package org.webslinger.servlet;

 import java.io.IOException;

 import javax.servlet.ServletException;

 import org.webslinger.collections.CollectionUtil;

 public final class ServletUtil {

     private ServletUtil() {

     }

     public static final <T> T checkException(Throwable t) throws IOException, ServletException {

         if (t instanceof IOException) throw (IOException) t;

         if (t instanceof ServletException) throw (ServletException) t;

         if (t instanceof RuntimeException) throw (RuntimeException) t;

         if (t instanceof Error) throw (Error) t;

         throw (ServletException) new ServletException(t.getMessage()).initCause(t);

     }

     public static String embedParameter(String path, String name, String value) {

         int question = path.indexOf("?");

         if (question == -1) return path + "?" + name + "=" + value;

         String[] params = path.substring(question + 1).split("\\&");

         String startMatch = name + "=";

         for (int i = 0; i < params.length; i++) {

             String param = params[i];

             if (param.startsWith(name) && param.length() > name.length() && param.charAt(name.length()) == '=') {

                 params[i] = name + "=" + value;

                 return path.substring(0, question) + "?" + CollectionUtil.join(params, "&");

             }

         }

         return path + "&" + name + "=" + value;

     }

 }