const footnoteMatch = /^\[\^([^\]]+)\]:([\s\S]*)$/;
const referenceMatch = /\[\^([^\]]+)\](?!\()/g;
const referencePrefix = "fnref";
const footnotePrefix = "fn";
const footnoteTemplate = (ref, text) => {
  return `<p id="${footnotePrefix}:${ref}">${ref}. ${text}</p>`;
};
const footnoteContainerTemplate = (text) => {
  return `<h3>Footnotes</h3>${text}`
}
const referenceTemplate = ref => {
  return `<sup id="${referencePrefix}:${ref}"><a href="#${footnotePrefix}:${ref}">[${ref}]</a></sup>`;
};
const interpolateReferences = (text) => {
  return text.replace(referenceMatch, (_, ref) => {
    return referenceTemplate(ref);
  });
}
const interpolateFootnotes = (text) => {
  const found = text.match(footnoteMatch)
  if (found) {
    const replacedText = text.replace(footnoteMatch, (_, value, text) => {
      return footnoteTemplate(value, text);
    });
    return footnoteContainerTemplate(replacedText)
  }
  return text
}

const renderer = {
  paragraph(text) {
    return marked.Renderer.prototype.paragraph.apply(null, [
      interpolateReferences(interpolateFootnotes(text))
    ]);
  },
  text(text) {
    return marked.Renderer.prototype.text.apply(null, [
      interpolateReferences(interpolateFootnotes(text))
    ]);
  }
};
marked.use({ renderer });