replacing Auth by C++ auth implementation (#802)

* lazy replacing FST(Firebase)CredentialsProvider by (Firebase)CredentialsProvider

* lazy replacing FSTUser by User

* adding error-code parameter to TokenListener

* actually use const user& instead of pointer; also add an error util

* add HashUser and pass into the unordered_map

* use User in test

* use c++ CredentialsProvider and subclass in test

* fix unit test

* use explicit capture in lambda instead of capture all by reference

* cache currentUser explicitly when reset sync engineer test driver

* objc object should be captured by value in lambda

* replacing Auth/FSTUser by C++ auth implementation

* address changes

* replacing FSTGetTokenResult by C++ Token implementation

* address changes

* fix unintentional change in merging

* patch the change in objc Auth up-stream

* somehow, the lambda-version of set-user-change-listener does not work... fallback to block

* address changes

* fix another const& v.s. dispatch bug

* fix more const& v.s. dispatch bug  zxu123 committed

* fix a bad sync line

* address changes

* address change

* address change

* fix upstream change from merge

* fix upstream changes

* Suggested fixes for cpp/port_auth (#846)

* Get rid of MockDatastore factory

This avoids the need to statically allocate (and leak) a credentials
provider

* Use absl::make_unique

std::make_unique technically does not exist until C++14.

* #include <utility> for std::move

* Use std::future for the initial user

* fix style

3 files changed, 11 insertions, 6 deletions

diff --git a/Firestore/core/src/firebase/firestore/auth/credentials_provider.h b/Firestore/core/src/firebase/firestore/auth/credentials_provider.h
index 917f8e1..b9a8a24 100644
--- a/Firestore/core/src/firebase/firestore/auth/credentials_provider.h
+++ b/Firestore/core/src/firebase/firestore/auth/credentials_provider.h
@@ -20,6 +20,7 @@
 #include <functional>
 #include <string>
 
+#include "Firestore/core/include/firebase/firestore/firestore_errors.h"
 #include "Firestore/core/src/firebase/firestore/auth/token.h"
 #include "Firestore/core/src/firebase/firestore/auth/user.h"
 #include "absl/strings/string_view.h"
@@ -30,8 +31,10 @@ namespace auth {
 
 // `TokenErrorListener` is a listener that gets a token or an error.
 // token: An auth token as a string, or nullptr if error occurred.
-// error: The error if one occurred, or else nullptr.
-typedef std::function<void(Token token, const absl::string_view error)>
+// error_code: The error code if one occurred, or else FirestoreErrorCode::Ok.
+// error_msg: The error if one occurred, or else nullptr.
+typedef std::function<void(
+    Token token, const int64_t error_code, const absl::string_view error_msg)>
     TokenListener;
 
 // Listener notified with a User change.
diff --git a/Firestore/core/src/firebase/firestore/auth/empty_credentials_provider.cc b/Firestore/core/src/firebase/firestore/auth/empty_credentials_provider.cc
index 6ee7f61..0fa70c0 100644
--- a/Firestore/core/src/firebase/firestore/auth/empty_credentials_provider.cc
+++ b/Firestore/core/src/firebase/firestore/auth/empty_credentials_provider.cc
@@ -26,7 +26,8 @@ void EmptyCredentialsProvider::GetToken(bool force_refresh,
                                         TokenListener completion) {
   UNUSED(force_refresh);
   if (completion) {
-    completion({"", User::Unauthenticated()}, "");
+    // Invalid token will force the GRPC fallback to use default settings.
+    completion(Token::Invalid(), FirestoreErrorCode::Ok, "");
   }
 }
 
diff --git a/Firestore/core/src/firebase/firestore/auth/firebase_credentials_provider_apple.mm b/Firestore/core/src/firebase/firestore/auth/firebase_credentials_provider_apple.mm
index fe3cb24..1babe82 100644
--- a/Firestore/core/src/firebase/firestore/auth/firebase_credentials_provider_apple.mm
+++ b/Firestore/core/src/firebase/firestore/auth/firebase_credentials_provider_apple.mm
@@ -53,7 +53,7 @@ FirebaseCredentialsProvider::FirebaseCredentialsProvider(FIRApp* app)
 
                 NSString* user_id =
                     user_info[FIRAuthStateDidChangeInternalNotificationUIDKey];
-                User new_user(util::MakeStringView(user_id));
+                User new_user = User::FromUid(user_id);
                 if (new_user != contents->current_user) {
                   contents->current_user = new_user;
                   contents->user_counter++;
@@ -96,11 +96,12 @@ void FirebaseCredentialsProvider::GetToken(bool force_refresh,
       // Cancel the request since the user changed while the request was
       // outstanding so the response is likely for a previous user (which
       // user, we can't be sure).
-      completion({"", User::Unauthenticated()},
+      completion(Token::Invalid(), FirestoreErrorCode::Aborted,
                  "getToken aborted due to user change.");
     } else {
       completion(
-          {util::MakeStringView(token), contents->current_user},
+          Token{util::MakeStringView(token), contents->current_user},
+          error == nil ? FirestoreErrorCode::Ok : error.code,
           error == nil ? "" : util::MakeStringView(error.localizedDescription));
     }
   };