create attachment remarkplugin

packages/app/src/services/renderer/remark-plugins/attachment.ts

@@ -0,0 +1,44 @@
+import { Schema as SanitizeOption } from 'hast-util-sanitize';
+import { Plugin } from 'unified';
+import { visit } from 'unist-util-visit';
+
+const SUPPORTED_ATTRIBUTES = ['url', 'attachmentName'];
+
+const isAttachmentLink = (url: unknown) => {
+  // https://regex101.com/r/9qZhiK/1
+  return url === new RegExp(/^\/(attachment)\/([^/^\n]+)$/);
+};
+
+export const remarkPlugin: Plugin = () => {
+  return (tree) => {
+    // TODO: do not use any for node.children[0].value
+    visit(tree, (node: any) => {
+      if (node.type === 'link') {
+        if (!isAttachmentLink(node.url)) {
+          const data = node.data ?? (node.data = {});
+          data.hName = 'attachment';
+          data.hProperties = {
+            url: node.url,
+            attachmentName: node.children[0].value,
+          };
+
+          // omit position to fix the key regardless of its position
+          // see:
+          //   https://github.com/remarkjs/react-markdown/issues/703
+          //   https://github.com/remarkjs/react-markdown/issues/466
+          //
+          //   https://github.com/remarkjs/react-markdown/blob/a80dfdee2703d84ac2120d28b0e4998a5b417c85/lib/ast-to-react.js#L201-L204
+          //   https://github.com/remarkjs/react-markdown/blob/a80dfdee2703d84ac2120d28b0e4998a5b417c85/lib/ast-to-react.js#L217-L222
+          delete node.position;
+        }
+      }
+    });
+  };
+};
+
+export const sanitizeOption: SanitizeOption = {
+  tagNames: ['attachment'],
+  attributes: {
+    attachment: SUPPORTED_ATTRIBUTES,
+  },
+};