/* 자체 PNG 생성기 — 외부 의존 없이 WISE 블루(#1f29fc) 배경 + 흰색 'ITMS' 아이콘. */
const zlib = require('zlib')
const fs = require('fs')
const path = require('path')

const SIZE = 1024
const BG = [0x1f, 0x29, 0xfc, 0xff] // WISE blue
const FG = [0xff, 0xff, 0xff, 0xff] // white

// 5x7 비트맵 글리프
const GLYPHS = {
  I: ['11111', '00100', '00100', '00100', '00100', '00100', '11111'],
  T: ['11111', '00100', '00100', '00100', '00100', '00100', '00100'],
  M: ['10001', '11011', '10101', '10101', '10001', '10001', '10001'],
  S: ['01111', '10000', '10000', '01110', '00001', '00001', '11110'],
}
const WORD = 'ITMS'

function makeBuffer() {
  const buf = Buffer.alloc(SIZE * SIZE * 4)
  for (let i = 0; i < SIZE * SIZE; i++) buf.set(BG, i * 4)

  // 글리프 레이아웃: 4글자 * 5px + 간격 1px = 23 units 폭, 7 units 높이
  const cols = WORD.length * 5 + (WORD.length - 1) // 23
  const rows = 7
  const scale = Math.floor((SIZE * 0.62) / cols) // 폭 62% 사용
  const wpx = cols * scale
  const hpx = rows * scale
  const ox = Math.floor((SIZE - wpx) / 2)
  const oy = Math.floor((SIZE - hpx) / 2)

  const setPx = (x, y) => {
    if (x < 0 || y < 0 || x >= SIZE || y >= SIZE) return
    buf.set(FG, (y * SIZE + x) * 4)
  }

  let cx = ox
  for (const ch of WORD) {
    const g = GLYPHS[ch]
    for (let r = 0; r < 7; r++) {
      for (let c = 0; c < 5; c++) {
        if (g[r][c] === '1') {
          for (let dy = 0; dy < scale; dy++)
            for (let dx = 0; dx < scale; dx++)
              setPx(cx + c * scale + dx, oy + r * scale + dy)
        }
      }
    }
    cx += 6 * scale // 5 글자폭 + 1 간격
  }
  return buf
}

function crc32(buf) {
  let c = ~0
  for (let i = 0; i < buf.length; i++) {
    c ^= buf[i]
    for (let k = 0; k < 8; k++) c = (c >>> 1) ^ (0xedb88320 & -(c & 1))
  }
  return ~c >>> 0
}
function chunk(type, data) {
  const len = Buffer.alloc(4); len.writeUInt32BE(data.length, 0)
  const t = Buffer.from(type, 'ascii')
  const body = Buffer.concat([t, data])
  const crc = Buffer.alloc(4); crc.writeUInt32BE(crc32(body), 0)
  return Buffer.concat([len, body, crc])
}
function encodePng(rgba) {
  const sig = Buffer.from([137, 80, 78, 71, 13, 10, 26, 10])
  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
  // 각 스캔라인 앞 filter byte 0
  const raw = Buffer.alloc(SIZE * (SIZE * 4 + 1))
  for (let y = 0; y < SIZE; y++) {
    raw[y * (SIZE * 4 + 1)] = 0
    rgba.copy(raw, y * (SIZE * 4 + 1) + 1, y * SIZE * 4, (y + 1) * SIZE * 4)
  }
  const idat = zlib.deflateSync(raw, { level: 9 })
  return Buffer.concat([sig, chunk('IHDR', ihdr), chunk('IDAT', idat), chunk('IEND', Buffer.alloc(0))])
}

const png = encodePng(makeBuffer())
const outDir = path.join(__dirname, '..', 'assets')
fs.mkdirSync(outDir, { recursive: true })
for (const name of ['icon.png', 'adaptive-icon.png', 'splash.png']) {
  fs.writeFileSync(path.join(outDir, name), png)
}
console.log('generated', png.length, 'bytes ->', outDir)