import React, {
  type JSX,
  useCallback,
  useEffect,
  useMemo,
  useRef,
  useState,
} from 'react';
import dynamic from 'next/dynamic';
import type { IPagePopulatedToShowRevision } from '@growi/core';
import { isUsersHomepage } from '@growi/core/dist/utils/page-path-utils';
import { useSlidesByFrontmatter } from '@growi/presentation/dist/services';

import { PagePathNavTitle } from '~/components/Common/PagePathNavTitle';
import type { RendererConfig } from '~/interfaces/services/renderer';
import { useShouldExpandContent } from '~/services/layout/use-should-expand-content';
import { generateSSRViewOptions } from '~/services/renderer/renderer';
import { useIsNotFound, useSWRxCurrentPage } from '~/stores/page';
import { useViewOptions } from '~/stores/renderer';
import {
  useIsForbidden,
  useIsIdenticalPath,
  useIsNotCreatable,
} from '~/stores-universal/context';

import { UserInfo } from '../User/UserInfo';
import { PageAlerts } from './PageAlerts/PageAlerts';
import { PageContentFooter } from './PageContentFooter';
import { PageViewLayout } from './PageViewLayout';
import RevisionRenderer from './RevisionRenderer';

const NotCreatablePage = dynamic(
  () =>
    import('~/client/components/NotCreatablePage').then(
      (mod) => mod.NotCreatablePage,
    ),
  { ssr: false },
);
const ForbiddenPage = dynamic(
  () => import('~/client/components/ForbiddenPage'),
  { ssr: false },
);
const NotFoundPage = dynamic(() => import('~/client/components/NotFoundPage'), {
  ssr: false,
});
const PageSideContents = dynamic(
  () =>
    import('~/client/components/PageSideContents').then(
      (mod) => mod.PageSideContents,
    ),
  { ssr: false },
);
const PageContentsUtilities = dynamic(
  () =>
    import('~/client/components/Page/PageContentsUtilities').then(
      (mod) => mod.PageContentsUtilities,
    ),
  { ssr: false },
);
const Comments = dynamic(
  () => import('~/client/components/Comments').then((mod) => mod.Comments),
  { ssr: false },
);
const UsersHomepageFooter = dynamic(
  () =>
    import('~/client/components/UsersHomepageFooter').then(
      (mod) => mod.UsersHomepageFooter,
    ),
  { ssr: false },
);
const IdenticalPathPage = dynamic(
  () =>
    import('~/client/components/IdenticalPathPage').then(
      (mod) => mod.IdenticalPathPage,
    ),
  { ssr: false },
);
const SlideRenderer = dynamic(
  () =>
    import('~/client/components/Page/SlideRenderer').then(
      (mod) => mod.SlideRenderer,
    ),
  { ssr: false },
);

type Props = {
  pagePath: string;
  rendererConfig: RendererConfig;
  initialPage?: IPagePopulatedToShowRevision;
  className?: string;
};

export const PageView = (props: Props): JSX.Element => {
  const commentsContainerRef = useRef<HTMLDivElement>(null);

  const { pagePath, initialPage, rendererConfig, className } = props;

  const { data: isIdenticalPathPage } = useIsIdenticalPath();
  const { data: isForbidden } = useIsForbidden();
  const { data: isNotCreatable } = useIsNotCreatable();
  const { data: isNotFoundMeta } = useIsNotFound();

  const { data: pageBySWR } = useSWRxCurrentPage();
  const { data: viewOptions } = useViewOptions();

  const page = pageBySWR ?? initialPage;
  const isNotFound = isNotFoundMeta || page == null;
  const isUsersHomepagePath = isUsersHomepage(pagePath);

  const shouldExpandContent = useShouldExpandContent(page);

  const markdown = page?.revision?.body;
  const isSlide = useSlidesByFrontmatter(
    markdown,
    rendererConfig.isEnabledMarp,
  );

  const [currentPageId, setCurrentPageId] = useState<string | undefined>(
    page?._id,
  );

  useEffect(() => {
    if (page?._id !== undefined) {
      setCurrentPageId(page._id);
    }
  }, [page?._id]);

  // ***************************  Auto Scroll  ***************************
  useEffect(() => {
    if (currentPageId == null) {
      return;
    }

    // do nothing if hash is empty
    const { hash } = window.location;
    if (hash.length === 0) {
      return;
    }

    const contentContainer = document.getElementById(
      'page-view-content-container',
    );
    if (contentContainer == null) return;

    const targetId = decodeURIComponent(hash.slice(1));
    const target = document.getElementById(targetId);
    if (target != null) {
      target.scrollIntoView();
      return;
    }

    const observer = new MutationObserver(() => {
      const target = document.getElementById(targetId);
      if (target != null) {
        target.scrollIntoView();
        observer.disconnect();
      }
    });

    observer.observe(contentContainer, { childList: true, subtree: true });

    return () => observer.disconnect();
  }, [currentPageId]);

  // *******************************  end  *******************************

  const specialContents = useMemo(() => {
    if (isIdenticalPathPage) {
      return <IdenticalPathPage />;
    }
    if (isForbidden) {
      return <ForbiddenPage />;
    }
    if (isNotCreatable) {
      return <NotCreatablePage />;
    }
  }, [isForbidden, isIdenticalPathPage, isNotCreatable]);

  const headerContents = (
    <PagePathNavTitle
      pageId={page?._id}
      pagePath={pagePath}
      isWipPage={page?.wip}
    />
  );

  const sideContents =
    !isNotFound && !isNotCreatable ? <PageSideContents page={page} /> : null;

  const footerContents =
    !isIdenticalPathPage && !isNotFound ? (
      <>
        {isUsersHomepagePath && page.creator != null && (
          <UsersHomepageFooter creatorId={page.creator._id} />
        )}
        <PageContentFooter page={page} />
      </>
    ) : null;

  const Contents = useCallback(() => {
    if (isNotFound || page?.revision == null) {
      return <NotFoundPage path={pagePath} />;
    }

    const markdown = page.revision.body;
    const rendererOptions =
      viewOptions ?? generateSSRViewOptions(rendererConfig, pagePath);

    return (
      <>
        <PageContentsUtilities />

        <div className="flex-expand-vert justify-content-between">
          {isSlide != null ? (
            <SlideRenderer marp={isSlide.marp} markdown={markdown} />
          ) : (
            <RevisionRenderer
              rendererOptions={rendererOptions}
              markdown={markdown}
            />
          )}

          {!isIdenticalPathPage && !isNotFound && (
            <div id="comments-container" ref={commentsContainerRef}>
              <Comments
                pageId={page._id}
                pagePath={pagePath}
                revision={page.revision}
              />
            </div>
          )}
        </div>
      </>
    );
  }, [
    isNotFound,
    page?.revision,
    page?._id,
    rendererConfig,
    pagePath,
    viewOptions,
    isSlide,
    isIdenticalPathPage,
  ]);

  return (
    <PageViewLayout
      className={className}
      headerContents={headerContents}
      sideContents={sideContents}
      footerContents={footerContents}
      expandContentWidth={shouldExpandContent}
    >
      <PageAlerts />

      {specialContents}
      {specialContents == null && (
        <>
          {isUsersHomepagePath && page?.creator != null && (
            <UserInfo author={page.creator} />
          )}
          <div id="page-view-content-container" className="flex-expand-vert">
            <Contents />
          </div>
        </>
      )}
    </PageViewLayout>
  );
};