Use Wikimedia extracts API to retrieve hints (#278)

Furthermore, filter out more references from hints.

src/WikiBattle.js

@@ -117,7 +117,8 @@ export default class WikiBattle extends EventEmitter {
   async sendHint () {
     debug('sending hint for', this.goal)
     const page = await wiki.get(this.goal)
-    this.emitSocket('hint', page.getHint())
+    const hint = await page.getHint()
+    this.emitSocket('hint', hint)
   }
 
   /**

src/wiki.js

@@ -1,7 +1,6 @@
 import qs from 'querystring'
 import fs from 'fs'
 import fetch from 'node-fetch'
-import * as cheerio from 'cheerio'
 
 const pkg = JSON.parse(fs.readFileSync(new URL('../package.json', import.meta.url), 'utf8'))
 
@@ -43,19 +42,21 @@ class WikiPage {
    * Extract a short hint text from the article content.
    */
 
-  getHint () {
-    try {
-      const hint = cheerio('.mw-parser-output > p', this.content)
-        .filter((i, el) => cheerio(el).text().trim() !== '')
-        .first()
-        .text()
-        .replace(/\[\d+]/gm, '')
-      return hint.length > HINT_LENGTH
-        ? `${hint.substr(0, HINT_LENGTH)}…`
-        : hint
-    } catch (e) {
-      return `(Could not load hint: [${e.message}])`
-    }
+  async getHint () {
+    const query = qs.stringify({
+      action: 'query',
+      format: 'json',
+      prop: 'extracts',
+      titles: this.title,
+      exchars: HINT_LENGTH.toString(),
+      explaintext: true
+    })
+
+    const response = await fetch(`https://en.wikipedia.org/w/api.php?${query}`)
+    const body = await response.json()
+    const hint = Object.values(body.query.pages)[0].extract
+    return hint
+      .replace(/\[((Note )?\d+|\w)]/gmi, '')
   }
 
   /**