import cheerio from 'cheerio';
import 'babel-polyfill';

import { nodeIsSufficient } from 'utils/dom';
import { cleanContent } from 'cleaners';
import { normalizeSpaces } from 'utils/text';

import extractBestNode from './extract-best-node';

const GenericContentExtractor = {
  defaultOpts: {
    stripUnlikelyCandidates: true,
    weightNodes: true,
    cleanConditionally: true,
  },

  // Extract the content for this resource - initially, pass in our
  // most restrictive opts which will return the highest quality
  // content. On each failure, retry with slightly more lax opts.
  //
  // :param return_type: string. If "node", should return the content
  // as a cheerio node rather than as an HTML string.
  //
  // Opts:
  // stripUnlikelyCandidates: Remove any elements that match
  // non-article-like criteria first.(Like, does this element
  //   have a classname of "comment")
  //
  // weightNodes: Modify an elements score based on whether it has
  // certain classNames or IDs. Examples: Subtract if a node has
  // a className of 'comment', Add if a node has an ID of
  // 'entry-content'.
  //
  // cleanConditionally: Clean the node to return of some
  // superfluous content. Things like forms, ads, etc.
  extract({ $, html, title, url }, opts) {
    opts = { ...this.defaultOpts, ...opts };

    $ = $ || cheerio.load(html);

    // Cascade through our extraction-specific opts in an ordered fashion,
    // turning them off as we try to extract content.
    let node = this.getContentNode($, title, url, opts);

    if (nodeIsSufficient(node)) {
      return this.cleanAndReturnNode(node, $);
    }

    // We didn't succeed on first pass, one by one disable our
    // extraction opts and try again.
    for (const key of Reflect.ownKeys(opts).filter(k => opts[k] === true)) {
      opts[key] = false;
      $ = cheerio.load(html);

      node = this.getContentNode($, title, url, opts);

      if (nodeIsSufficient(node)) {
        break;
      }
    }

    return this.cleanAndReturnNode(node, $);
  },

  // Get node given current options
  getContentNode($, title, url, opts) {
    return cleanContent(
              extractBestNode($, opts),
      {
        $,
        cleanConditionally: opts.cleanConditionally,
        title,
        url,
      });
  },

  // Once we got here, either we're at our last-resort node, or
  // we broke early. Make sure we at least have -something- before we
  // move forward.
  cleanAndReturnNode(node, $) {
    if (!node) {
      return null;
    }

    return normalizeSpaces($.html(node));

    // if return_type == "html":
    //     return normalize_spaces(node_to_html(node))
    // else:
    //     return node
  },

};

export default GenericContentExtractor;