Implement Firestore DatabaseInfo and port both Database{Id,Info} C++ to the iOS code (#738)

* implement Firestore DatabaseInfo in C++

* temporary stash changes; blocking on the massive renaming of .m to .mm

* add database_info_test to project

* finish port DatabaseId and fix style, modular fixing DatabaseInfo

* port DatabaseInfo

* remove FSTDatabase{ID,Info} and their tests from project

* fix unit test

* use namespace alias

* use namespace alias, leftover

* address more changes

* refactoring to use raw pointer instead of value for property

* address changes

* remove self->

* fix style

* remove the name suffix Alloc

* fix a bug

5 files changed, 66 insertions, 35 deletions

diff --git a/Firestore/Source/API/FIRDocumentSnapshot.mm b/Firestore/Source/API/FIRDocumentSnapshot.mm
index 10709e8..ddf4cca 100644
--- a/Firestore/Source/API/FIRDocumentSnapshot.mm
+++ b/Firestore/Source/API/FIRDocumentSnapshot.mm
@@ -21,7 +21,6 @@
 #import "Firestore/Source/API/FIRFirestore+Internal.h"
 #import "Firestore/Source/API/FIRSnapshotMetadata+Internal.h"
 #import "Firestore/Source/API/FIRSnapshotOptions+Internal.h"
-#import "Firestore/Source/Model/FSTDatabaseID.h"
 #import "Firestore/Source/Model/FSTDocument.h"
 #import "Firestore/Source/Model/FSTDocumentKey.h"
 #import "Firestore/Source/Model/FSTFieldValue.h"
@@ -29,6 +28,12 @@
 #import "Firestore/Source/Util/FSTAssert.h"
 #import "Firestore/Source/Util/FSTUsageValidation.h"
 
+#include "Firestore/core/src/firebase/firestore/model/database_id.h"
+#include "Firestore/core/src/firebase/firestore/util/string_apple.h"
+
+namespace util = firebase::firestore::util;
+using firebase::firestore::model::DatabaseId;
+
 NS_ASSUME_NONNULL_BEGIN
 
 @interface FIRDocumentSnapshot ()
@@ -173,16 +178,18 @@ NS_ASSUME_NONNULL_BEGIN
     return [self convertedArray:(FSTArrayValue *)value options:options];
   } else if ([value isKindOfClass:[FSTReferenceValue class]]) {
     FSTReferenceValue *ref = (FSTReferenceValue *)value;
-    FSTDatabaseID *refDatabase = ref.databaseID;
-    FSTDatabaseID *database = self.firestore.databaseID;
-    if (![refDatabase isEqualToDatabaseId:database]) {
+    const DatabaseId *refDatabase = ref.databaseID;
+    const DatabaseId *database = self.firestore.databaseID;
+    if (*refDatabase != *database) {
       // TODO(b/32073923): Log this as a proper warning.
       NSLog(
           @"WARNING: Document %@ contains a document reference within a different database "
            "(%@/%@) which is not supported. It will be treated as a reference within the "
            "current database (%@/%@) instead.",
-          self.reference.path, refDatabase.projectID, refDatabase.databaseID, database.projectID,
-          database.databaseID);
+          self.reference.path, util::WrapNSStringNoCopy(refDatabase->project_id()),
+          util::WrapNSStringNoCopy(refDatabase->database_id()),
+          util::WrapNSStringNoCopy(database->project_id()),
+          util::WrapNSStringNoCopy(database->database_id()));
     }
     return [FIRDocumentReference referenceWithKey:[ref valueWithOptions:options]
                                         firestore:self.firestore];
diff --git a/Firestore/Source/API/FIRFirestore+Internal.h b/Firestore/Source/API/FIRFirestore+Internal.h
index c2e995a..717a08b 100644
--- a/Firestore/Source/API/FIRFirestore+Internal.h
+++ b/Firestore/Source/API/FIRFirestore+Internal.h
@@ -16,9 +16,10 @@
 
 #import "FIRFirestore.h"
 
+#include "Firestore/core/src/firebase/firestore/model/database_id.h"
+
 NS_ASSUME_NONNULL_BEGIN
 
-@class FSTDatabaseID;
 @class FSTDispatchQueue;
 @class FSTFirestoreClient;
 @class FSTUserDataConverter;
@@ -54,7 +55,8 @@ NS_ASSUME_NONNULL_BEGIN
 - (void)shutdownWithCompletion:(nullable void (^)(NSError *_Nullable error))completion
     NS_SWIFT_NAME(shutdown(completion:));
 
-@property(nonatomic, strong, readonly) FSTDatabaseID *databaseID;
+// FIRFirestore ownes the DatabaseId instance.
+@property(nonatomic, assign, readonly) const firebase::firestore::model::DatabaseId *databaseID;
 @property(nonatomic, strong, readonly) FSTFirestoreClient *client;
 @property(nonatomic, strong, readonly) FSTUserDataConverter *dataConverter;
 
diff --git a/Firestore/Source/API/FIRFirestore.mm b/Firestore/Source/API/FIRFirestore.mm
index 10367bd..5e978cc 100644
--- a/Firestore/Source/API/FIRFirestore.mm
+++ b/Firestore/Source/API/FIRFirestore.mm
@@ -29,9 +29,7 @@
 #import "Firestore/Source/API/FSTUserDataConverter.h"
 
 #import "Firestore/Source/Auth/FSTCredentialsProvider.h"
-#import "Firestore/Source/Core/FSTDatabaseInfo.h"
 #import "Firestore/Source/Core/FSTFirestoreClient.h"
-#import "Firestore/Source/Model/FSTDatabaseID.h"
 #import "Firestore/Source/Model/FSTDocumentKey.h"
 #import "Firestore/Source/Model/FSTPath.h"
 #import "Firestore/Source/Util/FSTAssert.h"
@@ -39,13 +37,23 @@
 #import "Firestore/Source/Util/FSTLogger.h"
 #import "Firestore/Source/Util/FSTUsageValidation.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/string_apple.h"
+
+namespace util = firebase::firestore::util;
+using firebase::firestore::core::DatabaseInfo;
+using firebase::firestore::model::DatabaseId;
+
 NS_ASSUME_NONNULL_BEGIN
 
 extern "C" NSString *const FIRFirestoreErrorDomain = @"FIRFirestoreErrorDomain";
 
-@interface FIRFirestore ()
+@interface FIRFirestore () {
+  /** The actual owned DatabaseId instance is allocated in FIRFirestore. */
+  firebase::firestore::model::DatabaseId _databaseID;
+}
 
-@property(nonatomic, strong) FSTDatabaseID *databaseID;
 @property(nonatomic, strong) NSString *persistenceKey;
 @property(nonatomic, strong) id<FSTCredentialsProvider> credentialsProvider;
 @property(nonatomic, strong) FSTDispatchQueue *workerDispatchQueue;
@@ -79,11 +87,13 @@ extern "C" NSString *const FIRFirestoreErrorDomain = @"FIRFirestoreErrorDomain";
                          @"Failed to get FirebaseApp instance. Please call FirebaseApp.configure() "
                          @"before using Firestore");
   }
-  return [self firestoreForApp:app database:kDefaultDatabaseID];
+  return
+      [self firestoreForApp:app database:util::WrapNSStringNoCopy(DatabaseId::kDefaultDatabaseId)];
 }
 
 + (instancetype)firestoreForApp:(FIRApp *)app {
-  return [self firestoreForApp:app database:kDefaultDatabaseID];
+  return
+      [self firestoreForApp:app database:util::WrapNSStringNoCopy(DatabaseId::kDefaultDatabaseId)];
 }
 
 // TODO(b/62410906): make this public
@@ -97,7 +107,7 @@ extern "C" NSString *const FIRFirestoreErrorDomain = @"FIRFirestoreErrorDomain";
     FSTThrowInvalidArgument(
         @"database identifier may not be nil. Use '%@' if you want the default "
          "database",
-        kDefaultDatabaseID);
+        util::WrapNSStringNoCopy(DatabaseId::kDefaultDatabaseId));
   }
   NSString *key = [NSString stringWithFormat:@"%@|%@", app.name, database];
 
@@ -136,7 +146,7 @@ extern "C" NSString *const FIRFirestoreErrorDomain = @"FIRFirestoreErrorDomain";
               workerDispatchQueue:(FSTDispatchQueue *)workerDispatchQueue
                       firebaseApp:(FIRApp *)app {
   if (self = [super init]) {
-    _databaseID = [FSTDatabaseID databaseIDWithProject:projectID database:database];
+    _databaseID = DatabaseId(util::MakeStringView(projectID), util::MakeStringView(database));
     FSTPreConverterBlock block = ^id _Nullable(id _Nullable input) {
       if ([input isKindOfClass:[FIRDocumentReference class]]) {
         FIRDocumentReference *documentReference = (FIRDocumentReference *)input;
@@ -147,7 +157,7 @@ extern "C" NSString *const FIRFirestoreErrorDomain = @"FIRFirestoreErrorDomain";
       }
     };
     _dataConverter =
-        [[FSTUserDataConverter alloc] initWithDatabaseID:_databaseID preConverter:block];
+        [[FSTUserDataConverter alloc] initWithDatabaseID:&_databaseID preConverter:block];
     _persistenceKey = persistenceKey;
     _credentialsProvider = credentialsProvider;
     _workerDispatchQueue = workerDispatchQueue;
@@ -193,15 +203,12 @@ extern "C" NSString *const FIRFirestoreErrorDomain = @"FIRFirestoreErrorDomain";
       FSTAssert(_settings.host, @"FirestoreSettings.host cannot be nil.");
       FSTAssert(_settings.dispatchQueue, @"FirestoreSettings.dispatchQueue cannot be nil.");
 
-      FSTDatabaseInfo *databaseInfo =
-          [FSTDatabaseInfo databaseInfoWithDatabaseID:_databaseID
-                                       persistenceKey:_persistenceKey
-                                                 host:_settings.host
-                                           sslEnabled:_settings.sslEnabled];
+      const DatabaseInfo database_info(*self.databaseID, util::MakeStringView(_persistenceKey),
+                                       util::MakeStringView(_settings.host), _settings.sslEnabled);
 
       FSTDispatchQueue *userDispatchQueue = [FSTDispatchQueue queueWith:_settings.dispatchQueue];
 
-      _client = [FSTFirestoreClient clientWithDatabaseInfo:databaseInfo
+      _client = [FSTFirestoreClient clientWithDatabaseInfo:database_info
                                             usePersistence:_settings.persistenceEnabled
                                        credentialsProvider:_credentialsProvider
                                          userDispatchQueue:userDispatchQueue
@@ -312,6 +319,10 @@ extern "C" NSString *const FIRFirestoreErrorDomain = @"FIRFirestoreErrorDomain";
   [self.client disableNetworkWithCompletion:completion];
 }
 
+- (const DatabaseId *)databaseID {
+  return &_databaseID;
+}
+
 @end
 
 NS_ASSUME_NONNULL_END
diff --git a/Firestore/Source/API/FSTUserDataConverter.h b/Firestore/Source/API/FSTUserDataConverter.h
index 2c52ad8..1058848 100644
--- a/Firestore/Source/API/FSTUserDataConverter.h
+++ b/Firestore/Source/API/FSTUserDataConverter.h
@@ -16,8 +16,9 @@
 
 #import <Foundation/Foundation.h>
 
+#include "Firestore/core/src/firebase/firestore/model/database_id.h"
+
 @class FIRSetOptions;
-@class FSTDatabaseID;
 @class FSTDocumentKey;
 @class FSTObjectValue;
 @class FSTFieldMask;
@@ -87,10 +88,12 @@ NS_ASSUME_NONNULL_BEGIN
 - (instancetype)init NS_UNAVAILABLE;
 
 - (instancetype)initWithKey:(FSTDocumentKey *)key
-                 databaseID:(FSTDatabaseID *)databaseID NS_DESIGNATED_INITIALIZER;
+                 databaseID:(const firebase::firestore::model::DatabaseId *)databaseID
+    NS_DESIGNATED_INITIALIZER;
 
 @property(nonatomic, strong, readonly) FSTDocumentKey *key;
-@property(nonatomic, strong, readonly) FSTDatabaseID *databaseID;
+// Does not own the DatabaseId instance.
+@property(nonatomic, assign, readonly) const firebase::firestore::model::DatabaseId *databaseID;
 
 @end
 
@@ -107,7 +110,7 @@ typedef id _Nullable (^FSTPreConverterBlock)(id _Nullable);
 @interface FSTUserDataConverter : NSObject
 
 - (instancetype)init NS_UNAVAILABLE;
-- (instancetype)initWithDatabaseID:(FSTDatabaseID *)databaseID
+- (instancetype)initWithDatabaseID:(const firebase::firestore::model::DatabaseId *)databaseID
                       preConverter:(FSTPreConverterBlock)preConverter NS_DESIGNATED_INITIALIZER;
 
 /** Parse document data from a non-merge setData call.*/
diff --git a/Firestore/Source/API/FSTUserDataConverter.mm b/Firestore/Source/API/FSTUserDataConverter.mm
index 414aadb..80d4625 100644
--- a/Firestore/Source/API/FSTUserDataConverter.mm
+++ b/Firestore/Source/API/FSTUserDataConverter.mm
@@ -23,7 +23,6 @@
 #import "Firestore/Source/API/FIRFirestore+Internal.h"
 #import "Firestore/Source/API/FIRSetOptions+Internal.h"
 #import "Firestore/Source/Core/FSTTimestamp.h"
-#import "Firestore/Source/Model/FSTDatabaseID.h"
 #import "Firestore/Source/Model/FSTDocumentKey.h"
 #import "Firestore/Source/Model/FSTFieldValue.h"
 #import "Firestore/Source/Model/FSTMutation.h"
@@ -31,6 +30,12 @@
 #import "Firestore/Source/Util/FSTAssert.h"
 #import "Firestore/Source/Util/FSTUsageValidation.h"
 
+#include "Firestore/core/src/firebase/firestore/model/database_id.h"
+#include "Firestore/core/src/firebase/firestore/util/string_apple.h"
+
+namespace util = firebase::firestore::util;
+using firebase::firestore::model::DatabaseId;
+
 NS_ASSUME_NONNULL_BEGIN
 
 static NSString *const RESERVED_FIELD_DESIGNATOR = @"__";
@@ -271,7 +276,7 @@ typedef NS_ENUM(NSInteger, FSTUserDataSource) {
 
 @implementation FSTDocumentKeyReference
 
-- (instancetype)initWithKey:(FSTDocumentKey *)key databaseID:(FSTDatabaseID *)databaseID {
+- (instancetype)initWithKey:(FSTDocumentKey *)key databaseID:(const DatabaseId *)databaseID {
   self = [super init];
   if (self) {
     _key = key;
@@ -285,13 +290,14 @@ typedef NS_ENUM(NSInteger, FSTUserDataSource) {
 #pragma mark - FSTUserDataConverter
 
 @interface FSTUserDataConverter ()
-@property(strong, nonatomic, readonly) FSTDatabaseID *databaseID;
+// Does not own the DatabaseId instance.
+@property(assign, nonatomic, readonly) const DatabaseId *databaseID;
 @property(strong, nonatomic, readonly) FSTPreConverterBlock preConverter;
 @end
 
 @implementation FSTUserDataConverter
 
-- (instancetype)initWithDatabaseID:(FSTDatabaseID *)databaseID
+- (instancetype)initWithDatabaseID:(const DatabaseId *)databaseID
                       preConverter:(FSTPreConverterBlock)preConverter {
   self = [super init];
   if (self) {
@@ -540,12 +546,14 @@ typedef NS_ENUM(NSInteger, FSTUserDataSource) {
 
   } else if ([input isKindOfClass:[FSTDocumentKeyReference class]]) {
     FSTDocumentKeyReference *reference = input;
-    if (![reference.databaseID isEqual:self.databaseID]) {
-      FSTDatabaseID *other = reference.databaseID;
+    if (*reference.databaseID != *self.databaseID) {
+      const DatabaseId *other = reference.databaseID;
       FSTThrowInvalidArgument(
           @"Document Reference is for database %@/%@ but should be for database %@/%@%@",
-          other.projectID, other.databaseID, self.databaseID.projectID, self.databaseID.databaseID,
-          [context fieldDescription]);
+          util::WrapNSStringNoCopy(other->project_id()),
+          util::WrapNSStringNoCopy(other->database_id()),
+          util::WrapNSStringNoCopy(self.databaseID->project_id()),
+          util::WrapNSStringNoCopy(self.databaseID->database_id()), [context fieldDescription]);
     }
     return [FSTReferenceValue referenceValue:reference.key databaseID:self.databaseID];