
+}
+
+#pragma mark - Sending Logs
 
 - (void)sendLogsWithServiceName:(NSString *)serviceName
                         version:(NSString *)version
                           error:(NSError *)error {
+  // If the user has manually turned off data collection, return and don't send logs.
+  if (![self isAutomaticDataCollectionEnabled]) {
+    return;
+  }
+
   NSMutableDictionary *userInfo = [[NSMutableDictionary alloc] initWithDictionary:@{
     kFIRAppDiagnosticsConfigurationTypeKey : @(FIRConfigTypeSDK),
     kFIRAppDiagnosticsSDKNameKey : serviceName,
diff --git a/Firebase/Core/Private/FIRAppInternal.h b/Firebase/Core/Private/FIRAppInternal.h
index b7cf5e8..66979eb 100644
--- a/Firebase/Core/Private/FIRAppInternal.h
+++ b/Firebase/Core/Private/FIRAppInternal.h
@@ -60,6 +60,22 @@ extern NSString *const kFIRAppIsDefaultAppKey;
 extern NSString *const kFIRAppNameKey;
 extern NSString *const kFIRGoogleAppIDKey;
 
+/**
+ * The format string for the User Defaults key used for storing the data collection enabled flag.
+ * This includes formatting to append the Firebase App's name.
+ */
+extern NSString *const kFIRGlobalAppDataCollectionEnabledDefaultsKeyFormat;
+
+/**
+ * The plist key used for storing the data collection enabled flag.
+ */
+extern NSString *const kFIRGlobalAppDataCollectionEnabledPlistKey;
+
+/**
+ * A notification fired containing diagnostic information when SDK errors occur.
+ */
+extern NSString *const kFIRAppDiagnosticsNotification;
+
 /** @var FIRAuthStateDidChangeInternalNotification
  @brief The name of the @c NSNotificationCenter notification which is posted when the auth state
  changes (e.g. a new token has been produced, a user logs in or out). The object parameter of
@@ -181,6 +197,18 @@ typedef NSString *_Nullable (^FIRAppGetUIDImplementation)(void);
  */
 - (nullable NSString *)getUID;
 
+/**
+ * WARNING: THIS SETTING DOES NOT WORK YET. IT WILL BE MOVED TO THE PUBLIC HEADER ONCE ALL SDKS
+ *          CONFORM TO THIS PREFERENCE. DO NOT RELY ON IT.
+ *
+ * Gets or sets whether automatic data collection is enabled for all products. Defaults to `YES`
+ * unless `FirebaseAutomaticDataCollectionEnabled` is set to `NO` in your app's Info.plist. This
+ * value is persisted across runs of the app so that it can be set once when users have consented to
+ * collection.
+ */
+@property(nonatomic, readwrite, getter=isAutomaticDataCollectionEnabled)
+    BOOL automaticDataCollectionEnabled;
+
 @end
 
 NS_ASSUME_NONNULL_END