import { createHash } from 'node:crypto';
import { lstat, readFile, readdir } from 'node:fs/promises';
import { dirname, relative, resolve, sep } from 'node:path';
import { fileURLToPath, pathToFileURL } from 'node:url';
import { loadProductionInputs } from '../src/content/load-production-inputs.ts';
import { createPageMetadata, createStaticHostArtifacts } from '../src/content/metadata.ts';
import { Window } from 'happy-dom';
import { parseArtifactContract, parseBuildAuthority } from './build-contract.mjs';
import { parseExactConfigArgument } from './config-argument.mjs';

const scriptPath = fileURLToPath(import.meta.url);
const repositoryRoot = resolve(dirname(scriptPath), '..');
const canonicalSectionIds = [
  'start', 'profile', 'experience', 'infrastructure', 'selected-builds', 'additional-work', 'toolkit', 'contact',
];
const prohibitedSurfaces = [
  /__PORTFOLIO_INPUTS__/iu,
  /__PORTFOLIO_TEST_HOOKS__/iu,
  /__PORTFOLIO_PERFORMANCE__/iu,
  /__portfolio_performance/iu,
  /PORTFOLIO_TEST_TOKEN/iu,
  /__PORTFOLIO_(?:TEST|INSTRUMENTATION)__/iu,
  /__portfolio(?:Journey)?Instrumentation/iu,
  /(?:evidenceId|sourcePath|sourceFingerprint|approvalOwner|privacyClassification|denylist|originalFilename)/iu,
  /sourceMappingURL/iu,
];

const escapeRegularExpression = (value) => value.replace(/[.*+?^${}()|[\]\\]/gu, '\\$&');
const escapeHtml = (value) => value
  .replace(/&/gu, '&')
  .replace(/</gu, '&lt;')
  .replace(/>/gu, '&gt;')
  .replace(/"/gu, '&quot;');

const readRequiredText = async (root, name) => {
  try {
    return await readFile(resolve(root, name), 'utf8');
  } catch (error) {
    if (typeof error === 'object' && error !== null && 'code' in error && error.code === 'ENOENT') {
      throw new Error(`Missing required artifact: ${name}`);
    }
    throw error;
  }
};

const listArtifacts = async (root) => {
  const rootStats = await lstat(root);
  if (rootStats.isSymbolicLink() || !rootStats.isDirectory()) {
    throw new Error('Artifact root must be a non-symlink directory.');
  }
  const files = [];
  for (const entry of await readdir(root, { withFileTypes: true })) {
    const entryPath = resolve(root, entry.name);
    if (entry.isSymbolicLink()) throw new Error(`Unexpected linked artifact: ${entry.name}`);
    if (entry.isDirectory()) {
      if (entry.name !== 'assets') throw new Error(`Unexpected artifact directory: ${entry.name}`);
      for (const asset of await readdir(entryPath, { withFileTypes: true })) {
        if (asset.isSymbolicLink() || !asset.isFile()) {
          throw new Error(`Unexpected linked or nested artifact: assets/${asset.name}`);
        }
        files.push(`assets/${asset.name}`);
      }
      continue;
    }
    if (!entry.isFile()) throw new Error(`Unexpected special artifact: ${entry.name}`);
    files.push(entry.name);
  }
  return files.sort();
};

const assertArtifactInventory = (files, inputs, contract) => {
  const expectedRootFiles = new Set(['index.html', 'robots.txt', '_headers.example', '_redirects.example']);
  if (inputs.site.environment === 'production') expectedRootFiles.add('sitemap.xml');
  const expectedAssets = new Set(contract.files.map((record) => record.path));
  const expectedPublicAssets = inputs.manifest.assets.map((asset) => `assets/${asset.fileName}`).sort();
  if (contract.buildId !== inputs.site.buildId ||
    JSON.stringify(contract.publicAssets) !== JSON.stringify(expectedPublicAssets)) {
    throw new Error('Artifact contract does not match the validated production inputs.');
  }

  for (const file of files) {
    if (file.endsWith('.map')) throw new Error(`Source map artifact is prohibited: ${file}`);
    if (file.startsWith('assets/')) {
      if (!expectedAssets.has(file)) throw new Error(`Unexpected artifact outside trusted contract: ${file}`);
    } else if (!expectedRootFiles.has(file)) {
      if (inputs.site.environment === 'preview' && file === 'sitemap.xml') {
        throw new Error('Preview artifacts must not publish a sitemap.');
      }
      throw new Error(`Unexpected artifact: ${file}`);
    }
  }
  for (const required of [...expectedRootFiles, ...expectedAssets]) {
    if (!files.includes(required)) throw new Error(`Missing required artifact: ${required}`);
  }
};

const assertArtifactDigests = async (root, contract) => {
  for (const record of contract.files) {
    const digest = createHash('sha256').update(await readFile(resolve(root, record.path))).digest('hex');
    if (digest !== record.sha256) throw new Error(`Artifact digest does not match trusted contract: ${record.path}`);
  }
};

const sortedAttributeValues = (elements, attribute) =>
  [...elements].map((element) => element.getAttribute(attribute)).filter((value) => value !== null).sort();

const assertTrustedHtmlAssets = (html, contract) => {
  const window = new Window();
  try {
    window.document.write(html);
    const scripts = [...window.document.querySelectorAll('script')];
    const jsonLd = scripts.filter((script) => script.type === 'application/ld+json' && !script.hasAttribute('src'));
    const snapshot = scripts.filter((script) =>
      script.id === 'portfolio-inputs' && script.type === 'application/json' && !script.hasAttribute('src'));
    const modules = scripts.filter((script) => script.type === 'module' && script.getAttribute('src') === `/${contract.entryModule}`);
    if (scripts.length !== 3 || jsonLd.length !== 1 || snapshot.length !== 1 || modules.length !== 1) {
      throw new Error('Unexpected executable script outside the exact JSON-LD, inert snapshot, and trusted client module set.');
    }
    const preloads = sortedAttributeValues(window.document.querySelectorAll('link[rel="modulepreload"]'), 'href');
    const expectedPreloads = contract.modulePreloads.map((path) => `/${path}`).sort();
    if (JSON.stringify(preloads) !== JSON.stringify(expectedPreloads)) {
      throw new Error('Final HTML module preload set does not match the trusted contract.');
    }
    const styles = sortedAttributeValues(window.document.querySelectorAll('link[rel="stylesheet"]'), 'href');
    const expectedStyles = contract.styles.map((path) => `/${path}`).sort();
    if (JSON.stringify(styles) !== JSON.stringify(expectedStyles)) {
      throw new Error('Final HTML style set does not match the trusted contract.');
    }
  } finally {
    window.close();
  }
};

const assertNoProhibitedSurfaces = async (root, files) => {
  for (const file of files) {
    const bytes = await readFile(resolve(root, file));
    const text = bytes.toString('utf8');
    for (const pattern of prohibitedSurfaces) {
      if (pattern.test(text)) throw new Error(`Prohibited surface detected in ${file}.`);
    }
  }
};

const exactlyOneMatch = (text, expression, label) => {
  const matches = [...text.matchAll(expression)];
  if (matches.length !== 1) throw new Error(`Expected exactly one ${label}.`);
  return matches[0];
};

const excludedSemanticContainers = new Set(['SCRIPT', 'STYLE', 'TEMPLATE', 'NOSCRIPT']);

const isVisibleSemanticNode = (node, appRoot) => {
  if (!node.isConnected || !appRoot.contains(node)) return false;
  const originElement = node.nodeType === 1 ? node : node.parentElement;
  let element = originElement;
  while (element !== null) {
    if (excludedSemanticContainers.has(element.tagName) || element.hasAttribute('hidden') ||
      element.hasAttribute('inert') || element.getAttribute('aria-hidden')?.toLowerCase() === 'true' ||
      (element.tagName === 'DIALOG' && !element.hasAttribute('open')) ||
      element.style?.display === 'none' || element.style?.visibility === 'hidden') {
      return false;
    }
    if (element.tagName === 'DETAILS' && !element.hasAttribute('open') && originElement !== element) {
      const summary = [...element.children].find((child) => child.tagName === 'SUMMARY');
      if (summary === undefined || (originElement !== summary && !summary.contains(originElement))) return false;
    }
    if (element === appRoot) return true;
    element = element.parentElement;
  }
  return false;
};

const visibleText = (node, appRoot) => {
  if (node.nodeType === 3) return isVisibleSemanticNode(node, appRoot) ? node.textContent ?? '' : '';
  if (node.nodeType === 1 && !isVisibleSemanticNode(node, appRoot)) return '';
  return [...node.childNodes].map((child) => visibleText(child, appRoot)).join('');
};

const assertSemanticHtml = (html, inputs, contract) => {
  const window = new Window();
  try {
    window.document.write(html);
    const document = window.document;
    if (document.documentElement.lang !== 'en') throw new Error('Final HTML must declare lang=en.');
    const appRoots = [...document.querySelectorAll('#app')];
    if (appRoots.length !== 1 || !isVisibleSemanticNode(appRoots[0], appRoots[0])) {
      throw new Error('Expected one connected visible semantic #app root.');
    }
    const appRoot = appRoots[0];
    const h1s = [...appRoot.querySelectorAll('h1')].filter((node) => isVisibleSemanticNode(node, appRoot));
    if (h1s.length !== 1 || h1s[0].textContent !== inputs.content.identity.name) {
      throw new Error('Expected exactly one visible H1 with the canonical identity.');
    }
    const role = h1s[0].nextElementSibling;
    if (role === null || !isVisibleSemanticNode(role, appRoot) || role.textContent !== inputs.content.identity.role) {
      throw new Error('Expected the visible canonical role immediately after the H1.');
    }

    const navigations = [...appRoot.querySelectorAll('nav[aria-label="Portfolio sections"]')]
      .filter((node) => isVisibleSemanticNode(node, appRoot));
    if (navigations.length !== 1) throw new Error('Expected exactly one visible navigation.');
    const navigationLinks = [...navigations[0].querySelectorAll('a')]
      .filter((node) => isVisibleSemanticNode(node, appRoot));
    if (JSON.stringify(navigationLinks.map((link) => link.getAttribute('href'))) !==
      JSON.stringify(canonicalSectionIds.map((id) => `#${id}`))) {
      throw new Error('Visible navigation does not contain the exact canonical native links.');
    }

    const sections = [...appRoot.querySelectorAll('main > section')]
      .filter((node) => isVisibleSemanticNode(node, appRoot));
    if (JSON.stringify(sections.map((section) => section.id)) !== JSON.stringify(canonicalSectionIds)) {
      throw new Error('Visible sections do not match the eight canonical sections.');
    }
    for (const section of sections) {
      const label = inputs.content.navigation.find((item) => item.id === section.id)?.label;
      if (section.id === 'start') {
        const heroHeadings = [...section.querySelectorAll(':scope h1')]
          .filter((node) => isVisibleSemanticNode(node, appRoot));
        if (heroHeadings.length !== 1 || heroHeadings[0].id !== 'start-heading' ||
          heroHeadings[0].textContent !== inputs.content.identity.name) {
          throw new Error('Missing visible hero heading: start');
        }
        continue;
      }
      const headings = [...section.querySelectorAll(':scope > h2')]
        .filter((node) => isVisibleSemanticNode(node, appRoot));
      if (label === undefined || headings.length !== 1 || headings[0].id !== `${section.id}-heading` ||
        headings[0].textContent !== label) {
        throw new Error(`Missing visible section heading: ${section.id}`);
      }
    }

    const semanticText = visibleText(appRoot, appRoot);
    const requiredVisibleCopy = [
      inputs.content.systemsOperations.title,
      inputs.content.infrastructure.title,
      ...inputs.content.infrastructure.bands.flatMap((band) => [band.title, band.summary]),
      ...inputs.content.projects.selected.flatMap((project) => [project.title, project.summary]),
      ...inputs.content.toolkit.flatMap((group) => [group.title, ...group.technologies.map((technology) => technology.name)]),
      inputs.content.contact.email,
    ];
    for (const copy of requiredVisibleCopy) {
      if (!semanticText.includes(copy)) throw new Error(`Missing visible semantic evidence: ${copy}`);
    }
    const mailLinks = [...document.querySelectorAll('a[href^="mailto:"]')];
    const startMailLinks = [...document.querySelectorAll('#start a[href^="mailto:"]')];
    const contactMailLinks = [...document.querySelectorAll('#contact a[href^="mailto:"]')];
    if (mailLinks.length !== 2 || startMailLinks.length !== 1 || contactMailLinks.length !== 1 || mailLinks.some((link) =>
      link.getAttribute('href') !== `mailto:${inputs.content.contact.email}` || link.textContent !== 'Email Luca'
    )) {
      throw new Error('Mailto links must be exactly one Email Luca action beneath each hero and contact section.');
    }

    const moduleScript = document.querySelector(`script[type="module"][src="/${contract.entryModule}"]`);
    const snapshot = document.querySelector('script#portfolio-inputs[type="application/json"]');
    if (moduleScript === null || snapshot === null ||
      (appRoot.compareDocumentPosition(moduleScript) & window.Node.DOCUMENT_POSITION_FOLLOWING) === 0 ||
      (snapshot.compareDocumentPosition(moduleScript) & window.Node.DOCUMENT_POSITION_FOLLOWING) === 0) {
      throw new Error('Connected visible semantic content and snapshot must precede the trusted module script.');
    }
    let parsedSnapshot;
    try {
      parsedSnapshot = JSON.parse(snapshot.textContent ?? '');
    } catch {
      throw new Error('The inert input snapshot is malformed.');
    }
    if (JSON.stringify(parsedSnapshot) !== JSON.stringify(inputs)) {
      throw new Error('Hydration snapshot does not match the server input bytes and meaning.');
    }
  } finally {
    window.close();
  }
};

const assertMetadata = (html, inputs) => {
  const expectedTitle = escapeHtml(inputs.content.metadata.title);
  const title = exactlyOneMatch(html, /<title>([\s\S]*?)<\/title>/gu, 'page title');
  if (title[1] !== expectedTitle) throw new Error('Page title does not match public content.');
  const canonical = exactlyOneMatch(html, /<link rel="canonical" href="([^"]+)" \/>/gu, 'canonical link');
  if (canonical[1] !== inputs.site.canonicalUrl) throw new Error('Canonical URL does not match site config.');
  const description = exactlyOneMatch(html, /<meta name="description" content="([^"]+)" \/>/gu, 'meta description');
  if (description[1] !== escapeHtml(inputs.content.metadata.description)) {
    throw new Error('Meta description does not match public content.');
  }
  for (const property of ['og:type', 'og:title', 'og:description', 'og:url']) {
    exactlyOneMatch(html, new RegExp(`<meta property="${property}" content="[^"]+" \\/>`, 'gu'), `${property} metadata`);
  }
  const ogImages = [...html.matchAll(/<meta property="og:image"/gu)];
  if (inputs.content.metadata.socialPreviewAssetId === undefined && ogImages.length !== 0) {
    throw new Error('Open Graph image must be omitted without an approved manifest asset.');
  }

  const jsonLdMatch = exactlyOneMatch(
    html,
    /<script type="application\/ld\+json">([\s\S]*?)<\/script>/gu,
    'JSON-LD block',
  );
  let jsonLd;
  try {
    jsonLd = JSON.parse(jsonLdMatch[1]);
  } catch {
    throw new Error('JSON-LD is malformed.');
  }
  if (jsonLd['@type'] !== 'ProfilePage' || jsonLd.mainEntity?.['@type'] !== 'Person') {
    throw new Error('JSON-LD must contain one ProfilePage with one nested Person.');
  }
  const person = jsonLd.mainEntity;
  if (
    person.name !== inputs.content.identity.name ||
    person.jobTitle !== inputs.content.identity.role ||
    person.url !== inputs.site.canonicalUrl ||
    jsonLd.url !== inputs.site.canonicalUrl
  ) {
    throw new Error('JSON-LD identity or canonical URL is inconsistent.');
  }
  const expectedSameAs = inputs.content.contact.social.map((link) => link.url);
  if (JSON.stringify(person.sameAs ?? []) !== JSON.stringify(expectedSameAs)) {
    throw new Error('JSON-LD sameAs contains an unverified or missing profile.');
  }
  if (jsonLdMatch[1].toLowerCase().includes('</script')) throw new Error('JSON-LD contains a script-closing hazard.');
  return jsonLdMatch[1];
};

const assertSecurityHeaders = (headers, inputs, serializedJsonLd) => {
  const required = [
    "default-src 'self'", "script-src 'self'", "style-src 'self'", "img-src 'self' data:", "media-src 'self'",
    "font-src 'self'", "connect-src 'self'", "object-src 'none'", "base-uri 'none'", "frame-ancestors 'none'",
    "form-action 'self'", 'upgrade-insecure-requests', 'X-Content-Type-Options: nosniff',
    'Referrer-Policy: no-referrer', 'X-Frame-Options: DENY',
    'Permissions-Policy: camera=(), microphone=(), geolocation=(), payment=(), usb=(), accelerometer=(), gyroscope=(), magnetometer=()',
  ];
  for (const value of required) {
    if (!headers.includes(value)) throw new Error(`Missing security header policy: ${value}`);
  }
  if (/unsafe-inline|unsafe-eval|(?:^|[;\s])\*(?:[;\s]|$)|https?:\/\//iu.test(headers)) {
    throw new Error('Security header policy contains an unsafe or external source expression.');
  }
  const expectedHash = `sha256-${createHash('sha256').update(serializedJsonLd).digest('base64')}`;
  const hashes = headers.match(/sha256-[A-Za-z0-9+/=]+/gu) ?? [];
  if (hashes.length !== 1 || hashes[0] !== expectedHash) {
    throw new Error('CSP hash does not match the actual JSON-LD bytes.');
  }
  if (inputs.site.environment === 'preview') {
    if (!headers.includes('Cache-Control: private, no-store') ||
      !headers.includes('X-Robots-Tag: noindex, nofollow, noarchive')) {
      throw new Error('Preview headers must be private and noindex.');
    }
    if (headers.includes('Strict-Transport-Security')) throw new Error('Preview headers must omit HSTS.');
  } else {
    if (!headers.includes('Strict-Transport-Security: max-age=31536000')) {
      throw new Error('Production headers must include HSTS.');
    }
    if (headers.includes('X-Robots-Tag') || headers.includes('private, no-store')) {
      throw new Error('Production headers must omit preview directives.');
    }
  }
};

const assertCrawlArtifacts = async (root, inputs, headers) => {
  const robots = await readRequiredText(root, 'robots.txt');
  const redirects = await readRequiredText(root, '_redirects.example');
  if (/https?:\/\//iu.test(redirects)) throw new Error('Redirect example must not invent a host.');
  if (inputs.site.environment === 'preview') {
    if (robots !== 'User-agent: *\nDisallow: /\n' || /sitemap/iu.test(robots)) {
      throw new Error('Preview robots must disallow crawling without advertising a sitemap.');
    }
    return;
  }
  const sitemapUrl = new URL('/sitemap.xml', inputs.site.canonicalUrl).href;
  if (robots !== `User-agent: *\nAllow: /\nSitemap: ${sitemapUrl}\n`) {
    throw new Error('Production robots policy must allow the canonical page and advertise its sitemap.');
  }
  const sitemap = await readRequiredText(root, 'sitemap.xml');
  if (!sitemap.includes(`<loc>${inputs.site.canonicalUrl}</loc>`)) {
    throw new Error('Production sitemap must contain the canonical site URL.');
  }
  if (!headers.includes('Cache-Control: public, max-age=0, must-revalidate')) {
    throw new Error('Production HTML requires revalidation caching.');
  }
};

const assertExactHostArtifacts = async (root, inputs) => {
  const expected = createStaticHostArtifacts(
    createPageMetadata(inputs.content, inputs.manifest, inputs.site),
    inputs.site,
  );
  const actualHeaders = await readRequiredText(root, '_headers.example');
  if (actualHeaders !== expected.headers) throw new Error('Headers must exactly equal the generated expected headers.');
  const actualRobots = await readRequiredText(root, 'robots.txt');
  if (actualRobots !== expected.robots) throw new Error('Robots must exactly equal the generated expected robots policy.');
  const actualRedirects = await readRequiredText(root, '_redirects.example');
  if (actualRedirects !== expected.redirects) throw new Error('Redirects must exactly equal the generated expected redirect example.');
  if (expected.sitemap !== undefined) {
    const actualSitemap = await readRequiredText(root, 'sitemap.xml');
    if (actualSitemap !== expected.sitemap) throw new Error('Sitemap must exactly equal the generated expected sitemap.');
  }
};

export const verifyArtifactDirectory = async (root, inputs, contractInput) => {
  const contract = parseArtifactContract(contractInput);
  const html = await readRequiredText(root, 'index.html');
  const files = await listArtifacts(root);
  assertArtifactInventory(files, inputs, contract);
  await assertArtifactDigests(root, contract);
  await assertNoProhibitedSurfaces(root, files);
  assertTrustedHtmlAssets(html, contract);
  assertSemanticHtml(html, inputs, contract);
  const serializedJsonLd = assertMetadata(html, inputs);
  await assertExactHostArtifacts(root, inputs);
  const headers = await readRequiredText(root, '_headers.example');
  assertSecurityHeaders(headers, inputs, serializedJsonLd);
  await assertCrawlArtifacts(root, inputs, headers);
};

const assertInsideRepository = (path) => {
  const pathRelativeToRoot = relative(repositoryRoot, path);
  if (pathRelativeToRoot === '..' || pathRelativeToRoot.startsWith(`..${sep}`)) {
    throw new Error('Verification input escaped the repository root.');
  }
};

export const verifyArtifacts = async (configPath) => {
  const configAbsolutePath = resolve(repositoryRoot, configPath);
  assertInsideRepository(configAbsolutePath);
  const inputs = await loadProductionInputs({
    contentJson: pathToFileURL(resolve(repositoryRoot, 'content/public/portfolio-content.json')),
    assetManifestJson: pathToFileURL(resolve(repositoryRoot, 'content/public/asset-manifest.json')),
    preparedAssetRoot: pathToFileURL(`${resolve(repositoryRoot, 'inputs/prepared-assets')}${sep}`),
    siteConfigJson: pathToFileURL(configAbsolutePath),
  });
  const authoritySource = await readRequiredText(resolve(repositoryRoot, 'dist-ssr'), 'artifact-authority.json');
  let authority;
  try {
    authority = parseBuildAuthority(JSON.parse(authoritySource));
  } catch (error) {
    throw new Error('Persisted build authority is invalid.', { cause: error });
  }
  await verifyArtifactDirectory(resolve(repositoryRoot, 'dist'), inputs, authority.artifactContract);
};

if (process.argv[1] !== undefined && resolve(process.argv[1]) === scriptPath) {
  const configPath = parseExactConfigArgument(process.argv.slice(2));
  await verifyArtifacts(configPath);
}