_worker.js

/**
 * Copyright Dani Akash (https://github.com/DaniAkash)
 * SPDX-License-Identifier: PolyForm-Noncommercial-1.0.0
 * https://polyformproject.org/licenses/noncommercial/1.0.0
 */

/**
 * WikiWall Cloudflare Worker
 *
 * GET /api/batch?count=N
 *   Streams filtered, display-ready Wikipedia articles as NDJSON
 *   (one JSON object per line) as soon as each one passes the filters.
 *   The client can start displaying slides the moment 10 articles arrive
 *   instead of waiting for all N to be fetched.
 *
 * Everything else falls through to static assets (index.html, etc.)
 */

// ── Wikipedia API ──────────────────────────────────────────────────────────
const WIKI_URL     = 'https://en.wikipedia.org/api/rest_v1/page/random/summary';
const WIKI_HEADERS = {
  'User-Agent': 'WikiWall/1.0 (https://github.com/2dapps/wikiwall)',
  'Accept':     'application/json',
};

// ── Fetch tuning ───────────────────────────────────────────────────────────
const WAVE_SIZE  = 10;  // parallel Wikipedia requests per wave
const WAVE_DELAY = 300; // ms between waves — polite gap, faster on server-side
const MAX_COUNT  = 5;   // hard cap per request — keeps Worker well within time limits

// ── Image quality thresholds ───────────────────────────────────────────────
const MIN_IMG_WIDTH  = 1280;
const MIN_IMG_HEIGHT = 720;

// ── NSFW / inappropriate content blocklist ─────────────────────────────────
// Applied to title + description + extract before including an article.
const BLOCKLIST = [
  'murder', 'homicide', 'massacre', 'genocide', 'war crime',
  'pornograph', 'nude', 'naked', 'nudity', 'erotic',
  'sexual', 'genitalia', 'penis', 'vagina', 'breast',
  'autopsy', 'corpse', 'cadaver', 'decompos',
  'execution', 'beheading', 'torture', 'mutilat',
  'suicide', 'self-harm',
  'surgery', 'surgical wound', 'graphic injury',
  'drug use', 'overdose',
];

// ── Helpers ────────────────────────────────────────────────────────────────

function isGoodArticle(a) {
  if (!a) return false;

  // Must have a high-res original image meeting minimum dimensions
  const orig = a.originalimage;
  if (!orig || orig.width < MIN_IMG_WIDTH || orig.height < MIN_IMG_HEIGHT) return false;

  // Must have a usable thumbnail URL for display
  if (!a.thumbnail?.source) return false;

  // Must have enough text to show something meaningful
  if (!a.extract || a.extract.length < 80) return false;
  if (!a.titles?.normalized) return false;

  // NSFW check — scan title + description + extract together
  const text = [
    a.titles?.normalized ?? '',
    a.description ?? '',
    a.extract ?? '',
  ].join(' ').toLowerCase();

  if (BLOCKLIST.some(word => text.includes(word))) return false;

  return true;
}

function toSlide(a) {
  // Rewrite thumbnail URL to request a 1920px-wide version for crisp display
  const image = a.thumbnail.source.replace(/\/\d+px-/, '/1920px-');
  return {
    image,
    title:    a.titles.normalized,
    // First two sentences — enough context without overflowing the screen
    extract:  a.extract.split('. ').slice(0, 2).join('. ').trim().replace(/\.+$/, '') + '.',
    category: a.description ?? 'Wikipedia',
  };
}

// ── Worker entry point ─────────────────────────────────────────────────────

export default {
  async fetch(request, env) {
    const { pathname, searchParams } = new URL(request.url);

    if (pathname === '/api/batch') {
      const count = Math.min(
        Math.max(1, parseInt(searchParams.get('count') || '10', 10)),
        MAX_COUNT
      );

      const encoder = new TextEncoder();
      const { readable, writable } = new TransformStream();
      const writer = writable.getWriter();

      // Fetch and filter articles in the background, writing each one to the
      // stream as soon as it passes. The client can start rendering immediately
      // rather than waiting for the full batch to be assembled.
      (async () => {
        let sent = 0;

        while (sent < count) {
          const wave = await Promise.all(
            Array.from({ length: WAVE_SIZE }, () =>
              fetch(WIKI_URL, { headers: WIKI_HEADERS })
                .then(r => r.json())
                .catch(() => null)
            )
          );

          for (const article of wave) {
            if (sent >= count) break;
            if (!isGoodArticle(article)) continue;
            // Write one article as a JSON line — client reads these one by one
            await writer.write(encoder.encode(JSON.stringify(toSlide(article)) + '\n'));
            sent++;
          }

          if (sent < count) await new Promise(r => setTimeout(r, WAVE_DELAY));
        }

        await writer.close();
      })();

      return new Response(readable, {
        headers: {
          'Content-Type':  'application/x-ndjson',
          'Cache-Control': 'no-store',
        },
      });
    }

    // All other routes — serve static assets (index.html, etc.)
    return env.ASSETS.fetch(request);
  },
};