import fs from "node:fs";
import path from "node:path";

import frontmatter from "front-matter";
import { fdir, PathsOutput } from "fdir";

import { m2h } from "../markdown/index.js";
import * as kumascript from "../kumascript/index.js";

import {
  VALID_LOCALES,
  MDN_PLUS_TITLE,
  DEFAULT_LOCALE,
  OBSERVATORY_TITLE_FULL,
  OBSERVATORY_TITLE,
} from "../libs/constants/index.js";
import {
  CONTENT_ROOT,
  CONTENT_TRANSLATED_ROOT,
  CONTRIBUTOR_SPOTLIGHT_ROOT,
  BUILD_OUT_ROOT,
  DEV_MODE,
  GENERIC_CONTENT_ROOT,
} from "../libs/env/index.js";
import { isValidLocale } from "../libs/locale-utils/index.js";
import { DocFrontmatter, DocParent, NewsItem } from "../libs/types/document.js";
import {
  getSlugByBlogPostUrl,
  injectLoadingLazyAttributes,
  makeTOC,
  postProcessExternalLinks,
} from "./utils.js";
import { findByURL } from "../content/document.js";
import { buildDocument } from "./index.js";
import { findPostBySlug } from "./blog.js";
import { buildSitemap } from "./sitemaps.js";
import { type Locale } from "../libs/types/core.js";
import { HydrationData } from "../libs/types/hydration.js";
import { extractSections } from "./extract-sections.js";
import { wrapTables } from "./wrap-tables.js";

const FEATURED_ARTICLES = [
  "blog/mdn-scrimba-partnership/",
  "blog/learn-javascript-console-methods/",
  "blog/introduction-to-web-sustainability/",
  "docs/Web/API/CSS_Custom_Highlight_API",
];

const LATEST_NEWS: (NewsItem | string)[] = [
  "blog/mdn-scrimba-partnership/",
  "blog/mdn-http-observatory-launch/",
  "blog/mdn-curriculum-launch/",
  "blog/baseline-evolution-on-mdn/",
];

const PAGE_DESCRIPTIONS = Object.freeze({
  observatory:
    "Test your site’s HTTP headers, including CSP and HSTS, to find security problems and get actionable recommendations to make your website more secure. Test other websites to see how you compare.",
});

const contributorSpotlightRoot = CONTRIBUTOR_SPOTLIGHT_ROOT;

async function buildContributorSpotlight(
  locale: Locale,
  options: { verbose?: boolean }
) {
  const prefix = "community/spotlight";
  const profileImg = "profile-image.jpg";
  let featuredContributorFrontmatter: DocFrontmatter;

  for (const contributor of fs.readdirSync(contributorSpotlightRoot)) {
    const file = `${contributorSpotlightRoot}/${contributor}/index.md`;
    const markdown = fs.readFileSync(file, "utf-8");
    const url = `/${locale}/${prefix}/${contributor}`;

    const frontMatter = frontmatter<DocFrontmatter>(markdown);
    const contributorHTML = await m2h(frontMatter.body, { locale });
    const d = {
      url,
      rawBody: contributorHTML,
      metadata: {
        locale: DEFAULT_LOCALE,
        slug: `${prefix}/${contributor}`,
        url,
      },

      isMarkdown: true,
      fileInfo: {
        path: file,
      },
    };
    const [$] = await kumascript.render(url, {}, d);
    const [sections] = await extractSections($);

    const hyData = {
      sections: sections,
      contributorName: frontMatter.attributes.contributor_name,
      folderName: frontMatter.attributes.folder_name,
      isFeatured: frontMatter.attributes.is_featured,
      profileImg,
      profileImgAlt: frontMatter.attributes.img_alt,
      usernames: frontMatter.attributes.usernames,
      quote: frontMatter.attributes.quote,
    };
    const context: HydrationData = {
      hyData,
      url: `/${locale}/${prefix}/${contributor}`,
    };

    const outPath = path.join(
      BUILD_OUT_ROOT,
      locale.toLowerCase(),
      `${prefix}/${hyData.folderName}`
    );
    const imgFilePath = `${contributorSpotlightRoot}/${contributor}/profile-image.jpg`;
    const imgFileDestPath = path.join(outPath, profileImg);
    const jsonFilePath = path.join(outPath, "index.json");

    fs.mkdirSync(outPath, { recursive: true });
    fs.copyFileSync(imgFilePath, imgFileDestPath);
    fs.writeFileSync(jsonFilePath, JSON.stringify(context));

    if (options.verbose) {
      console.log("Wrote", jsonFilePath);
    }

    if (frontMatter.attributes.is_featured) {
      featuredContributorFrontmatter = frontMatter.attributes;
    }
  }

  return featuredContributorFrontmatter
    ? {
        contributorName: featuredContributorFrontmatter.contributor_name,
        url: `/${locale}/${prefix}/${featuredContributorFrontmatter.folder_name}`,
        quote: featuredContributorFrontmatter.quote,
      }
    : undefined;
}

export async function buildSPAs(options: {
  quiet?: boolean;
  verbose?: boolean;
}) {
  let buildCount = 0;
  const sitemap: {
    url: string;
  }[] = [];

  // The URL isn't very important as long as it triggers the right route in the <App/>
  const locale = DEFAULT_LOCALE;
  const url = `/${locale}/404/index.html`;
  const context: HydrationData = { url, pageNotFound: true };
  const outPath = path.join(BUILD_OUT_ROOT, locale.toLowerCase(), "404");
  fs.mkdirSync(outPath, { recursive: true });
  const jsonFilePath = path.join(
    outPath,
    path.basename(url).replace(/\.html$/, ".json")
  );
  fs.writeFileSync(jsonFilePath, JSON.stringify(context));
  buildCount++;
  if (options.verbose) {
    console.log("Wrote", jsonFilePath);
  }

  // Basically, this builds one (for example) `search/index.html` for every
  // locale we intend to build.
  for (const root of [CONTENT_ROOT, CONTENT_TRANSLATED_ROOT]) {
    if (!root) {
      continue;
    }
    for (const pathLocale of fs.readdirSync(root)) {
      if (
        !fs.statSync(path.join(root, pathLocale)).isDirectory() ||
        !isValidLocale(pathLocale)
      ) {
        continue;
      }

      const SPAs = [
        { prefix: "play", pageTitle: "Playground | MDN" },
        {
          prefix: "observatory",
          pageTitle: `HTTP Header Security Test - ${OBSERVATORY_TITLE_FULL}`,
          pageDescription: PAGE_DESCRIPTIONS.observatory,
        },
        {
          prefix: "observatory/analyze",
          pageTitle: `Scan results - ${OBSERVATORY_TITLE_FULL}`,
          pageDescription: PAGE_DESCRIPTIONS.observatory,
          noIndexing: true,
        },
        {
          prefix: "observatory/docs/tests_and_scoring",
          pageTitle: `Tests & Scoring - ${OBSERVATORY_TITLE_FULL}`,
          pageDescription: PAGE_DESCRIPTIONS.observatory,
        },
        {
          prefix: "observatory/docs/faq",
          pageTitle: `FAQ - ${OBSERVATORY_TITLE_FULL}`,
          pageDescription: PAGE_DESCRIPTIONS.observatory,
        },
        { prefix: "search", pageTitle: "Search", onlyFollow: true },
        { prefix: "plus", pageTitle: MDN_PLUS_TITLE },
        {
          prefix: "plus/ai-help",
          pageTitle: `AI Help | ${MDN_PLUS_TITLE}`,
        },
        {
          prefix: "plus/collections",
          pageTitle: `Collections | ${MDN_PLUS_TITLE}`,
          noIndexing: true,
        },
        {
          prefix: "plus/collections/frequently_viewed",
          pageTitle: `Frequently viewed articles | ${MDN_PLUS_TITLE}`,
          noIndexing: true,
        },
        {
          prefix: "plus/updates",
          pageTitle: `Updates | ${MDN_PLUS_TITLE}`,
        },
        {
          prefix: "plus/settings",
          pageTitle: `Settings | ${MDN_PLUS_TITLE}`,
          noIndexing: true,
        },
        { prefix: "about", pageTitle: "About MDN" },
        {
          prefix: "advertising",
          pageTitle: "Advertise with us",
        },
        {
          prefix: "newsletter",
          pageTitle: "Stay Informed with MDN",
        },
      ];
      const locale = VALID_LOCALES.get(pathLocale) || pathLocale;
      for (const {
        prefix,
        pageTitle,
        pageDescription,
        noIndexing,
        onlyFollow,
      } of SPAs) {
        const url = `/${locale}/${prefix}`;
        const context: HydrationData = {
          pageTitle,
          pageDescription,
          locale,
          noIndexing,
          onlyFollow,
          url,
        };

        const outPath = path.join(BUILD_OUT_ROOT, pathLocale, prefix);
        fs.mkdirSync(outPath, { recursive: true });
        const jsonFilePath = path.join(outPath, "index.json");
        fs.writeFileSync(jsonFilePath, JSON.stringify(context));
        buildCount++;
        if (options.verbose) {
          console.log("Wrote", jsonFilePath);
        }

        if (!noIndexing && !onlyFollow) {
          sitemap.push({
            url,
          });
        }
      }
    }
  }

  // Building the MDN Plus pages.
  async function buildStaticPages(
    dirpath: string,
    slugPrefix?: string,
    title?: string
  ) {
    const crawler = new fdir()
      .withFullPaths()
      .withErrors()
      .filter((path) => path.endsWith(".md"))
      .crawl(dirpath);
    const filepaths = [...(crawler.sync() as PathsOutput)];

    for (const filepath of filepaths) {
      const file = filepath.replace(dirpath, "");
      const page = file.split(".")[0].slice(1);

      const locale = DEFAULT_LOCALE;
      const pathLocale = locale.toLowerCase();
      const markdown = fs.readFileSync(filepath, "utf-8");

      const frontMatter = frontmatter<DocFrontmatter>(markdown);
      const rawHTML = await m2h(frontMatter.body, { locale });

      const slug = slugPrefix ? `${slugPrefix}/${page}` : `${page}`;
      const url = `/${locale}/${slug}`;
      const d = {
        url,
        rawBody: rawHTML,
        metadata: {
          locale: DEFAULT_LOCALE,
          slug,
          url,
        },

        isMarkdown: true,
        fileInfo: {
          path: file,
        },
      };
      const [$] = await kumascript.render(url, {}, d);
      wrapTables($);
      postProcessExternalLinks($);
      injectLoadingLazyAttributes($);
      const [sections] = await extractSections($);
      const toc = makeTOC({ body: sections });

      const hyData = {
        id: page,
        ...frontMatter.attributes,
        sections,
        toc,
      };
      const context: HydrationData = {
        hyData,
        pageTitle: title
          ? `${frontMatter.attributes.title} | ${title}`
          : frontMatter.attributes.title,
        url,
      };

      const outPath = path.join(BUILD_OUT_ROOT, pathLocale, ...slug.split("/"));
      fs.mkdirSync(outPath, { recursive: true });
      const jsonFilePath = path.join(outPath, "index.json");
      fs.writeFileSync(jsonFilePath, JSON.stringify(context));
      buildCount++;
      if (options.verbose) {
        console.log("Wrote", jsonFilePath);
      }
      const filePathContext = path.join(outPath, "index.json");
      fs.writeFileSync(filePathContext, JSON.stringify(context));

      sitemap.push({
        url,
      });
    }
  }

  if (GENERIC_CONTENT_ROOT) {
    await buildStaticPages(
      path.join(GENERIC_CONTENT_ROOT, "plus"),
      "plus/docs",
      "MDN Plus"
    );
    await buildStaticPages(
      path.join(GENERIC_CONTENT_ROOT, "observatory"),
      "observatory/docs",
      OBSERVATORY_TITLE
    );
    await buildStaticPages(path.join(GENERIC_CONTENT_ROOT, "community"));
    await buildStaticPages(path.join(GENERIC_CONTENT_ROOT, "about"));
  }

  // Build all the home pages in all locales.
  // Fetch merged content PRs for the latest contribution section.
  const recentContributions = await fetchRecentContributions();

  // Fetch latest Hacks articles.
  const latestNews = await fetchLatestNews();

  for (const root of [CONTENT_ROOT, CONTENT_TRANSLATED_ROOT]) {
    if (!root) {
      continue;
    }
    for (const localeLC of fs.readdirSync(root)) {
      const locale = VALID_LOCALES.get(localeLC) || (localeLC as Locale);
      if (!isValidLocale(locale)) {
        continue;
      }
      if (!fs.statSync(path.join(root, localeLC)).isDirectory()) {
        continue;
      }

      const featuredContributor = contributorSpotlightRoot
        ? await buildContributorSpotlight(locale, options)
        : null;

      const featuredArticles = (
        await Promise.all(
          FEATURED_ARTICLES.map(async (url) => {
            const segment = url.split("/")[0];
            if (segment === "docs") {
              const document =
                findByURL(`/${locale}/${url}`) ||
                findByURL(`/${DEFAULT_LOCALE}/${url}`);
              if (document) {
                const {
                  doc: { mdn_url, summary, title, parents },
                } = await buildDocument(document);
                return {
                  mdn_url,
                  summary,
                  title,
                  tag: parents.length > 2 ? parents[1] : null,
                };
              }
            } else if (segment === "blog") {
              const post = await findPostBySlug(
                getSlugByBlogPostUrl(`/${DEFAULT_LOCALE}/${url}`)
              );
              if (post) {
                const {
                  doc: { title },
                  blogMeta: { description, slug },
                } = post;
                return {
                  mdn_url: `/${DEFAULT_LOCALE}/blog/${slug}/`,
                  summary: description,
                  title,
                  tag: {
                    uri: `/${DEFAULT_LOCALE}/blog/`,
                    title: "Blog",
                  } satisfies DocParent,
                };
              }
            }
          })
        )
      ).filter(Boolean);

      const url = `/${locale}/`;
      const hyData = {
        recentContributions,
        featuredContributor,
        latestNews,
        featuredArticles,
      };
      const context: HydrationData = { hyData, url };
      const outPath = path.join(BUILD_OUT_ROOT, localeLC);
      fs.mkdirSync(outPath, { recursive: true });

      sitemap.push({
        url,
      });

      // Also, dump the recent pull requests in a file so the data can be gotten
      // in client-side rendering.
      const jsonFilePath = path.join(outPath, "index.json");
      fs.writeFileSync(jsonFilePath, JSON.stringify(context));
      buildCount++;
      if (options.verbose) {
        console.log("Wrote", jsonFilePath);
      }
    }
  }

  // Sitemap.
  const sitemapFilePath = await buildSitemap(
    sitemap.map(({ url }) => ({
      slug: url,
      modified: "",
    })),
    { pathSuffix: ["misc"] }
  );

  if (!options.quiet) {
    console.log("Wrote", sitemapFilePath);
  }

  if (!options.quiet) {
    console.log(`Built ${buildCount} SPA related files`);
  }
}

async function fetchGitHubPRs(repo, count = 5) {
  const twoDaysAgo = new Date(Date.now() - 48 * 60 * 60 * 1000);
  const pullRequestsQuery = [
    `repo:${repo}`,
    "is:pr",
    "is:merged",
    `merged:>${twoDaysAgo.toISOString()}`,
    "sort:updated",
  ].join("+");
  const pullRequestUrl = `https://api.github.com/search/issues?q=${pullRequestsQuery}&per_page=${count}`;
  try {
    // eslint-disable-next-line n/no-unsupported-features/node-builtins
    const response = await fetch(pullRequestUrl);
    const pullRequestsData = (await response.json()) as {
      items: any[];
    };
    const prDataRepo = pullRequestsData.items.map((item) => ({
      ...item,
      repo: { name: repo, url: `https://github.com/${repo}` },
    }));
    return prDataRepo;
  } catch (e) {
    const msg = `Couldn't fetch recent GitHub contributions for repo ${repo}!`;
    if (!DEV_MODE) {
      console.error(`Error: ${msg}`);
      throw e;
    }

    console.warn(`Warning: ${msg}`);
    return [];
  }
}

async function fetchRecentContributions() {
  const repos = ["mdn/content", "mdn/translated-content"];
  const countPerRepo = 5;
  const pullRequests = (
    await Promise.all(
      repos.map(async (repo) => await fetchGitHubPRs(repo, countPerRepo))
    )
  ).flat();
  const pullRequestsData = pullRequests.sort((a, b) =>
    a.updated_at < b.updated_at ? 1 : -1
  );
  return {
    items: pullRequestsData.map(
      ({ number, title, updated_at, pull_request: { html_url }, repo }) => ({
        number,
        title,
        updated_at,
        url: html_url,
        repo,
      })
    ),
  };
}

async function fetchLatestNews() {
  const items: NewsItem[] = (
    await Promise.all(
      LATEST_NEWS.map(async (itemOrUrl) => {
        if (typeof itemOrUrl !== "string") {
          return itemOrUrl;
        }
        const url = itemOrUrl;
        const post = await findPostBySlug(
          getSlugByBlogPostUrl(`/${DEFAULT_LOCALE}/${url}`)
        );
        if (post) {
          const {
            doc: { title },
            blogMeta: { author, date, slug },
          } = post;
          return {
            title,
            url: `/${DEFAULT_LOCALE}/blog/${slug}/`,
            author: author?.name || "The MDN Team",
            published_at: new Date(date).toString(),
            source: {
              name: "developer.mozilla.org",
              url: `/${DEFAULT_LOCALE}/blog/`,
            },
          };
        }
      })
    )
  ).filter(Boolean);

  return {
    items,
  };
}