graphbrainz/src/extensions/mediawiki/client.js

A GraphQL schema, Express server, and middleware for querying the MusicBrainz.

import ExtendableError from 'es6-error';
import Client from '../../api/client.js';

export class MediaWikiError extends ExtendableError {}

export default class MediaWikiClient extends Client {
  constructor({ limit = 10, period = 1000, ...options } = {}) {
    super({ limit, period, ...options });
  }

  imageInfo(page) {
    const pageURL = new URL(page);

    if (!pageURL.pathname.startsWith('/wiki/')) {
      return Promise.reject(
        new MediaWikiError(
          `MediaWiki page URL does not have the expected /wiki/ prefix: ${page}`
        )
      );
    }

    const apiURL = new URL('/w/api.php', pageURL);
    apiURL.search = new URLSearchParams({
      action: 'query',
      titles: decodeURI(pageURL.pathname.slice(6)),
      prop: 'imageinfo',
      iiprop: 'url|size|canonicaltitle|user|extmetadata',
      format: 'json',
    }).toString();

    return this.get(apiURL.toString(), { resolveBodyOnly: true }).then(
      (body) => {
        const pageIDs = Object.keys(body.query.pages);
        if (pageIDs.length !== 1) {
          throw new MediaWikiError(
            `Query returned multiple pages: [${pageIDs.join(', ')}]`
          );
        }
        if (pageIDs[0] === '-1') {
          throw new MediaWikiError(
            body.query.pages['-1'].invalidreason || 'Unknown error'
          );
        }
        const imageInfo = body.query.pages[pageIDs[0]].imageinfo;
        if (imageInfo.length !== 1) {
          throw new MediaWikiError(
            `Query returned info for ${imageInfo.length} images, expected 1.`
          );
        }
        return imageInfo[0];
      }
    );
  }
}