import type { Root as HastRoot } from 'hast';
import type { Root as MdastRoot } from 'mdast';
import remarkGfm from 'remark-gfm';
import remarkMdx from 'remark-mdx';
import remarkStringify from 'remark-stringify';
import { unified } from 'unified';

import { convertHeaderLinksToText } from '../components/link.js';
import { CONTENT_FAILURE_MSG, MDAST_FAILURE_MSG } from '../constants.js';
import {
  createCallout,
  createCard,
  createAccordion,
  createAccordionGroup,
  createFrame,
  createCodeGroup,
  createTabs,
  createCardGroup,
} from '../customComponents/create.js';
import { rehypeToRemarkCustomComponents } from '../customComponents/plugin.js';
import { selectiveRehypeRemark } from '../customComponents/selective.js';
import { retrieveRootContent } from '../root/retrieve.js';
import type { Result } from '../types/result.js';
import { unifiedRemoveBreadCrumbs } from '../utils/breadcrumbs.js';
import { unifiedRemoveBreaks } from '../utils/breaks.js';
import { unifiedRemoveClassNames } from '../utils/className.js';
import { unifiedRemoveCopyButtons } from '../utils/copyButton.js';
import { detectFramework, framework } from '../utils/detectFramework.js';
import { remarkRemoveEmptyEmphases } from '../utils/emptyEmphasis.js';
import { unifiedRemoveEmptyParagraphs } from '../utils/emptyParagraphs.js';
import { getErrorMessage, logErrorResults } from '../utils/errors.js';
import { writePage } from '../utils/file.js';
import { remarkProperlyFormatEmphasis } from '../utils/formatEmphasis.js';
import { removeHastComments } from '../utils/hastComments.js';
import { remarkSpaceListsOut } from '../utils/lists.js';
import { log } from '../utils/log.js';
import { remarkRemoveBottomMetadata } from '../utils/metadata.js';
import { unifiedRemoveNestedRoots } from '../utils/nestedRoots.js';
import { unifiedRemovePositions } from '../utils/position.js';
import { removeLeadingSlash, removeTrailingSlash } from '../utils/strings.js';
import { remarkRemoveCodeBlocksInCells } from '../utils/tableCells.js';
import { getDescriptionFromRoot, getTitleFromHeading } from '../utils/title.js';
import { unifiedRemoveTableOfContents } from '../utils/toc.js';
import { remarkRemoveUpdatedAt } from '../utils/updatedAt.js';
import { downloadImagesFromFile } from './images.js';
import { htmlToHast } from './root.js';

export async function scrapePage(
  html: string,
  url: string | URL,
  opts: {
    externalLink: boolean;
    isOverviewPage?: boolean;
    rootPath?: string;
  } = { externalLink: false }
): Promise<Result<[string, string]>> {
  url = new URL(url);

  if (opts.externalLink) {
    let filename = html || 'index';
    if (filename.endsWith('/')) filename += 'index';
    const filenameWithExt = `${filename}.mdx`;
    writePage(filenameWithExt, '', '', '', url.toString());
    return { success: true, data: [url.toString(), filename] };
  }

  const hast = htmlToHast(html);
  removeHastComments(hast);

  if (!framework.vendor) detectFramework(hast);

  const urlStr = url.toString();
  const content = retrieveRootContent(hast);
  if (!content)
    return { success: false, message: `${urlStr}: ${CONTENT_FAILURE_MSG}`, data: [urlStr, ''] };

  const contentAsRoot: HastRoot = {
    type: 'root',
    children: [content],
  };

  const mdastTree: MdastRoot = unified()
    .use(unifiedRemoveBreaks)
    .use(unifiedRemoveBreadCrumbs)
    .use(unifiedRemoveTableOfContents)
    .use(unifiedRemoveCopyButtons)
    .use(createCard)
    .use(createAccordion)
    .use(createFrame)
    .use(createCallout)
    .use(createCardGroup)
    .use(createAccordionGroup)
    .use(createCodeGroup)
    .use(createTabs)
    .use(unifiedRemoveClassNames)
    .use(unifiedRemoveEmptyParagraphs)
    .use(unifiedRemovePositions)
    .use(selectiveRehypeRemark)

    // Cleans up any nested components left untouched
    // by `selectiveRehypeRemark`, and converts them to
    // MDX compatible components
    .use(rehypeToRemarkCustomComponents)
    .use(convertHeaderLinksToText)
    .use(unifiedRemoveNestedRoots)
    .use(remarkSpaceListsOut)
    .use(remarkRemoveBottomMetadata)
    .use(remarkRemoveUpdatedAt)
    .use(remarkRemoveEmptyEmphases)
    .use(remarkProperlyFormatEmphasis)
    .use(remarkRemoveCodeBlocksInCells)
    // @ts-expect-error moving some of the pipeline around results in contentAsRoot being treated differently than its type which is Root Element
    .runSync(contentAsRoot) as MdastRoot;

  try {
    const imageResults = await downloadImagesFromFile(mdastTree, url);
    logErrorResults(`scraping images from ${url.toString()}`, imageResults);
  } catch (error) {
    const errorMessage = getErrorMessage(error);
    log(`We encountered an error when scraping the images from ${url.toString()}${errorMessage}`);
    throw error;
  }

  const title = getTitleFromHeading(mdastTree);
  const description = getDescriptionFromRoot(mdastTree);

  try {
    const result = unified()
      .use(remarkMdx)
      .use(remarkGfm)
      .use(remarkStringify)
      .stringify(mdastTree);

    const resultStr = String(result).replace(/\n{3,}/g, '\n\n');

    if (opts.rootPath) {
      url = new URL(opts.rootPath, url.origin);
    } else if (url.origin === removeTrailingSlash(url.toString())) {
      url = new URL('home', new URL(url).origin);
    }

    writePage(url, opts.isOverviewPage ? 'Overview' : title, description, resultStr);
    return {
      success: true,
      data: opts.rootPath
        ? [removeLeadingSlash(removeTrailingSlash(new URL(urlStr).pathname)), opts.rootPath]
        : undefined,
    };
  } catch (error) {
    const errorMessage = getErrorMessage(error);
    return {
      success: false,
      message: `${urlStr}: ${MDAST_FAILURE_MSG}${errorMessage}`,
      data: [urlStr, ''],
    };
  }
}