package org.doxla.spring.resource.util;

 import java.io.IOException;

 import org.springframework.core.io.Resource;

 import org.springframework.util.Assert;

 import org.springframework.util.StringUtils;

 public class ResouceToClassUtil {

         private static final String JAR_RESOURCE_PREFIX = "jar!";

         /**

          * Util class, non contructable

          */

         private ResouceToClassUtil(){}

         public static final Class resolveClassFromJarResouce(Resource resource) throws ClassNotFoundException{

                 Assert.isTrue(resource.exists(),"Resource didn't exist ["+resource.toString()+"]");

                 String resourcePath;

                 try {

                         resourcePath = resource.getURL().getPath();

                 } catch (IOException e) {

                         //why are these checked exceptions :(

                         throw new RuntimeException(e);

                 }

                 int jarIndex = resourcePath.indexOf(JAR_RESOURCE_PREFIX);

                 Assert.isTrue(jarIndex > 0,"Resource is not inside a jar");

                 // remove 'jar!/'

                 resourcePath = resourcePath.substring(jarIndex + JAR_RESOURCE_PREFIX.length() + 1);

                 resourcePath = resourcePath.replaceAll("\\.class", "");

                 String className = resourcePath.replaceAll(getDirectorySeparatorPattern(resourcePath),".");                                

                 Assert.isTrue(StringUtils.hasLength(className),"couldn't resolve classname from String "+resourcePath);

                 Class clazz = Class.forName(className);

                 return clazz;

         }

         // DIRTY

         private static final String getDirectorySeparatorPattern(String path) {

                 if(path.contains("/")) return "/";

                 else return "\\\\";

         }        

 }