const puppeteer = require('puppeteer');

(async () => {
  const browser = await puppeteer.launch({
    headless: false
  });
  const page = await browser.newPage();

  // 转到要下载的网页并设置视口大小
  await page.goto('http://c.gb688.cn/bzgk/gb/showGb?type=online&hcno=FDA38AB7D08A715C6B6D69DFDEABB2C0');
  // 把 width/height 调整到适合 pdf 大小
  await page.setViewport({width: 1920, height: 2000});

  // 监听页面上的控制台输出
  page.on('console', message => {
    const args = message.args();
    console.log(`${message.type().substr(0, 3).toUpperCase()} ${message.text()} ${args.length ? '\n' : ''}`);
    for (let i = 0; i < args.length; ++i) {
      console.log(`  ${i}: ${args[i]}`);
    }
  });

  console.log('wait for user stdin')
  await new Promise(resolve => process.stdin.once('data', resolve));

  console.log('start scroll page...')
  // 模拟用户滚动页面
  await page.evaluate(async () => {
    await new Promise(resolve => {
      let totalHeight = 0;
      let distance = 100;
      let timer = setInterval(() => {
        // #viewer
        const node = document.getElementById('viewer')
        let scrollHeight = node.scrollHeight;
        document.getElementById('viewerContainer').scrollBy(0, distance);
        totalHeight += distance;
        if (totalHeight >= scrollHeight) {
          clearInterval(timer);
          resolve();
        }
      }, 100);
    });
  });
  console.log('scroll page finished')

  console.log('wait for network idle')
  // 等待所有资源加载完成
  await page.waitForNetworkIdle({idleTime: 1000, timeout: 30 * 1000});
  console.log('wait for network finished')

  console.log('start task')
  // 获取指定的 DOM 元素
  const pages = await page.$$('.page');

  let number = 1
  for await (let element of pages) {
    // await page.evaluate((node) => node.scrollIntoView(), element)
    // 获取指定 DOM 元素在页面中的位置和尺寸
    const boundingBox = await element.boundingBox();
    console.log(page, boundingBox)
    // 截取指定区域的截图，并将截图保存到本地文件系统中
    const screenshotOptions = {
      path: `./dist/${number++}.png`,
      clip: {
        x: boundingBox.x,
        y: boundingBox.y,
        width: boundingBox.width,
        height: boundingBox.height
      }
    };
    // debug
    // await new Promise(resolve => process.stdin.once('data', resolve));
    await page.screenshot(screenshotOptions);
  }
  await browser.close();
})();