/* ============================================================
 * tools/build_zip.mjs — package the game for itch.io.
 * Store-only ZIP (no deps). Excludes tools/ and dev files.
 *   node tools/build_zip.mjs
 * ============================================================ */
import fs from 'node:fs';
import path from 'node:path';

const CRC_TABLE = (() => {
  const t = new Int32Array(256);
  for (let n = 0; n < 256; n++) {
    let c = n;
    for (let k = 0; k < 8; k++) c = c & 1 ? 0xedb88320 ^ (c >>> 1) : c >>> 1;
    t[n] = c;
  }
  return t;
})();
function crc32(buf) {
  let c = 0xffffffff;
  for (let i = 0; i < buf.length; i++) c = CRC_TABLE[(c ^ buf[i]) & 0xff] ^ (c >>> 8);
  return (c ^ 0xffffffff) >>> 0;
}

const ROOT = path.join(process.cwd());
const INCLUDE = ['index.html', 'manifest.webmanifest', 'LICENSE', 'README.md', 'server.js', 'css', 'js', 'icons'];
const EXCLUDE_DIR = new Set(['tools', 'node_modules', '.git']);

function walk(rel, out) {
  const full = path.join(ROOT, rel);
  const st = fs.statSync(full);
  if (st.isDirectory()) {
    if (EXCLUDE_DIR.has(path.basename(rel))) return;
    for (const name of fs.readdirSync(full)) walk(path.join(rel, name), out);
  } else {
    out.push({ rel: rel.split(path.sep).join('/'), full });
  }
}
const files = [];
for (const f of INCLUDE) if (fs.existsSync(path.join(ROOT, f))) walk(f, files);

/* ---- assemble store-only zip ---- */
const locals = [];
const centrals = [];
let offset = 0;
const u16 = v => { const b = Buffer.alloc(2); b.writeUInt16LE(v); return b; };
const u32 = v => { const b = Buffer.alloc(4); b.writeUInt32LE(v); return b; };

for (const f of files) {
  const data = fs.readFileSync(f.full);
  const name = Buffer.from(f.rel, 'utf8');
  const crc = crc32(data);

  const lh = Buffer.concat([
    u32(0x04034b50), u16(20), u16(0), u16(0), u16(0x21), u16(0),
    u32(crc), u32(data.length), u32(data.length), u16(name.length), u16(0), name,
  ]);
  locals.push(lh, data);

  centrals.push(Buffer.concat([
    u32(0x02014b50), u16(20), u16(20), u16(0), u16(0), u16(0x21), u16(0),
    u32(crc), u32(data.length), u32(data.length), u16(name.length), u16(0), u16(0),
    u16(0), u16(0), u32(0), u32(offset), name,
  ]));
  offset += lh.length + data.length;
}

const cdBuf = Buffer.concat(centrals);
const eocd = Buffer.concat([
  u32(0x06054b50), u16(0), u16(0), u16(files.length), u16(files.length),
  u32(cdBuf.length), u32(offset), u16(0),
]);

const zip = Buffer.concat([...locals, cdBuf, eocd]);
const outName = 'diablo2d-itch.zip';
fs.writeFileSync(path.join(ROOT, outName), zip);
console.log(`wrote ${outName}: ${files.length} files, ${(zip.length / 1024).toFixed(1)} KB`);