/*

  * Copyright 2012-2013 smartics, Kronseder & Reiner GmbH

  *

  * Licensed under the Apache License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  *

  *     http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 package de.smartics.properties.spi.config.support;

 import java.io.IOException;

 import java.net.MalformedURLException;

 import java.net.URL;

 import java.util.Collections;

 import java.util.Enumeration;

 import java.util.LinkedList;

 import org.slf4j.Logger;

 import org.slf4j.LoggerFactory;

 /**

  * Utiliy methody regarding Classloader URLs.

  */

 public final class UrlUtil

 {

   // ********************************* Fields *********************************

   // --- constants ------------------------------------------------------------

   /**

    * Reference to the logger for this class.

    */

   private static final Logger LOG = LoggerFactory.getLogger(UrlUtil.class);

   // --- members --------------------------------------------------------------

   // ****************************** Initializer *******************************

   // ****************************** Constructors ******************************

   // ****************************** Inner Classes *****************************

   // ********************************* Methods ********************************

   // --- init -----------------------------------------------------------------

   // --- get&set --------------------------------------------------------------

   // --- business -------------------------------------------------------------

   // --- object basics --------------------------------------------------------

   /**

    * Get all resourceURLs of the given class loader.

    *

    * @param classLoader the class loader from which all resource URLs shall be

    *          fetched.

    *

    * @return the enumeration of resource URLs of the given class loader.

    * @throws IOException when the URL can not be retrieved.

    */

   public static Enumeration<URL> getResourceUrlsFromFolder(

       final ClassLoader classLoader, final String resourceFolderName)

     throws IOException

   {

     return getResourceUrls(classLoader, resourceFolderName.endsWith("/")

         ? resourceFolderName : resourceFolderName + "/");

   }

   /**

    * Get all resourceURLs of the given class loader.

    *

    * @param classLoader the class loader from which all resource URLs shall be

    *          fetched.

    * @return the enumeration of resource URLs of the given class loader.

    * @throws IOException when the URL can not be retrieved.

    */

   public static Enumeration<URL> getResourceUrls(final ClassLoader classLoader,

       final String resourceName) throws IOException

   {

     final Enumeration<URL> rootUrls = classLoader.getResources(resourceName);

     final LinkedList<URL> rootResourceUrls = new LinkedList<URL>();

     while (rootUrls.hasMoreElements())

     {

       final URL current = rootUrls.nextElement();

       rootResourceUrls.add(shortenUrl(current, resourceName));

     }

     return Collections.enumeration(rootResourceUrls);

   }

   public static URL shortenUrl(final URL current, final String resourceName)

     throws MalformedURLException

   {

     final String path = current.getPath();

     String strippedPath =

         path.substring(0, path.length() - resourceName.length());

     strippedPath = ensureEndsWith(strippedPath, "/");

     final URL stripped;

     try

     {

       if ("jar".equals(current.getProtocol()))

       {

         stripped =

             new URL("jar:" + new URL(current, strippedPath).toExternalForm());

       }

       else

       {

         stripped = new URL(current, strippedPath);

       }

     }

     catch (final MalformedURLException e)

     {

       LOG.warn("Cannot use URL '{}' in its truncated form '{}'.", current,

           strippedPath);

       return current;

     }

     return stripped;

   }

   private static String ensureEndsWith(final String inputString,

       final String endsWith)

   {

     String ensuredString = inputString;

     if (!ensuredString.endsWith(endsWith))

     {

       ensuredString += endsWith;

     }

     return ensuredString;

   }

 }