package org.oxerr.okcoin.rest;
   
   import static java.lang.String.format;
   import static java.nio.charset.StandardCharsets.UTF_8;
   
   import java.security.MessageDigest;
   import java.security.NoSuchAlgorithmException;
   import java.util.Map;
   import java.util.TreeMap;
  
  import javax.ws.rs.FormParam;
  
  import org.knowm.xchange.utils.DigestUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import si.mazi.rescu.Params;
  import si.mazi.rescu.ParamsDigest;
  import si.mazi.rescu.RestInvocation;
  
  /**
   * {@link ParamsDigest} implementation.
   */
  public class OKCoinDigest implements ParamsDigest {
  
  	private final Logger log = LoggerFactory.getLogger(OKCoinDigest.class);
  
  	private final String secretKey;
  	private final MessageDigest md;
  
  	public OKCoinDigest(String secretKey) {
  		this.secretKey = secretKey;
  		try {
  			this.md = MessageDigest.getInstance("MD5");
  		} catch (NoSuchAlgorithmException e) {
  			throw new RuntimeException(e);
  		}
  	}
  
  	/**
  	 * {@inheritDoc}
  	 */
  	@Override
  	public String digestParams(RestInvocation restInvocation) {
  		return digestParams(restInvocation.getParamsMap().get(FormParam.class).asHttpHeaders());
  	}
  
  	public String digestParams(Map<String, String> parameters) {
  		Params params = Params.of();
  
  		new TreeMap<>(parameters)
  				.entrySet()
  				.stream()
  				.filter(e -> !e.getKey().equals("sign"))
  				.forEach(e -> params.add(e.getKey(), e.getValue()));
  
  		String payload = format("%s&secret_key=%s", params.toString(), secretKey);
  		log.trace("payload: {}", payload);
  
  		return DigestUtils.bytesToHex(md.digest(payload.getBytes(UTF_8)));
  	}
  
  }