Migrate AnimatedNode.java to Kotlin (facebook#45601)

Summary:
Pull Request resolved: facebook#45601

AnimatedNode.java  -> AnimatedNode.kt

changelog: [internal] internal

Reviewed By: tdn120

Differential Revision: D60076481

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

@@ -440,6 +440,23 @@ public abstract interface class com/facebook/react/ViewManagerOnDemandReactPacka
 	public abstract fun getViewManagerNames (Lcom/facebook/react/bridge/ReactApplicationContext;)Ljava/util/Collection;
 }
 
+public abstract class com/facebook/react/animated/AnimatedNode {
+	public static final field Companion Lcom/facebook/react/animated/AnimatedNode$Companion;
+	public static final field DEFAULT_ANIMATED_NODE_CHILD_COUNT I
+	public static final field INITIAL_BFS_COLOR I
+	public fun <init> ()V
+	public final fun addChild (Lcom/facebook/react/animated/AnimatedNode;)V
+	public fun onAttachedToNode (Lcom/facebook/react/animated/AnimatedNode;)V
+	public fun onDetachedFromNode (Lcom/facebook/react/animated/AnimatedNode;)V
+	public abstract fun prettyPrint ()Ljava/lang/String;
+	public final fun prettyPrintWithChildren ()Ljava/lang/String;
+	public final fun removeChild (Lcom/facebook/react/animated/AnimatedNode;)V
+	public fun update ()V
+}
+
+public final class com/facebook/react/animated/AnimatedNode$Companion {
+}
+
 public class com/facebook/react/animated/NativeAnimatedModule : com/facebook/fbreact/specs/NativeAnimatedModuleSpec, com/facebook/react/bridge/LifecycleEventListener, com/facebook/react/bridge/UIManagerListener {
 	public static final field ANIMATED_MODULE_DEBUG Z
 	public fun <init> (Lcom/facebook/react/bridge/ReactApplicationContext;)V

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/animated/AnimatedNode.kt

@@ -0,0 +1,74 @@
+/*
+ * 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.animated
+
+import java.util.ArrayList
+
+/** Base class for all Animated.js library node types that can be created on the "native" side. */
+public abstract class AnimatedNode {
+
+  public companion object {
+    public const val INITIAL_BFS_COLOR: Int = 0
+    public const val DEFAULT_ANIMATED_NODE_CHILD_COUNT: Int = 1
+  }
+
+  // TODO: T196787278 Reduce the visibility of these fields to package once we have
+  // converted the whole module to Kotlin
+
+  @JvmField
+  internal var mChildren: MutableList<AnimatedNode>? =
+      null /* lazy-initialized when a child is added */
+  @JvmField internal var mActiveIncomingNodes: Int = 0
+  @JvmField internal var mBFSColor: Int = INITIAL_BFS_COLOR
+  @JvmField internal var mTag: Int = -1
+
+  public fun addChild(child: AnimatedNode): Unit {
+    val children =
+        mChildren
+            ?: ArrayList<AnimatedNode>(DEFAULT_ANIMATED_NODE_CHILD_COUNT).also { mChildren = it }
+
+    children.add(child)
+    child.onAttachedToNode(this)
+  }
+
+  public fun removeChild(child: AnimatedNode): Unit {
+    val children = mChildren ?: return
+    child.onDetachedFromNode(this)
+    children.remove(child)
+  }
+
+  /**
+   * Subclasses may want to override this method in order to store a reference to the parent of a
+   * given node that can then be used to calculate current node's value in {@link #update}. In that
+   * case it is important to also override {@link #onDetachedFromNode} to clear that reference once
+   * current node gets detached.
+   */
+  public open fun onAttachedToNode(parent: AnimatedNode): Unit = Unit
+
+  /** See {@link #onAttachedToNode} */
+  public open fun onDetachedFromNode(parent: AnimatedNode): Unit = Unit
+
+  /**
+   * This method will be run on each node at most once every repetition of the animation loop. It
+   * will be executed on a node only when all the node's parent has already been updated. Therefore
+   * it can be used to calculate node's value.
+   */
+  public open fun update(): Unit = Unit
+
+  /**
+   * Pretty-printer for the AnimatedNode. Only called in production pre-crash for debug diagnostics.
+   */
+  public abstract fun prettyPrint(): String
+
+  public fun prettyPrintWithChildren(): String {
+    val children = StringBuilder()
+    mChildren?.forEach { child -> children.append(" ${child.mTag}") }
+
+    return prettyPrint() + if (children.isNotEmpty()) " children: $children" else ""
+  }
+}