#!/usr/bin/env node
import fs from 'fs';
import zlib from 'zlib';
import path from 'path';
import { fileURLToPath } from 'url';

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const dir = path.join(__dirname, '..', 'public', 'icons');
fs.mkdirSync(dir, { recursive: true });

function crc32(data) {
  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 < data.length; i++) crc = table[(crc ^ data[i]) & 0xff] ^ (crc >>> 8);
  return (crc ^ 0xffffffff) >>> 0;
}

function chunk(type, data) {
  const len = Buffer.alloc(4);
  len.writeUInt32BE(data.length);
  const typeData = Buffer.concat([Buffer.from(type), data]);
  const crcBuf = Buffer.alloc(4);
  crcBuf.writeUInt32BE(crc32(typeData));
  return Buffer.concat([len, typeData, crcBuf]);
}

function makePNG(w, h) {
  const rowBytes = 1 + w * 3;
  const buf = Buffer.alloc(rowBytes * h);
  const cx = w / 2, cy = h / 2;
  const outerR = Math.min(w, h) / 2 - 2;
  const innerR = outerR * 0.65;

  let offset = 0;
  for (let y = 0; y < h; y++) {
    buf[offset++] = 0; // filter none
    for (let x = 0; x < w; x++) {
      const dx = x - cx, dy = y - cy;
      const dist = Math.sqrt(dx * dx + dy * dy);
      if (dist <= outerR && dist >= innerR) {
        buf[offset++] = 90; buf[offset++] = 140; buf[offset++] = 255;
      } else {
        buf[offset++] = 6; buf[offset++] = 7; buf[offset++] = 10;
      }
    }
  }

  const compressed = zlib.deflateSync(buf.slice(0, offset));
  const ihdr = Buffer.alloc(13);
  ihdr.writeUInt32BE(w, 0);
  ihdr.writeUInt32BE(h, 4);
  ihdr[8] = 8; ihdr[9] = 2;

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

const icons = [
  [192, 'icon-192.png'],
  [512, 'icon-512.png'],
  [512, 'icon-512-maskable.png'],
  [180, 'apple-touch-icon.png'],
];

for (const [size, name] of icons) {
  const png = makePNG(size, size);
  fs.writeFileSync(path.join(dir, name), png);
  console.log(`Created ${name} (${png.length} bytes)`);
}

console.log('Done!');