// Minimal PNG generator — run before build to create icon files
const { writeFileSync, mkdirSync } = require('fs')

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

function pngChunk(type, data) {
  const len = data.length
  const chunk = new Uint8Array(4 + 4 + len + 4)
  const view = new DataView(chunk.buffer)
  view.setUint32(0, len, false)
  chunk.set(new TextEncoder().encode(type), 4)
  chunk.set(data, 8)
  const crc = crc32(chunk.slice(4, 8 + len))
  view.setUint32(8 + len, crc, false)
  return chunk
}

function generatePNG(size, color) {
  const header = new Uint8Array([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a])
  const ihdr = new Uint8Array(13)
  const v = new DataView(ihdr.buffer)
  v.setUint32(0, size, false)
  v.setUint32(4, size, false)
  v.setUint8(8, 8)
  v.setUint8(9, 2)
  v.setUint8(10, 0)
  v.setUint8(11, 0)
  v.setUint8(12, 0)

  const rowLen = 1 + size * 3
  const raw = new Uint8Array(size * rowLen)
  for (let y = 0; y < size; y++) {
    raw[y * rowLen] = 0
    for (let x = 0; x < size; x++) {
      const off = y * rowLen + 1 + x * 3
      raw[off] = color[0]
      raw[off + 1] = color[1]
      raw[off + 2] = color[2]
    }
  }

  const compressed = new Uint8Array(require('zlib').deflateSync(raw))
  const idat = pngChunk('IDAT', compressed)
  const iend = pngChunk('IEND', new Uint8Array(0))

  const out = new Uint8Array(header.length + 4 + 4 + 13 + 4 + idat.length + iend.length)
  let p = 0
  out.set(header, p); p += header.length
  out.set(pngChunk('IHDR', ihdr), p); p += 4 + 4 + 13 + 4
  out.set(idat, p); p += idat.length
  out.set(iend, p)
  return out
}

mkdirSync('icons', { recursive: true })
const teal = [0, 180, 170]
writeFileSync('icons/icon16.png', generatePNG(16, teal))
writeFileSync('icons/icon48.png', generatePNG(48, teal))
writeFileSync('icons/icon128.png', generatePNG(128, teal))
console.log('Icons generated')