import { writeFileSync, mkdirSync } from "fs";
import { resolve } from "path";
import { deflateSync } from "zlib";

const __dirname = import.meta.dirname;
const iconsDir = resolve(__dirname, "../public/icons");
mkdirSync(iconsDir, { recursive: true });

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

function chunk(type, data) {
  const len = Buffer.alloc(4);
  len.writeUInt32BE(data.length);
  const typeB = Buffer.from(type, "ascii");
  const crcData = Buffer.concat([typeB, data]);
  const crcV = Buffer.alloc(4);
  crcV.writeUInt32BE(crc32(crcData));
  return Buffer.concat([len, typeB, data, crcV]);
}

function createPNG(size) {
  const raw = Buffer.alloc(size * size * 4);
  const cx = size / 2;
  const cy = size / 2;
  const r = size * 0.42;

  for (let y = 0; y < size; y++) {
    for (let x = 0; x < size; x++) {
      const dx = x - cx;
      const dy = y - cy;
      const dist = Math.sqrt(dx * dx + dy * dy);
      const i = (y * size + x) * 4;
      if (dist <= r) {
        raw[i] = 99;
        raw[i + 1] = 102;
        raw[i + 2] = 241;
        raw[i + 3] = 255;
      } else {
        raw[i] = 0;
        raw[i + 1] = 0;
        raw[i + 2] = 0;
        raw[i + 3] = 0;
      }
    }
  }

  const filter = Buffer.alloc(size * size + size);
  for (let y = 0; y < size; y++) {
    filter[y * (size * 4 + 1)] = 0;
    raw.copy(filter, y * (size * 4 + 1) + 1, y * size * 4, (y + 1) * size * 4);
  }

  const compressed = deflateSync(filter);
  const ihdr = Buffer.alloc(13);
  ihdr.writeUInt32BE(size, 0);
  ihdr.writeUInt32BE(size, 4);
  ihdr[8] = 8;
  ihdr[9] = 6;
  ihdr[10] = 0;
  ihdr[11] = 0;
  ihdr[12] = 0;

  const sig = Buffer.from([137, 80, 78, 71, 13, 10, 26, 10]);
  return Buffer.concat([sig, chunk("IHDR", ihdr), chunk("IDAT", compressed), chunk("IEND", Buffer.alloc(0))]);
}

for (const size of [16, 48, 128]) {
  writeFileSync(resolve(iconsDir, `icon-${size}.png`), createPNG(size));
  console.log(`Created icon-${size}.png`);
}