refactor(firestore,apple): migrate iOS/macOS plugin implementation to Swift (#18607)

* refactor(firestore,apple): migrate iOS/macOS plugin implementation to Swift

Replace the Objective-C Firestore plugin with a Swift implementation so Apple platforms can use Pigeon swiftOut and the typed pipeline Expression APIs.

* format

* fix(firestore,apple): address leak, retain-cycle, and parser review notes

Unregister event channels when streams cancel, avoid capturing self in snapshot listeners, copy snapshot maps without an intermediate array, cap pipeline nesting, and replace forced casts in query parsing with typed errors.

* format

* fix(firestore,apple): catch Firestore NSExceptions while parsing queries

Swift do/catch does not catch NSException, so an invalid query crashed
the release app instead of returning the parse error. Aggregate group
expressions now fail the pipeline instead of being dropped.

* fix(firestore,apple): point the macOS resources symlink at the iOS file

The Resources gitkeep had one extra parent segment, so the macOS package
resource directory did not exist.

* fix(firestore,apple): accept List<int> pipeline constants as bytes

Dart sends a byte constant as an array of numbers. Map that array to Data and pass it to Constant, the public bytes API.

* fix(firestore,apple): keep transaction results consistent across threads

The handler stays alive for the whole Firestore transaction, and the
result and commands are read and written under one lock.

Author: SelaseKay

packages/cloud_firestore/cloud_firestore/ios/cloud_firestore.podspec

@@ -24,10 +24,10 @@ Pod::Spec.new do |s|
   s.license          = { :file => '../LICENSE' }
   s.authors          = 'The Chromium Authors'
   s.source           = { :path => '.' }
-  s.source_files     = 'cloud_firestore/Sources/cloud_firestore/**/*.{h,m,mm}'
-  s.public_header_files = 'cloud_firestore/Sources/cloud_firestore/include/Public/**/*.h'
-  s.private_header_files = 'cloud_firestore/Sources/cloud_firestore/include/Private/**/*.h'
+  s.source_files     = 'cloud_firestore/Sources/**/*.{swift,h,m,mm}'
+  s.public_header_files = 'cloud_firestore/Sources/cloud_firestore_objc/include/*.h'
 
+  s.swift_version = '5.0'
   s.ios.deployment_target = '15.0'
   s.dependency 'Flutter'
 
@@ -36,7 +36,6 @@ Pod::Spec.new do |s|
 
   s.static_framework = true
   s.pod_target_xcconfig = {
-    'GCC_PREPROCESSOR_DEFINITIONS' => "LIBRARY_VERSION=\\\"#{library_version}\\\" LIBRARY_NAME=\\\"flutter-fire-fst\\\"",
     'DEFINES_MODULE' => 'YES'
   }
 end

packages/cloud_firestore/cloud_firestore/ios/cloud_firestore/Package.swift

@@ -24,23 +24,33 @@ let package = Package(
     .package(name: "FlutterFramework", path: "../FlutterFramework"),
   ],
   targets: [
+    // SPM does not allow mixing Swift and ObjC in a single target.
+    .target(
+      name: "cloud_firestore_objc",
+      dependencies: [
+        .product(name: "FirebaseFirestore", package: "firebase-ios-sdk")
+      ],
+      path: "Sources/cloud_firestore_objc",
+      publicHeadersPath: "include",
+      cSettings: [
+        .headerSearchPath("include")
+      ]
+    ),
     .target(
       name: "cloud_firestore",
       dependencies: [
+        "cloud_firestore_objc",
         .product(name: "FirebaseFirestore", package: "firebase-ios-sdk"),
         .product(name: "firebase-core", package: "firebase_core"),
         .product(name: "FlutterFramework", package: "FlutterFramework"),
       ],
+      path: "Sources/cloud_firestore",
       resources: [
         .process("Resources")
       ],
-      cSettings: [
-        .headerSearchPath("include/cloud_firestore/Private"),
-        .headerSearchPath("include/cloud_firestore/Public"),
-        .define("LIBRARY_VERSION", to: "\"\(libraryVersion)\""),
-        .define("LIBRARY_NAME", to: "\"flutter-fire-fst\""),
-        .define("FLT_FIREBASE_SDK_13"),
+      swiftSettings: [
+        .define("FLT_FIREBASE_SDK_13")
       ]
-    )
+    ),
   ]
 )

packages/cloud_firestore/cloud_firestore/ios/cloud_firestore/Sources/cloud_firestore/Constants.swift

@@ -0,0 +1,19 @@
+// Copyright 2021 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/// Auto-generated file. Do not edit.
+public let versionNumber = "7.1.0"
+
+let kFLTFirebaseFirestoreChannelName = "plugins.flutter.io/firebase_firestore"
+let kFLTFirebaseFirestoreQuerySnapshotEventChannelName =
+  "plugins.flutter.io/firebase_firestore/query"
+let kFLTFirebaseFirestoreDocumentSnapshotEventChannelName =
+  "plugins.flutter.io/firebase_firestore/document"
+let kFLTFirebaseFirestoreSnapshotsInSyncEventChannelName =
+  "plugins.flutter.io/firebase_firestore/snapshotsInSync"
+let kFLTFirebaseFirestoreTransactionChannelName =
+  "plugins.flutter.io/firebase_firestore/transaction"
+let kFLTFirebaseFirestoreLoadBundleChannelName =
+  "plugins.flutter.io/firebase_firestore/loadBundle"
+let kFirebaseFirestoreLibraryName = "flutter-fire-fst"

packages/cloud_firestore/cloud_firestore/ios/cloud_firestore/Sources/cloud_firestore/DocumentSnapshotStreamHandler.swift

@@ -0,0 +1,81 @@
+// Copyright 2021 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import FirebaseFirestore
+import Foundation
+
+#if canImport(firebase_core)
+  import firebase_core
+#else
+  import firebase_core_shared
+#endif
+
+#if os(iOS)
+  import Flutter
+#elseif os(macOS)
+  import FlutterMacOS
+#endif
+
+final class DocumentSnapshotStreamHandler: NSObject, FlutterStreamHandler {
+  private let firestore: Firestore
+  private let reference: DocumentReference
+  private let includeMetadataChanges: Bool
+  private let serverTimestampBehavior: FirebaseFirestore.ServerTimestampBehavior
+  private let source: FirebaseFirestore.ListenSource
+  private var listenerRegistration: ListenerRegistration?
+
+  init(
+    firestore: Firestore,
+    reference: DocumentReference,
+    includeMetadataChanges: Bool,
+    serverTimestampBehavior: FirebaseFirestore.ServerTimestampBehavior,
+    source: FirebaseFirestore.ListenSource
+  ) {
+    self.firestore = firestore
+    self.reference = reference
+    self.includeMetadataChanges = includeMetadataChanges
+    self.serverTimestampBehavior = serverTimestampBehavior
+    self.source = source
+  }
+
+  func onListen(withArguments arguments: Any?, eventSink events: @escaping FlutterEventSink)
+    -> FlutterError?
+  {
+    let options = SnapshotListenOptions()
+      .withIncludeMetadataChanges(includeMetadataChanges)
+      .withSource(source)
+
+    listenerRegistration = reference.addSnapshotListener(options: options) {
+      [serverTimestampBehavior] snapshot, error in
+      if let error {
+        let (code, message) = FirebaseFirestoreUtils.errorCodeAndMessage(from: error)
+        DispatchQueue.main.async {
+          events(
+            FLTFirebasePlugin.createFlutterError(
+              fromCode: code,
+              message: message,
+              optionalDetails: ["code": code, "message": message],
+              andOptionalNSError: error as NSError
+            )
+          )
+        }
+      } else if let snapshot {
+        DispatchQueue.main.async {
+          events(
+            PigeonParser.toPigeonDocumentSnapshot(
+              snapshot, serverTimestampBehavior: serverTimestampBehavior
+            )
+          )
+        }
+      }
+    }
+    return nil
+  }
+
+  func onCancel(withArguments arguments: Any?) -> FlutterError? {
+    listenerRegistration?.remove()
+    listenerRegistration = nil
+    return nil
+  }
+}