import { NextSeo } from "next-seo";
import LiteYouTubeEmbed from "react-lite-youtube-embed";
import { useState, useEffect } from "react";

import { YOUTUBE_REGEX } from "../lib/constants";
import siteConfig from "../config/siteConfig";
import getMDXComponents from "./_getMDXComponents";
import getObserver from "./_getIntersectionObserver"
import MdxContent from "./MdxContent"

// import { Paragraph } from "./Paragraph";
// import { Anchor } from "./Anchor";

// const Anchor = dynamic(() => import('./Anchor').then(module => module.Anchor), {
//   ssr: false
// })

// const Paragraph = dynamic(() => import("./Paragraph").then(mod => mod.Paragraph))

export default function MdxPage({ body, frontMatter, editUrl }) {
  const [activeHeading, setActiveHeading] = useState("");
  const [observer, setObserver] = useState(null);

  // run only after first render, in order to preserve the observer
  // between component rerenders
  useEffect((() => {
    const observer = getObserver((entry) => {
      if (entry.isIntersecting) {
        setActiveHeading(entry.target.id);
      }
    });
    setObserver(observer);

    return observer.disconnect();
  }), [])

  useEffect(() => {
    // on initial render activeHeading will be `null`
    // however, we still want to highlight the current heading in the toc
    // based on the current url
    if (!activeHeading) {
      try {
        const path = window.location.hash;
        if (path) {
          setActiveHeading(path.slice(1))
        } else {
          const firstTocHeading = document.querySelector(".toc-link");
          const href = firstTocHeading.href;
          setActiveHeading(href.match(/.+#(.+)/)[1]);
        }
      } finally {
        return
      }
    }

    const tocLink = document.querySelector(`.toc-link[href="#${activeHeading}"]`)
    tocLink.classList.add("active");

    return () => {
      tocLink.classList.remove("active")
    }
  }, [activeHeading])

  const {
    title, description, date, authors, youtube, podcast, image, _raw
  } = frontMatter

  let youtubeThumnbnail;

  const youtubeId =
    youtube && YOUTUBE_REGEX.test(youtube) && youtube.split(/^|=|\//).pop();

  if (youtubeId && !image) {
    //  get the youtube thumbnail image from https://img.youtube.com/vi/<youtube-video-id>/maxresdefault.jpg
    youtubeThumnbnail = youtube.replace(
      YOUTUBE_REGEX,
      `https://img.youtube.com/vi/${youtubeId}/maxresdefault.jpg`
    );
  }

  const PodcastIcon = siteConfig.social.find((s) => s.name === "Podcast").icon;

  const titleFromUrl = _raw.flattenedPath
    .split("/")
    .pop()
    .replace(/-/g, " ")
    // capitalize first char of each word
    .replace(/(^\w{1})|(\s{1}\w{1})/g, (str) => str.toUpperCase());

  const SeoTitle = title ?? titleFromUrl;
  const imageUrl = image
    ? siteConfig.url + image
    : youtubeThumnbnail
    ? youtubeThumnbnail
    : null;

  // enable editing content only for claims, concepts, and guide for now
  const editUrl = ["claims", "concepts", "guide"].includes(_raw.sourceFileDir)
    ? siteConfig.repoRoot + siteConfig.repoEditPath + _raw.sourceFilePath
    : null;

  return (
    <>
      <NextSeo
        title={SeoTitle}
        description={description}
        canonical={`${siteConfig.url}/${_raw.flattenedPath}`}
        openGraph={{
          title: SeoTitle,
          description: description,
          url: `${siteConfig.url}/${_raw.flattenedPath}`,
          type: "article",
          article: {
            tags: keywords ? keywords.split(",") : [],
          },
          images: imageUrl
            ? [
                {
                  url: imageUrl,
                  width: 1200,
                  height: 627,
                  alt: title,
                  type: "image/png",
                },
              ]
            : siteConfig.nextSeo.openGraph.images,
        }}
        additionalMetaTags={[
          { name: "keywords", content: keywords ? keywords : "" },
        ]}
      />
      <article className="prose dark:prose-invert prose-a:break-all mx-auto lg:mr-[20rem] p-6">
        <header>
          <div className="mb-6">
            {title && <h1 className="mb-0">{title}</h1>}
            {date && (
              <p className="text-gray-900 dark:text-gray-500 text-sm pl-2">
                on {date}
              </p>
            )}
            {description && <p className="">{description}</p>}
            {youtubeId && <LiteYouTubeEmbed id={youtubeId} />}
            {podcast && (
              <div className="pt-4">
                <ul className="list-disc">
                  <li>
                    <a
                      className="flex items-center"
                      target="_blank"
                      rel="noopener"
                      href={podcast}
                    >
                      <div className="w-4 mr-2">
                        <PodcastIcon />
                      </div>
                      <p className="m-0">Listen to this podcast</p>
                    </a>
                  </li>
                </ul>
              </div>
            )}
          </div>
        </header>
        <main className="my-6">
          <MdxContent body={body} observer={observer}/>
          {editUrl && (
            <div className="mt-12 mb-6">
              <a
                className="flex no-underline font-semibold text-yellow-li"
                href={editUrl}
                target="_blank"
              >
                Edit this page
                <span className="mx-1">
                  <svg
                    xmlns="http://www.w3.org/2000/svg"
                    className="h-6 w-6"
                    fill="none"
                    viewBox="0 0 24 24"
                    stroke="currentColor"
                    strokeWidth="2"
                  >
                    <path
                      strokeLinecap="round"
                      strokeLinejoin="round"
                      d="M10 6H6a2 2 0 00-2 2v10a2 2 0 002 2h10a2 2 0 002-2v-4M14 4h6m0 0v6m0-6L10 14"
                    />
                  </svg>
                </span>
              </a>
            </div>
          )}
        </main>
      </article>
    </>
  );
}