#!/usr/bin/env node
/**
 * Publish gate: every published post must carry its own artwork.
 *
 * Why this exists: the "one art, four targets" pipeline writes five files per
 * slug (banner .jpg/.webp, EN card, ZH card, two list thumbs) but the two
 * frontmatter fields that *point* at them (`ogImage`, `banner`) are added by
 * hand — they were bulk-migrated for the first 72 posts and nothing wrote them
 * for posts added later. Two posts shipped on 2026-10-20 with an empty
 * `ogImage`, so their pages advertised /og-default.jpg and rendered no hero
 * banner, and every related-post card showed the generic default. Nothing in
 * the build noticed. This script is that notice.
 *
 * Runs as the first step of `npm run build`, so a post that is text-complete
 * but not image-complete cannot reach nginx.
 *
 * Rules checked per non-draft post:
 *   - `ogImage` present, language-correct (EN /og/<slug>.jpg, ZH /og/zh-<slug>.jpg)
 *   - `banner` present (/banners/<slug>.jpg) — the same banner serves both languages
 *   - every referenced file exists in public/, plus the derived banner .webp and
 *     the two list thumbs the post list and related grid link to
 *
 * Usage: node scripts/check-assets.mjs   (exit 1 with a list on any problem)
 */
import { readFileSync, existsSync, readdirSync } from 'node:fs';
import { basename, join, dirname } from 'node:path';
import { fileURLToPath } from 'node:url';

const ROOT = dirname(dirname(fileURLToPath(import.meta.url)));
const POSTS = join(ROOT, 'src', 'content', 'posts');
const PUBLIC = join(ROOT, 'public');

/** Minimal frontmatter reader: top-level `key: value` scalars only, which is all we need. */
function frontmatter(file) {
  const text = readFileSync(file, 'utf8').replace(/^\uFEFF/, '');
  const m = text.match(/^---\r?\n([\s\S]*?)\r?\n---/);
  if (!m) return null;
  const out = {};
  for (const line of m[1].split(/\r?\n/)) {
    const kv = line.match(/^([A-Za-z_][\w-]*):\s*(.*)$/);
    if (!kv) continue;
    let value = kv[2].trim();
    if (
      (value.startsWith('"') && value.endsWith('"')) ||
      (value.startsWith("'") && value.endsWith("'"))
    ) {
      value = value.slice(1, -1);
    }
    out[kv[1]] = value;
  }
  return out;
}

const problems = [];
const notes = [];

/** Resolve a site-absolute path (/og/x.jpg) to a file on disk under public/. */
const publicFile = (urlPath) => join(PUBLIC, urlPath.replace(/^\//, ''));

function requireFile(urlPath, label) {
  if (!existsSync(publicFile(urlPath))) problems.push(`${label}: missing file ${urlPath}`);
}

const files = [
  ...readdirSync(POSTS)
    .filter((f) => f.endsWith('.md'))
    .map((f) => ({ dir: POSTS, file: f, lang: 'en' })),
  ...(existsSync(join(POSTS, 'zh'))
    ? readdirSync(join(POSTS, 'zh'))
        .filter((f) => f.endsWith('.md'))
        .map((f) => ({ dir: join(POSTS, 'zh'), file: f, lang: 'zh' }))
    : []),
];

let checked = 0;
for (const { dir, file, lang } of files) {
  const path = join(dir, file);
  const slug = basename(file, '.md');
  const fm = frontmatter(path);
  if (!fm) {
    problems.push(`${file}: no frontmatter block`);
    continue;
  }
  if (fm.draft === 'true') continue;
  checked++;

  const where = lang === 'zh' ? `zh/${file}` : file;
  const expectedOg = lang === 'zh' ? `/og/zh-${slug}.jpg` : `/og/${slug}.jpg`;
  const expectedBanner = `/banners/${slug}.jpg`;

  if (!fm.ogImage) {
    problems.push(`${where}: no og:image in frontmatter (expected ogImage: "${expectedOg}")`);
  } else if (fm.ogImage !== expectedOg) {
    problems.push(`${where}: ogImage is "${fm.ogImage}", expected "${expectedOg}"`);
  } else {
    requireFile(fm.ogImage, where);
  }

  if (!fm.banner) {
    problems.push(`${where}: no banner in frontmatter (expected banner: "${expectedBanner}")`);
  } else if (fm.banner !== expectedBanner) {
    problems.push(`${where}: banner is "${fm.banner}", expected "${expectedBanner}"`);
  } else {
    requireFile(fm.banner, where);
    requireFile(fm.banner.replace(/\.(png|jpe?g)$/, '.webp'), where);
  }

  // The post list serves 400w/800w WebP thumbs keyed by BASE slug (a ZH card is
  // zh-<slug>.jpg while its thumb is <slug>-<w>.webp), so check both languages here.
  for (const w of [400, 800]) requireFile(`/og/thumb/${slug}-${w}.webp`, where);
}

// Every post should have a twin, and both should agree it exists.
const enSlugs = new Set(files.filter((f) => f.lang === 'en').map((f) => basename(f.file, '.md')));
const zhSlugs = new Set(files.filter((f) => f.lang === 'zh').map((f) => basename(f.file, '.md')));
for (const s of enSlugs) if (!zhSlugs.has(s)) notes.push(`no ZH twin for ${s}`);
for (const s of zhSlugs) if (!enSlugs.has(s)) notes.push(`no EN twin for zh/${s}`);

if (problems.length) {
  console.error(`assets: ${problems.length} problem(s) across ${checked} published posts\n`);
  for (const p of problems) console.error(`  ✗ ${p}`);
  if (notes.length) {
    console.error('');
    for (const n of notes) console.error(`  ! ${n}`);
  }
  console.error(
    '\nFix: cd C:/AI/ideogram4 && uv run --with pillow python post_art.py --slug <slug> --metaphor "..." --evidence "..."' +
      '\nthen add ogImage + banner to BOTH language files (see docs/design-guide.md, image policy).'
  );
  process.exit(1);
}

console.log(`assets: ${checked} published posts OK (og card + banner + webp + 2 thumbs each)`);
for (const n of notes) console.log(`  ! ${n}`);