/**
 * The Astro + Starlight configuration every Norsk product docs site is built
 * from. A site's own `astro.config.mjs` is reduced to what genuinely differs:
 * its origin, its two names, its sidebar, and the versions it was built
 * against.
 *
 *     export default defineConfig(
 *       norskDocsSite({
 *         origin: PUBLIC_SITE_ORIGIN,
 *         tabTitle: "Norsk",
 *         wordmark: "norsk-ctl",
 *         buildVersions: [...],
 *         sidebar: [...],
 *       }),
 *     );
 *
 * Everything here is the part that must NOT differ between sites: the theme,
 * the component overrides, the mermaid pipeline, the favicon convention, and
 * the two-build (public / embedded) shape described on `publicBuild` below.
 */
import { readdirSync, readFileSync, statSync, writeFileSync } from "node:fs";
import { join } from "node:path";
import { fileURLToPath } from "node:url";
import { unified } from "@astrojs/markdown-remark";
import starlight from "@astrojs/starlight";
import rehypeMermaid from "rehype-mermaid";

/** One row of the sidebar's "Built against" footer (components/Sidebar.astro). */
export interface BuildVersion {
  /** Row label, e.g. "norsk-ctl". */
  label: string;
  /** Row value, read at build time from the product's own files. */
  value: string;
  /** Break a `repo:tag` image pin after the last colon so it wraps sensibly. */
  splitOnLastColon?: boolean;
}

export interface NorskDocsSiteOptions {
  /** Canonical public origin. Drives the sitemap and <link rel="canonical">. */
  origin: string;
  /** BROWSER TAB suffix only ("Quickstart | Norsk"), kept short — tabs truncate. */
  tabTitle: string;
  /** Masthead wordmark. Deliberately different from `tabTitle`; see SiteTitle.astro. */
  wordmark: string;
  /** Starlight's sidebar. The one part of the nav a site fully owns. */
  sidebar: unknown[];
  /** Rows for the sidebar's "Built against" footer. */
  buildVersions: BuildVersion[];
  /**
   * Dev-preview only: machine names `astro dev --host` may be reached by on the
   * LAN (Vite 403s unknown Host headers otherwise). No effect on builds.
   */
  devAllowedHosts?: string[];
}

/**
 * Two builds from one content collection, selected by ASTRO_BUILD:
 * `dist-embedded` (base `/docs`) is the bundle baked into a product binary and
 * served by the daemon, `dist-public` (base `/`) is the standalone site on the
 * product's own domain. Exported because a site's sidebar legitimately differs
 * between the two — a section that only exists once it is published.
 */
export function isPublicBuild(): boolean {
  return process.env.ASTRO_BUILD === "public";
}

/**
 * Content (and any vendored HTML) is authored with absolute /docs/... links —
 * correct for the daemon-embedded build (served under /docs), but a 404 in the
 * public build (served at /). Astro doesn't base-prefix absolute links in
 * MDX/components/static files, so for the public build a post-build pass strips
 * the /docs prefix from href/src attributes across the emitted HTML.
 * Attribute-scoped so it never touches /docs literals in body text. No-op for
 * the embedded build.
 */
function stripDocsBaseForPublic() {
  const rewriteHtml = (html: string) =>
    html.replace(/((?:href|src)=")\/docs(\/|")/g, (_m, attr, tail) => (tail === "/" ? `${attr}/` : `${attr}/"`));
  const walk = (root: string, fn: (p: string) => void) => {
    for (const name of readdirSync(root)) {
      const p = join(root, name);
      if (statSync(p).isDirectory()) walk(p, fn);
      else if (p.endsWith(".html")) fn(p);
    }
  };
  return {
    name: "strip-docs-base-public",
    hooks: {
      "astro:build:done": ({ dir }: { dir: URL }) => {
        if (!isPublicBuild()) return;
        walk(fileURLToPath(dir), (p) => {
          writeFileSync(p, rewriteHtml(readFileSync(p, "utf-8")));
        });
      },
    },
  };
}

export function norskDocsSite(options: NorskDocsSiteOptions) {
  const isPublic = isPublicBuild();
  const mermaidLaunchOptions = process.env.BROWSER_FOR_TESTING
    ? { executablePath: process.env.BROWSER_FOR_TESTING }
    : undefined;

  return {
    // The public site lives at the domain root; the embedded bundle is served
    // by the daemon under /docs. `site` is the canonical origin: it drives the
    // sitemap and <link rel="canonical">, and without it @astrojs/sitemap
    // (pulled in by Starlight) skips and warns. The embedded build reuses the
    // same origin — its sitemap is inert since it is never crawled, but setting
    // `site` keeps the build warning-free.
    site: options.origin,
    base: isPublic ? "/" : "/docs",
    outDir: isPublic ? "./dist-public" : "./dist-embedded",
    markdown: {
      syntaxHighlight: { excludeLangs: ["mermaid"] },
      // Astro 6 deprecated top-level `rehypePlugins`; the pipeline now lives in
      // a `unified()` processor. `syntaxHighlight` stays at the markdown level.
      processor: unified({
        rehypePlugins: [
          [
            rehypeMermaid,
            { strategy: "img-svg", dark: true, mermaidConfig: { theme: "dark" }, launchOptions: mermaidLaunchOptions },
          ],
        ],
      }),
    },
    integrations: [
      stripDocsBaseForPublic(),
      starlight({
        title: options.tabTitle,
        customCss: ["./src/custom.css"],
        components: {
          // Appends the "Built against" footer below the nav.
          Sidebar: "./src/components/Sidebar.astro",
          // Decouples the masthead wordmark from `title` above.
          SiteTitle: "./src/components/SiteTitle.astro",
          // Adds the "captured against" line to a generated guide (front
          // matter `capturedAgainst`, see content.config.ts).
          Footer: "./src/components/Footer.astro",
        },
        // Starlight base-prefixes this (emits a `/docs/favicon.png`
        // shortcut-icon link for the embedded build); a raw head <link> would
        // not, and 404s the embedded link-check.
        favicon: "/favicon.png",
        sidebar: options.sidebar,
      }),
    ],
    vite: {
      server: { allowedHosts: options.devAllowedHosts ?? [] },
      // Injected rather than imported: a component resolving its own path at
      // runtime finds dist-embedded/.prerender/chunks/ instead of the source
      // tree and fails the build, and the site's version readers want the
      // product's files, not the site's. Both values are build-time constants,
      // so a define is the cheapest correct channel.
      define: {
        __BUILD_VERSIONS__: JSON.stringify(options.buildVersions),
        __SITE_WORDMARK__: JSON.stringify(options.wordmark),
      },
    },
  };
}