/*

  * 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 CODITIONS 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.io.File;

 import java.util.Collection;

 import java.util.Iterator;

 import org.apache.commons.classscan.ClassFile;

 import org.apache.commons.classscan.ResourceFile;

 import org.apache.commons.classscan.spi.model.SpiClassPathElement;

 import org.apache.commons.classscan.spi.model.SpiMetaRegistry;

 public class FileClassPathElement implements SpiClassPathElement {

         private final File baseLocation;

         FileClassPathElement(File baseLocation) {

                 this.baseLocation= baseLocation;

         }

         private static class FileCursor {

                 final private FileCursor prior;

                 final private File[] files;

                 private int fileIdx;

                 private final int priorLength;

                 private final StringBuilder sb;

                 FileCursor(FileCursor prior, File dir, StringBuilder sb) {

                         this.prior = prior;

                         files= dir.listFiles();

                         this.sb = sb;

                         if(prior!=null) {

                                 sb.append('/');

                         }

                         priorLength = sb.length();

                 }

                 File nextFile() {

                         if(fileIdx==files.length) {

                                 return null;

                         }

                         File file = files[fileIdx++];

                         sb.setLength(priorLength);

                         sb.append(file.getName());

                         return file;

                 }

                 FileCursor pop() {

                         return prior;

                 }

         }

         @Override

         public Iterator<ClassFile> iterator() {        

                 return new ClassFileIterator() {

                         StringBuilder sb = new StringBuilder();

                         FileCursor cursor= new FileCursor(null, baseLocation, sb);

                         ClassFile getNext() {

                                 for(;;) {

                                         File file = cursor.nextFile();

                                         if(file == null) {

                                                 cursor = cursor.pop();

                                                 if(cursor==null) {

                                                         return null;

                                                 }

                                                 continue;

                                         }

                                         String path = sb.toString();

                                         if(file.isDirectory()) {

                                                 String fileName = file.getName();

                                                 if( ClassNameHelper.isValidIdentifier(fileName) ) {

                                                         cursor= new FileCursor(cursor, file, sb);

                                                 }

                                                 continue;

                                         }

                                         if(file.canRead()) {

                                                 String className= ClassNameHelper.getClassNameFromFileName(file.getName());

                                                 if(className!=null) {

                                                         return new FileClassFile(file, path);

                                                 }

                                                 continue;

                                         }

                                 }

                         }

                 };

         }

         @Override

         public String getLocation() {

                 return baseLocation.toURI().toString();

         }

         @Override

         public Collection<SpiClassPathElement> getAdditionalLocations(SpiMetaRegistry registry) {

                 return null;

         }

         @Override

         public ResourceFile getResource(String fileName) {

                 File file= new File(baseLocation, fileName);

                 if(file.isFile()) {

                         return new FileResourceFile(file, fileName);

                 }

                 return null;

         }

 }