import URL from 'url'
import Client from '../../api/client'

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

  imageInfo (page) {
    const pageURL = URL.parse(page, true)
    const ClientError = this.errorClass

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

    const apiURL = URL.format({
      protocol: pageURL.protocol,
      auth: pageURL.auth,
      host: pageURL.host,
      pathname: '/w/api.php',
      query: {
        action: 'query',
        titles: pageURL.pathname.slice(6),
        prop: 'imageinfo',
        iiprop: 'url|size|canonicaltitle|user|extmetadata',
        format: 'json'
      }
    })

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