package usecase.auth;
   
   import javax.crypto.SecretKeyFactory;
   import javax.crypto.spec.PBEKeySpec;
   import java.io.Serializable;
   import java.security.NoSuchAlgorithmException;
   import java.security.SecureRandom;
   import java.security.spec.InvalidKeySpecException;
   import java.security.spec.KeySpec;
  import java.util.Arrays;
  
  /**
   * Classe dedicata alla sicurezza delle password.
   */
  public class Pbkdf2PasswordHash implements Serializable {
      public HashedPassword generate(String password, byte[] salt){
          try {
              KeySpec spec = new PBEKeySpec(password.toCharArray(), salt, 65536, 128);
              SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
              byte[] hash = factory.generateSecret(spec).getEncoded();
  
              return new HashedPassword(hash, salt);
          } catch (InvalidKeySpecException | NoSuchAlgorithmException e) {
              throw new RuntimeException(e);
          }
      }
  
      public HashedPassword generate(String password){
          return generate(password, generateSalt());
      }
  
      public boolean verify(String password, byte[] hashedPassword, byte[] salt){
          return verify(password, new HashedPassword(hashedPassword, salt));
      }
  
      public boolean verify(String password, HashedPassword hashedPassword){
          return hashedPassword.equals(generate(password, hashedPassword.getSalt()));
      }
  
      private static byte[] generateSalt(){
          SecureRandom ss = new SecureRandom();
          byte[] salt = new byte[16];
          ss.nextBytes(salt);
          return salt;
      }
  
      public static class HashedPassword{
          private byte[] password;
          private byte[] salt;
  
          private HashedPassword(byte[] password, byte[] salt) {
              this.password = password;
              this.salt = salt;
          }
  
          public byte[] getPassword() {
              return password;
          }
  
          public byte[] getSalt() {
              return salt;
          }
  
          @Override
          public boolean equals(Object o) {
              if (this == o) return true;
              if (o == null || getClass() != o.getClass()) return false;
              HashedPassword that = (HashedPassword) o;
              return Arrays.equals(password, that.password) && Arrays.equals(salt, that.salt);
          }
      }
  }