import { readFile } from "node:fs/promises";
import { fileURLToPath } from "node:url";
import esbuild from "esbuild";

// `@babel/code-frame` and `@babel/highlight` use syntax that is not available in Node.js 14,
// such as `??=`. When bundled into dist/ they are compiled to be compatible with Node.js 14,
// however we also need to load them at runtime from node_modules to run our tests.
// We can use an `--experimental-loader` to compile them on-the-fly with esbuild.

export async function getSource(url, context, defaultGetSource) {
  if (
    !/node_modules\/@babel\/(?:code-frame|highlight)/u.test(url) ||
    context.format !== "module"
  ) {
    return defaultGetSource(url, context, defaultGetSource);
  }

  const raw = await readFile(fileURLToPath(url));
  try {
    const result = await esbuild.transform(raw, { target: "node14" });
    return { source: result.code };
  } catch (error) {
    error.message += ` (in ${url})`;
    throw error;
  }
}