/**
 * TabBar 图标生成脚本
 * 运行: node scripts/generateIcons.js
 * 需要先安装依赖: npm install canvas
 */

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

// 尝试使用 canvas，如果没有安装则使用简单的 PNG 生成
let useCanvas = false;
let createCanvas;

try {
  const canvas = require('canvas');
  createCanvas = canvas.createCanvas;
  useCanvas = true;
} catch (e) {
  console.log('canvas 未安装，将生成简单的占位图标');
}

const imagesDir = path.join(__dirname, '..', 'images');

// 确保 images 目录存在
if (!fs.existsSync(imagesDir)) {
  fs.mkdirSync(imagesDir, { recursive: true });
}

// 图标配置
const icons = [
  { name: 'tab-rank', icon: '排', desc: '排名' },
  { name: 'tab-match', icon: '赛', desc: '比赛' },
  { name: 'tab-points', icon: '分', desc: '积分' },
  { name: 'tab-user', icon: '我', desc: '我的' }
];

const normalColor = '#999999';
const activeColor = '#FF6B35';
const size = 81; // 微信推荐 81x81

function generateIconWithCanvas(iconConfig, isActive) {
  const canvas = createCanvas(size, size);
  const ctx = canvas.getContext('2d');
  
  // 清空背景（透明）
  ctx.clearRect(0, 0, size, size);
  
  // 绘制圆形背景
  ctx.beginPath();
  ctx.arc(size / 2, size / 2, size / 2 - 4, 0, Math.PI * 2);
  ctx.fillStyle = isActive ? activeColor : '#f5f5f5';
  ctx.fill();
  
  // 绘制文字
  ctx.font = 'bold 32px sans-serif';
  ctx.textAlign = 'center';
  ctx.textBaseline = 'middle';
  ctx.fillStyle = isActive ? '#ffffff' : normalColor;
  ctx.fillText(iconConfig.icon, size / 2, size / 2);
  
  return canvas.toBuffer('image/png');
}

// 简单的 PNG 生成（不依赖 canvas）
function generateSimplePNG(iconConfig, isActive) {
  // 创建一个简单的 1x1 像素的 PNG 作为占位符
  // 实际项目中应该使用真实的图标文件
  const color = isActive ? [255, 107, 53] : [153, 153, 153]; // RGB
  
  // 最简单的 PNG 文件头 + IHDR + IDAT + IEND
  // 这是一个 8x8 的纯色 PNG
  const width = 8;
  const height = 8;
  
  // PNG 签名
  const signature = Buffer.from([137, 80, 78, 71, 13, 10, 26, 10]);
  
  // IHDR chunk
  const ihdr = createChunk('IHDR', Buffer.from([
    0, 0, 0, width,  // width
    0, 0, 0, height, // height
    8,               // bit depth
    2,               // color type (RGB)
    0,               // compression
    0,               // filter
    0                // interlace
  ]));
  
  // IDAT chunk - 简化的图像数据
  const zlib = require('zlib');
  const rawData = Buffer.alloc((width * 3 + 1) * height);
  for (let y = 0; y < height; y++) {
    rawData[y * (width * 3 + 1)] = 0; // filter byte
    for (let x = 0; x < width; x++) {
      const offset = y * (width * 3 + 1) + 1 + x * 3;
      rawData[offset] = color[0];
      rawData[offset + 1] = color[1];
      rawData[offset + 2] = color[2];
    }
  }
  const compressed = zlib.deflateSync(rawData);
  const idat = createChunk('IDAT', compressed);
  
  // IEND chunk
  const iend = createChunk('IEND', Buffer.alloc(0));
  
  return Buffer.concat([signature, ihdr, idat, iend]);
}

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

// CRC32 计算
function crc32(data) {
  let crc = 0xffffffff;
  const table = getCRC32Table();
  
  for (let i = 0; i < data.length; i++) {
    crc = table[(crc ^ data[i]) & 0xff] ^ (crc >>> 8);
  }
  
  return crc ^ 0xffffffff;
}

let crc32Table = null;
function getCRC32Table() {
  if (crc32Table) return crc32Table;
  
  crc32Table = 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);
    }
    crc32Table[i] = c;
  }
  return crc32Table;
}

// 生成图标
console.log('开始生成 TabBar 图标...\n');

icons.forEach(iconConfig => {
  // 生成普通状态图标
  const normalPath = path.join(imagesDir, `${iconConfig.name}.png`);
  const normalBuffer = useCanvas 
    ? generateIconWithCanvas(iconConfig, false)
    : generateSimplePNG(iconConfig, false);
  fs.writeFileSync(normalPath, normalBuffer);
  console.log(`✓ 已生成: ${iconConfig.name}.png (${iconConfig.desc})`);
  
  // 生成选中状态图标
  const activePath = path.join(imagesDir, `${iconConfig.name}-active.png`);
  const activeBuffer = useCanvas 
    ? generateIconWithCanvas(iconConfig, true)
    : generateSimplePNG(iconConfig, true);
  fs.writeFileSync(activePath, activeBuffer);
  console.log(`✓ 已生成: ${iconConfig.name}-active.png (${iconConfig.desc} - 选中)`);
});

console.log('\n图标生成完成！');
console.log(`图标目录: ${imagesDir}`);

if (!useCanvas) {
  console.log('\n提示: 当前生成的是简单占位图标。');
  console.log('如需更好的图标效果，请：');
  console.log('1. 安装 canvas: npm install canvas');
  console.log('2. 重新运行此脚本');
  console.log('或者从 iconfont.cn 下载合适的图标替换');
}