// After next build, the standalone server needs the static files beside it; Next leaves
// that copy to us (Next docs, config/output.md). Also drops in the CLI's own modules, so
// the published package can run from anywhere (vrek iss-ej4ahga).
import { access, cp, mkdir, readdir, rm, stat, writeFile } from "node:fs/promises";
import path from "node:path";

const root = process.cwd();
const standalone = path.join(root, ".next", "standalone");

const exists = (file) => access(file).then(() => true, () => false);

/** Bytes under a path, so the build can say what it dropped. */
async function size(target) {
  const info = await stat(target);
  if (!info.isDirectory()) return info.size;
  let total = 0;
  for (const entry of await readdir(target)) total += await size(path.join(target, entry));
  return total;
}

if (!(await exists(standalone))) {
  console.error("No .next/standalone: is output: 'standalone' still set in next.config.ts?");
  process.exit(1);
}

await mkdir(path.join(standalone, ".next"), { recursive: true });
await cp(path.join(root, ".next", "static"), path.join(standalone, ".next", "static"), { recursive: true });
if (await exists(path.join(root, "public"))) {
  await cp(path.join(root, "public"), path.join(standalone, "public"), { recursive: true });
}
// Next's tracing sweeps in things the app never runs: the MediaMTX binary that happens to
// sit in bin/, and sharp's platform binaries, which are only for next/image (unused here).
// outputFileTracingExcludes didn't keep them out, so they go now, before publishing.
const prune = ["bin", "node_modules/@img", "node_modules/sharp"];
let freed = 0;
for (const name of prune) {
  const target = path.join(standalone, name);
  if (!(await exists(target))) continue;
  freed += await size(target);
  await rm(target, { recursive: true, force: true });
}

// The compiled CLI modules are ES modules; without this Node would read them as CommonJS.
await writeFile(path.join(root, "dist", "package.json"), '{\n  "type": "module"\n}\n');

console.log(
  `Bundled the standalone server with its static files` +
    (freed ? `, and dropped ${(freed / 1024 / 1024).toFixed(0)} MB it doesn't need.` : "."),
);