feat(v2): add support to import assets using relative link in markdown syntax (#3096)

* add a rehyper plugin

* fix yarn.lok

* add target

* convert to remark

* add docs

* remove unused package

* remove file-loader

* add test for file-loader

* fix test

packages/docusaurus-mdx-loader/src/index.js

@@ -14,6 +14,7 @@ const stringifyObject = require('stringify-object');
 const slug = require('./remark/slug');
 const rightToc = require('./remark/rightToc');
 const transformImage = require('./remark/transformImage');
+const tranformAsset = require('./remark/transformAssets');
 
 const DEFAULT_OPTIONS = {
   rehypePlugins: [],
@@ -34,11 +35,16 @@ module.exports = async function (fileString) {
         transformImage,
         {staticDir: reqOptions.staticDir, filePath: this.resourcePath},
       ],
+      [
+        tranformAsset,
+        {staticDir: reqOptions.staticDir, filePath: this.resourcePath},
+      ],
       ...(reqOptions.remarkPlugins || []),
     ],
     rehypePlugins: [
       ...(reqOptions.beforeDefaultRehypePlugins || []),
       ...DEFAULT_OPTIONS.rehypePlugins,
+
       ...(reqOptions.rehypePlugins || []),
     ],
     filepath: this.resourcePath,

packages/docusaurus-mdx-loader/src/remark/transformAssets/__tests__/__snapshots__/index.test.js.snap

@@ -0,0 +1,33 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`transformAsset plugin fail if asset does not exist 1`] = `"Asset packages/docusaurus-mdx-loader/src/remark/transformAssets/__tests__/fixtures/doesNotExist.pdf used in packages/docusaurus-mdx-loader/src/remark/transformAssets/__tests__/fixtures/fail.md not found."`;
+
+exports[`transformAsset plugin fail if asset url is absent 1`] = `"Markdown link url is mandatory. filePath=packages/docusaurus-mdx-loader/src/remark/transformAssets/__tests__/fixtures/noUrl.md"`;
+
+exports[`transformAsset plugin pathname protocol 1`] = `
+"[asset](/asset/unchecked.pdf)
+"
+`;
+
+exports[`transformAsset plugin transform md links to <a /> 1`] = `
+"[asset](https://example.com/asset.pdf)
+
+<a  target=\\"_blank\\" href={require('./asset.pdf').default}  ></a>
+
+<a  target=\\"_blank\\" href={require('./asset.pdf').default}  >asset</a>
+
+[asset](asset.pdf \\"Title\\") ![seet](asset)
+
+## Heading
+
+\`\`\`md
+[asset](./asset.pdf)
+\`\`\`
+
+<a  target=\\"_blank\\" href={require('!file-loader!./asset.pdf').default}  >assets</a>
+
+[assets](/github/!file-loader!/assets.pdf)
+
+[asset](asset.pdf)
+"
+`;

packages/docusaurus-mdx-loader/src/remark/transformAssets/__tests__/fixtures/asset.md

@@ -0,0 +1,19 @@
+[asset](https://example.com/asset.pdf)
+
+[](./asset.pdf)
+
+[asset](./asset.pdf)
+
+[asset](asset.pdf 'Title') ![seet](asset)
+
+## Heading
+
+```md
+[asset](./asset.pdf)
+```
+
+[assets](!file-loader!./asset.pdf)
+
+[assets](/github/!file-loader!/assets.pdf)
+
+[asset](asset.pdf)

packages/docusaurus-mdx-loader/src/remark/transformAssets/__tests__/fixtures/fail.md

@@ -0,0 +1 @@
+[asset](./doesNotExist.pdf)

packages/docusaurus-mdx-loader/src/remark/transformAssets/__tests__/fixtures/noUrl.md

@@ -0,0 +1 @@
+[asset]()

packages/docusaurus-mdx-loader/src/remark/transformAssets/__tests__/fixtures/pathname.md

@@ -0,0 +1 @@
+[asset](pathname:///asset/unchecked.pdf)

packages/docusaurus-mdx-loader/src/remark/transformAssets/__tests__/index.test.js

@@ -0,0 +1,46 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {join} from 'path';
+import remark from 'remark';
+import mdx from 'remark-mdx';
+import vfile from 'to-vfile';
+import plugin from '..';
+import slug from '../../slug';
+
+const processFixture = async (name, options) => {
+  const path = join(__dirname, 'fixtures', `${name}.md`);
+  const file = await vfile.read(path);
+  const result = await remark()
+    .use(slug)
+    .use(mdx)
+    .use(plugin, {...options, filePath: path})
+    .process(file);
+
+  return result.toString();
+};
+
+describe('transformAsset plugin', () => {
+  test('fail if asset does not exist', async () => {
+    await expect(processFixture('fail')).rejects.toThrowErrorMatchingSnapshot();
+  });
+  test('fail if asset url is absent', async () => {
+    await expect(
+      processFixture('noUrl'),
+    ).rejects.toThrowErrorMatchingSnapshot();
+  });
+
+  test('transform md links to <a />', async () => {
+    const result = await processFixture('asset');
+    expect(result).toMatchSnapshot();
+  });
+
+  test('pathname protocol', async () => {
+    const result = await processFixture('pathname');
+    expect(result).toMatchSnapshot();
+  });
+});

packages/docusaurus-mdx-loader/src/remark/transformAssets/index.js

@@ -0,0 +1,91 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+const visit = require('unist-util-visit');
+const path = require('path');
+const url = require('url');
+const fs = require('fs-extra');
+
+// Needed to throw errors with computer-agnostic path messages
+// Absolute paths are too dependant of user FS
+function toRelativePath(filePath) {
+  return path.relative(process.cwd(), filePath);
+}
+
+async function ensureAssetFileExist(assetPath, sourceFilePath) {
+  const assetExists = await fs.exists(assetPath);
+  if (!assetExists) {
+    throw new Error(
+      `Asset ${toRelativePath(assetPath)} used in ${toRelativePath(
+        sourceFilePath,
+      )} not found.`,
+    );
+  }
+}
+
+async function processLinkNode(node, index, parent, {filePath}) {
+  if (!node.url) {
+    throw new Error(
+      `Markdown link url is mandatory. filePath=${toRelativePath(filePath)}`,
+    );
+  }
+  const parsedUrl = url.parse(node.url);
+  const assetPath = node.url;
+  if (parsedUrl.protocol) {
+    // pathname:// is an escape hatch,
+    // in case user does not want his assets to be converted to require calls going through webpack loader
+    // we don't have to document this for now,
+    // it's mostly to make next release less risky (2.0.0-alpha.59)
+    if (parsedUrl.protocol === 'pathname:') {
+      node.url = node.url.replace('pathname://', '');
+    }
+    return;
+  }
+  if (
+    assetPath.match(/#|.md|.mdx/) ||
+    path.isAbsolute(assetPath) ||
+    !path.extname(assetPath) ||
+    !assetPath.startsWith('.')
+  ) {
+    if (!assetPath.startsWith('!')) {
+      return;
+    }
+  }
+
+  const expectedAssetPath = path.join(
+    path.dirname(filePath),
+    assetPath.replace(/!.*!/, ''),
+  );
+  await ensureAssetFileExist(expectedAssetPath, filePath);
+
+  node.type = 'jsx';
+  node.value = `<a  target="_blank" ${
+    assetPath ? `href={require('${assetPath}').default}` : ''
+  } ${node.title ? `title={${node.title}}` : ''} >`;
+  const {children} = node;
+  delete node.children;
+
+  parent.children.splice(index + 1, 0, {
+    type: 'paragraph',
+    children,
+  });
+
+  parent.children.splice(index + 2, 0, {type: 'jsx', value: '</a>'});
+}
+
+const plugin = (options) => {
+  const transformer = async (root) => {
+    const promises = [];
+    visit(root, 'link', (node, index, parent) => {
+      promises.push(processLinkNode(node, index, parent, options));
+    });
+    await Promise.all(promises);
+  };
+  return transformer;
+};
+
+module.exports = plugin;