/*

  * 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 org.apache.commons.classscan.builtin;

 import java.util.regex.Matcher;

 import java.util.regex.Pattern;

 /**

  * Classname helper methods

  */

 public final class ClassNameHelper {

         private ClassNameHelper() {

         }

     private static final String IDENTIFIER_REGEX = "\\p{javaJavaIdentifierStart}\\p{javaJavaIdentifierPart}*";

     private static final String FILE_REGEX = "(" + IDENTIFIER_REGEX + ")\\.class";

     private static final String PATH_REGEX = "((" + IDENTIFIER_REGEX + "/)*)" + FILE_REGEX;

     private static Pattern pathPattern = Pattern.compile(PATH_REGEX);

     /**

      * Check if supplied path name is a valid pathed file name. The path must

      * contain valid package names, the file name must be a valid Class name,

      * and must be followed by ".class"

      * 

      * @param path

      *            A file name with path

      * @return The class name without the trailing ".class", with the dotted

      *         package prefix, or null if the supplied filename is invalid

      */

     public static String getCannonicalClassNameFromPathName(String path) {

         Matcher m = pathPattern.matcher(path);

         if (m.matches()) {

             String packagePrefix = m.group(1).replace('/', '.');

             String className = m.group(3);

             return packagePrefix + className;

         }

         else {

             return null;

         }

     }

     private static Pattern IDENTIFIER_PACKAGE = Pattern.compile(IDENTIFIER_REGEX);

     /**

      * Check if supplied name is a valid java package name portion or class

      * identifier.

      * 

      * @param identifier

      *            The name of a package file

      * @return true if the identifier is a valid part of a package or class name

      */

     public static boolean isValidIdentifier(String identifier) {

         Matcher ipm = IDENTIFIER_PACKAGE.matcher(identifier);

         return ipm.matches();

     }

     private static Pattern filePattern = Pattern.compile(FILE_REGEX);

     /**

      * Check if supplied file name is a valid class file name. The name must be

      * a valid Class name followed by ".class"

      * 

      * @param fileName

      *            The name of a file (without path)

      * @return The class name without the trailing ".class", or null if the

      *         supplied filename is invalid

      */

     public static String getClassNameFromFileName(String fileName) {

         Matcher fpm = filePattern.matcher(fileName);

         if (fpm.matches()) {

             return fpm.group(1);

         }

         else {

             return null;

         }

     }

     /**

      * Get the canonical name from the internal name

      * 

      * @param internalName

      *            The internal name in the form Ljava/lang/Object;

      * @return The canonical name in the form java.lang.Object

      */

     public static String internalToCanonicalName(String internalName) {

         return internalName.substring(1, internalName.length() - 1).replace('/', '.');

     }

 }