feat(parser): handle multi-file solutions

tools/challenge-md-parser/solution-to-data.js

@@ -2,11 +2,15 @@ const visit = require('unist-util-visit');
 const { selectAll } = require('hast-util-select');
 
 const { sectionFilter } = require('./utils');
+const { createCodeGetter } = require('./challengeSeed-to-data');
+
+const solutionRE = /(.+)-solution$/;
 
 function createPlugin() {
   return function transformer(tree, file) {
     function visitor(node) {
       if (sectionFilter(node, 'solution')) {
+        // fallback for single-file challenges
         const solutions = selectAll('code', node).map(
           element => element.children[0].value
         );
@@ -14,6 +18,21 @@ function createPlugin() {
           ...file.data,
           solutions
         };
+        const solutionFiles = {};
+        const codeDivs = selectAll('div', node);
+        const solutionContainers = codeDivs.filter(({ properties: { id } }) =>
+          solutionRE.test(id)
+        );
+        solutionContainers.forEach(
+          createCodeGetter('contents', solutionRE, solutionFiles)
+        );
+
+        file.data = {
+          ...file.data,
+          solutionFiles: Object.keys(solutionFiles).map(
+            lang => solutionFiles[lang]
+          )
+        };
       }
     }
     visit(tree, 'element', visitor);