package civitas.crypto.messagedigest;
   
   import java.security.MessageDigest;
   import java.security.NoSuchAlgorithmException;
   import java.util.Arrays;
   import java.util.List;
   import java.util.Objects;
   import java.util.stream.Stream;
   
  import org.springframework.stereotype.Service;
  
  import civitas.crypto.Constants;
  import civitas.crypto.CryptoError;
  import civitas.util.CivitasBigInteger;
  import civitas.util.CivitasBigIntegerFactory;
  import civitas.util.CivitasBigintegerBase;
  
  @Service
  public class CryptoHash implements Constants {
  
  	MessageDigest messageDigest;
  
  	CryptoHash() {
  		try {
  			messageDigest = MessageDigest.getInstance(MESSAGE_DIGEST_ALG);
  		} catch (NoSuchAlgorithmException e) {
  			throw new CryptoError(e);
  		}
  	}
  
  	public byte[] apply(final List<CivitasBigInteger> list) {
  		return apply(list.stream()
  				.filter(Objects::nonNull)
  				.map(CivitasBigintegerBase::toByteArray)
  				.toList()
  				.toArray(new byte[0][0]));
  	}
  
  	public CivitasBigInteger apply(
  			final CivitasBigInteger a, final CivitasBigInteger b, final CivitasBigInteger c, final byte[] d) {
  		Stream<byte[]> bigintStream =
  				Stream.of(a, b, c).filter(Objects::nonNull).map(CivitasBigintegerBase::toByteArray);
  		List<byte[]> nums = Stream.concat(bigintStream, Stream.of(d)).toList();
  		return CivitasBigIntegerFactory.obtain(apply(nums.toArray(new byte[0][0])));
  	}
  
  	public byte[] apply(final byte[]... bytearrays) {
  		Arrays.asList(bytearrays).forEach(x -> {
  			if (null != x) {
  				messageDigest.update(x);
  			}
  		});
  		return messageDigest.digest();
  	}
  }