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

async function compareBaseline() {
  const reportsDir = path.join(__dirname, 'reports');
  const baselinePath = path.join(reportsDir, 'baseline.json');
  const currentPath = path.join(reportsDir, 'current.json');
  
  const baselineThreshold = parseFloat(process.env.BASELINE_THRESHOLD) || 0.1;
  
  if (!fs.existsSync(baselinePath)) {
    console.log('No baseline found, creating initial baseline');
    createBaseline();
    return;
  }
  
  const baseline = JSON.parse(fs.readFileSync(baselinePath, 'utf8'));
  const current = JSON.parse(fs.readFileSync(currentPath, 'utf8'));
  
  const avgTimeChange = (current.avgResponseTime - baseline.avgResponseTime) / baseline.avgResponseTime;
  const successRateChange = current.successRate - baseline.successRate;
  
  console.log('\n=== Baseline Comparison ===');
  console.log(`Baseline Avg Response Time: ${baseline.avgResponseTime.toFixed(2)}ms`);
  console.log(`Current Avg Response Time: ${current.avgResponseTime.toFixed(2)}ms`);
  console.log(`Change: ${(avgTimeChange * 100).toFixed(2)}%`);
  console.log(`Baseline Success Rate: ${baseline.successRate.toFixed(2)}%`);
  console.log(`Current Success Rate: ${current.successRate.toFixed(2)}%`);
  console.log(`Change: ${successRateChange.toFixed(2)}%`);
  
  const passed = Math.abs(avgTimeChange) <= baselineThreshold && successRateChange >= -1;
  
  if (passed) {
    console.log('\n✓ Performance baseline check PASSED');
    process.exit(0);
  } else {
    console.log('\n✗ Performance baseline check FAILED');
    if (Math.abs(avgTimeChange) > baselineThreshold) {
      console.log(`  - Response time changed by ${(avgTimeChange * 100).toFixed(2)}% (threshold: ${baselineThreshold * 100}%)`);
    }
    if (successRateChange < -1) {
      console.log(`  - Success rate dropped by ${successRateChange.toFixed(2)}%`);
    }
    process.exit(1);
  }
}

function createBaseline() {
  const reportsDir = path.join(__dirname, 'reports');
  const baseline = {
    avgResponseTime: 100,
    successRate: 99.0,
    createdAt: new Date().toISOString()
  };
  
  if (!fs.existsSync(reportsDir)) {
    fs.mkdirSync(reportsDir, { recursive: true });
  }
  
  fs.writeFileSync(baselinePath, JSON.stringify(baseline, null, 2));
  console.log('Initial baseline created');
}

const baselinePath = path.join(__dirname, 'reports', 'baseline.json');
if (!fs.existsSync(baselinePath)) {
  createBaseline();
} else {
  compareBaseline();
}