/**
 * steam-proxy-worker.js — Cloudflare Worker that gives a *hosted* copy of
 * la-li-lu-le-lo (the MGS2 Master Collection 100% companion) working Steam sync.
 *
 * WHY THIS EXISTS
 * ---------------
 * The companion reads a public Steam Community page to find out which achievements an
 * account already has. That page is served as XML and sends no CORS headers, so a browser
 * cannot fetch it from another origin. Running steam-sync.py locally solves this on your own
 * machine; this Worker solves it once the page is hosted on GitHub Pages / Netlify / Vercel /
 * Cloudflare Pages.
 *
 * DEPLOY (free tier is plenty — this is a handful of requests per page load)
 * -------------------------------------------------------------------------
 *   1. https://dash.cloudflare.com -> Workers & Pages -> Create -> Worker
 *   2. Paste this whole file in, replacing the starter code. Deploy.
 *   3. Copy the worker URL (e.g. https://mgs2-steam-proxy.YOURNAME.workers.dev)
 *   4. In index.html, set:   const STEAM_PROXY = 'https://mgs2-steam-proxy.YOURNAME.workers.dev';
 *   5. Done — the page will use it automatically when it is not running on localhost.
 *
 * Optional: change ALLOW_ORIGIN below from '*' to your page's origin to stop anyone else
 * pointing their own page at your Worker.
 *
 * The Worker makes exactly one outbound request, to the public Steam Community page for the
 * profile it is asked about. It stores nothing and logs nothing.
 */

const APPID = '2131640';
const ALLOW_ORIGIN = '*';        // e.g. 'https://yourname.github.io'
const UA = 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0 Safari/537.36';

function cors(res) {
  res.headers.set('Access-Control-Allow-Origin', ALLOW_ORIGIN);
  res.headers.set('Access-Control-Allow-Headers', '*');
  res.headers.set('Access-Control-Allow-Methods', 'GET, OPTIONS');
  res.headers.set('Cache-Control', 'no-store');
  return res;
}
function json(obj) {
  return new Response(JSON.stringify(obj), {
    status: 200,
    headers: { 'Content-Type': 'application/json; charset=utf-8' },
  });
}
function cdata(block, tag) {
  const m = block.match(new RegExp('<' + tag + '><!\\[CDATA\\[([\\s\\S]*?)\\]\\]></' + tag + '>'));
  return m ? m[1].trim() : '';
}

export default {
  async fetch(request) {
    const url = new URL(request.url);

    if (request.method === 'OPTIONS') return cors(new Response(null, { status: 204 }));
    if (url.pathname.replace(/\/$/, '') !== '/api/steam') {
      return cors(new Response('Not found — this Worker only serves /api/steam', { status: 404 }));
    }

    const profile = (url.searchParams.get('profile') || '').trim();
    if (!profile) {
      return cors(json({ ok: false, error: 'No profile given.', hint: 'Enter a vanity name or SteamID64.' }));
    }

    const target = /^\d{17}$/.test(profile)
      ? 'https://steamcommunity.com/profiles/' + profile + '/stats/' + APPID + '/?tab=achievements&xml=1'
      : 'https://steamcommunity.com/id/' + encodeURIComponent(profile) + '/stats/' + APPID + '/?tab=achievements&xml=1';

    let xml;
    try {
      const r = await fetch(target, { headers: { 'User-Agent': UA, 'Accept-Language': 'en' } });
      xml = await r.text();
    } catch (e) {
      return cors(json({ ok: false, error: 'Could not reach Steam.', hint: 'Try again in a moment.' }));
    }

    const err = xml.match(/<error><!\[CDATA\[([\s\S]*?)\]\]><\/error>/);
    if (err) {
      return cors(json({
        ok: false,
        error: err[1].trim(),
        hint: 'Check the spelling, or paste the whole profile URL.',
      }));
    }
    const privacy = (xml.match(/<privacyState>(.*?)<\/privacyState>/) || [, ''])[1].trim();
    if (privacy && privacy !== 'public') {
      return cors(json({
        ok: false,
        error: 'That profile is ' + privacy + '.',
        hint: "Steam > Edit Profile > Privacy Settings > set 'Game details' to Public, then sync again.",
      }));
    }

    const achievements = [];
    const re = /<achievement closed="(\d)">([\s\S]*?)<\/achievement>/g;
    let m;
    while ((m = re.exec(xml)) !== null) {
      const body = m[2];
      achievements.push({
        api: cdata(body, 'apiname'),
        name: cdata(body, 'name'),
        desc: cdata(body, 'description'),
        unlocked: m[1] === '1',
        icon: cdata(body, 'iconOpen'),
        iconLocked: cdata(body, 'iconClosed'),
      });
    }

    if (!achievements.length) {
      return cors(json({
        ok: false,
        error: 'No MGS2 Master Collection stats on that account.',
        hint: 'The account must own the game (appid ' + APPID + ') and have launched it at least once.',
      }));
    }

    const id64 = (xml.match(/<steamID64>(\d+)<\/steamID64>/) || [, ''])[1];
    // This XML carries no persona name, only steamID64 and customURL, so fall back sensibly.
    let persona = '';
    const pm = xml.match(/<steamID>(?:<!\[CDATA\[)?([\s\S]*?)(?:\]\]>)?<\/steamID>/);
    if (pm && pm[1].trim()) persona = pm[1].trim();
    if (!persona) {
      const cm = xml.match(/<customURL><!\[CDATA\[(.*?)\]\]><\/customURL>/);
      if (cm && cm[1].trim()) persona = cm[1].trim();
    }
    if (!persona) persona = profile;

    return cors(json({
      ok: true,
      game: 'METAL GEAR SOLID 2: Sons of Liberty - Master Collection Version',
      appid: APPID,
      steamid64: id64,
      persona: persona,
      unlockedCount: achievements.filter((a) => a.unlocked).length,
      total: achievements.length,
      achievements: achievements,
    }));
  },
};