feat(challenge-md): Parse seed files from md

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

@@ -0,0 +1,72 @@
+const visit = require('unist-util-visit');
+const { selectAll, select } = require('hast-util-select');
+
+const { sectionFilter } = require('./utils');
+
+const seedRE = /(.+)-seed$/;
+const headRE = /(.+)-setup$/;
+const tailRE = /(.+)-teardown$/;
+
+function defaultFile(lang) {
+  return {
+    key: `index${lang}`,
+    ext: lang,
+    name: 'index',
+    contents: '',
+    head: '',
+    tail: ''
+  };
+}
+function createCodeGetter(key, regEx, seeds) {
+  return container => {
+    const {
+      properties: { id }
+    } = container;
+    const lang = id.match(regEx)[1];
+    const code = select('code', container).children[0].value;
+    if (lang in seeds) {
+      seeds[lang] = {
+        ...seeds[lang],
+        [key]: code
+      };
+    } else {
+      seeds[lang] = {
+        ...defaultFile(lang),
+        [key]: code
+      };
+    }
+  };
+}
+
+function createPlugin() {
+  return function transformer(tree, file) {
+    function visitor(node) {
+      if (sectionFilter(node, 'challengeSeed')) {
+        let seeds = {};
+        const codeDivs = selectAll('div', node);
+        const seedConatiners = codeDivs.filter(({ properties: { id } }) =>
+          seedRE.test(id)
+        );
+        seedConatiners.forEach(createCodeGetter('contents', seedRE, seeds));
+
+        const headConatiners = codeDivs.filter(({ properties: { id } }) =>
+          headRE.test(id)
+        );
+        headConatiners.forEach(createCodeGetter('head', headRE, seeds));
+
+        const tailConatiners = codeDivs.filter(({ properties: { id } }) =>
+          tailRE.test(id)
+        );
+        tailConatiners.forEach(createCodeGetter('tail', tailRE, seeds));
+
+        file.data = {
+          ...file.data,
+          files: Object.keys(seeds).map(lang => seeds[lang])
+        };
+      }
+    }
+    visit(tree, 'element', visitor);
+  };
+}
+
+module.exports = createPlugin;