package com.atlassian.plugins.rest.sample.entities;
   
   import org.apache.commons.lang.StringUtils;
   
   import java.net.URI;
   import java.net.URISyntaxException;
   import java.util.LinkedList;
   import java.util.List;
   
  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 static final String CONTEXT;
      private static final 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 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() {
          return null;
      }
  
      private String buildFragment() {
          return null;
      }
  }