package org.kuali.kpme.edo.util;
   
   /**
    * $HeadURL$
    * $Revision$
    * Created with IntelliJ IDEA.
    * User: bradleyt
    * Date: 3/13/13
    * Time: 8:20 AM
   */
  import java.util.*;
  import java.net.URLEncoder;
  import java.net.URLDecoder;
  
  public class QueryParams {
      private static class KVP {
          final String key;
          final String value;
          KVP (String key, String value) {
              this.key = key;
              this.value = value;
          }
      }
  
      List<KVP> query = new ArrayList<KVP>();
  
      public QueryParams(String queryString) {
          parse(queryString);
      }
  
      public QueryParams() {
      }
  
      public void addParam(String key, String value) {
          if (key == null || value == null)
              throw new NullPointerException("null parameter key or value");
          query.add(new KVP(key, value));
      }
  
      private void parse(String queryString) {
          for (String pair : queryString.split("&")) {
              int eq = pair.indexOf("=");
              if (eq < 0) {
                  // key with no value
                  addParam(URLDecoder.decode(pair), "");
              } else {
                  // key=value
                  String key = URLDecoder.decode(pair.substring(0, eq));
                  String value = URLDecoder.decode(pair.substring(eq + 1));
                  query.add(new KVP(key, value));
              }
          }
      }
  
      public String toQueryString() {
          StringBuilder sb = new StringBuilder();
          for (KVP kvp : query) {
              if (sb.length() > 0) {
                  sb.append('&');
              }
              sb.append(URLEncoder.encode(kvp.key));
              if (!kvp.value.equals("")) {
                  sb.append('=');
                  sb.append(URLEncoder.encode(kvp.value));
              }
          }
          return sb.toString();
      }
  
      public String getParameter(String key) {
          for (KVP kvp : query) {
              if (kvp.key.equals(key)) {
                  return kvp.value;
              }
          }
          return null;
      }
  
      public List<String> getParameterValues(String key) {
          List<String> list = new LinkedList<String>();
          for (KVP kvp : query) {
              if (kvp.key.equals(key)) {
                  list.add(kvp.value);
              }
          }
          return list;
      }
  
      public static void main(String[] args) {
          QueryParams qp = new QueryParams("k1=v1&k2&k3=v3&k1=v4&k1&k5=hello+%22world");
          System.out.println("getParameter:");
          String[] keys = new String[] { "k1", "k2", "k3", "k5" };
          for (String key : keys) {
              System.out.println(key + ": " + qp.getParameter(key));
          }
          System.out.println("getParameters(k1): " + qp.getParameterValues("k1"));
      }
  }