#!/usr/bin/env node
/**
 * Render a .drawio file to PNG via a real draw.io instance (embed.diagrams.net),
 * driven headlessly with Puppeteer -- this is an actual render, not an
 * approximation, so switch icons, patch panel styling, and port labels all
 * come out exactly as they'd look opening the file in the app.
 *
 * Needs `npm install puppeteer` first (downloads its own Chromium; not the
 * system browser). Needs network access to embed.diagrams.net.
 *
 * Usage:
 *   node render_png.js Field-Switch-Topology.drawio Field-Switch-Topology.png
 */
const puppeteer = require('puppeteer');
const fs = require('fs');
const path = require('path');

const xmlPath = process.argv[2];
const outPath = process.argv[3];
if (!xmlPath || !outPath) {
  console.error('usage: node render_png.js <in.drawio> <out.png>');
  process.exit(1);
}
const xml = fs.readFileSync(xmlPath, 'utf8');

(async () => {
  const browser = await puppeteer.launch({
    headless: 'new',
    args: ['--no-sandbox', '--disable-setuid-sandbox'],
  });
  const page = await browser.newPage();
  await page.setViewport({ width: 1700, height: 1300 });
  page.on('pageerror', (err) => console.error('PAGE ERROR:', err));

  await page.evaluateOnNewDocument((x) => { window.__XML__ = x; }, xml);
  await page.goto('file://' + path.join(__dirname, 'render_host.html'), {
    waitUntil: 'load',
    timeout: 30000,
  });

  let dataUrl = null;
  const deadline = Date.now() + 60000;
  while (Date.now() < deadline) {
    dataUrl = await page.evaluate(() => window.__RESULT__);
    const err = await page.evaluate(() => window.__ERR__);
    if (err) throw new Error('draw.io export error: ' + err);
    if (dataUrl) break;
    await new Promise((r) => setTimeout(r, 500));
  }
  if (!dataUrl) throw new Error('timed out waiting for draw.io to export (network to embed.diagrams.net?)');

  const base64 = dataUrl.split(',')[1];
  fs.writeFileSync(outPath, Buffer.from(base64, 'base64'));
  console.log('wrote', outPath, fs.statSync(outPath).size, 'bytes');
  await browser.close();
})().catch((e) => { console.error(e); process.exit(1); });