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import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import javax.ws.rs.HttpMethod;
import javax.ws.rs.core.MultivaluedMap;

import org.apache.cxf.jaxrs.ext.ResourceComparator;
import org.apache.cxf.jaxrs.model.ClassResourceInfo;
import org.apache.cxf.jaxrs.model.OperationResourceInfo;
import org.apache.cxf.jaxrs.model.OperationResourceInfoComparatorBase;
import org.apache.cxf.jaxrs.model.Parameter;
import org.apache.cxf.jaxrs.utils.HttpUtils;
import org.apache.cxf.jaxrs.util.JAXRSUtils;
import org.apache.cxf.message.Message;

public class QueryResourceInfoComparator extends OperationResourceInfoComparatorBase implements
         ResourceComparator {

     public QueryResourceInfoComperatorQueryResourceInfoComparator() {
     }

     @Override
     public int compare(ClassResourceInfo cri1, ClassResourceInfo cri2, Message message) {
         // Leave Class selection to CXF
         return 0;
     }

     @Override
     public int compare(OperationResourceInfo oper1, OperationResourceInfo oper2, Message message) {
         // HTTP method
         final String httpMethod = HttpUtils.getProtocolHeader(message, Message.HTTP_REQUEST_METHOD, HttpMethod.POST, true);
        
         // Check if CXF can make a decision
         final int cxfResult = compare(oper1, oper2, httpMethod);
         if (cxfResult != 0) {
             return cxfResult;
         }

         int op1Counter = getMatchingRate(oper1, message);
         int op2Counter = getMatchingRate(oper2, message);

         return op1Counter == op2Counter
                 ? 0
                 : op1Counter<  op2Counter
                         ? 1
                         : -1;
     }

     /**
      * This method calculates a number indicating a good or bad match between
      * values provided within the request and expected method parameters. A
      * higher number means a better match.
      *
      * @param operation
      *            The operation to be rated, based on contained parameterInfo
      *            values.
      * @param message
      *            A message containing query from user request
      * @return A positive or negative number, indicating a good match between
      *         query and method
      */
     protected int getMatchingRate(OperationResourceInfo operation, Message message) {

         List<Parameter>  params = operation.getParameters();
         if (params == null || params.size() == 0)
             return 0;

         // Get Request QueryParams
         Set<String>  qParams = getParams((String) message.get(Message.QUERY_STRING));

         int rate = 0;
         for (Parameter p : params) {
             switch (p.getType()) {
             case QUERY:
                 if (qParams.contains(p.getName()))
                     rate += 2;
                 else if (p.getDefaultValue() == null)
                     rate -= 1;
                 break;
             // optionally support other parameter types such as headers, etc
             // case HEADER:
             //  break;
             default:
                 break;
             }
         }
         return rate;
     }

     /**
      * @param query
      *            URL Query Example: 'key=value&key2=value2'
      * @return A Set of all keys, contained within query.
      */
     protected Set<String>  getParams(String query) {
         Set<String>  params = new HashSet<String>();
         if (query == null || query.length() == 0)
             return params;

         MultivaluedMap<String, String> allQueries =
             JAXRSUtils.getStructuredParams(query, "&", false, false);
         return allQueries.keySet();
     }
}