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

8 files changed, 195 insertions, 16 deletions

diff --git a/Firestore/core/include/firebase/firestore/firestore_errors.h b/Firestore/core/include/firebase/firestore/firestore_errors.h
new file mode 100644
index 0000000..7a0ff7c
--- /dev/null
+++ b/Firestore/core/include/firebase/firestore/firestore_errors.h
@@ -0,0 +1,115 @@
+/*
+ * Copyright 2018 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.
+ */
+
+#ifndef FIRESTORE_CORE_INCLUDE_FIREBASE_FIRESTORE_FIRESTORE_ERRORS_H_
+#define FIRESTORE_CORE_INCLUDE_FIREBASE_FIRESTORE_FIRESTORE_ERRORS_H_
+
+namespace firebase {
+namespace firestore {
+
+/**
+ * Error codes used by Cloud Firestore.
+ *
+ * The codes are in sync with the Firestore iOS client SDK header file
+ * FIRFirestoreErrors.h.
+ */
+enum FirestoreErrorCode {
+  /**
+   * The operation completed successfully. NSError objects will never have a
+   * code with this value.
+   */
+  Ok = 0,
+
+  /** The operation was cancelled (typically by the caller). */
+  Cancelled = 1,
+
+  /** Unknown error or an error from a different error domain. */
+  Unknown = 2,
+
+  /**
+   * Client specified an invalid argument. Note that this differs from
+   * FailedPrecondition. InvalidArgument indicates arguments that are
+   * problematic regardless of the state of the system (e.g., an invalid field
+   * name).
+   */
+  InvalidArgument = 3,
+
+  /**
+   * Deadline expired before operation could complete. For operations that
+   * change the state of the system, this error may be returned even if the
+   * operation has completed successfully. For example, a successful response
+   * from a server could have been delayed long enough for the deadline to
+   * expire.
+   */
+  DeadlineExceeded = 4,
+
+  /** Some requested document was not found. */
+  NotFound = 5,
+
+  /** Some document that we attempted to create already exists. */
+  AlreadyExists = 6,
+
+  /** The caller does not have permission to execute the specified operation. */
+  PermissionDenied = 7,
+
+  /**
+   * Some resource has been exhausted, perhaps a per-user quota, or perhaps the
+   * entire file system is out of space.
+   */
+  ResourceExhausted = 8,
+
+  /**
+   * Operation was rejected because the system is not in a state required for
+   * the operation's execution.
+   */
+  FailedPrecondition = 9,
+
+  /**
+   * The operation was aborted, typically due to a concurrency issue like
+   * transaction aborts, etc.
+   */
+  Aborted = 10,
+
+  /** Operation was attempted past the valid range. */
+  OutOfRange = 11,
+
+  /** Operation is not implemented or not supported/enabled. */
+  Unimplemented = 12,
+
+  /**
+   * Internal errors. Means some invariants expected by underlying system has
+   * been broken. If you see one of these errors, something is very broken.
+   */
+  Internal = 13,
+
+  /**
+   * The service is currently unavailable. This is a most likely a transient
+   * condition and may be corrected by retrying with a backoff.
+   */
+  Unavailable = 14,
+
+  /** Unrecoverable data loss or corruption. */
+  DataLoss = 15,
+
+  /** The request does not have valid authentication credentials for the
+     operation. */
+  Unauthenticated = 16
+};
+
+}  // namespace firestore
+}  // namespace firebase
+
+#endif  // FIRESTORE_CORE_INCLUDE_FIREBASE_FIRESTORE_FIRESTORE_ERRORS_H_
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));
     }
   };
diff --git a/Firestore/core/src/firebase/firestore/util/error_apple.h b/Firestore/core/src/firebase/firestore/util/error_apple.h
new file mode 100644
index 0000000..e31cfd6
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/util/error_apple.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2018 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.
+ */
+
+#ifndef FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_UTIL_ERROR_APPLE_H_
+#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_UTIL_ERROR_APPLE_H_
+
+// Everything in this header exists for compatibility with Objective-C.
+#if __OBJC__
+
+#import <Foundation/Foundation.h>
+
+#include "Firestore/Source/Public/FIRFirestoreErrors.h"  // for FIRFirestoreErrorDomain
+#include "Firestore/core/include/firebase/firestore/firestore_errors.h"
+#include "Firestore/core/src/firebase/firestore/util/string_apple.h"
+#include "absl/strings/string_view.h"
+
+namespace firebase {
+namespace firestore {
+namespace util {
+
+// Translates a set of error_code and error_msg to an NSError.
+inline NSError* WrapNSError(const int64_t error_code,
+                            const absl::string_view error_msg) {
+  if (error_code == FirestoreErrorCode::Ok) {
+    return nil;
+  }
+  return [NSError
+      errorWithDomain:FIRFirestoreErrorDomain
+                 code:error_code
+             userInfo:@{NSLocalizedDescriptionKey : WrapNSString(error_msg)}];
+}
+
+}  // namespace util
+}  // namespace firestore
+}  // namespace firebase
+
+#endif  // __OBJC__
+
+#endif  // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_UTIL_ERROR_APPLE_H_
diff --git a/Firestore/core/test/firebase/firestore/auth/credentials_provider_test.cc b/Firestore/core/test/firebase/firestore/auth/credentials_provider_test.cc
index 9ae71ba..6895061 100644
--- a/Firestore/core/test/firebase/firestore/auth/credentials_provider_test.cc
+++ b/Firestore/core/test/firebase/firestore/auth/credentials_provider_test.cc
@@ -25,10 +25,11 @@ namespace auth {
 #define UNUSED(x) (void)(x)
 
 TEST(CredentialsProvider, Typedef) {
-  TokenListener token_listener = [](Token token,
-                                    const absl::string_view error) {
+  TokenListener token_listener = [](Token token, const int64_t error_code,
+                                    const absl::string_view error_msg) {
     UNUSED(token);
-    UNUSED(error);
+    UNUSED(error_code);
+    UNUSED(error_msg);
   };
   EXPECT_NE(nullptr, token_listener);
   EXPECT_TRUE(token_listener);
diff --git a/Firestore/core/test/firebase/firestore/auth/empty_credentials_provider_test.cc b/Firestore/core/test/firebase/firestore/auth/empty_credentials_provider_test.cc
index 39012f0..3b487f3 100644
--- a/Firestore/core/test/firebase/firestore/auth/empty_credentials_provider_test.cc
+++ b/Firestore/core/test/firebase/firestore/auth/empty_credentials_provider_test.cc
@@ -25,12 +25,14 @@ namespace auth {
 TEST(EmptyCredentialsProvider, GetToken) {
   EmptyCredentialsProvider credentials_provider;
   credentials_provider.GetToken(
-      /*force_refresh=*/true, [](Token token, const absl::string_view error) {
-        EXPECT_EQ("", token.token());
+      /*force_refresh=*/true, [](Token token, const int64_t error_code,
+                                 const absl::string_view error_msg) {
+        EXPECT_FALSE(token.is_valid());
         const User& user = token.user();
         EXPECT_EQ("", user.uid());
         EXPECT_FALSE(user.is_authenticated());
-        EXPECT_EQ("", error);
+        EXPECT_EQ(FirestoreErrorCode::Ok, error_code);
+        EXPECT_EQ("", error_msg);
       });
 }
 
diff --git a/Firestore/core/test/firebase/firestore/auth/firebase_credentials_provider_test.mm b/Firestore/core/test/firebase/firestore/auth/firebase_credentials_provider_test.mm
index a6ccc4a..3660d53 100644
--- a/Firestore/core/test/firebase/firestore/auth/firebase_credentials_provider_test.mm
+++ b/Firestore/core/test/firebase/firestore/auth/firebase_credentials_provider_test.mm
@@ -42,12 +42,14 @@ TEST(FirebaseCredentialsProviderTest, GetTokenUnauthenticated) {
 
   FirebaseCredentialsProvider credentials_provider(app);
   credentials_provider.GetToken(
-      /*force_refresh=*/true, [](Token token, const absl::string_view error) {
+      /*force_refresh=*/true, [](Token token, const int64_t error_code,
+                                 const absl::string_view error_msg) {
         EXPECT_EQ("", token.token());
         const User& user = token.user();
         EXPECT_EQ("", user.uid());
         EXPECT_FALSE(user.is_authenticated());
-        EXPECT_EQ("", error) << error;
+        EXPECT_EQ(FirestoreErrorCode::Ok, error_code) << error_code;
+        EXPECT_EQ("", error_msg) << error_msg;
       });
 }
 
@@ -56,12 +58,14 @@ TEST(FirebaseCredentialsProviderTest, GetToken) {
 
   FirebaseCredentialsProvider credentials_provider(app);
   credentials_provider.GetToken(
-      /*force_refresh=*/true, [](Token token, const absl::string_view error) {
+      /*force_refresh=*/true, [](Token token, const int64_t error_code,
+                                 const absl::string_view error_msg) {
         EXPECT_EQ("", token.token());
         const User& user = token.user();
         EXPECT_EQ("fake uid", user.uid());
         EXPECT_TRUE(user.is_authenticated());
-        EXPECT_EQ("", error) << error;
+        EXPECT_EQ(FirestoreErrorCode::Ok, error_code) << error_code;
+        EXPECT_EQ("", error_msg) << error_msg;
       });
 }