/**
 * Génère l'icône Météo Exam V2 : papier quadrillé + 0 rouge manuscrit.
 */
import { writeFileSync, mkdirSync } from 'node:fs'
import { resolve } from 'node:path'
import { deflateSync } from 'node:zlib'

const OUT = resolve(import.meta.dirname, '../web/public')
mkdirSync(OUT, { recursive: true })

function crc32(buf) {
  const table = []
  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
    table[n] = c >>> 0
  }
  let crc = 0xffffffff
  for (const b of buf) crc = table[(crc ^ b) & 0xff] ^ (crc >>> 8)
  return (crc ^ 0xffffffff) >>> 0
}

function chunk(type, data) {
  const len = Buffer.alloc(4)
  len.writeUInt32BE(data.length)
  const body = Buffer.concat([Buffer.from(type, 'ascii'), data])
  const crc = Buffer.alloc(4)
  crc.writeUInt32BE(crc32(body))
  return Buffer.concat([len, body, crc])
}

function encodePng(width, height, rgba) {
  const raw = Buffer.alloc(height * (1 + width * 4))
  for (let y = 0; y < height; y++) {
    raw[y * (1 + width * 4)] = 0
    rgba.copy(raw, y * (1 + width * 4) + 1, y * width * 4, (y + 1) * width * 4)
  }
  const ihdr = Buffer.alloc(13)
  ihdr.writeUInt32BE(width, 0)
  ihdr.writeUInt32BE(height, 4)
  ihdr[8] = 8
  ihdr[9] = 6
  return Buffer.concat([
    Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]),
    chunk('IHDR', ihdr),
    chunk('IDAT', deflateSync(raw)),
    chunk('IEND', Buffer.alloc(0)),
  ])
}

function drawIcon(size) {
  const buf = Buffer.alloc(size * size * 4)
  const paperR = 248, paperG = 250, paperB = 252  // #F8FAFC
  const gridR = 185, gridG = 213, gridB = 246     // #B9D5F6
  const redR = 239, redG = 68, redB = 68          // #EF4444
  const lineR = 236, lineG = 73, lineB = 73       // #EC4949
  const cx = size / 2
  const cy = size / 2
  const gridSize = size / 10

  for (let y = 0; y < size; y++) {
    for (let x = 0; x < size; x++) {
      const i = (y * size + x) * 4

      // Fond papier
      let r = paperR, g = paperG, b = paperB, a = 255

      // Quadrillage
      const gx = x % gridSize
      const gy = y % gridSize
      const nearVx = gx < 1.5 || gx > gridSize - 1.5
      const nearHy = gy < 1.5 || gy > gridSize - 1.5
      if (nearVx || nearHy) {
        r = gridR; g = gridG; b = gridB
      }

      // Marge rouge verticale (style cahier)
      if (x < size * 0.08 && x > size * 0.05) {
        r = lineR; g = lineG; b = lineB
      }

      // Dessiner le "0" rouge (ellipse inclinée)
      const dx = (x - cx) / (size * 0.22)
      const dy = (y - cy) / (size * 0.3)
      const dist0 = Math.sqrt(dx * dx + dy * dy)

      // Anneau du 0
      if (dist0 > 0.7 && dist0 < 1.15) {
        r = redR; g = redG; b = redB
      }

      // Rayons du soleil (petits traits autour du 0)
      const angle = Math.atan2(y - cy, x - cx)
      const rayDist = Math.sqrt((x - cx) ** 2 + (y - cy) ** 2)
      const rayOuter = size * 0.42
      const rayInner = size * 0.36
      if (rayDist > rayInner && rayDist < rayOuter) {
        // 8 rayons
        const rayAngle = (Math.round(angle / (Math.PI / 4)) * Math.PI) / 4
        const perpDist = Math.abs((x - cx) * Math.sin(rayAngle) - (y - cy) * Math.cos(rayAngle))
        if (perpDist < size * 0.02) {
          r = redR; g = redG; b = redB
        }
      }

      // Soulignement double en bas
      const underY1 = cy + size * 0.38
      const underY2 = cy + size * 0.42
      if (Math.abs(y - underY1) < size * 0.015 && x > cx - size * 0.3 && x < cx + size * 0.3) {
        r = redR; g = redG; b = redB
      }
      if (Math.abs(y - underY2) < size * 0.015 && x > cx - size * 0.28 && x < cx + size * 0.32) {
        r = redR; g = redG; b = redB
      }

      buf[i] = r
      buf[i + 1] = g
      buf[i + 2] = b
      buf[i + 3] = a
    }
  }
  return buf
}

for (const size of [192, 512]) {
  const png = encodePng(size, size, drawIcon(size))
  writeFileSync(resolve(OUT, `icon-${size}.png`), png)
  console.log(`icon-${size}.png (${png.length} octets)`)
}