package com.atlassian.plugins.rest.sample.expansion;
   
   import org.apache.commons.lang.StringUtils;
   
   import java.net.URI;
   import java.net.URISyntaxException;
   import java.util.*;
   
   public class UriBuilder
  {
      private static final String CONTEXT_SYSTEM_PROPERTY = "context.path";
      private static final String HTTP_PORT_SYSTEM_PROPERTY = "http.port";
      private static final int DEFAULT_HTTP_PORT = 0;
  
      private final static String CONTEXT;
      private final static int HTTP_PORT;
  
      static
      {
          CONTEXT = System.getProperty(CONTEXT_SYSTEM_PROPERTY);
          HTTP_PORT = Integer.valueOf(System.getProperty(HTTP_PORT_SYSTEM_PROPERTY, String.valueOf(DEFAULT_HTTP_PORT)));
  
          if (CONTEXT == null || HTTP_PORT == DEFAULT_HTTP_PORT)
          {
              throw new IllegalStateException(CONTEXT_SYSTEM_PROPERTY + " or " + HTTP_PORT_SYSTEM_PROPERTY + " not set!");
          }
      }
  
      private final List<String> paths = new LinkedList<String>();
      private Map<String,String> params = new HashMap<String,String>();
  
      private UriBuilder()
      {
      }
  
      public static UriBuilder create()
      {
          return new UriBuilder();
      }
  
      public UriBuilder path(String path)
      {
          paths.add(path);
          return this;
      }
  
      public URI build()
      {
          try
          {
              return new URI("http", null, "localhost", HTTP_PORT, buildPath(), buildQuery(), buildFragment());
          }
          catch (URISyntaxException e)
          {
              // will not happen
              return null;
          }
      }
  
      private String buildPath()
      {
          final StringBuilder path = new StringBuilder(paths.size() * 8);
          if (StringUtils.isNotBlank(CONTEXT))
          {
              path.append(CONTEXT).append("/");
          }
          for (String element : paths)
          {
              path.append(element).append("/");
          }
          if (path.charAt(0) != '/')
          {
              path.insert(0, '/');
          }
          return path.toString();
      }
  
      private String buildQuery()
      {
          final StringBuilder query = new StringBuilder();
          for (Iterator<Map.Entry<String, String>> iterator = params.entrySet().iterator(); iterator.hasNext();)
          {
              Map.Entry<String, String> entry = iterator.next();
              query.append(entry.getKey());
              query.append("=");
              query.append(entry.getValue());
              if(iterator.hasNext())
                  query.append("&");
          }
          return query.toString();
      }
  
      private String buildFragment()
      {
          return null;
      }
  
      public UriBuilder param(String param, String value)
      {
         params.put(param,value);
         return this;
     }
 }