// 使用Node.js生成PNG图标
// 运行: node generate-icons.js

const fs = require('fs')
const path = require('path')

// 简单的PNG生成器（使用PNG文件格式规范）
function createSimplePNG(width, height, bgColor) {
  // PNG文件签名
  const signature = Buffer.from([0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A])
  
  // IHDR chunk (图像头)
  const ihdrData = Buffer.alloc(13)
  ihdrData.writeUInt32BE(width, 0)   // width
  ihdrData.writeUInt32BE(height, 4)  // height
  ihdrData[8] = 8                    // bit depth
  ihdrData[9] = 2                    // color type (RGB)
  ihdrData[10] = 0                   // compression method
  ihdrData[11] = 0                   // filter method
  ihdrData[12] = 0                   // interlace method
  
  const ihdrChunk = createChunk('IHDR', ihdrData)
  
  // IDAT chunk (图像数据)
  // 创建简单的纯色图像
  const rawData = Buffer.alloc(height * (1 + width * 3))
  let offset = 0
  
  const r = bgColor.r
  const g = bgColor.g  
  const b = bgColor.b
  
  for (let y = 0; y < height; y++) {
    rawData[offset++] = 0 // filter type: none
    for (let x = 0; x < width; x++) {
      rawData[offset++] = r
      rawData[offset++] = g
      rawData[offset++] = b
    }
  }
  
  // 使用zlib压缩
  const zlib = require('zlib')
  const compressedData = zlib.deflateSync(rawData)
  const idatChunk = createChunk('IDAT', compressedData)
  
  // IEND chunk (图像结束)
  const iendChunk = createChunk('IEND', Buffer.alloc(0))
  
  // 组合所有chunk
  return Buffer.concat([signature, ihdrChunk, idatChunk, iendChunk])
}

function createChunk(type, data) {
  const length = Buffer.alloc(4)
  length.writeUInt32BE(data.length, 0)
  
  const typeBuffer = Buffer.from(type, 'ascii')
  
  // CRC32计算
  const crcData = Buffer.concat([typeBuffer, data])
  const crc = crc32(crcData)
  const crcBuffer = Buffer.alloc(4)
  crcBuffer.writeUInt32BE(crc >>> 0, 0)
  
  return Buffer.concat([length, typeBuffer, data, crcBuffer])
}

// CRC32计算
function crc32(buffer) {
  let crc = 0xFFFFFFFF
  const table = getCrc32Table()
  
  for (let i = 0; i < buffer.length; i++) {
    crc = (crc >>> 8) ^ table[(crc ^ buffer[i]) & 0xFF]
  }
  
  return crc ^ 0xFFFFFFFF
}

function getCrc32Table() {
  const table = new Uint32Array(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
  }
  return table
}

// 生成图标
const sizes = [16, 48, 128]
const color = { r: 102, g: 126, b: 234 } // #667eea 紫色

sizes.forEach(size => {
  const png = createSimplePNG(size, size, color)
  const filename = path.join(__dirname, `icon${size}.png`)
  fs.writeFileSync(filename, png)
  console.log(`生成: ${filename} (${size}x${size})`)
})

console.log('图标生成完成!')
console.log('请替换为更好的图标设计，推荐使用 https://favicon.io/')