// 生成 icons/app.png（256x256 纯蓝方块图标）
const zlib = require("zlib");
const fs = require("fs");
const path = require("path");

const W = 256, H = 256;
const row = Buffer.alloc(1 + W * 4);
row[0] = 0;
for (let x = 0; x < W; x++) {
  row[1 + x * 4] = 0;
  row[2 + x * 4] = 110;
  row[3 + x * 4] = 255;
  row[4 + x * 4] = 255;
}
const raw = Buffer.concat(Array(H).fill(row));

const crcTable = [];
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);
  crcTable[n] = c >>> 0;
}
function crc32(buf) {
  let c = 0xffffffff;
  for (const b of buf) c = crcTable[(c ^ b) & 0xff] ^ (c >>> 8);
  return (c ^ 0xffffffff) >>> 0;
}
function chunk(type, data) {
  const len = Buffer.alloc(4);
  len.writeUInt32BE(data.length);
  const t = Buffer.from(type, "ascii");
  const crc = Buffer.alloc(4);
  crc.writeUInt32BE(crc32(Buffer.concat([t, data])));
  return Buffer.concat([len, t, data, crc]);
}

const ihdr = Buffer.alloc(13);
ihdr.writeUInt32BE(W, 0);
ihdr.writeUInt32BE(H, 4);
ihdr[8] = 8;  // bit depth
ihdr[9] = 6;  // color type RGBA
const png = Buffer.concat([
  Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]),
  chunk("IHDR", ihdr),
  chunk("IDAT", zlib.deflateSync(raw)),
  chunk("IEND", Buffer.alloc(0)),
]);
fs.mkdirSync(path.join(__dirname, "icons"), { recursive: true });
fs.writeFileSync(path.join(__dirname, "icons", "app.png"), png);
console.log("icon generated:", png.length, "bytes");