Add support for deferred OAuth provisioning (#6121)

* Use GOOGLE_APP_ID instead of CLIENT_ID if CLIENT_ID is unavailable for generic IDP and phone auth flows.

* Add a prefix to the custom URL scheme when using the Firebase app ID.

* Add tests for FIROAuthProvider.

* Add tests for FIRPhoneAuthProvider.

* Change query param from firebaseAppId to appId.

* Fix tests.

* Address review comments.

* Add changelog entry.

Author: rosalyntan

FirebaseAuth/CHANGELOG.md

@@ -1,3 +1,6 @@
+# Unreleased
+- [changed] Added support for using GOOGLE_APP_ID in generic IDP and phone auth reCAPTCHA fallback flows. (#6121).
+
 # v6.7.1
 - [fixed] Fixed a multithreaded memory access issue on iOS (#5979).
 

FirebaseAuth/Sources/AuthProvider/OAuth/FIROAuthProvider.m

@@ -52,6 +52,11 @@ typedef void (^FIRHeadfulLiteURLCallBack)(NSURL *_Nullable headfulLiteURL,
  */
 static NSString *const kAuthTypeSignInWithRedirect = @"signInWithRedirect";
 
+/** @var kCustomUrlSchemePrefix
+    @brief The prefix to append to the Firebase app ID custom callback scheme..
+ */
+static NSString *const kCustomUrlSchemePrefix = @"app-";
+
 @implementation FIROAuthProvider {
   /** @var _auth
       @brief The auth instance used for launching the URL presenter.
@@ -203,8 +208,15 @@ - (nullable instancetype)initWithProviderID:(NSString *)providerID auth:(FIRAuth
   if (self) {
     _auth = auth;
     _providerID = providerID;
-    _callbackScheme = [[[_auth.app.options.clientID componentsSeparatedByString:@"."]
-                           reverseObjectEnumerator].allObjects componentsJoinedByString:@"."];
+    if (_auth.app.options.clientID) {
+      _callbackScheme = [[[_auth.app.options.clientID componentsSeparatedByString:@"."]
+                             reverseObjectEnumerator].allObjects componentsJoinedByString:@"."];
+    } else {
+      _callbackScheme = [kCustomUrlSchemePrefix
+          stringByAppendingString:[_auth.app.options.googleAppID
+                                      stringByReplacingOccurrencesOfString:@":"
+                                                                withString:@"-"]];
+    }
   }
   return self;
 }
@@ -272,19 +284,24 @@ - (void)getHeadFulLiteURLWithEventID:(NSString *)eventID
                                      }
                                      __strong __typeof__(self) strongSelf = weakSelf;
                                      NSString *bundleID = [NSBundle mainBundle].bundleIdentifier;
-                                     NSString *clienID = strongSelf->_auth.app.options.clientID;
+                                     NSString *clientID = strongSelf->_auth.app.options.clientID;
+                                     NSString *appID = strongSelf->_auth.app.options.googleAppID;
                                      NSString *apiKey =
                                          strongSelf->_auth.requestConfiguration.APIKey;
                                      NSMutableDictionary *urlArguments = [@{
                                        @"apiKey" : apiKey,
-                                       @"authType" : @"signInWithRedirect",
+                                       @"authType" : kAuthTypeSignInWithRedirect,
                                        @"ibi" : bundleID ?: @"",
-                                       @"clientId" : clienID,
                                        @"sessionId" : [strongSelf hashforString:sessionID],
                                        @"v" : [FIRAuthBackend authUserAgent],
                                        @"eventId" : eventID,
                                        @"providerId" : strongSelf->_providerID,
                                      } mutableCopy];
+                                     if (clientID) {
+                                       urlArguments[@"clientId"] = clientID;
+                                     } else {
+                                       urlArguments[@"appId"] = appID;
+                                     }
                                      if (strongSelf.scopes.count) {
                                        urlArguments[@"scopes"] =
                                            [strongSelf.scopes componentsJoinedByString:@","];

FirebaseAuth/Sources/AuthProvider/Phone/FIRPhoneAuthProvider.m

@@ -83,6 +83,11 @@ typedef void (^FIRFetchAuthDomainCallback)(NSString *_Nullable authDomain,
  */
 static NSString *const kAuthTypeVerifyApp = @"verifyApp";
 
+/** @var kCustomUrlSchemePrefix
+    @brief The prefix to append to the Firebase app ID custom callback scheme..
+ */
+static NSString *const kCustomUrlSchemePrefix = @"app-";
+
 /** @var kReCAPTCHAURLStringFormat
     @brief The format of the URL used to open the reCAPTCHA page during app verification.
  */
@@ -111,8 +116,15 @@ - (nullable instancetype)initWithAuth:(FIRAuth *)auth {
   self = [super init];
   if (self) {
     _auth = auth;
-    _callbackScheme = [[[_auth.app.options.clientID componentsSeparatedByString:@"."]
-                           reverseObjectEnumerator].allObjects componentsJoinedByString:@"."];
+    if (_auth.app.options.clientID) {
+      _callbackScheme = [[[_auth.app.options.clientID componentsSeparatedByString:@"."]
+                             reverseObjectEnumerator].allObjects componentsJoinedByString:@"."];
+    } else {
+      _callbackScheme = [kCustomUrlSchemePrefix
+          stringByAppendingString:[_auth.app.options.googleAppID
+                                      stringByReplacingOccurrencesOfString:@":"
+                                                                withString:@"-"]];
+    }
   }
   return self;
 }
@@ -675,20 +687,28 @@ - (void)reCAPTCHAURLWithEventID:(NSString *)eventID completion:(FIRReCAPTCHAURLC
                                      }
                                      NSString *bundleID = [NSBundle mainBundle].bundleIdentifier;
                                      NSString *clientID = self->_auth.app.options.clientID;
+                                     NSString *appID = self->_auth.app.options.googleAppID;
                                      NSString *apiKey = self->_auth.requestConfiguration.APIKey;
                                      NSMutableArray<NSURLQueryItem *> *queryItems = [@[
                                        [NSURLQueryItem queryItemWithName:@"apiKey" value:apiKey],
                                        [NSURLQueryItem queryItemWithName:@"authType"
                                                                    value:kAuthTypeVerifyApp],
                                        [NSURLQueryItem queryItemWithName:@"ibi"
                                                                    value:bundleID ?: @""],
-                                       [NSURLQueryItem queryItemWithName:@"clientId"
-                                                                   value:clientID],
                                        [NSURLQueryItem
                                            queryItemWithName:@"v"
                                                        value:[FIRAuthBackend authUserAgent]],
                                        [NSURLQueryItem queryItemWithName:@"eventId" value:eventID]
                                      ] mutableCopy];
+                                     if (clientID) {
+                                       [queryItems
+                                           addObject:[NSURLQueryItem queryItemWithName:@"clientId"
+                                                                                 value:clientID]];
+                                     } else {
+                                       [queryItems
+                                           addObject:[NSURLQueryItem queryItemWithName:@"appId"
+                                                                                 value:appID]];
+                                     }
 
                                      if (self->_auth.requestConfiguration.languageCode) {
                                        [queryItems