package org.oxerr.peatio.rest.service;
   
   import java.lang.annotation.Annotation;
   import java.lang.reflect.Field;
   import java.nio.charset.StandardCharsets;
   import java.util.Map;
   import java.util.SortedMap;
   import java.util.TreeMap;
   
  import javax.crypto.Mac;
  import javax.ws.rs.FormParam;
  import javax.ws.rs.QueryParam;
  import javax.ws.rs.core.UriBuilder;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import si.mazi.rescu.Params;
  import si.mazi.rescu.ParamsDigest;
  import si.mazi.rescu.RestInvocation;
  
  import com.xeiam.xchange.service.BaseParamsDigest;
  import com.xeiam.xchange.utils.DigestUtils;
  
  /**
   * {@link ParamsDigest} implementation for Peatio.
   */
  public class PeatioDigest extends BaseParamsDigest {
  
  	private final Logger log = LoggerFactory.getLogger(PeatioDigest.class);
  	private final Field invocationUrlField;
  
  	public PeatioDigest(String secretKey)
  			throws IllegalArgumentException {
  		super(secretKey, HMAC_SHA_256);
  
  		try {
  			invocationUrlField = RestInvocation.class.getDeclaredField("invocationUrl");
  			invocationUrlField.setAccessible(true);
  		} catch (NoSuchFieldException | SecurityException e) {
  			throw new RuntimeException(e);
  		}
  	}
  
  	/**
  	 * {@inheritDoc}
  	 */
  	@Override
  	public String digestParams(RestInvocation restInvocation) {
  		final String verb = restInvocation.getHttpMethod();
  		final String uri = restInvocation.getPath();
  		final String query = getSortedParams(restInvocation);
  
  		final String payload = String.join("|", verb, uri, query);
  		log.debug("payload: {}", payload);
  
  		String signature = sign(payload);
  
  		// Seems rescu does not support ParamsDigest in QueryParam.
  		// hack to replace the signature in the invocation URL.
  		String invocationUrl = restInvocation.getInvocationUrl();
  		log.debug("old invocationUrl: {}", invocationUrl);
  		String newInvocationUrl = UriBuilder.fromUri(invocationUrl).replaceQueryParam("signature", signature).build().toString();
  		try {
  			invocationUrlField.set(restInvocation, newInvocationUrl);
  		} catch (IllegalArgumentException | IllegalAccessException e) {
  			throw new RuntimeException(e);
  		}
  		log.debug("new invocationUrl: {}", restInvocation.getInvocationUrl());
  
  		return signature;
  	}
  
  	public String sign(String payload) {
  		Mac mac = getMac();
  		byte[] hash = mac.doFinal(payload.getBytes(StandardCharsets.UTF_8));
  		String signature = DigestUtils.bytesToHex(hash).toLowerCase();
  		return signature;
  	}
  
  	private String getSortedParams(RestInvocation restInvocation) {
  		final Map<Class<? extends Annotation>, Params> paramsMap = restInvocation.getParamsMap();
  
  		final Params queryParams = paramsMap.get(QueryParam.class);
  		final Params formParams = paramsMap.get(FormParam.class);
  
  		final SortedMap<String, String> sortedQueryParams = new TreeMap<>();
  		sortedQueryParams.putAll(queryParams.asHttpHeaders());
  		sortedQueryParams.putAll(formParams.asHttpHeaders());
  
  		final Params sortedParams = Params.of();
  		for (Map.Entry<String, String> param : sortedQueryParams.entrySet()) {
  			if (!param.getKey().equals("signature")) {
  				sortedParams.add(param.getKey(), param.getValue());
  			}
  		}
  
  		return sortedParams.asQueryString();
  	}
 
 }