/*

  * Licensed to the Apache Software Foundation (ASF) under one or more

  * contributor license agreements.  See the NOTICE file distributed with

  * this work for additional information regarding copyright ownership.

  * The ASF licenses this file to You 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.javaflow.utils;

 import org.apache.commons.javaflow.bytecode.transformation.ResourceTransformer;

 import org.apache.commons.javaflow.bytecode.transformation.bcel.BcelClassTransformer;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import java.io.ByteArrayOutputStream;

 import java.io.File;

 import java.io.FileInputStream;

 import java.io.FileNotFoundException;

 import java.io.FileOutputStream;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.OutputStream;

 import java.util.jar.JarEntry;

 import java.util.jar.JarInputStream;

 import java.util.jar.JarOutputStream;

 public final class RewritingUtils {

     private final static Log log = LogFactory.getLog(RewritingUtils.class);

     public interface Matcher {

         boolean isMatching( final String name );

     }

     private final static Matcher MATCH_ALL = new Matcher() {

         public boolean isMatching(final String pName) {

             return true;

         }

     };

     /*

      * @todo multiple transformers

      */

     public static void rewriteClassFile(

             final File pInput,

             final ResourceTransformer transformer,

             final File pOutput

             ) throws IOException {

         final byte[] original = toByteArray(pInput);

         byte[] transformed = transformer.transform(original);

         final FileOutputStream os = new FileOutputStream(pOutput);

         os.write(transformed);

         os.close();

     }

     public static boolean rewriteJar(

             final JarInputStream pInput,

             final ResourceTransformer transformer,

             final JarOutputStream pOutput

             ) throws IOException {

         return rewriteJar(pInput, transformer, pOutput, MATCH_ALL);

     }

     public static boolean rewriteJar(

             final JarInputStream pInput,

             final ResourceTransformer transformer,

             final JarOutputStream pOutput,

             final Matcher pMatcher

             ) throws IOException {

         boolean changed = false;

         while(true) {

             final JarEntry entry = pInput.getNextJarEntry();

             if (entry == null) {

                 break;

             }

             if (entry.isDirectory()) {

                 pOutput.putNextEntry(new JarEntry(entry));

                 continue;

             }

             final String name = entry.getName();

             pOutput.putNextEntry(new JarEntry(name));

             if (name.endsWith(".class")) {

                 if (pMatcher.isMatching(name)) {

                     if (log.isDebugEnabled()) {

                         log.debug("transforming " + name);

                     }

                     final byte[] original = toByteArray(pInput);

                     byte[] transformed = transformer.transform(original);

                     pOutput.write(transformed);

                     changed |= transformed.length != original.length;

                     continue;

                 }

             } else if (name.endsWith(".jar")

                 || name.endsWith(".ear")

                 || name.endsWith(".zip")

                 || name.endsWith(".war")) {

                 changed |= rewriteJar(

                         new JarInputStream(pInput),

                         transformer,

                         new JarOutputStream(pOutput),

                         pMatcher

                         );

                 continue;

             }

             int length = copy(pInput,pOutput);

             log.debug("copied " + name + "(" + length + ")");

         }

         pInput.close();

         pOutput.close();

         return changed;

     }

     public static byte[] toByteArray(File f) throws IOException {

         InputStream in = new FileInputStream(f);

         try {

             return toByteArray(in);

         } finally {

             in.close();

         }

     }

     public static byte[] toByteArray(InputStream in) throws IOException {

         ByteArrayOutputStream baos = new ByteArrayOutputStream();

         copy(in,baos);

         return baos.toByteArray();

     }

     /**

      * Copies the entire {@link InputStream} to the given {@link OutputStream}.

      *

      * @return

      *      the number of bytes copied.

      */

     public static int copy(InputStream in, OutputStream out) throws IOException {

         byte[] buf = new byte[8192];

         int n;

         int total = 0;

         while ((n = in.read(buf)) >= 0) {

             out.write(buf, 0, n);

             total += n;

         }

         return total;

     }

     public static void main(final String[] args) throws FileNotFoundException, IOException {

         ResourceTransformer transformer = new BcelClassTransformer();

         for (int i=0; i<args.length; i+=2) {

             System.out.println("rewriting " + args[i]);

             RewritingUtils.rewriteJar(

                     new JarInputStream(new FileInputStream(args[i])),

                     transformer,

                     new JarOutputStream(new FileOutputStream(args[i+1]))

                     );

         }

         System.out.println("done");

     }

 }