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

/**
 * Generate a secure JWT secret key
 */
function generateJWTSecret(length = 64) {
  return crypto.randomBytes(length).toString('hex');
}

/**
 * Generate multiple secrets for different purposes
 */
function generateSecrets() {
  return {
    jwt_secret: generateJWTSecret(64),
    refresh_token_secret: generateJWTSecret(64),
    session_secret: generateJWTSecret(32)
  };
}

/**
 * Update .env file with generated JWT secret
 */
function updateEnvFile() {
  const envPath = path.join(__dirname, '.env');
  const envExamplePath = path.join(__dirname, '.env.example');
  
  console.log('\n🔐 Generating Secure JWT Secret...\n');
  
  const secrets = generateSecrets();
  
  console.log('Generated Secrets:');
  console.log('━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━');
  console.log('JWT_SECRET:', secrets.jwt_secret.substring(0, 20) + '...');
  console.log('Length:', secrets.jwt_secret.length, 'characters');
  console.log('━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\n');
  
  try {
    // Read current .env file
    let envContent = fs.readFileSync(envPath, 'utf8');
    
    // Update JWT_SECRET
    envContent = envContent.replace(
      /JWT_SECRET=.*/,
      `JWT_SECRET=${secrets.jwt_secret}`
    );
    
    // Write back to .env
    fs.writeFileSync(envPath, envContent);
    
    console.log('✅ JWT_SECRET updated in .env file\n');
    
    // Also update .env.example with a placeholder
    if (fs.existsSync(envExamplePath)) {
      let exampleContent = fs.readFileSync(envExamplePath, 'utf8');
      exampleContent = exampleContent.replace(
        /JWT_SECRET=.*/,
        `JWT_SECRET=your_generated_secret_key_here_change_in_production`
      );
      fs.writeFileSync(envExamplePath, exampleContent);
      console.log('✅ .env.example updated with placeholder\n');
    }
    
    console.log('⚠️  IMPORTANT: Keep your JWT secret secure!');
    console.log('   - Never commit .env to version control');
    console.log('   - Use different secrets for different environments');
    console.log('   - Rotate secrets periodically in production\n');
    
    return secrets;
  } catch (error) {
    console.error('❌ Error updating .env file:', error.message);
    console.log('\nManually add this to your .env file:');
    console.log(`JWT_SECRET=${secrets.jwt_secret}\n`);
    return null;
  }
}

// Run if called directly
if (require.main === module) {
  updateEnvFile();
}

module.exports = {
  generateJWTSecret,
  generateSecrets,
  updateEnvFile
};