feat: add TypeScript support for hooks and filters

docs/authoring.md

@@ -391,3 +391,12 @@ async function asyncCamelCase(str, callback) {
 ```
 
 In case you have more than one template and want to reuse filters, you can put them in a single library. You can configure such a library in the template configuration under `filters` property. You can also use the official AsyncAPI [filters library](https://github.com/asyncapi/generator-filters). To learn how to add such filters to configuration [read more about the configuration file](#configuration-file).
+
+## TypeScript support 
+
+The AsyncAPI generator has TypeScript support for [hooks](#hooks) and Nunjucks's [filters](#filters). Assumptions:
+
+- Installing the `typescript` package and creating the` tsconfig.json` file isn't necessary.
+- Source code of the hook/filter must have `.ts` extension.
+- Each package related to the typings for TypeScript like `@types/node` must be installed in the template under `dependencies` array. This is because the Generator transpiles the TypeScript code on-the-fly while rendering the template, and cannot use packages under `devDependencies`.
+- Each template should have `@types/node` package installed to enable support for typings for Node.

lib/generator.js

@@ -28,14 +28,12 @@ const {
   getInvalidOptions,
   isReactTemplate,
   isJsFile,
+  registerSourceMap,
+  registerTypeScript,
 } = require('./utils');
 const { registerFilters } = require('./filtersRegistry');
 const { registerHooks } = require('./hooksRegistry');
 
-parser.registerSchemaParser(openapiSchemaParser);
-parser.registerSchemaParser(ramlDtParser);
-parser.registerSchemaParser(avroSchemaParser);
-
 const FILTERS_DIRNAME = 'filters';
 const HOOKS_DIRNAME = 'hooks';
 const CONFIG_FILENAME = 'package.json';
@@ -56,6 +54,12 @@ const shouldIgnoreDir = dirPath =>
   dirPath === '.git'
   || dirPath.startsWith(`.git${path.sep}`);
 
+parser.registerSchemaParser(openapiSchemaParser);
+parser.registerSchemaParser(ramlDtParser);
+parser.registerSchemaParser(avroSchemaParser);
+registerSourceMap();
+registerTypeScript();
+
 class Generator {
   /**
    * Instantiates a new Generator object.

lib/hooksRegistry.js

@@ -98,6 +98,15 @@ async function registerConfigHooks(hooks, templateDir, templateConfig) {
  * @param {Array} config List of hooks configured in template configuration
  */
 function addHook(hooks, mod, config) {
+  /**
+   * ESM `export default { ... }` is transpiled to:
+   * module.exports = { default: { ... } };
+   * First check the `default` object, and if it exists the override mod to `default`.
+   */
+  if (typeof mod.default === 'object') {
+    mod = mod.default;
+  }
+
   Object.keys(mod).forEach(hookType => {
     const moduleHooksArray = [].concat(mod[hookType]);
 

lib/utils.js

@@ -127,3 +127,22 @@ utils.getInvalidOptions = (generatorOptions, options) => {
 utils.isAsyncFunction = (fn) => {  
   return fn && fn.constructor && fn.constructor.name === 'AsyncFunction';
 };
+
+/**
+ * Register `source-map-support` package.
+ * This package provides source map support for stack traces in Node - also for transpiled code from TS.
+ * 
+ * @private
+ */
+utils.registerSourceMap = () => {
+  require('source-map-support').install();
+};
+
+/**
+ * Register TypeScript transpiler. It enables transpilation of TS filters and hooks on the fly. 
+ * 
+ * @private
+ */
+utils.registerTypeScript = () => {
+  require('ts-node').register();
+};

package.json

@@ -74,7 +74,10 @@
     "nunjucks": "^3.2.0",
     "resolve-pkg": "^2.0.0",
     "semver": "^7.3.2",
-    "simple-git": "^1.131.0"
+    "simple-git": "^1.131.0",
+    "source-map-support": "^0.5.19",
+    "ts-node": "^9.1.1",
+    "typescript": "^4.2.2"
   },
   "devDependencies": {
     "@semantic-release/commit-analyzer": "^8.0.1",