Add EventEmitter Code-gen support for Java and ObjC Turbo Modules (#45119)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/45119

## Changelog:

[iOS][Added] - Add EventEmitter Code-gen support for Java and ObjC Turbo Modules

Reviewed By: RSNara

Differential Revision: D58929417

fbshipit-source-id: 5208ba5ecb5882d47c3827c2aa8e3a54a3d7f2b6

packages/react-native-codegen/src/generators/modules/GenerateModuleJavaSpec.js

@@ -12,6 +12,7 @@
 
 import type {
   NamedShape,
+  NativeModuleEventEmitterShape,
   NativeModuleFunctionTypeAnnotation,
   NativeModuleParamTypeAnnotation,
   NativeModulePropertyShape,
@@ -23,6 +24,7 @@ import type {AliasResolver} from './Utils';
 
 const {unwrapNullable} = require('../../parsers/parsers-commons');
 const {wrapOptional} = require('../TypeUtils/Java');
+const {toPascalCase} = require('../Utils');
 const {createAliasResolver, getModules} = require('./Utils');
 
 type FilesOutput = Map<string, string>;
@@ -32,11 +34,13 @@ function FileTemplate(
     packageName: string,
     className: string,
     jsName: string,
+    eventEmitters: string,
     methods: string,
     imports: string,
   }>,
 ): string {
-  const {packageName, className, jsName, methods, imports} = config;
+  const {packageName, className, jsName, eventEmitters, methods, imports} =
+    config;
   return `
 /**
  * This code was generated by [react-native-codegen](https://www.npmjs.com/package/react-native-codegen).
@@ -65,11 +69,28 @@ public abstract class ${className} extends ReactContextBaseJavaModule implements
     return NAME;
   }
 
-${methods}
+${eventEmitters}${eventEmitters.length > 0 ? '\n\n' : ''}${methods}
 }
 `;
 }
 
+function EventEmitterTemplate(
+  eventEmitter: NativeModuleEventEmitterShape,
+  imports: Set<string>,
+): string {
+  return `  protected final void emit${toPascalCase(eventEmitter.name)}(${
+    eventEmitter.typeAnnotation.typeAnnotation.type !== 'VoidTypeAnnotation'
+      ? `${translateEventEmitterTypeToJavaType(eventEmitter, imports)} value`
+      : ''
+  }) {
+    mEventEmitterCallback.invoke("${eventEmitter.name}"${
+    eventEmitter.typeAnnotation.typeAnnotation.type !== 'VoidTypeAnnotation'
+      ? ', value'
+      : ''
+  });
+  }`;
+}
+
 function MethodTemplate(
   config: $ReadOnly<{
     abstract: boolean,
@@ -102,6 +123,34 @@ function MethodTemplate(
 
 type Param = NamedShape<Nullable<NativeModuleParamTypeAnnotation>>;
 
+function translateEventEmitterTypeToJavaType(
+  eventEmitter: NativeModuleEventEmitterShape,
+  imports: Set<string>,
+): string {
+  switch (eventEmitter.typeAnnotation.typeAnnotation.type) {
+    case 'StringTypeAnnotation':
+      return 'String';
+    case 'NumberTypeAnnotation':
+    case 'FloatTypeAnnotation':
+    case 'DoubleTypeAnnotation':
+    case 'Int32TypeAnnotation':
+      return 'double';
+    case 'BooleanTypeAnnotation':
+      return 'boolean';
+    case 'ObjectTypeAnnotation':
+    case 'TypeAliasTypeAnnotation':
+      imports.add('com.facebook.react.bridge.ReadableMap');
+      return 'ReadableMap';
+    case 'ArrayTypeAnnotation':
+      imports.add('com.facebook.react.bridge.ReadableArray');
+      return 'ReadableArray';
+    default:
+      throw new Error(
+        `Unsupported eventType for ${eventEmitter.name}. Found: ${eventEmitter.typeAnnotation.typeAnnotation.type}`,
+      );
+  }
+}
+
 function translateFunctionParamToJavaType(
   param: Param,
   createErrorMessage: (typeName: string) => string,
@@ -533,6 +582,9 @@ module.exports = {
           packageName: normalizedPackageName,
           className,
           jsName: moduleName,
+          eventEmitters: spec.eventEmitters
+            .map(eventEmitter => EventEmitterTemplate(eventEmitter, imports))
+            .join('\n\n'),
           methods: methods.filter(Boolean).join('\n\n'),
           imports: Array.from(imports)
             .sort()