Make the Fabric Interop layer work in Bridgeless (#40732)

Summary:

This change allows the Fabric Interop Layer to work in bridgeless mode.

Given that the legacy components requires a Bridge to send events and use commands, this change simulates a bridge when it doesn't exists (i.e.: we are in bridgeless mode).

In order to make it work, we had to simulate a few elements from the Bridge and the UIManager.

## Changelog:
[iOS][Fixed] - Make the Fabric interop layer works in bridgeless mode.

## Facebook:
As an alternative approach, we could have created a `protocol RCTBridging`, have the `RCTBridge` conform to that protocol, and create a new type for it.
Practically this would have been much more cumbersome:
1. The [RCTBridge](https://www.internalfb.com/code/fbsource/[916531b9bf7a9943036807f7563c925b4c3e0101]/xplat/js/react-native-github/packages/react-native/React/Base/RCTBridge.h?lines=87-238) interface is quite big. All the props and method should be part of the protocol.
2. Extensions declared on RCTBridge would not have worked. For example, [`RCTBridge (RCTUIManager)`](https://www.internalfb.com/code/fbsource/[916531b9bf7a9943036807f7563c925b4c3e0101]/xplat/js/react-native-github/packages/react-native/React/Modules/RCTUIManager.h?lines=170-174).
3. It would require a major overhaul of the APIs, returning `id<RCTBridging>` in place of **every** function that takes/return an instance of `RCTBridge *`.

Clearly, not a feasible way to go.

Reviewed By: RSNara

Differential Revision: D50079929

Author: Riccardo Cipolleschi

packages/react-native/React/Base/RCTBridgeProxy.mm

@@ -351,6 +351,11 @@ - (RCTUIManager *)uiManager
   return (RCTUIManager *)_uiManagerProxy;
 }
 
+- (RCTBridgeProxy *)object
+{
+  return self;
+}
+
 /**
  * NSProxy setup
  */
@@ -387,12 +392,14 @@ - (void)logError:(NSString *)message cmd:(SEL)cmd
 
 @implementation RCTUIManagerProxy {
   RCTViewRegistry *_viewRegistry;
+  NSMutableDictionary<NSNumber *, UIView *> *_legacyViewRegistry;
 }
 - (instancetype)initWithViewRegistry:(RCTViewRegistry *)viewRegistry
 {
   self = [super self];
   if (self) {
     _viewRegistry = viewRegistry;
+    _legacyViewRegistry = [NSMutableDictionary new];
   }
   return self;
 }
@@ -404,20 +411,21 @@ - (UIView *)viewForReactTag:(NSNumber *)reactTag
 {
   [self logWarning:@"Please migrate to RCTViewRegistry: @synthesize viewRegistry_DEPRECATED = _viewRegistry_DEPRECATED."
                cmd:_cmd];
-  return [_viewRegistry viewForReactTag:reactTag];
+  return [_viewRegistry viewForReactTag:reactTag] ? [_viewRegistry viewForReactTag:reactTag]
+                                                  : [_legacyViewRegistry objectForKey:reactTag];
 }
 
 - (void)addUIBlock:(RCTViewManagerUIBlock)block
 {
   [self
       logWarning:
-          @"This method isn't implemented faithfully: the viewRegistry passed to RCTViewManagerUIBlock is nil. Please migrate to RCTViewRegistry: @synthesize viewRegistry_DEPRECATED = _viewRegistry_DEPRECATED."
+          @"This method isn't implemented faithfully. Please migrate to RCTViewRegistry if possible: @synthesize viewRegistry_DEPRECATED = _viewRegistry_DEPRECATED."
              cmd:_cmd];
   __weak __typeof(self) weakSelf = self;
   RCTExecuteOnMainQueue(^{
     __typeof(self) strongSelf = weakSelf;
     if (strongSelf) {
-      block((RCTUIManager *)strongSelf, nil);
+      block((RCTUIManager *)strongSelf, strongSelf->_legacyViewRegistry);
     }
   });
 }

packages/react-native/React/Modules/RCTUIManager.h

@@ -9,6 +9,7 @@
 
 #import <React/RCTBridge.h>
 #import <React/RCTBridgeModule.h>
+#import <React/RCTBridgeProxy.h>
 #import <React/RCTInvalidating.h>
 #import <React/RCTRootView.h>
 #import <React/RCTViewManager.h>
@@ -173,6 +174,12 @@ RCT_EXTERN NSString *const RCTUIManagerWillUpdateViewsDueToContentSizeMultiplier
 
 @end
 
+@interface RCTBridgeProxy (RCTUIManager)
+
+@property (nonatomic, readonly) RCTUIManager *uiManager;
+
+@end
+
 RCT_EXTERN NSMutableDictionary<NSString *, id> *RCTModuleConstantsForDestructuredComponent(
     NSMutableDictionary<NSString *, NSDictionary *> *directEvents,
     NSMutableDictionary<NSString *, NSDictionary *> *bubblingEvents,

packages/react-native/React/Views/RCTComponentData.m

@@ -71,7 +71,7 @@ - (RCTViewManager *)manager
                                                         object:nil
                                                       userInfo:@{@"module" : _bridgelessViewManager}];
   }
-  return _manager ?: _bridgelessViewManager;
+  return _manager ? _manager : _bridgelessViewManager;
 }
 
 RCT_NOT_IMPLEMENTED(-(instancetype)init)

packages/react-native/ReactCommon/react/renderer/components/legacyviewmanagerinterop/LegacyViewManagerInteropComponentDescriptor.mm

@@ -8,6 +8,7 @@
 #include "LegacyViewManagerInteropComponentDescriptor.h"
 #include <React/RCTBridge.h>
 #include <React/RCTBridgeModuleDecorator.h>
+#include <React/RCTBridgeProxy.h>
 #include <React/RCTComponentData.h>
 #include <React/RCTEventDispatcher.h>
 #include <React/RCTModuleData.h>
@@ -86,6 +87,12 @@ static Class getViewManagerFromComponentName(const std::string &componentName)
     bridge = unwrapManagedObjectWeakly(optionalBridge.value());
   }
 
+  RCTBridgeProxy *bridgeProxy;
+  auto optionalBridgeProxy = contextContainer->find<std::shared_ptr<void>>("RCTBridgeProxy");
+  if (optionalBridgeProxy) {
+    bridgeProxy = unwrapManagedObjectWeakly(optionalBridgeProxy.value());
+  }
+
   auto optionalEventDispatcher = contextContainer->find<std::shared_ptr<void>>("RCTEventDispatcher");
   RCTEventDispatcher *eventDispatcher;
   if (optionalEventDispatcher) {
@@ -104,6 +111,7 @@ static Class getViewManagerFromComponentName(const std::string &componentName)
   return wrapManagedObject([[RCTLegacyViewManagerInteropCoordinator alloc]
       initWithComponentData:componentData
                      bridge:bridge
+                bridgeProxy:bridgeProxy
       bridgelessInteropData:bridgeModuleDecorator]);
 }
 

packages/react-native/ReactCommon/react/renderer/components/legacyviewmanagerinterop/RCTLegacyViewManagerInteropCoordinator.h

@@ -14,13 +14,15 @@ NS_ASSUME_NONNULL_BEGIN
 
 @class RCTComponentData;
 @class RCTBridge;
+@class RCTBridgeProxy;
 
 typedef void (^InterceptorBlock)(std::string eventName, folly::dynamic event);
 
 @interface RCTLegacyViewManagerInteropCoordinator : NSObject
 
 - (instancetype)initWithComponentData:(RCTComponentData *)componentData
-                               bridge:(RCTBridge *)bridge
+                               bridge:(nullable RCTBridge *)bridge
+                          bridgeProxy:(nullable RCTBridgeProxy *)bridgeProxy
                 bridgelessInteropData:(RCTBridgeModuleDecorator *)bridgelessInteropData;
 
 - (UIView *)createPaperViewWithTag:(NSInteger)tag;

packages/react-native/ReactCommon/react/renderer/components/legacyviewmanagerinterop/RCTLegacyViewManagerInteropCoordinator.mm

@@ -8,6 +8,7 @@
 #include "RCTLegacyViewManagerInteropCoordinator.h"
 #include <React/RCTBridge+Private.h>
 #include <React/RCTBridgeMethod.h>
+#include <React/RCTBridgeProxy.h>
 #include <React/RCTComponentData.h>
 #include <React/RCTEventDispatcherProtocol.h>
 #include <React/RCTFollyConvert.h>
@@ -16,6 +17,7 @@
 #include <React/RCTUIManager.h>
 #include <React/RCTUIManagerUtils.h>
 #include <React/RCTUtils.h>
+#include <React/RCTViewManager.h>
 #include <folly/json.h>
 #include <objc/runtime.h>
 
@@ -25,6 +27,8 @@ @implementation RCTLegacyViewManagerInteropCoordinator {
   RCTComponentData *_componentData;
   __weak RCTBridge *_bridge;
   __weak RCTBridgeModuleDecorator *_bridgelessInteropData;
+  __weak RCTBridgeProxy *_bridgeProxy;
+
   /*
    Each instance of `RCTLegacyViewManagerInteropComponentView` registers a block to which events are dispatched.
    This is the container that maps unretained UIView pointer to a block to which the event is dispatched.
@@ -40,13 +44,16 @@ @implementation RCTLegacyViewManagerInteropCoordinator {
 }
 
 - (instancetype)initWithComponentData:(RCTComponentData *)componentData
-                               bridge:(RCTBridge *)bridge
+                               bridge:(nullable RCTBridge *)bridge
+                          bridgeProxy:(nullable RCTBridgeProxy *)bridgeProxy
                 bridgelessInteropData:(RCTBridgeModuleDecorator *)bridgelessInteropData;
 {
   if (self = [super init]) {
     _componentData = componentData;
     _bridge = bridge;
     _bridgelessInteropData = bridgelessInteropData;
+    _bridgeProxy = bridgeProxy;
+
     if (bridgelessInteropData) {
       //  During bridge mode, RCTBridgeModules will be decorated with these APIs by the bridge.
       RCTAssert(
@@ -62,7 +69,9 @@ - (instancetype)initWithComponentData:(RCTComponentData *)componentData
       if (strongSelf) {
         InterceptorBlock block = [strongSelf->_eventInterceptors objectForKey:reactTag];
         if (block) {
-          block(std::string([RCTNormalizeInputEventName(eventName) UTF8String]), convertIdToFollyDynamic(event ?: @{}));
+          block(
+              std::string([RCTNormalizeInputEventName(eventName) UTF8String]),
+              convertIdToFollyDynamic(event ? event : @{}));
         }
       }
     };
@@ -131,15 +140,9 @@ - (void)handleCommand:(NSString *)commandName
   NSArray *newArgs = [@[ [NSNumber numberWithInteger:tag] ] arrayByAddingObjectsFromArray:args];
 
   if (_bridge) {
-    [_bridge.batchedBridge
-        dispatchBlock:^{
-          [method invokeWithBridge:self->_bridge module:self->_componentData.manager arguments:newArgs];
-          [self->_bridge.uiManager setNeedsLayout];
-        }
-                queue:RCTGetUIManagerQueue()];
+    [self _handleCommandsOnBridge:method withArgs:newArgs];
   } else {
-    // TODO T86826778 - Figure out which queue this should be dispatched to.
-    [method invokeWithBridge:nil module:self->_componentData.manager arguments:newArgs];
+    [self _handleCommandsOnBridgeless:method withArgs:newArgs];
   }
 }
 
@@ -169,8 +172,37 @@ - (void)removeViewFromRegistryWithTag:(NSInteger)tag
 }
 
 #pragma mark - Private
+- (void)_handleCommandsOnBridge:(id<RCTBridgeMethod>)method withArgs:(NSArray *)newArgs
+{
+  [_bridge.batchedBridge
+      dispatchBlock:^{
+        [method invokeWithBridge:self->_bridge module:self->_componentData.manager arguments:newArgs];
+        [self->_bridge.uiManager setNeedsLayout];
+      }
+              queue:RCTGetUIManagerQueue()];
+}
+
+- (void)_handleCommandsOnBridgeless:(id<RCTBridgeMethod>)method withArgs:(NSArray *)newArgs
+{
+  RCTViewManager *componentViewManager = self->_componentData.manager;
+  [componentViewManager setValue:_bridgeProxy forKey:@"bridge"];
+
+  [self->_bridgeProxy.uiManager
+      addUIBlock:^(RCTUIManager *uiManager, NSDictionary<NSNumber *, UIView *> *viewRegistry) {
+        [method invokeWithBridge:nil module:componentViewManager arguments:newArgs];
+      }];
+}
 
 - (void)_addUIBlock:(RCTViewManagerUIBlock)block
+{
+  if (_bridge) {
+    [self _addUIBlockOnBridge:block];
+  } else {
+    [self->_bridgeProxy.uiManager addUIBlock:block];
+  }
+}
+
+- (void)_addUIBlockOnBridge:(RCTViewManagerUIBlock)block
 {
   __weak __typeof__(self) weakSelf = self;
   [_bridge.batchedBridge

packages/react-native/ReactCommon/react/runtime/platform/ios/ReactCommon/RCTInstance.mm

@@ -227,24 +227,23 @@ - (void)_start
   RuntimeExecutor bufferedRuntimeExecutor = _reactInstance->getBufferedRuntimeExecutor();
   timerManager->setRuntimeExecutor(bufferedRuntimeExecutor);
 
-  RCTBridgeProxy *bridgeProxy = RCTTurboModuleInteropEnabled() && RCTTurboModuleInteropBridgeProxyEnabled()
-      ? [[RCTBridgeProxy alloc] initWithViewRegistry:_bridgeModuleDecorator.viewRegistry_DEPRECATED
-            moduleRegistry:_bridgeModuleDecorator.moduleRegistry
-            bundleManager:_bridgeModuleDecorator.bundleManager
-            callableJSModules:_bridgeModuleDecorator.callableJSModules
-            dispatchToJSThread:^(dispatch_block_t block) {
-              __strong __typeof(self) strongSelf = weakSelf;
-              if (strongSelf && strongSelf->_valid) {
-                strongSelf->_reactInstance->getBufferedRuntimeExecutor()([=](jsi::Runtime &runtime) { block(); });
-              }
+  RCTBridgeProxy *bridgeProxy =
+      [[RCTBridgeProxy alloc] initWithViewRegistry:_bridgeModuleDecorator.viewRegistry_DEPRECATED
+          moduleRegistry:_bridgeModuleDecorator.moduleRegistry
+          bundleManager:_bridgeModuleDecorator.bundleManager
+          callableJSModules:_bridgeModuleDecorator.callableJSModules
+          dispatchToJSThread:^(dispatch_block_t block) {
+            __strong __typeof(self) strongSelf = weakSelf;
+            if (strongSelf && strongSelf->_valid) {
+              strongSelf->_reactInstance->getBufferedRuntimeExecutor()([=](jsi::Runtime &runtime) { block(); });
             }
-            registerSegmentWithId:^(NSNumber *segmentId, NSString *path) {
-              __strong __typeof(self) strongSelf = weakSelf;
-              if (strongSelf && strongSelf->_valid) {
-                [strongSelf registerSegmentWithId:segmentId path:path];
-              }
-            }]
-      : nil;
+          }
+          registerSegmentWithId:^(NSNumber *segmentId, NSString *path) {
+            __strong __typeof(self) strongSelf = weakSelf;
+            if (strongSelf && strongSelf->_valid) {
+              [strongSelf registerSegmentWithId:segmentId path:path];
+            }
+          }];
 
   // Set up TurboModules
   _turboModuleManager = [[RCTTurboModuleManager alloc]
@@ -269,6 +268,7 @@ - (void)_start
       facebook::react::wrapManagedObject([_turboModuleManager moduleForName:"RCTEventDispatcher"]));
   contextContainer->insert("RCTBridgeModuleDecorator", facebook::react::wrapManagedObject(_bridgeModuleDecorator));
   contextContainer->insert("RuntimeScheduler", std::weak_ptr<RuntimeScheduler>(_reactInstance->getRuntimeScheduler()));
+  contextContainer->insert("RCTBridgeProxy", facebook::react::wrapManagedObject(bridgeProxy));
 
   _surfacePresenter = [[RCTSurfacePresenter alloc]
         initWithContextContainer:contextContainer