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

// Function to hash a file using streams
function hashFile(filePath, algorithm) {
  return new Promise((resolve, reject) => {
    // Create hash object
    const hash = crypto.createHash(algorithm);
    
    // Create read stream
    const stream = fs.createReadStream(filePath);
    
    // Handle stream events
    stream.on('data', (data) => {
      hash.update(data);
    });
    
    stream.on('end', () => {
      const digest = hash.digest('hex');
      resolve(digest);
    });
    
    stream.on('error', (error) => {
      reject(error);
    });
  });
}

// Example usage (adjust file path as needed)
const filePath = 'example.txt';

// Create a test file if it doesn't exist
if (!fs.existsSync(filePath)) {
  fs.writeFileSync(filePath, 'This is a test file for hashing.\n'.repeat(100));
  console.log(`Created test file: ${filePath}`);
}

// Hash the file with different algorithms
Promise.all([
  hashFile(filePath, 'md5'),
  hashFile(filePath, 'sha1'),
  hashFile(filePath, 'sha256')
])
.then(([md5Digest, sha1Digest, sha256Digest]) => {
  console.log(`File: ${filePath}`);
  console.log(`MD5: ${md5Digest}`);
  console.log(`SHA-1: ${sha1Digest}`);
  console.log(`SHA-256: ${sha256Digest}`);
})
.catch(error => {
  console.error('Error hashing file:', error.message);
});