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

4 files changed, 60 insertions, 48 deletions

diff --git a/Firestore/Source/Remote/FSTDatastore.h b/Firestore/Source/Remote/FSTDatastore.h
index 481b6e8..7b8274c 100644
--- a/Firestore/Source/Remote/FSTDatastore.h
+++ b/Firestore/Source/Remote/FSTDatastore.h
@@ -18,6 +18,7 @@
 
 #import "Firestore/Source/Core/FSTTypes.h"
 
+#include "Firestore/core/src/firebase/firestore/auth/credentials_provider.h"
 #include "Firestore/core/src/firebase/firestore/core/database_info.h"
 #include "Firestore/core/src/firebase/firestore/model/database_id.h"
 #include "absl/strings/string_view.h"
@@ -35,8 +36,6 @@
 @class GRPCCall;
 @class GRXWriter;
 
-@protocol FSTCredentialsProvider;
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
@@ -56,13 +55,15 @@ NS_ASSUME_NONNULL_BEGIN
 /** Creates a new Datastore instance with the given database info. */
 + (instancetype)datastoreWithDatabase:(const firebase::firestore::core::DatabaseInfo *)databaseInfo
                   workerDispatchQueue:(FSTDispatchQueue *)workerDispatchQueue
-                          credentials:(id<FSTCredentialsProvider>)credentials;
+                          credentials:(firebase::firestore::auth::CredentialsProvider *)
+                                          credentials;  // no passing ownership
 
 - (instancetype)init __attribute__((unavailable("Use a static constructor method.")));
 
 - (instancetype)initWithDatabaseInfo:(const firebase::firestore::core::DatabaseInfo *)databaseInfo
                  workerDispatchQueue:(FSTDispatchQueue *)workerDispatchQueue
-                         credentials:(id<FSTCredentialsProvider>)credentials
+                         credentials:(firebase::firestore::auth::CredentialsProvider *)
+                                         credentials  // no passing ownership
     NS_DESIGNATED_INITIALIZER;
 
 /**
diff --git a/Firestore/Source/Remote/FSTDatastore.mm b/Firestore/Source/Remote/FSTDatastore.mm
index a6029ee..cb4516e 100644
--- a/Firestore/Source/Remote/FSTDatastore.mm
+++ b/Firestore/Source/Remote/FSTDatastore.mm
@@ -22,7 +22,6 @@
 #import "FIRFirestoreErrors.h"
 #import "Firestore/Source/API/FIRFirestore+Internal.h"
 #import "Firestore/Source/API/FIRFirestoreVersion.h"
-#import "Firestore/Source/Auth/FSTCredentialsProvider.h"
 #import "Firestore/Source/Local/FSTLocalStore.h"
 #import "Firestore/Source/Model/FSTDocument.h"
 #import "Firestore/Source/Model/FSTDocumentKey.h"
@@ -35,12 +34,15 @@
 
 #import "Firestore/Protos/objc/google/firestore/v1beta1/Firestore.pbrpc.h"
 
+#include "Firestore/core/src/firebase/firestore/auth/credentials_provider.h"
 #include "Firestore/core/src/firebase/firestore/auth/token.h"
 #include "Firestore/core/src/firebase/firestore/core/database_info.h"
 #include "Firestore/core/src/firebase/firestore/model/database_id.h"
+#include "Firestore/core/src/firebase/firestore/util/error_apple.h"
 #include "Firestore/core/src/firebase/firestore/util/string_apple.h"
 
 namespace util = firebase::firestore::util;
+using firebase::firestore::auth::CredentialsProvider;
 using firebase::firestore::auth::Token;
 using firebase::firestore::core::DatabaseInfo;
 using firebase::firestore::model::DatabaseId;
@@ -70,8 +72,11 @@ typedef GRPCProtoCall * (^RPCFactory)(void);
 
 @property(nonatomic, strong, readonly) FSTDispatchQueue *workerDispatchQueue;
 
-/** An object for getting an auth token before each request. */
-@property(nonatomic, strong, readonly) id<FSTCredentialsProvider> credentials;
+/**
+ * An object for getting an auth token before each request. Does not own the CredentialsProvider
+ * instance.
+ */
+@property(nonatomic, assign, readonly) CredentialsProvider *credentials;
 
 @property(nonatomic, strong, readonly) FSTSerializerBeta *serializer;
 
@@ -81,7 +86,7 @@ typedef GRPCProtoCall * (^RPCFactory)(void);
 
 + (instancetype)datastoreWithDatabase:(const DatabaseInfo *)databaseInfo
                   workerDispatchQueue:(FSTDispatchQueue *)workerDispatchQueue
-                          credentials:(id<FSTCredentialsProvider>)credentials {
+                          credentials:(CredentialsProvider *)credentials {
   return [[FSTDatastore alloc] initWithDatabaseInfo:databaseInfo
                                 workerDispatchQueue:workerDispatchQueue
                                         credentials:credentials];
@@ -89,7 +94,7 @@ typedef GRPCProtoCall * (^RPCFactory)(void);
 
 - (instancetype)initWithDatabaseInfo:(const DatabaseInfo *)databaseInfo
                  workerDispatchQueue:(FSTDispatchQueue *)workerDispatchQueue
-                         credentials:(id<FSTCredentialsProvider>)credentials {
+                         credentials:(CredentialsProvider *)credentials {
   if (self = [super init]) {
     _databaseInfo = databaseInfo;
     NSString *host = util::WrapNSStringNoCopy(databaseInfo->host());
@@ -301,24 +306,24 @@ typedef GRPCProtoCall * (^RPCFactory)(void);
                 errorHandler:(FSTVoidErrorBlock)errorHandler {
   // TODO(mikelehen): We should force a refresh if the previous RPC failed due to an expired token,
   // but I'm not sure how to detect that right now. http://b/32762461
-  [self.credentials
-      getTokenForcingRefresh:NO
-                  completion:^(Token result, NSError *_Nullable error) {
-                    error = [FSTDatastore firestoreErrorForError:error];
-                    [self.workerDispatchQueue dispatchAsyncAllowingSameQueue:^{
-                      if (error) {
-                        errorHandler(error);
-                      } else {
-                        GRPCProtoCall *rpc = rpcFactory();
-                        [FSTDatastore
-                            prepareHeadersForRPC:rpc
-                                      databaseID:&self.databaseInfo->database_id()
-                                           token:(result.is_valid() ? result.token()
-                                                                    : absl::string_view())];
-                        [rpc start];
-                      }
-                    }];
-                  }];
+  _credentials->GetToken(
+      /*force_refresh=*/false,
+      [self, rpcFactory, errorHandler](Token result, const int64_t error_code,
+                                       const absl::string_view error_msg) {
+        NSError *error = util::WrapNSError(error_code, error_msg);
+        [self.workerDispatchQueue dispatchAsyncAllowingSameQueue:^{
+          if (error) {
+            errorHandler(error);
+          } else {
+            GRPCProtoCall *rpc = rpcFactory();
+            [FSTDatastore
+                prepareHeadersForRPC:rpc
+                          databaseID:&self.databaseInfo->database_id()
+                               token:(result.is_valid() ? result.token() : absl::string_view())];
+            [rpc start];
+          }
+        }];
+      });
 }
 
 - (FSTWatchStream *)createWatchStream {
diff --git a/Firestore/Source/Remote/FSTStream.h b/Firestore/Source/Remote/FSTStream.h
index 297d016..e48f1da 100644
--- a/Firestore/Source/Remote/FSTStream.h
+++ b/Firestore/Source/Remote/FSTStream.h
@@ -19,6 +19,7 @@
 #import "Firestore/Source/Core/FSTTypes.h"
 #import "Firestore/Source/Util/FSTDispatchQueue.h"
 
+#include "Firestore/core/src/firebase/firestore/auth/credentials_provider.h"
 #include "Firestore/core/src/firebase/firestore/core/database_info.h"
 
 @class FSTDocumentKey;
@@ -34,7 +35,6 @@
 @class GRPCCall;
 @class GRXWriter;
 
-@protocol FSTCredentialsProvider;
 @protocol FSTWatchStreamDelegate;
 @protocol FSTWriteStreamDelegate;
 
@@ -47,7 +47,7 @@ NS_ASSUME_NONNULL_BEGIN
  *
  *   - Restarting a stream is allowed (after failure)
  *   - Exponential backoff on failure (independent of the underlying channel)
- *   - Authentication via FSTCredentialsProvider
+ *   - Authentication via CredentialsProvider
  *   - Dispatching all callbacks into the shared worker queue
  *
  * Subclasses of FSTStream implement serialization of models to and from bytes (via protocol
@@ -94,7 +94,7 @@ NS_ASSUME_NONNULL_BEGIN
              workerDispatchQueue:(FSTDispatchQueue *)workerDispatchQueue
                connectionTimerID:(FSTTimerID)connectionTimerID
                      idleTimerID:(FSTTimerID)idleTimerID
-                     credentials:(id<FSTCredentialsProvider>)credentials
+                     credentials:(firebase::firestore::auth::CredentialsProvider *)credentials  // no passing ownership
             responseMessageClass:(Class)responseMessageClass NS_DESIGNATED_INITIALIZER;
 
 - (instancetype)init NS_UNAVAILABLE;
@@ -208,14 +208,16 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (instancetype)initWithDatabase:(const firebase::firestore::core::DatabaseInfo *)database
              workerDispatchQueue:(FSTDispatchQueue *)workerDispatchQueue
-                     credentials:(id<FSTCredentialsProvider>)credentials
+                     credentials:(firebase::firestore::auth::CredentialsProvider *)
+                                     credentials  // no passsing ownership
                       serializer:(FSTSerializerBeta *)serializer NS_DESIGNATED_INITIALIZER;
 
 - (instancetype)initWithDatabase:(const firebase::firestore::core::DatabaseInfo *)database
              workerDispatchQueue:(FSTDispatchQueue *)workerDispatchQueue
                connectionTimerID:(FSTTimerID)connectionTimerID
                      idleTimerID:(FSTTimerID)idleTimerID
-                     credentials:(id<FSTCredentialsProvider>)credentials
+                     credentials:(firebase::firestore::auth::CredentialsProvider *)
+                                     credentials  // no passing ownership
             responseMessageClass:(Class)responseMessageClass NS_UNAVAILABLE;
 
 - (instancetype)init NS_UNAVAILABLE;
@@ -284,14 +286,16 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (instancetype)initWithDatabase:(const firebase::firestore::core::DatabaseInfo *)database
              workerDispatchQueue:(FSTDispatchQueue *)workerDispatchQueue
-                     credentials:(id<FSTCredentialsProvider>)credentials
+                     credentials:(firebase::firestore::auth::CredentialsProvider *)
+                                     credentials  // no passing ownership
                       serializer:(FSTSerializerBeta *)serializer;
 
 - (instancetype)initWithDatabase:(const firebase::firestore::core::DatabaseInfo *)database
              workerDispatchQueue:(FSTDispatchQueue *)workerDispatchQueue
                connectionTimerID:(FSTTimerID)connectionTimerID
                      idleTimerID:(FSTTimerID)idleTimerID
-                     credentials:(id<FSTCredentialsProvider>)credentials
+                     credentials:(firebase::firestore::auth::CredentialsProvider *)
+                                     credentials  // no passing ownership
             responseMessageClass:(Class)responseMessageClass NS_UNAVAILABLE;
 
 - (instancetype)init NS_UNAVAILABLE;
diff --git a/Firestore/Source/Remote/FSTStream.mm b/Firestore/Source/Remote/FSTStream.mm
index a9aa245..6bec3ad 100644
--- a/Firestore/Source/Remote/FSTStream.mm
+++ b/Firestore/Source/Remote/FSTStream.mm
@@ -21,7 +21,6 @@
 
 #import "FIRFirestoreErrors.h"
 #import "Firestore/Source/API/FIRFirestore+Internal.h"
-#import "Firestore/Source/Auth/FSTCredentialsProvider.h"
 #import "Firestore/Source/Local/FSTQueryData.h"
 #import "Firestore/Source/Model/FSTMutation.h"
 #import "Firestore/Source/Remote/FSTBufferedWriter.h"
@@ -38,9 +37,11 @@
 #include "Firestore/core/src/firebase/firestore/auth/token.h"
 #include "Firestore/core/src/firebase/firestore/core/database_info.h"
 #include "Firestore/core/src/firebase/firestore/model/database_id.h"
+#include "Firestore/core/src/firebase/firestore/util/error_apple.h"
 #include "Firestore/core/src/firebase/firestore/util/string_apple.h"
 
 namespace util = firebase::firestore::util;
+using firebase::firestore::auth::CredentialsProvider;
 using firebase::firestore::auth::Token;
 using firebase::firestore::core::DatabaseInfo;
 using firebase::firestore::model::DatabaseId;
@@ -103,12 +104,12 @@ typedef NS_ENUM(NSInteger, FSTStreamState) {
  */
 - (instancetype)initWithDatabase:(const DatabaseInfo *)database
              workerDispatchQueue:(FSTDispatchQueue *)workerDispatchQueue
-                     credentials:(id<FSTCredentialsProvider>)credentials
+                     credentials:(CredentialsProvider *)credentials
                       serializer:(FSTSerializerBeta *)serializer NS_DESIGNATED_INITIALIZER;
 
 - (instancetype)initWithDatabase:(const DatabaseInfo *)database
              workerDispatchQueue:(FSTDispatchQueue *)workerDispatchQueue
-                     credentials:(id<FSTCredentialsProvider>)credentials
+                     credentials:(CredentialsProvider *)credentials
             responseMessageClass:(Class)responseMessageClass NS_UNAVAILABLE;
 
 @end
@@ -126,7 +127,7 @@ typedef NS_ENUM(NSInteger, FSTStreamState) {
 // Does not own this DatabaseInfo.
 @property(nonatomic, assign, readonly) const DatabaseInfo *databaseInfo;
 @property(nonatomic, strong, readonly) FSTDispatchQueue *workerDispatchQueue;
-@property(nonatomic, strong, readonly) id<FSTCredentialsProvider> credentials;
+@property(nonatomic, assign, readonly) CredentialsProvider *credentials;
 @property(nonatomic, unsafe_unretained, readonly) Class responseMessageClass;
 @property(nonatomic, strong, readonly) FSTExponentialBackoff *backoff;
 
@@ -213,7 +214,7 @@ static const NSTimeInterval kIdleTimeout = 60.0;
              workerDispatchQueue:(FSTDispatchQueue *)workerDispatchQueue
                connectionTimerID:(FSTTimerID)connectionTimerID
                      idleTimerID:(FSTTimerID)idleTimerID
-                     credentials:(id<FSTCredentialsProvider>)credentials
+                     credentials:(CredentialsProvider *)credentials
             responseMessageClass:(Class)responseMessageClass {
   if (self = [super init]) {
     _databaseInfo = database;
@@ -263,13 +264,14 @@ static const NSTimeInterval kIdleTimeout = 60.0;
   FSTAssert(_delegate == nil, @"Delegate must be nil");
   _delegate = delegate;
 
-  [self.credentials getTokenForcingRefresh:NO
-                                completion:^(Token result, NSError *_Nullable error) {
-                                  error = [FSTDatastore firestoreErrorForError:error];
-                                  [self.workerDispatchQueue dispatchAsyncAllowingSameQueue:^{
-                                    [self resumeStartWithToken:result error:error];
-                                  }];
-                                }];
+  _credentials->GetToken(
+      /*force_refresh=*/false,
+      [self](Token result, const int64_t error_code, const absl::string_view error_msg) {
+        NSError *error = util::WrapNSError(error_code, error_msg);
+        [self.workerDispatchQueue dispatchAsyncAllowingSameQueue:^{
+          [self resumeStartWithToken:result error:error];
+        }];
+      });
 }
 
 /** Add an access token to our RPC, after obtaining one from the credentials provider. */
@@ -614,7 +616,7 @@ static const NSTimeInterval kIdleTimeout = 60.0;
 
 - (instancetype)initWithDatabase:(const DatabaseInfo *)database
              workerDispatchQueue:(FSTDispatchQueue *)workerDispatchQueue
-                     credentials:(id<FSTCredentialsProvider>)credentials
+                     credentials:(CredentialsProvider *)credentials
                       serializer:(FSTSerializerBeta *)serializer {
   self = [super initWithDatabase:database
              workerDispatchQueue:workerDispatchQueue
@@ -699,7 +701,7 @@ static const NSTimeInterval kIdleTimeout = 60.0;
 
 - (instancetype)initWithDatabase:(const DatabaseInfo *)database
              workerDispatchQueue:(FSTDispatchQueue *)workerDispatchQueue
-                     credentials:(id<FSTCredentialsProvider>)credentials
+                     credentials:(CredentialsProvider *)credentials
                       serializer:(FSTSerializerBeta *)serializer {
   self = [super initWithDatabase:database
              workerDispatchQueue:workerDispatchQueue