feat: replace relative markdown link to corrrect url

docs/hello.md

@@ -3,6 +3,20 @@ id: hello
 title: Hello, World !
 ---
 
+## Relative links
+
+Replace this
+[highlight](highlight.md) [docusaurus](docusaurus.md)
+
+Can't replace this
+[file](file.md)
+
+Do not replace below
+
+```
+[highlight](highlight.md) [docusaurus](docusaurus.md)
+```
+
 ## Blockquotes
 
 > Blockquotes can also be nested...

lib/load/index.js

@@ -26,6 +26,12 @@ module.exports = async function load(siteDir) {
     `export default ${JSON.stringify(docsData, null, 2)};`
   );
 
+  /* Create source to permalink mapping */
+  const sourceToLink = {};
+  Object.values(docsData).forEach(({source, permalink}) => {
+    sourceToLink[source] = permalink;
+  });
+
   // pages
   const pagesDir = path.resolve(siteDir, 'pages');
   const pagesData = await loadPages(pagesDir);
@@ -41,6 +47,8 @@ module.exports = async function load(siteDir) {
   const themePath = loadTheme(siteDir);
 
   const baseUrl = siteConfig.baseUrl || '/';
+  const versionedDir = path.join(siteDir, 'versioned_docs');
+  const translatedDir = path.join(siteDir, 'translated_docs');
 
   const props = {
     siteConfig,
@@ -52,7 +60,10 @@ module.exports = async function load(siteDir) {
     pagesData,
     outDir,
     themePath,
-    baseUrl
+    baseUrl,
+    sourceToLink,
+    versionedDir,
+    translatedDir
   };
 
   // Generate React Router Config

lib/theme/Layout/index.js

@@ -1,6 +1,5 @@
 import React from 'react';
 import {Link} from 'react-router-dom';
-import siteConfig from '@site/siteConfig';
 import styles from './styles.css';
 
 /* eslint-disable react/prefer-stateless-function */

lib/webpack/base.js

@@ -13,6 +13,9 @@ module.exports = function createBaseConfig(props, isServer) {
     docsDir,
     pagesDir,
     siteDir,
+    sourceToLink,
+    versionedDir,
+    translatedDir,
     baseUrl
   } = props;
 
@@ -33,8 +36,8 @@ module.exports = function createBaseConfig(props, isServer) {
     .set('symlinks', true)
     .alias.set('@theme', themePath)
     .set('@site', siteDir)
-    .set('@versioned_docs', path.resolve(siteDir, 'versioned_docs'))
-    .set('@translated_docs', path.resolve(siteDir, 'translated_docs'))
+    .set('@versioned_docs', versionedDir)
+    .set('@translated_docs', translatedDir)
     .set('@docs', docsDir)
     .set('@pages', pagesDir)
     .set('@build', outDir)
@@ -75,7 +78,7 @@ module.exports = function createBaseConfig(props, isServer) {
   mdRule
     .use('markdown-loader')
     .loader(mdLoader)
-    .options({siteConfig, siteDir, docsDir});
+    .options({siteConfig, versionedDir, translatedDir, docsDir, sourceToLink});
 
   const cssRule = config.module.rule('css').test(/\.css$/);
   if (isProd) {
@@ -110,12 +113,12 @@ module.exports = function createBaseConfig(props, isServer) {
           warnings: false,
           compress: false,
           ecma: 6,
-          mangle: true,
+          mangle: true
         },
         sourceMap: true
       })
     ]);
   }
-  
+
   return config;
 };

lib/webpack/loader/markdown.js

@@ -3,13 +3,58 @@ const fm = require('front-matter');
 
 module.exports = function(fileString) {
   const options = getOptions(this);
-  const {siteConfig, siteDir, docsDir } = options;
+  const {
+    siteConfig,
+    versionedDir,
+    docsDir,
+    translatedDir,
+    sourceToLink
+  } = options;
 
-  /* 
-    Process the markdown file content, including replacing all relative markdown links
-  */
-  const {body: content = ''} = fm(fileString);
-  
+  /* Extract content of markdown (without frontmatter) */
+  const {body} = fm(fileString);
+
+  /* Determine whether this file is in @docs, @versioned_docs or @translated_docs */
+  let dirAlias;
+  if (this.resourcePath.startsWith(translatedDir)) {
+    dirAlias = '@translated_docs';
+  } else if (this.resourcePath.startsWith(versionedDir)) {
+    dirAlias = '@versioned_docs';
+  } else if (this.resourcePath.startsWith(docsDir)) {
+    dirAlias = '@docs';
+  }
+
+  /* Replace internal markdown linking (except in fenced blocks) */
+  let content = body;
+  if (dirAlias) {
+    let fencedBlock = false;
+    const lines = body.split('\n').map(line => {
+      if (line.trim().startsWith('```')) {
+        fencedBlock = !fencedBlock;
+      }
+      if (fencedBlock) return line;
+
+      let modifiedLine = line;
+      const mdLinks = [];
+      const mdRegex = /(?:\]\()(?:\.\/)?([^'")\]\s>]+\.md)/g;
+      let match = mdRegex.exec(content);
+      while (match !== null) {
+        mdLinks.push(match[1]);
+        match = mdRegex.exec(content);
+      }
+      mdLinks.forEach(mdLink => {
+        const source = `${dirAlias}/${mdLink}`;
+        const permalink = sourceToLink[source];
+        if (permalink) {
+          modifiedLine = modifiedLine.replace(mdLink, permalink);
+        }
+      });
+      return modifiedLine;
+    });
+    content = lines.join('\n');
+  }
+
+  /* Return a React component */
   return (
     `import React from 'react';\n` +
     `import Markdown from '@theme/Markdown'\n` +