const lighthouse = require('lighthouse');
const chromeLauncher = require('chrome-launcher');
const fs = require('fs');
const path = require('path');

async function runLighthouse(url, options = {}) {
  const chrome = await chromeLauncher.launch({ chromeFlags: ['--headless'] });
  options.port = chrome.port;

  const runnerResult = await lighthouse(url, options);
  await chrome.kill();

  return runnerResult;
}

function generateReport(result, outputPath) {
  const reportHtml = result.report;
  fs.writeFileSync(outputPath, reportHtml);
  return outputPath;
}

function extractMetrics(result) {
  const categories = result.reportCategories;
  return {
    performance: categories.performance?.score * 100 || 0,
    accessibility: categories.accessibility?.score * 100 || 0,
    bestPractices: categories['best-practices']?.score * 100 || 0,
    seo: categories.seo?.score * 100 || 0,
    pwa: categories.pwa?.score * 100 || 0
  };
}

module.exports = { runLighthouse, generateReport, extractMetrics };