package civitas.common.mix.revelation;
   
   import java.math.BigInteger;
   import java.util.Arrays;
   
   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.stereotype.Controller;
   
   import civitas.common.mix.VoterMix;
  import civitas.common.mix.elementrevelation.MixElementRevelation;
  import civitas.common.mix.elementrevelation.VerifyMixElementRevelation;
  import civitas.crypto.messagedigest.CryptoHash;
  import civitas.crypto.publickey.ElGamalPublicKey;
  
  @Controller
  public class VerifyMixRevelation {
  	@Autowired
  	VerifyMixElementRevelation verifyMixElementRevelation;
  
  	@Autowired
  	CryptoHash cryptoHash;
  
  	public boolean apply(
  			final MixRevelation that,
  			final ElGamalPublicKey key,
  			final VoterMix initialMix,
  			final VoterMix leftMix,
  			final VoterMix rightMix,
  			final boolean[] revelationDirections) {
  		if (revelationDirections == null
  				|| that.revelations.length != revelationDirections.length
  				|| that.revelations.length != that.indicators.length) {
  			return false;
  		}
  
  		for (int i = 0; i < that.revelations.length; i++) {
  			if (revelationDirections[i] != that.indicators[i]) {
  				return false;
  			}
  
  			MixElementRevelation mer = that.revelations[i];
  			if (mer == null) {
  				return false;
  			}
  			int fromIndex = -1;
  			int toIndex = -1;
  			VoterMix fromMix = null;
  			VoterMix toMix = null;
  
  			if (revelationDirections[i]) {
  				// taken from the right
  				fromMix = leftMix;
  				toMix = rightMix;
  				fromIndex = i;
  				toIndex = mer.getMapping();
  			} else {
  				// taken from the left
  				fromMix = initialMix;
  				toMix = leftMix;
  				fromIndex = mer.getMapping();
  				toIndex = i;
  			}
  			byte[] commitment = toMix.getCommitments()[toIndex].clone();
  			byte[] mappingBytes = BigInteger.valueOf(mer.getMapping()).toByteArray();
  			byte[] hash = cryptoHash.apply(mer.getNonce(), mappingBytes);
  			if (!Arrays.equals(commitment, hash)
  					|| !verifyMixElementRevelation.apply(mer, key, fromIndex, toIndex, fromMix, toMix)) {
  				return false;
  			}
  		}
  
  		return true;
  	}
  }