chore: Move editor into codebase (#2930)

shared/editor/rules/embeds.ts

@@ -0,0 +1,91 @@
+import MarkdownIt from "markdown-it";
+import Token from "markdown-it/lib/token";
+import { EmbedDescriptor } from "../types";
+
+function isParagraph(token: Token) {
+  return token.type === "paragraph_open";
+}
+
+function isInline(token: Token) {
+  return token.type === "inline" && token.level === 1;
+}
+
+function isLinkOpen(token: Token) {
+  return token.type === "link_open";
+}
+
+function isLinkClose(token: Token) {
+  return token.type === "link_close";
+}
+
+export default function (embeds: EmbedDescriptor[]) {
+  function isEmbed(token: Token, link: Token) {
+    const href = link.attrs ? link.attrs[0][1] : "";
+    const simpleLink = href === token.content;
+
+    if (!simpleLink) return false;
+    if (!embeds) return false;
+
+    for (const embed of embeds) {
+      const matches = embed.matcher(href);
+      if (matches) {
+        return {
+          ...embed,
+          matches,
+        };
+      }
+    }
+
+    return false;
+  }
+
+  return function markdownEmbeds(md: MarkdownIt) {
+    md.core.ruler.after("inline", "embeds", (state) => {
+      const tokens = state.tokens;
+      let insideLink;
+
+      for (let i = 0; i < tokens.length - 1; i++) {
+        // once we find an inline token look through it's children for links
+        if (isInline(tokens[i]) && isParagraph(tokens[i - 1])) {
+          const tokenChildren = tokens[i].children || [];
+
+          for (let j = 0; j < tokenChildren.length - 1; j++) {
+            const current = tokenChildren[j];
+            if (!current) continue;
+
+            if (isLinkOpen(current)) {
+              insideLink = current;
+              continue;
+            }
+
+            if (isLinkClose(current)) {
+              insideLink = null;
+              continue;
+            }
+
+            // of hey, we found a link – lets check to see if it should be
+            // considered to be an embed
+            if (insideLink) {
+              const result = isEmbed(current, insideLink);
+              if (result) {
+                const { content } = current;
+
+                // convert to embed token
+                const token = new Token("embed", "iframe", 0);
+                token.attrSet("href", content);
+
+                // delete the inline link – this makes the assumption that the
+                // embed is the only thing in the para.
+                // TODO: double check this
+                tokens.splice(i - 1, 3, token);
+                break;
+              }
+            }
+          }
+        }
+      }
+
+      return false;
+    });
+  };
+}