From 1a5cab57a1b28806479ce6ce1c25eaef3114e51b Mon Sep 17 00:00:00 2001
From: Stuart Taylor <staylor1012@gmail.com>
Date: Mon, 19 Feb 2018 20:41:01 +0000
Subject: [PATCH] feat(sass): Enable client-side sass compiling (#16747)

---
 .../routes/Challenges/rechallenge/builders.js |  2 +-
 .../Challenges/rechallenge/transformers.js    | 78 ++++++++++++++-----
 common/utils/polyvinyl.js                     |  8 ++
 .../03-front-end-libraries/sass.json          | 36 ++++-----
 4 files changed, 86 insertions(+), 38 deletions(-)

diff --git a/common/app/routes/Challenges/rechallenge/builders.js b/common/app/routes/Challenges/rechallenge/builders.js
index 3984c83e0d..c38c1a6f30 100644
--- a/common/app/routes/Challenges/rechallenge/builders.js
+++ b/common/app/routes/Challenges/rechallenge/builders.js
@@ -95,7 +95,7 @@ export function concactHtml(required, template) {
 
   const body = source
     .flatMap(file => file.reduce((body, file) => {
-      return body + file.contents + htmlCatch;
+      return body + file.contents + file.tail + htmlCatch;
     }, ''))
     .map(source => ({ source }))
     .map(createBody);
diff --git a/common/app/routes/Challenges/rechallenge/transformers.js b/common/app/routes/Challenges/rechallenge/transformers.js
index 5eb60d5c8e..c0b3a9a94a 100644
--- a/common/app/routes/Challenges/rechallenge/transformers.js
+++ b/common/app/routes/Challenges/rechallenge/transformers.js
@@ -1,4 +1,13 @@
-import _ from 'lodash';
+import {
+  cond,
+  flow,
+  identity,
+  matchesProperty,
+  overEvery,
+  overSome,
+  partial,
+  stubTrue
+} from 'lodash';
 
 import * as babel from 'babel-core';
 import presetEs2015 from 'babel-preset-es2015';
@@ -24,15 +33,34 @@ function loopProtectHit(line) {
 const console$logReg = /(?:\b)console(\.log\S+)/g;
 const NBSPReg = new RegExp(String.fromCharCode(160), 'g');
 
-const isJS = _.matchesProperty('ext', 'js');
-const testHTMLJS = _.overSome(isJS, _.matchesProperty('ext', 'html'));
-const testJS$JSX = _.overSome(isJS, _.matchesProperty('ext', 'jsx'));
+const isJS = matchesProperty('ext', 'js');
+const testHTMLJS = overSome(isJS, matchesProperty('ext', 'html'));
+const testJS$JSX = overSome(isJS, matchesProperty('ext', 'jsx'));
 
+// work around the absence of multi-flile editing
+// this can be replaced with `matchesProperty('ext', 'sass')`
+// when the time comes
+const testSASS = file => (/type='text\/sass'/i).test(file.contents);
+// This can be done in the transformer when we have multi-file editing
+const browserSassCompiler = `
+  <script>
+    var styleTags = [ ...document.querySelectorAll('style') ];
+    [].slice.call(styleTags, 1).forEach(
+      function compileSass(tag) {
+        var scss = tag.innerHTML;
+        Sass.compile(scss, function(result) {
+          tag.type = 'text/css';
+          tag.innerHTML = result.text;
+        });
+      }
+    )
+  </script>
+`;
 // if shouldProxyConsole then we change instances of console log
 // to `window.__console.log`
 // this let's us tap into logging into the console.
 // currently we only do this to the main window and not the test window
-export const proxyLoggerTransformer = _.partial(
+export const proxyLoggerTransformer = partial(
   vinyl.transformHeadTailAndContents,
   source => (
       source.replace(console$logReg, (match, methodCall) => {
@@ -40,7 +68,7 @@ export const proxyLoggerTransformer = _.partial(
   })),
 );
 
-const addLoopProtect = _.partial(
+const addLoopProtect = partial(
   vinyl.transformContents,
   contents => {
     /* eslint-disable import/no-unresolved */
@@ -51,11 +79,11 @@ const addLoopProtect = _.partial(
   }
 );
 
-export const addLoopProtectHtmlJsJsx = _.cond([
+export const addLoopProtectHtmlJsJsx = cond([
   [
-    _.overEvery(
+    overEvery(
       testHTMLJS,
-      _.partial(
+      partial(
         vinyl.testContents,
         contents => contents.toLowerCase().includes('<script>')
       )
@@ -63,38 +91,50 @@ export const addLoopProtectHtmlJsJsx = _.cond([
     addLoopProtect
   ],
   [ testJS$JSX, addLoopProtect ],
-  [ _.stubTrue, _.identity ]
+  [ stubTrue, identity ]
 ]);
 
-export const replaceNBSP = _.cond([
+export const replaceNBSP = cond([
   [
     testHTMLJS,
-    _.partial(
+    partial(
       vinyl.transformContents,
       contents => contents.replace(NBSPReg, ' ')
     )
   ],
-  [ _.stubTrue, _.identity ]
+  [ stubTrue, identity ]
 ]);
 
-export const babelTransformer = _.cond([
+export const babelTransformer = cond([
   [
     testJS$JSX,
-    _.flow(
-      _.partial(
+    flow(
+      partial(
         vinyl.transformHeadTailAndContents,
         babelTransformCode
       ),
-      _.partial(vinyl.setExt, 'js')
+      partial(vinyl.setExt, 'js')
     )
   ],
-  [ _.stubTrue, _.identity ]
+  [ stubTrue, identity ]
+]);
+
+export const sassTransformer = cond([
+  [
+    testSASS,
+    partial(
+      vinyl.appendToTail,
+      browserSassCompiler
+    )
+  ],
+  [ stubTrue, identity ]
 ]);
 
 export const _transformers = [
   addLoopProtectHtmlJsJsx,
   replaceNBSP,
-  babelTransformer
+  babelTransformer,
+  sassTransformer
 ];
 
 export function applyTransformers(file, transformers = _transformers) {
diff --git a/common/utils/polyvinyl.js b/common/utils/polyvinyl.js
index cd5dd9aeda..881b2709be 100644
--- a/common/utils/polyvinyl.js
+++ b/common/utils/polyvinyl.js
@@ -166,6 +166,14 @@ export function clearHeadTail(poly) {
   };
 }
 
+export function appendToTail(tail, poly) {
+  checkPoly(poly);
+  return {
+    ...poly,
+    tail: poly.tail.concat(tail)
+  };
+}
+
 // compileHeadTail(contents: String, poly: PolyVinyl) => PolyVinyl
 export function compileHeadTail(padding = '', poly) {
   return clearHeadTail(transformContents(
diff --git a/seed/challenges/03-front-end-libraries/sass.json b/seed/challenges/03-front-end-libraries/sass.json
index ba2b4eadcb..28fbbf87bd 100644
--- a/seed/challenges/03-front-end-libraries/sass.json
+++ b/seed/challenges/03-front-end-libraries/sass.json
@@ -28,7 +28,7 @@
       "title": "Store Data with Sass Variables",
       "required": [
         {
-          "link": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.9.13/sass.min.js",
+          "src": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.10.9/sass.sync.min.js",
           "raw": true
         }
       ],
@@ -42,13 +42,13 @@
         "Create a variable <code>$text-color</code> and set it to red. Then change the value of the <code>color</code> property for the <code>.blog-post</code> and <code>h2</code> to the <code>$text-color</code> variable."
       ],
       "challengeSeed": [
-        "<style>",
+        "<style type='text/sass'>",
         "  ",
         "  ",
         "  .header{",
         "    text-align: center;",
         "  }",
-        "  .blog-post h2 {",
+        "  .blog-post, h2 {",
         "    color: red;",
         "  }",
         "</style>",
@@ -85,7 +85,7 @@
       "title": "Nest CSS with Sass",
       "required": [
         {
-          "link": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.9.13/sass.min.js",
+          "src": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.10.9/sass.sync.min.js",
           "raw": true
         }
       ],
@@ -99,7 +99,7 @@
         "Use the <code>nesting</code> technique shown above to re-organize the CSS rules for both children of <code>.blog-post</code> element. For testing purposes, the <code>h1</code> should come before the <code>p</code> element."
       ],
       "challengeSeed": [
-        "<style>",
+        "<style type='text/sass'>",
         "  .blog-post {",
         "    ",
         "  }",
@@ -132,7 +132,7 @@
       "title": "Create Reusable CSS with Mixins",
       "required": [
         {
-          "link": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.9.13/sass.min.js",
+          "src": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.10.9/sass.sync.min.js",
           "raw": true
         }
       ],
@@ -150,7 +150,7 @@
         "Write a <code>mixin</code> for <code>border-radius</code> and give it a <code>$radius</code> parameter. It should use all the vendor prefixes from the example. Then use the <code>border-radius</code> <code>mixin</code> to give the <code>#awesome</code> element a border radius of 15px."
       ],
       "challengeSeed": [
-        "<style>",
+        "<style type='text/sass'>",
         "  ",
         "  ",
         "  ",
@@ -185,7 +185,7 @@
       "title": "Use @if and @else to Add Logic To Your Styles",
       "required": [
         {
-          "link": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.9.13/sass.min.js",
+          "src": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.10.9/sass.sync.min.js",
           "raw": true
         }
       ],
@@ -199,7 +199,7 @@
         "<blockquote>light - 1px solid black<br>medium - 3px solid black<br>heavy - 6px solid black<br>none - no border</blockquote>"
       ],
       "challengeSeed": [
-        "<style>",
+        "<style type='text/sass'>",
         "  ",
         "  ",
         "  ",
@@ -232,7 +232,7 @@
       "title": "Use @for to Create a Sass Loop",
       "required": [
         {
-          "link": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.9.13/sass.min.js",
+          "src": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.10.9/sass.sync.min.js",
           "raw": true
         }
       ],
@@ -249,7 +249,7 @@
         "It should create 5 classes called <code>.text-1</code> to <code>.text-5</code> where each has a <code>font-size</code> set to 10px multiplied by the index."
       ],
       "challengeSeed": [
-        "<style>",
+        "<style type='text/sass'>",
         "  ",
         "  ",
         "  ",
@@ -281,7 +281,7 @@
       "title": "Use @each to Map Over Items in a List",
       "required": [
         {
-          "link": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.9.13/sass.min.js",
+          "src": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.10.9/sass.sync.min.js",
           "raw": true
         }
       ],
@@ -299,7 +299,7 @@
         "Each class should set the <code>background-color</code> the respective color."
       ],
       "challengeSeed": [
-        "<style>",
+        "<style type='text/sass'>",
         "  ",
         "  ",
         "  ",
@@ -331,7 +331,7 @@
       "title": "Apply a Style Until a Condition is Met with @while",
       "required": [
         {
-          "link": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.9.13/sass.min.js",
+          "src": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.10.9/sass.sync.min.js",
           "raw": true
         }
       ],
@@ -346,7 +346,7 @@
         "There should be 10 different classes from <code>text-1</code> to <code>text-10</code>. Then set <code>font-size</code> to 5px multiplied by the current index number. Make sure to avoid an infinite loop!"
       ],
       "challengeSeed": [
-        "<style>",
+        "<style type='text/sass'>",
         "  ",
         "  ",
         "  ",
@@ -390,7 +390,7 @@
       "title": "Split Your Styles into Smaller Chunks with Partials",
       "required": [
         {
-          "link": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.9.13/sass.min.js",
+          "src": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.10.9/sass.sync.min.js",
           "raw": true
         }
       ],
@@ -425,7 +425,7 @@
       "title": "Extend One Set of CSS Styles to Another Element",
       "required": [
         {
-          "link": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.9.13/sass.min.js",
+          "src": "https://cdnjs.cloudflare.com/ajax/libs/sass.js/0.10.9/sass.sync.min.js",
           "raw": true
         }
       ],
@@ -442,7 +442,7 @@
         "Make a class <code>.info-important</code> that extends <code>.info</code> and also has a <code>background-color</code> set to magenta."
       ],
       "challengeSeed": [
-        "<style>",
+        "<style type='text/sass'>",
         "  h3{",
         "    text-align: center;",
         "  }",