import { execFileSync } from "node:child_process";
import { mkdtemp, readFile, rm } from "node:fs/promises";
import { createRequire } from "node:module";
import { tmpdir } from "node:os";
import path from "node:path";
import { pathToFileURL } from "node:url";

const vendor = import.meta.dirname;
const source = await mkdtemp(path.join(tmpdir(), "avril-webstreams-build-"));
const commit = "12b4fedec6c01503a137d837204ca0b85992461e";
const run = (command, args) =>
  execFileSync(command, args, { cwd: source, stdio: "inherit" });
const previousDirectory = process.cwd();

try {
  run("git", ["init", "-q"]);
  run("git", [
    "fetch",
    "--depth=1",
    "https://github.com/MattiasBuelens/web-streams-polyfill.git",
    commit,
  ]);
  run("git", ["checkout", "--detach", "-q", "FETCH_HEAD"]);
  run("git", ["apply", path.join(vendor, "avril.patch")]);
  run("npm", [
    "ci",
    "--include=dev",
    "--ignore-scripts",
    "--no-audit",
    "--no-fund",
  ]);

  process.chdir(source);
  const { default: configs } = await import(
    pathToFileURL(path.join(source, "rollup.config.mjs"))
  );
  const config = configs.find((config) =>
    config.input === "src/polyfill.ts" &&
    config.output[0].file === "dist/polyfill.js"
  );
  if (!config) throw new Error("Upstream polyfill build configuration changed");
  const original = await readFile(path.join(vendor, "polyfill.js"), "utf8");
  const banner = original.match(/^\/\*\*[\s\S]*?\*\//)?.[0];
  if (!banner) throw new Error("Missing upstream license banner");

  const { rollup } = createRequire(path.join(source, "package.json"))("rollup");
  const { output, ...input } = config;
  const bundle = await rollup(input);
  try {
    await bundle.write({
      ...output[0],
      banner,
      file: path.join(vendor, "polyfill.avril.js"),
    });
  } finally {
    await bundle.close();
  }
} finally {
  process.chdir(previousDirectory);
  await rm(source, { recursive: true, force: true });
}