Backport addUIBlock and prependUIBlock to Fabric for Android

Summary:
The `.addUIBlock` and `.prependUIBlock` APIs on UiManagerModule are missing on Fabric.
Here I'm re-implementing them to make migration to Fabric easier.

Set of changes:
- Moved `NativeViewHierarchyManager` to `NativeViewHierarchyManagerImpl` and extracted an interface
- Moved `addUIBlock` and `prependUIBlock` to the shared `UIManager` interface
- Added a `InteropUIBlockListener` class that takes care of executing the UI Blocks, implemented as a `UIManagerListener`

Changelog:
[Android] [Changed] - Changed the API of addUIBlock and prependUIBlock to implement it also in Fabric.

Reviewed By: mdvacca

Differential Revision: D53612514

fbshipit-source-id: 1cddbc391477318064f15c733a380983c3737373

Author: cortinico

packages/react-native/ReactAndroid/api/ReactAndroid.api

@@ -2520,6 +2520,7 @@ public class com/facebook/react/fabric/FabricUIManager : com/facebook/react/brid
 	public field mDevToolsReactPerfLogger Lcom/facebook/react/fabric/DevToolsReactPerfLogger;
 	public fun <init> (Lcom/facebook/react/bridge/ReactApplicationContext;Lcom/facebook/react/uimanager/ViewManagerRegistry;Lcom/facebook/react/uimanager/events/BatchEventDispatchedListener;)V
 	public fun addRootView (Landroid/view/View;Lcom/facebook/react/bridge/WritableMap;)I
+	public fun addUIBlock (Lcom/facebook/react/fabric/interop/UIBlock;)V
 	public fun addUIManagerEventListener (Lcom/facebook/react/bridge/UIManagerListener;)V
 	public fun attachRootView (Lcom/facebook/react/interfaces/fabric/SurfaceHandler;Landroid/view/View;)V
 	public fun clearJSResponder ()V
@@ -2541,6 +2542,7 @@ public class com/facebook/react/fabric/FabricUIManager : com/facebook/react/brid
 	public fun onHostPause ()V
 	public fun onHostResume ()V
 	public fun onRequestEventBeat ()V
+	public fun prependUIBlock (Lcom/facebook/react/fabric/interop/UIBlock;)V
 	public fun profileNextBatch ()V
 	public fun receiveEvent (IILjava/lang/String;Lcom/facebook/react/bridge/WritableMap;)V
 	public fun receiveEvent (IILjava/lang/String;ZLcom/facebook/react/bridge/WritableMap;I)V
@@ -2633,6 +2635,14 @@ public class com/facebook/react/fabric/events/FabricEventEmitter : com/facebook/
 	public fun receiveTouches (Ljava/lang/String;Lcom/facebook/react/bridge/WritableArray;Lcom/facebook/react/bridge/WritableArray;)V
 }
 
+public abstract interface class com/facebook/react/fabric/interop/UIBlock {
+	public abstract fun execute (Lcom/facebook/react/fabric/interop/UIBlockViewResolver;)V
+}
+
+public abstract interface class com/facebook/react/fabric/interop/UIBlockViewResolver {
+	public abstract fun resolveView (I)Landroid/view/View;
+}
+
 public abstract interface class com/facebook/react/fabric/mounting/LayoutMetricsConversions {
 	public static fun getMaxSize (I)F
 	public static fun getMinSize (I)F

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java

@@ -56,6 +56,8 @@
 import com.facebook.react.config.ReactFeatureFlags;
 import com.facebook.react.fabric.events.EventEmitterWrapper;
 import com.facebook.react.fabric.events.FabricEventEmitter;
+import com.facebook.react.fabric.internal.interop.InteropUIBlockListener;
+import com.facebook.react.fabric.interop.UIBlock;
 import com.facebook.react.fabric.mounting.MountItemDispatcher;
 import com.facebook.react.fabric.mounting.MountingManager;
 import com.facebook.react.fabric.mounting.SurfaceMountingManager;
@@ -209,6 +211,10 @@ public void executeItems(Queue<MountItem> items) {
         }
       };
 
+  // Interop UIManagerListener used to support addUIBlock and prependUIBlock.
+  // It's initialized only when addUIBlock or prependUIBlock is called the first time.
+  @Nullable private InteropUIBlockListener mInteropUIBlockListener;
+
   public FabricUIManager(
       @NonNull ReactApplicationContext reactContext,
       @NonNull ViewManagerRegistry viewManagerRegistry,
@@ -446,6 +452,37 @@ public void invalidate() {
     }
   }
 
+  /**
+   * Method added to Fabric for backward compatibility reasons, as users on Paper could call
+   * [addUiBlock] and [prependUiBlock] on UIManagerModule.
+   */
+  public void addUIBlock(UIBlock block) {
+    if (ReactFeatureFlags.unstable_useFabricInterop) {
+      InteropUIBlockListener listener = getInteropUIBlockListener();
+      listener.addUIBlock(block);
+    }
+  }
+
+  /**
+   * Method added to Fabric for backward compatibility reasons, as users on Paper could call
+   * [addUiBlock] and [prependUiBlock] on UIManagerModule.
+   */
+  public void prependUIBlock(UIBlock block) {
+    if (ReactFeatureFlags.unstable_useFabricInterop) {
+      InteropUIBlockListener listener = getInteropUIBlockListener();
+      listener.prependUIBlock(block);
+    }
+  }
+
+  @NonNull
+  private InteropUIBlockListener getInteropUIBlockListener() {
+    if (mInteropUIBlockListener == null) {
+      mInteropUIBlockListener = new InteropUIBlockListener();
+      addUIManagerEventListener(mInteropUIBlockListener);
+    }
+    return mInteropUIBlockListener;
+  }
+
   @SuppressWarnings("unused")
   private NativeArray measureLines(
       ReadableMap attributedString, ReadableMap paragraphAttributes, float width, float height) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/internal/interop/InteropUiBlockListener.kt

@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+@file:Suppress("DEPRECATION") // We want to test UIBlock and UIBlockViewResolver here.
+
+package com.facebook.react.fabric.internal.interop
+
+import com.facebook.react.bridge.UIManager
+import com.facebook.react.bridge.UIManagerListener
+import com.facebook.react.fabric.interop.UIBlock
+import com.facebook.react.fabric.interop.UIBlockViewResolver
+
+/**
+ * Interop class used to support invoking [addUIBlock] and [prependUIBlock] in Fabric.
+ *
+ * Users on the Old Architecture used to call those methods to execute arbitrary [UIBlock]s This
+ * class effectively re-implements this logic by using a [UIManagerListener] and exposing the two
+ * methods that the user intend to call.
+ */
+internal class InteropUIBlockListener : UIManagerListener {
+
+  internal val beforeUIBlocks: MutableList<UIBlock> = mutableListOf()
+  internal val afterUIBlocks: MutableList<UIBlock> = mutableListOf()
+
+  @Synchronized
+  fun prependUIBlock(block: UIBlock) {
+    beforeUIBlocks.add(block)
+  }
+
+  @Synchronized
+  fun addUIBlock(block: UIBlock) {
+    afterUIBlocks.add(block)
+  }
+
+  override fun willMountItems(uiManager: UIManager) {
+    beforeUIBlocks.forEach {
+      if (uiManager is UIBlockViewResolver) {
+        it.execute(uiManager)
+      }
+    }
+    beforeUIBlocks.clear()
+  }
+
+  override fun didMountItems(uiManager: UIManager) {
+    afterUIBlocks.forEach {
+      if (uiManager is UIBlockViewResolver) {
+        it.execute(uiManager)
+      }
+    }
+    afterUIBlocks.clear()
+  }
+
+  override fun willDispatchViewUpdates(uiManager: UIManager) = Unit
+
+  override fun didDispatchMountItems(uiManager: UIManager) = Unit
+
+  override fun didScheduleMountItems(uiManager: UIManager) = Unit
+}

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/interop/UIBlock.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+@file:Suppress("DEPRECATION") // Deprecation is added for backward compatibility reasons
+
+package com.facebook.react.fabric.interop
+
+/**
+ * Interop Interface added to support `addUiBlock` and `prependUIBlock` methods in Fabric.
+ * Historically those methods were only available in `UIManagerModule` (Paper, the old renderer).
+ * We're re-adding them to Fabric to make it easier to migrate.
+ *
+ * @deprecated When developing new libraries for Fabric you should instead use [UIManagerListener]
+ *   or View Commands to achieve a same results.
+ */
+@Deprecated("Use UIManagerListener or View Commands instead of addUIBlock and prependUIBlock.")
+public fun interface UIBlock {
+  /**
+   * A method that will allow you to call [UIBlockViewResolver.resolveView] to obtain a view
+   * instance for a given tag.
+   */
+  public fun execute(resolver: UIBlockViewResolver)
+}

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/interop/UIBlockViewResolver.kt

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.react.fabric.interop
+
+import android.view.View
+
+/**
+ * This interface is used as receiver parameter for [UIBlock].
+ *
+ * Users can invoke [resolveView] on this instance to get an Android [View] from the view tag.
+ *
+ * @deprecated When developing new libraries for Fabric you should instead use [UIManagerListener]
+ *   or View Commands to achieve a same results.
+ */
+@Deprecated("Use UIManagerListener or View Commands instead of addUIBlock and prependUIBlock.")
+public interface UIBlockViewResolver {
+  /**
+   * Resolves a [View] from the given react tag.
+   *
+   * @param reactTag the react tag of the view to resolve
+   * @return the Android [View] instance for the given tag or null if the view is not found
+   */
+  public fun resolveView(reactTag: Int): View?
+}

packages/react-native/ReactAndroid/src/test/java/com/facebook/react/fabric/internal/interop/InteropUiBlockListenerTest.kt

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.react.fabric.internal.interop
+
+import com.facebook.testutils.fakes.FakeUIManager
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class InteropUiBlockListenerTest {
+
+  @Test
+  fun prependUIBlock_addsBlockCorrectly() {
+    val underTest = InteropUIBlockListener()
+    underTest.prependUIBlock {}
+
+    assertEquals(1, underTest.beforeUIBlocks.size)
+    assertEquals(0, underTest.afterUIBlocks.size)
+  }
+
+  @Test
+  fun addUIBlock_addsBlockCorrectly() {
+    val underTest = InteropUIBlockListener()
+    underTest.addUIBlock {}
+
+    assertEquals(0, underTest.beforeUIBlocks.size)
+    assertEquals(1, underTest.afterUIBlocks.size)
+  }
+
+  @Test
+  fun willMountItems_emptiesBeforeUIBlocks() {
+    val underTest = InteropUIBlockListener()
+    underTest.prependUIBlock {}
+    underTest.addUIBlock {}
+
+    underTest.willMountItems(FakeUIManager())
+
+    assertEquals(0, underTest.beforeUIBlocks.size)
+    assertEquals(1, underTest.afterUIBlocks.size)
+  }
+
+  @Test
+  fun didMountItems_emptiesAfterUIBlocks() {
+    val underTest = InteropUIBlockListener()
+    underTest.prependUIBlock {}
+    underTest.addUIBlock {}
+
+    underTest.didMountItems(FakeUIManager())
+
+    assertEquals(1, underTest.beforeUIBlocks.size)
+    assertEquals(0, underTest.afterUIBlocks.size)
+  }
+
+  @Test
+  fun willMountItems_deliversUiManagerCorrectly() {
+    val fakeUIManager = FakeUIManager()
+    val underTest = InteropUIBlockListener()
+
+    underTest.prependUIBlock { uiManager -> uiManager.resolveView(0) }
+
+    underTest.willMountItems(fakeUIManager)
+
+    assertEquals(1, fakeUIManager.resolvedViewCount)
+  }
+
+  @Test
+  fun didMountItems_deliversUiManagerCorrectly() {
+    val fakeUIManager = FakeUIManager()
+    val underTest = InteropUIBlockListener()
+
+    underTest.addUIBlock { uiManager -> uiManager.resolveView(0) }
+
+    underTest.didMountItems(fakeUIManager)
+
+    assertEquals(1, fakeUIManager.resolvedViewCount)
+  }
+}