refactor map topic module to not use breadcrumbs

lib/get-map-topic-content.js

@@ -1,12 +1,31 @@
+const { get, last } = require('lodash')
+const { getLanguageCode } = require('../lib/patterns')
+
 // get the childArticles set on map topics in lib/site-tree.js
-module.exports = function getMapTopicContent (parentProductId, breadcrumbs, siteTree) {
-  const childArticles = siteTree.products[parentProductId].categories[breadcrumbs.category.href].maptopics[breadcrumbs.maptopic.href].childArticles
+module.exports = function getMapTopicContent (productId, siteTree, currentLanguage, currentVersion, currentPath) {
+  const maptopicPath = currentPath
+  const categoryPath = currentPath.replace(`/${last(currentPath.split('/'))}`, '')
+  const siteTreePath = getSiteTreePath(currentVersion, productId, categoryPath, maptopicPath)
+  let childArticles = get(siteTree[currentLanguage], siteTreePath)
+
+  // try falling back to English if needed
+  if (!childArticles && currentLanguage !== 'en') {
+    const englishCategoryPath = categoryPath.replace(getLanguageCode, '/en')
+    const englishMaptopicPath = maptopicPath.replace(getLanguageCode, '/en')
+    const englishSiteTreePath = getSiteTreePath(currentVersion, productId, englishCategoryPath, englishMaptopicPath)
+    childArticles = get(siteTree.en, englishSiteTreePath)
+  }
 
   if (!childArticles) {
-    console.error(`can't find child articles from siteTree for map topic '${breadcrumbs.maptopic.href}'`)
+    console.error('can\'t find child articles for map topic')
+    return ''
   }
 
   return childArticles
     .map(article => `{% link_with_intro /${article.href} %}`)
     .join('\n\n')
 }
+
+function getSiteTreePath (version, productId, categoryPath, maptopicPath) {
+  return [version, 'products', productId, 'categories', categoryPath, 'maptopics', maptopicPath, 'childArticles']
+}

lib/page.js

@@ -149,7 +149,7 @@ class Page {
 
     let markdown = this.mapTopic
       // get the map topic child articles from the siteTree
-      ? getMapTopicContent(this.parentProduct.id, context.breadcrumbs, context.siteTree[context.currentLanguage][context.currentVersion])
+      ? getMapTopicContent(this.parentProduct.id, context.siteTree, context.currentLanguage, context.currentVersion, context.currentPath)
       : this.markdown
 
     // If the article is interactive parse the React!