Migrate ReactLegacyArchitectureProcessor to kotlin (facebook#49571)

Summary:
Pull Request resolved: facebook#49571

Migrate ReactLegacyArchitectureProcessor to kotlin

changelog: [internal] internal

Reviewed By: cortinico

Differential Revision: D69929877

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/processing/ReactLegacyArchitectureProcessor.kt

@@ -0,0 +1,48 @@
+/*
+ * 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.processing
+
+import com.facebook.annotationprocessors.common.ProcessorBase
+import com.facebook.react.common.annotations.internal.LegacyArchitecture
+import java.io.FileWriter
+import java.io.IOException
+import javax.annotation.processing.RoundEnvironment
+import javax.annotation.processing.SupportedAnnotationTypes
+import javax.annotation.processing.SupportedSourceVersion
+import javax.lang.model.SourceVersion
+import javax.lang.model.element.TypeElement
+
+@SupportedAnnotationTypes("com.facebook.react.common.annotations.internal.LegacyArchitecture")
+@SupportedSourceVersion(SourceVersion.RELEASE_11)
+class ReactLegacyArchitectureProcessor : ProcessorBase() {
+  override fun processImpl(annotations: Set<TypeElement>, roundEnv: RoundEnvironment): Boolean {
+    val outputFileName = System.getenv()["RN_LEGACY_ARCH_OUTPUT_FILE_NAME"]
+    if (outputFileName.isNullOrEmpty()) {
+      return true
+    }
+    val elements = roundEnv.getElementsAnnotatedWith(LegacyArchitecture::class.java)
+    val classes: MutableList<String> = mutableListOf()
+
+    elements.forEach { element ->
+      val classType = element as TypeElement
+      val className = classType.qualifiedName.toString().replace(".", "/")
+      classes.add("type L$className;")
+    }
+
+    try {
+      FileWriter(outputFileName, true).use { writer ->
+        for (clazz in classes) {
+          writer.write(clazz + "\n")
+        }
+      }
+    } catch (e: IOException) {
+      throw RuntimeException(e)
+    }
+    return true
+  }
+}