const fs = require('fs');
const path = require('path');
const readline = require('readline');
const puppeteer = require('puppeteer');
const os = require('os');

let browserPromise = null;
let userDataDir = null;

function chromeTmpRoot() {
  return process.env.CHROMIUM_TMP || (fs.existsSync('/dev/shm') ? '/dev/shm/chartpipeline_chromium' : path.join(os.tmpdir(), 'chartpipeline_chromium'));
}

function getBrowser() {
  if (!browserPromise) {
    const baseTmp = chromeTmpRoot();
    fs.mkdirSync(baseTmp, { recursive: true });
    const cacheDir = path.join(baseTmp, 'cache');
    const mediaCacheDir = path.join(baseTmp, 'media_cache');
    const crashDir = path.join(baseTmp, 'crash');
    fs.mkdirSync(cacheDir, { recursive: true });
    fs.mkdirSync(mediaCacheDir, { recursive: true });
    fs.mkdirSync(crashDir, { recursive: true });
    userDataDir = fs.mkdtempSync(path.join(baseTmp, 'puppeteer_profile_'));

    const launchOpts = {
      headless: 'new',
      args: [
        '--no-sandbox',
        '--disable-setuid-sandbox',
        `--user-data-dir=${userDataDir}`,
        `--disk-cache-dir=${cacheDir}`,
        `--media-cache-dir=${mediaCacheDir}`,
        `--crash-dumps-dir=${crashDir}`
      ]
    };
    if (process.env.PUPPETEER_EXECUTABLE_PATH) {
      launchOpts.executablePath = process.env.PUPPETEER_EXECUTABLE_PATH;
    }
    browserPromise = puppeteer.launch(launchOpts);
  }
  return browserPromise;
}

async function waitSvgReady(page) {
  const svgReady = () => page.evaluate(() => {
    const hasReadySvg = (svg) => {
      if (!svg || svg.childNodes.length === 0) return false;
      return svg.querySelectorAll('path, circle, rect, g, text').length > 0;
    };

    const chartSvg = document.querySelector('#chart-container svg');
    if (hasReadySvg(chartSvg)) return true;

    for (const selector of ['#svg-output', '#manual-svg-output']) {
      const output = document.querySelector(selector);
      if (output && output.innerHTML.trim() && output.querySelector('svg')) return true;
    }
    return false;
  });

  const waitStart = Date.now();
  while (Date.now() - waitStart < 3000 && !(await svgReady())) {
    await new Promise(resolve => setTimeout(resolve, 100));
  }
}

async function extractSvgContent(page, outputSvg, width, height) {
  const isECharts = await page.evaluate(() => typeof echarts !== 'undefined');
  let svgContent = null;

  if (isECharts) {
    svgContent = await page.evaluate(() => {
      const svgOutput = document.querySelector('#svg-output');
      return svgOutput ? svgOutput.innerHTML : null;
    });
  }

  if (!svgContent) {
    svgContent = await page.evaluate(() => {
      const container = document.querySelector('#chart-container');
      if (!container) return null;

      const hasGraphicElements = (svg) => (
        svg && svg.childNodes.length > 0 &&
        svg.querySelectorAll('path, circle, rect, g, text, line, polygon, polyline, ellipse, image').length > 0
      );
      const svgElement = Array.from(container.querySelectorAll('svg')).find(hasGraphicElements);
      if (!svgElement || svgElement.childNodes.length === 0) return null;

      if (typeof echarts !== 'undefined') {
        const chart = echarts.getInstanceByDom(container);
        if (chart) chart.setOption({ animation: false });
      }

      const svgClone = svgElement.cloneNode(true);
      if (!svgClone.hasAttribute('width')) {
        svgClone.setAttribute('width', container.clientWidth);
      }
      if (!svgClone.hasAttribute('height')) {
        svgClone.setAttribute('height', container.clientHeight);
      }
      if (!svgClone.hasAttribute('viewBox')) {
        svgClone.setAttribute('viewBox', `0 0 ${container.clientWidth} ${container.clientHeight}`);
      }
      return svgClone.outerHTML;
    });
  }

  if (!svgContent) {
    await new Promise(resolve => setTimeout(resolve, 500));
    const pngPath = outputSvg.replace('.svg', '.png');
    await page.screenshot({ path: pngPath, fullPage: true });
    const pngFileName = path.basename(pngPath);
    svgContent = `<svg width="${width}" height="${height}" xmlns="http://www.w3.org/2000/svg">
      <title>Chart (Fallback)</title>
      <desc>This is a fallback SVG using a PNG screenshot.</desc>
      <image href="${pngFileName}" width="${width}" height="${height}" />
    </svg>`;
  }

  return svgContent;
}

async function render(req) {
  const browser = await getBrowser();
  const page = await browser.newPage();
  try {
    await page.setViewport({ width: req.width, height: req.height });
    await page.goto('file://' + path.resolve(req.htmlFile), {
      waitUntil: 'networkidle0',
      timeout: 60000
    });
    await waitSvgReady(page);
    const svgContent = await extractSvgContent(page, req.outputSvg, req.width, req.height);
    if (!svgContent) {
      throw new Error('SVG content is empty');
    }
    fs.writeFileSync(req.outputSvg, svgContent);
    return { id: req.id, ok: true };
  } finally {
    await page.close();
  }
}

const rl = readline.createInterface({ input: process.stdin });

rl.on('line', (line) => {
  if (!line.trim()) return;
  const req = JSON.parse(line);
  render(req)
    .then(resp => process.stdout.write(JSON.stringify(resp) + '\n'))
    .catch(error => {
      process.stdout.write(JSON.stringify({
        id: req.id,
        ok: false,
        error: error && error.stack ? error.stack : String(error)
      }) + '\n');
    });
});

async function shutdown() {
  if (browserPromise) {
    const browser = await browserPromise;
    await browser.close();
  }
  if (userDataDir) {
    fs.rmSync(userDataDir, { recursive: true, force: true });
  }
  process.exit(0);
}

process.on('SIGTERM', shutdown);
process.on('SIGINT', shutdown);