import React, {
  useState,
  useEffect,
  useMemo,
  useContext,
  createContext,
} from 'react';
import { useRouter } from 'next/router';
import Head from 'next/head';
import Link from 'next/link';
import slugify from '@sindresorhus/slugify';
import 'focus-visible';
import cn from 'classnames';
import { SkipNavContent } from '@reach/skip-nav';

import Theme from './theme';
import SSGContext from './ssg';
import Search from './search';
// import DocSearch from './docsearch'
import GitHubIcon from './github-icon';
import ArrowRight from './arrow-right';

import getDirectories from './directories';
import getConfig from './config';
import * as ReactDOM from 'react-dom/server';
import stripHtml from 'string-strip-html';
const config = getConfig();
const directories = getDirectories();
const TreeState = new Map();
const titleType = ['h1', 'h2', 'h3', 'h4', 'h5', 'h6'];
const MenuContext = createContext(false);

const flatten = list => {
  return list.reduce((flat, toFlatten) => {
    return flat.concat(
      toFlatten.children ? flatten(toFlatten.children) : toFlatten
    );
  }, []);
};

const flatDirectories = flatten(directories);

function Folder({ item, anchors }) {
  const route = useRouter().route + '/';
  const active = route.startsWith(item.route + '/');
  const open = TreeState[item.route] ?? true;
  const [_, render] = useState(false);

  useEffect(() => {
    if (active) {
      TreeState[item.route] = true;
    }
  }, [active]);

  return (
    <li
      className={cn({
        'active-route': active,
        active: open,
      })}
    >
      <button
        onClick={() => {
          if (active) return;
          TreeState[item.route] = !open;
          render(x => !x);
        }}
        className="focus:shadow-outline"
      >
        {item.title}
      </button>
      <div
        style={{
          display: open ? '' : 'none',
        }}
      >
        <Menu dir={item.children} base={item.route} anchors={anchors} />
      </div>
    </li>
  );
}

function File({ item, anchors }) {
  const { setMenu } = useContext(MenuContext);
  const route = useRouter().route + '/';
  const active = route.startsWith(item.route + '/');

  let title = item.title;
  // if (item.title.startsWith('> ')) {
  // title = title.substr(2)
  if (anchors?.length) {
    if (active) {
      return (
        <li className={active ? 'active' : ''}>
          <Link href={item.route}>
            <a>{title}</a>
          </Link>
          <ul>
            {anchors.map(anchor => {
              const slug = slugify(
                stripHtml(ReactDOM.renderToString(anchor)) || ''
              );
              return (
                <li key={`a-${slug}`}>
                  <a
                    href={'#' + slug}
                    onClick={() => setMenu(false)}
                    className="focus:shadow-outline"
                  >
                    <span className="flex">
                      <span className="mr-2 opacity-25">#</span>
                      <span className="inline-block">{anchor}</span>
                    </span>
                  </a>
                </li>
              );
            })}
          </ul>
        </li>
      );
    }
  }

  return (
    <li className={active ? 'active' : ''}>
      <Link href={item.route}>
        <a onClick={() => setMenu(false)} className="focus:shadow-outline">
          {title}
        </a>
      </Link>
    </li>
  );
}

function Menu({ dir, anchors }) {
  return (
    <ul>
      {dir.map(item => {
        if (item.children) {
          return <Folder key={item.name} item={item} anchors={anchors} />;
        }
        return <File key={item.name} item={item} anchors={anchors} />;
      })}
    </ul>
  );
}

function Sidebar({ show, anchors }) {
  return (
    <aside
      className={`h-screen bg-white flex-shrink-0 w-full md:w-64 md:border-r md:block fixed md:sticky z-10 ${
        show ? '' : 'hidden'
      }`}
      style={{
        top: '4rem',
        height: 'calc(100vh - 4rem)',
      }}
    >
      <div className="sidebar w-full p-4 pb-40 md:pb-16 h-full overflow-y-auto">
        <Menu dir={directories} anchors={anchors} />
      </div>
    </aside>
  );
}

const NextLink = ({ currentIndex }) => {
  let next = flatDirectories[currentIndex + 1];

  if (!config.nextLinks || !next) {
    return null;
  }

  return (
    <Link href={next.route}>
      <a className="text-lg font-medium p-4 -m-4 no-underline text-gray-600 hover:text-blue-600 flex items-center ml-2">
        {next.title}
        <ArrowRight className="inline ml-1 flex-shrink-0" />
      </a>
    </Link>
  );
};

const PrevLink = ({ currentIndex }) => {
  let prev = flatDirectories[currentIndex - 1];

  if (!config.prevLinks || !prev) {
    return null;
  }

  return (
    <Link href={prev.route}>
      <a className="text-lg font-medium p-4 -m-4 no-underline text-gray-600 hover:text-blue-600 flex items-center mr-2">
        <ArrowRight className="transform rotate-180 inline mr-1 flex-shrink-0" />
        {prev.title}
      </a>
    </Link>
  );
};

const Layout = ({ filename, full, title: _title, ssg = {}, children }) => {
  const [menu, setMenu] = useState(false);
  const router = useRouter();
  const { route, pathname } = router;

  const filepath = route.slice(0, route.lastIndexOf('/') + 1);
  const titles = React.Children.toArray(children).filter(child =>
    titleType.includes(child.props.mdxType)
  );
  const anchors = titles
    .filter(child => child.props.mdxType === 'h2')
    .map(child => child.props.children);

  useEffect(() => {
    if (menu) {
      document.body.classList.add('overflow-hidden');
    } else {
      document.body.classList.remove('overflow-hidden');
    }
  }, [menu]);

  const currentIndex = useMemo(
    () => flatDirectories.findIndex(dir => dir.route === pathname),
    [flatDirectories, pathname]
  );

  const title =
    flatDirectories[currentIndex]?.title ||
    titles.find(child => child.props.mdxType === 'h1')?.props.children ||
    'Untitled';

  const props = {
    filepath: filepath + filename,
    route,
  };

  return (
    <>
      <Head>
        <title>
          {title}
          {config.titleSuffix || ''}
        </title>
        {config.head ? config.head(props) : null}
      </Head>
      <div className="main-container flex flex-col">
        <nav className="flex items-center bg-white z-20 fixed top-0 left-0 right-0 h-16 border-b px-6 ">
          <div className="mr-6 md:mr-0 md:w-full flex items-center">
            <Link href="/">
              <a className="no-underline text-current inline-flex items-center p-2 -m-2 hover:opacity-75">
                {config.logo}
              </a>
            </Link>
          </div>

          {config.search && <Search directories={flatDirectories} />}
          {/* <DocSearch /> */}

          {config.github ? (
            <a
              className="text-current p-2 -mr-2"
              href={config.github}
              target="_blank"
              rel="noopener"
              aria-label="GitHub Repository"
            >
              <GitHubIcon height={28} />
            </a>
          ) : null}
          <button
            className="block md:hidden p-2 -mr-2 ml-2"
            onClick={() => setMenu(!menu)}
          >
            <svg
              width="24"
              height="24"
              viewBox="0 0 24 24"
              fill="none"
              stroke="currentColor"
              strokeWidth="2"
              strokeLinecap="round"
              strokeLinejoin="round"
            >
              <line x1="3" y1="12" x2="21" y2="12"></line>
              <line x1="3" y1="6" x2="21" y2="6"></line>
              <line x1="3" y1="18" x2="21" y2="18"></line>
            </svg>
          </button>
        </nav>
        <div className="flex flex-1 h-full">
          <MenuContext.Provider value={{ setMenu }}>
            <Sidebar show={menu} anchors={anchors} />
          </MenuContext.Provider>
          <SSGContext.Provider value={ssg}>
            {full ? (
              <content className="relative pt-16 w-full overflow-x-hidden">
                {children}
              </content>
            ) : (
              <>
                <SkipNavContent />
                <content className="relative pt-20 pb-16 px-6 md:px-8 w-full max-w-full overflow-x-hidden">
                  <main className="max-w-screen-md">
                    <Theme>{children}</Theme>
                    <footer className="mt-24">
                      <nav className="flex flex-row items-center justify-between">
                        <div>
                          <PrevLink currentIndex={currentIndex} />
                        </div>

                        <div>
                          <NextLink currentIndex={currentIndex} />
                        </div>
                      </nav>

                      <hr />

                      {config.footer ? config.footer(props) : null}
                    </footer>
                  </main>{' '}
                </content>
              </>
            )}
          </SSGContext.Provider>
        </div>
      </div>
    </>
  );
};

export default filename => {
  return props => <Layout filename={filename} {...props} />;
};