test-repo/scripts/build/esmify-typescript-eslint.js

/* Transform `@typescript-eslint/*` module to ESM */

import * as path from "node:path";

import { outdent } from "outdent";

import { PROJECT_ROOT, writeFile } from "../utils/index.js";

function esmifyTypescriptEslint(text) {
  /*
  ```js
  const foo = __importStar(require("foo"));
  const foo = require("foo");
  ```
  ->
  ```js
  import * as foo from "foo";
  ````
  */
  text = text.replaceAll(
    // TODO: Use duplicate capture group name when eslint supports
    /(?<=\n)(?:const|let|var) (?<variable>\w+) = (?:__importStar\(require\(["'](?<moduleName1>.*?)["']\)\)|require\(["'](?<moduleName2>.*?)["']\));/gu,
    (...args) => {
      const groups = args.at(-1);
      return `import * as ${groups.variable} from "${groups.moduleName1 || groups.moduleName2}";`;
    },
  );

  /*
  ```js
  const foo = __importDefault(require("foo"));
  ```
  ->
  ```js
  import foo_default_export from "foo";
  const foo = {default: foo_default_export};
  ````
  */
  text = text.replaceAll(
    /(?<=\n)(?:const|let|var) (?<variable>\w+) = __importDefault\(require\(["'](?<moduleName>.*?)["']\)\);/gu,
    outdent`
      import $<variable>_default_export from "$<moduleName>";
      const $<variable> = {default: $<variable>_default_export};
    `,
  );

  text = text.replaceAll('"use strict";', "");
  text = text
    .replaceAll(
      'Object.defineProperty(exports, "__esModule", { value: true });',
      "",
    )
    .replaceAll(
      outdent`
        Object.defineProperty(exports, "__esModule", {
          value: true
        });
      `,
      "",
    );

  text = text.replaceAll(/(?<=\n)(?:exports\.\w+ = )+void 0;/gu, "");
  text = text.replaceAll(
    /(?<=\n)exports\.(?<specifier>\w+) = (?<variable>\w+);/gu,
    (...args) => {
      const { variable, specifier } = args.at(-1);
      if (specifier === variable) {
        return `export {${specifier}};`;
      }

      return `export const ${specifier} = ${variable};`;
    },
  );

  text = text.replaceAll(
    /(?<=\n)exports\.(?<specifier>\w+)(?= = `)/gu,
    "export const $<specifier>",
  );

  /*
  ```js
  __exportStar(require("foo"), exports);
  ```
  ->
  ```js
  export * from "foo";
  ````
  */
  text = text.replaceAll(
    /(?<=\n)__exportStar\(require\(["'](?<moduleName>.*?)["']\), exports\);/gu,
    'export * from "$<moduleName>";',
  );

  /*
  ```js
  Object.defineProperty(exports, "foo", { enumerable: true, get: function () { return foo; } });
  ```
  ->
  ```js
  export * from "foo";
  ````
  */
  text = text.replaceAll(
    /(?<=\n)Object\.defineProperty\(exports, "(?<specifier>\w+)", \{ enumerable: true, get: function \(\) \{ return (?<value>.*?); \} \}\);/gu,
    "export const $<specifier> = $<value>;",
  );

  /*
  ```js
  exports.foo = __importStar(require("foo"));
  ```
  ->
  ```js
  import * as foo_namespace_export from "foo";
  export {foo_namespace_export as foo};
  ````
  */
  text = text.replaceAll(
    /(?<=\n)exports\.(?<specifier>\w+) = __importStar\(require\(["'](?<moduleName>.*?)["']\)\);/gu,
    outdent`
      import * as $<specifier>_namespace_export from "$<moduleName>";
      export {$<specifier>_namespace_export as $<specifier>};
    `,
  );

  // Make sure ESBuild treat it as Module
  text += "\nexport {};";

  return text;
}

const NODE_MODULES_DIRECTORY = path.join(
  PROJECT_ROOT,
  "node_modules/@typescript-eslint/",
);
// Save modified code to `{PROJECT_ROOT}/.tmp/@typescript-eslint/` for debug
const saveToDisk = (process) => (text, file) => {
  if (!file.startsWith(NODE_MODULES_DIRECTORY)) {
    return text;
  }

  const code = process(text);

  writeFile(
    path.join(
      PROJECT_ROOT,
      ".tmp/@typescript-eslint-esm/",
      path.relative(NODE_MODULES_DIRECTORY, file),
    ),
    code,
  );

  return code;
};

export default saveToDisk(esmifyTypescriptEslint);