remark-gist-plugin.ts

import visit from "async-unist-util-visit";

const gist = () => async (ast: IAST) => {
  const promises: Promise<void>[] = [];

  const createGist = (node: IAST) => {
    if (node.children === undefined) return;
    if (node.children.length === 0) return;

    const hasGist = node.children.some(
      ({ type, value }) =>
        type === "inlineCode" && value?.startsWith("gist:") && value?.length > 5
    );

    if (hasGist) {
      const promise = loadAndTransformGist(node, node.children[0]).then(
        (newNode) => {
          Object.assign(node, newNode);

          if (node.children?.length === 0) {
            delete node.children;
          }
        }
      );

      promises.push(promise);
    }
  };

  await visit(ast, "paragraph", createGist);
  await Promise.all(promises);

  return;
};