/*
 * Copyright 2008 Google Inc.
 *
 * 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 com.tonicsystems.jarjar.util;

import java.io.*;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Enumeration;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
import java.util.zip.ZipOutputStream;

class IoUtil {
  private IoUtil() {}

  public static void pipe(InputStream is, OutputStream out, byte[] buf) throws IOException {
    for (; ; ) {
      int amt = is.read(buf);
      if (amt < 0) {
        break;
      }
      out.write(buf, 0, amt);
    }
  }

  public static void copy(File from, File to, byte[] buf) throws IOException {
    InputStream in = new FileInputStream(from);
    try {
      OutputStream out = new FileOutputStream(to);
      try {
        pipe(in, out, buf);
      } finally {
        out.close();
      }
    } finally {
      in.close();
    }
  }

  /**
   * Create a copy of an zip file without its empty directories.
   *
   * @param inputFile
   * @param outputFile
   * @throws IOException
   */
  public static void copyZipWithoutEmptyDirectories(final File inputFile, final File outputFile)
      throws IOException {
    final byte[] buf = new byte[0x2000];

    final ZipFile inputZip = new ZipFile(inputFile);
    final ZipOutputStream outputStream = new ZipOutputStream(new FileOutputStream(outputFile));
    try {
      // read a the entries of the input zip file and sort them
      final Enumeration<? extends ZipEntry> e = inputZip.entries();
      final ArrayList<ZipEntry> sortedList = new ArrayList<ZipEntry>();
      while (e.hasMoreElements()) {
        final ZipEntry entry = e.nextElement();
        sortedList.add(entry);
      }

      Collections.sort(
          sortedList,
          new Comparator<ZipEntry>() {
            public int compare(ZipEntry o1, ZipEntry o2) {
              return o1.getName().compareTo(o2.getName());
            }
          });

      // treat them again and write them in output, wenn they not are empty directories
      for (int i = sortedList.size() - 1; i >= 0; i--) {
        final ZipEntry inputEntry = sortedList.get(i);
        final String name = inputEntry.getName();
        final boolean isEmptyDirectory;
        if (inputEntry.isDirectory()) {
          if (i == sortedList.size() - 1) {
            // no item afterwards; it was an empty directory
            isEmptyDirectory = true;
          } else {
            final String nextName = sortedList.get(i + 1).getName();
            isEmptyDirectory = !nextName.startsWith(name);
          }
        } else {
          isEmptyDirectory = false;
        }

        // write the entry
        if (isEmptyDirectory) {
          sortedList.remove(inputEntry);
        } else {
          final ZipEntry outputEntry = new ZipEntry(inputEntry);
          outputStream.putNextEntry(outputEntry);
          ByteArrayOutputStream baos = new ByteArrayOutputStream();
          final InputStream is = inputZip.getInputStream(inputEntry);
          IoUtil.pipe(is, baos, buf);
          is.close();
          outputStream.write(baos.toByteArray());
        }
      }
    } finally {
      outputStream.close();
    }
  }
}