@coveo/semantic-monorepo-tools/src/changelog/doWriteChangelog.ts

A library of helper functions to do SemVer2 compliant releases from Conventional Commits in monorepos

import { join } from "node:path";
import {
  createReadStream,
  createWriteStream,
  statSync,
  truncateSync,
  writeFileSync,
  ReadStream,
} from "node:fs";
import tempfile from "tempfile";

export default async function (PATH: string, changelog: string) {
  const changelogPath = join(PATH, "CHANGELOG.md");
  ensureChangelogExist(changelogPath);

  const previousChangelogReadable =
    await getPreviousChangelogStream(changelogPath);

  truncateSync(changelogPath);
  const changelogWritable = createWriteStream(changelogPath);
  changelogWritable.write(changelog);

  return new Promise((resolve) => {
    previousChangelogReadable.pipe(changelogWritable).once("finish", resolve);
  });
}

function ensureChangelogExist(changelogPath: string) {
  if (!statSync(changelogPath, { throwIfNoEntry: false })) {
    writeFileSync(changelogPath, "");
  }
}

function getPreviousChangelogStream(changelogPath: string) {
  const tmp = tempfile();
  return new Promise<ReadStream>((resolve) => {
    createReadStream(changelogPath)
      .pipe(createWriteStream(tmp))
      .once("finish", () => resolve(createReadStream(tmp)));
  });
}