From 526db89c04975636d74acd71e0ff069f9d78ed15 Mon Sep 17 00:00:00 2001
From: Ryan Kennedy <ryan@rmkennedy.com>
Date: Mon, 22 Jan 2018 16:50:27 -0500
Subject: [PATCH] [gatsby-transformer-remark] Add `htmlAst` field (#3596)

This implements a GraphQL field that presents the rehype AST as JSON, allowing for this information to be consumed from a page template and presented dynamically.
---
 .../gatsby-transformer-remark/package.json    |  2 +
 .../src/extend-node-type.js                   | 40 +++++++++++++++----
 yarn.lock                                     |  2 +-
 3 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/packages/gatsby-transformer-remark/package.json b/packages/gatsby-transformer-remark/package.json
index 2b021bfe1f803..8aadbaaff7d74 100644
--- a/packages/gatsby-transformer-remark/package.json
+++ b/packages/gatsby-transformer-remark/package.json
@@ -6,6 +6,7 @@
   "dependencies": {
     "babel-runtime": "^6.26.0",
     "bluebird": "^3.5.0",
+    "graphql-type-json": "^0.1.4",
     "gray-matter": "^3.0.0",
     "hast-util-to-html": "^3.0.0",
     "lodash": "^4.17.4",
@@ -19,6 +20,7 @@
     "sanitize-html": "^1.14.1",
     "underscore.string": "^3.3.4",
     "unified": "^6.1.5",
+    "unist-util-remove-position": "^1.1.1",
     "unist-util-select": "^1.5.0",
     "unist-util-visit": "^1.1.1"
   },
diff --git a/packages/gatsby-transformer-remark/src/extend-node-type.js b/packages/gatsby-transformer-remark/src/extend-node-type.js
index c71155eb0b7e6..fa50d90805e7a 100644
--- a/packages/gatsby-transformer-remark/src/extend-node-type.js
+++ b/packages/gatsby-transformer-remark/src/extend-node-type.js
@@ -20,6 +20,8 @@ const parse = require(`remark-parse`)
 const stringify = require(`remark-stringify`)
 const english = require(`retext-english`)
 const remark2retext = require(`remark-retext`)
+const GraphQlJson = require(`graphql-type-json`)
+const stripPosition = require(`unist-util-remove-position`)
 
 let pluginsCacheStr = ``
 const astCacheKey = node =>
@@ -30,6 +32,10 @@ const htmlCacheKey = node =>
   `transformer-remark-markdown-html-${
     node.internal.contentDigest
   }-${pluginsCacheStr}`
+const htmlAstCacheKey = node =>
+  `transformer-remark-markdown-html-ast-${
+    node.internal.contentDigest
+  }-${pluginsCacheStr}`
 const headingsCacheKey = node =>
   `transformer-remark-markdown-headings-${
     node.internal.contentDigest
@@ -213,19 +219,29 @@ module.exports = (
       }
     }
 
+    async function getHTMLAst(markdownNode) {
+      const cachedAst = await cache.get(htmlAstCacheKey(markdownNode))
+      if (cachedAst) {
+        return cachedAst
+      } else {
+        const ast = await getAST(markdownNode)
+        const htmlAst = toHAST(ast, { allowDangerousHTML: true })
+
+        // Save new HTML AST to cache and return
+        cache.set(htmlAstCacheKey(markdownNode), htmlAst)
+        return htmlAst
+      }
+    }
+
     async function getHTML(markdownNode) {
       const cachedHTML = await cache.get(htmlCacheKey(markdownNode))
       if (cachedHTML) {
         return cachedHTML
       } else {
-        const html = await new Promise((resolve, reject) => {
-          getAST(markdownNode).then(ast => {
-            resolve(
-              hastToHTML(toHAST(ast, { allowDangerousHTML: true }), {
-                allowDangerousHTML: true,
-              })
-            )
-          })
+        const ast = await getHTMLAst(markdownNode)
+        // Save new HTML to cache and return
+        const html = hastToHTML(ast, {
+          allowDangerousHTML: true,
         })
 
         // Save new HTML to cache and return
@@ -271,6 +287,14 @@ module.exports = (
           return getHTML(markdownNode)
         },
       },
+      htmlAst: {
+        type: GraphQlJson,
+        resolve(markdownNode) {
+          const ast = _.clone(getHTMLAst(markdownNode))
+          stripPosition(ast, true)
+          return ast
+        },
+      },
       excerpt: {
         type: GraphQLString,
         args: {
diff --git a/yarn.lock b/yarn.lock
index 4c75b331f81ad..56c4a4b456999 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -13469,7 +13469,7 @@ unist-util-position@^3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/unist-util-position/-/unist-util-position-3.0.0.tgz#e6e1e03eeeb81c5e1afe553e8d4adfbd7c0d8f82"
 
-unist-util-remove-position@^1.0.0:
+unist-util-remove-position@^1.0.0, unist-util-remove-position@^1.1.1:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/unist-util-remove-position/-/unist-util-remove-position-1.1.1.tgz#5a85c1555fc1ba0c101b86707d15e50fa4c871bb"
   dependencies: