tunnckoCore/gibon

import parsePkgName from 'parse-package-name';
import ky from 'ky-universal';

export class PackageJsonError extends Error {
  constructor(message, err) {
    super(message);
    this.name = 'PackageJsonError';
    this.originalError = err;
  }
}

/**
 * Get package metadata from the Unpkg instead of NPM registry.
 * Optionally you can pass `endpoint` function and return the build
 * the registry url.
 *
 * @example
 * import packageJson from '@tunnckocore/package-json';
 *
 * async function main() {
 *   console.log(await packageJson('eslint'));
 *   console.log(await packageJson('package-json@4.0.0'));
 *   console.log(await packageJson('ava@next'));
 *   console.log(await packageJson('@babel/core'));
 *   console.log(await packageJson('@tunnckocore/package-json'));
 * }
 *
 * main().catch(console.error);
 *
 * @name  packageJson
 * @param {string} packageName the package name, supports `pkg-name@1.2.2` (version) and `pkg-name@next` (dist-tag)
 * @param {function} endpoint like `(name, tag) => url`
 * @returns {object} package metadata object
 * @public
 */
export default async function packageJson(packageName, endpoint) {
  const { name, version } = parsePkgName(packageName);
  const tag = version === '' ? 'latest' : version;
  const uri =
    typeof endpoint === 'function'
      ? endpoint(name, tag)
      : `https://cdn.jsdelivr.net/npm/${name}@${tag}/package.json`;

  let pkg = null;
  try {
    pkg = await ky
      .get(uri)
      .then((resp) => resp.text())
      .then(JSON.parse);
  } catch (err) {
    // NOTE: jsDelivr can response with 403 Forbidden, if over 50MB
    if (err.response && err.response.status === 403) {
      try {
        // ! so, try through UNPKG.com
        pkg = await packageJson(
          packageName,
          (x, t) => `https://unpkg.com/${x}@${t}/package.json`,
        );
      } catch (err_) {
        throw new PackageJsonError(
          `Package "${name}" not found, even through UNPKG.com!`,
          err_,
        );
      }
      return pkg;
    }

    throw new PackageJsonError(
      `Package "${name}" not found or loading error!`,
      err,
    );
  }
  return pkg;
}