// Check generated HTML, so Markdown links and MDX components are both covered.
import { existsSync, readFileSync, readdirSync, statSync } from 'node:fs';
import { join, relative, sep } from 'node:path';
import { fileURLToPath } from 'node:url';

const root = fileURLToPath(new URL('../dist/', import.meta.url));
if (!existsSync(root)) throw new Error('Missing dist/. Run npm run build first.');
const origin = 'https://docs.simba-robotics.com';
const files = [];
function walk(dir) {
  for (const entry of readdirSync(dir, { withFileTypes: true })) {
    const path = join(dir, entry.name);
    if (entry.isDirectory()) walk(path);
    else files.push(path);
  }
}
walk(root);
const pages = new Map(files.filter((path) => path.endsWith('.html'))
  .map((path) => [path, readFileSync(path, 'utf8')]));
const errors = [];
let checked = 0;
let diagrams = 0;

for (const [path, html] of pages) {
  const page = relative(root, path).split(sep).join('/');
  const base = new URL(page.replace(/index\.html$/, ''), origin);
  if (html.includes('class="katex-error"')) errors.push(`${page}: invalid math`);
  if (/<style\b[^>]*\sset:html=/.test(html)) errors.push(`${page}: MDX emitted inert SVG styles`);
  const diagramCount = [...html.matchAll(/class="mermaid-diagram"/g)].length;
  if (diagramCount) {
    diagrams += diagramCount;
    const staticCount = [...html.matchAll(/data-rendered="static"/g)].length;
    const lightCount = [...html.matchAll(/class="mermaid-variant mermaid-light"/g)].length;
    const darkCount = [...html.matchAll(/class="mermaid-variant mermaid-dark"/g)].length;
    const svgCount = [...html.matchAll(/<svg\b[^>]*\bid="mermaid-[^"]+"/g)].length;
    if ([staticCount, lightCount, darkCount].some((count) => count !== diagramCount) || svgCount !== diagramCount * 2) {
      errors.push(`${page}: Mermaid must contain both pre-rendered SVG themes`);
    }
    const ids = [...html.matchAll(/\sid="([^"]+)"/g)].map((match) => match[1]);
    if (ids.length !== new Set(ids).size) errors.push(`${page}: duplicate IDs may break inline SVG references`);
  }
  // Astro emits quoted, escaped attributes. Code examples escape '<', so they
  // are not mistaken for real links here. External URLs are not fetched.
  for (const tag of html.matchAll(/<(?:a|link|script|img)\b[^>]*>/g)) {
    // Canonical/hreflang are SEO metadata, not navigation or loaded assets.
    if (/^<link\b/.test(tag[0]) && /\srel="(?:canonical|alternate)"/.test(tag[0])) continue;
    for (const attribute of tag[0].matchAll(/\s(?:href|src)="([^"]*)"/g)) {
      const ref = attribute[1].replaceAll('&amp;', '&');
      const url = new URL(ref, base);
      if (url.origin !== base.origin) continue;
      let target = join(root, decodeURIComponent(url.pathname));
      if (existsSync(target) && statSync(target).isDirectory()) target = join(target, 'index.html');
      if (!existsSync(target)) {
        errors.push(`${page}: missing ${ref}`);
        continue;
      }
      checked++;
      if (url.hash && pages.has(target)) {
        const id = decodeURIComponent(url.hash.slice(1));
        if (!pages.get(target).includes(`id="${id}"`)) errors.push(`${page}: missing anchor ${ref}`);
      }
    }
  }
}

if (!existsSync(join(root, '404.html'))) errors.push('Missing 404.html');
for (const path of files) {
  if (/\.(?:woff2?|ttf|otf|eot)$/i.test(path)) errors.push(`Unexpected bundled font: ${relative(root, path)}`);
}
if (errors.length) {
  console.error(errors.join('\n'));
  process.exitCode = 1;
} else {
  console.log(`Checked ${pages.size} HTML pages, ${checked} local links/assets, and ${diagrams} static Mermaid diagrams; no broken anchors, math errors, or bundled fonts.`);
}