populateLibraries.ts

import { readdir, readFile, writeFile } from "node:fs/promises";
import { join } from "node:path";

const utf8: BufferEncoding = "utf8";
const readmePath = join(__dirname, "README.md");
const markers = {
  start: "<!-- START: Auto-generated by ./populateLibraries.ts -->",
  end: "<!-- END: Auto-generated by ./populateLibraries.ts -->",
};

async function updateReadme() {
  const [readme, dirNames] = await Promise.all([
    readFile(readmePath, utf8),
    readdir(join(__dirname, "packages"), { withFileTypes: true }).then((d) =>
      d.filter((dirent) => dirent.isDirectory()),
    ),
  ]);

  const readmeLines = await Promise.all(
    dirNames.map(async (dirent) => {
      const path = join(__dirname, "packages", dirent.name, "package.json");
      const { description } = JSON.parse(await readFile(path, utf8));
      return `- [${dirent.name}](./packages/${dirent.name}/README.md): ${description ?? ""}`;
    }),
  );

  const updatedReadme = readme.replace(
    new RegExp(`${markers.start}[\\s\\S]*${markers.end}`),
    `${markers.start}\n\n${readmeLines.join("\n")}\n\n${markers.end}`,
  );

  if (readme === updatedReadme) {
    console.log("No README file changes to '## Libraries' section.");
  } else {
    await writeFile(readmePath, updatedReadme, utf8);
  }
}

updateReadme();