content: /*
   * [The "BSD licence"]
   * Copyright (c) 2010 Ben Gruver
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. The name of the author may not be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  package org.jf.util;
  
  import com.google.common.collect.Lists;
  
  import java.io.File;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  
  public class PathUtil {
      private PathUtil() {
      }
  
      public static File getRelativeFile(File baseFile, File fileToRelativize) throws IOException {
          if (baseFile.isFile()) {
              baseFile = baseFile.getParentFile();
          }
  
          return new File(getRelativeFileInternal(baseFile.getCanonicalFile(), fileToRelativize.getCanonicalFile()));
      }
  
      static String getRelativeFileInternal(File canonicalBaseFile, File canonicalFileToRelativize) {
          List<String> basePath = getPathComponents(canonicalBaseFile);
          List<String> pathToRelativize = getPathComponents(canonicalFileToRelativize);
  
          //if the roots aren't the same (i.e. different drives on a windows machine), we can't construct a relative
          //path from one to the other, so just return the canonical file
          if (!basePath.get(0).equals(pathToRelativize.get(0))) {
              return canonicalFileToRelativize.getPath();
          }
  
          int commonDirs;
          StringBuilder sb = new StringBuilder();
  
          for (commonDirs=1; commonDirs<basePath.size() && commonDirs<pathToRelativize.size(); commonDirs++) {
              if (!basePath.get(commonDirs).equals(pathToRelativize.get(commonDirs))) {
                  break;
              }
          }
  
          boolean first = true;
          for (int i=commonDirs; i<basePath.size(); i++) {
              if (!first) {
                  sb.append(File.separatorChar);
              } else {
                  first = false;
              }
  
              sb.append("..");
          }
  
          first = true;
          for (int i=commonDirs; i<pathToRelativize.size(); i++) {
              if (first) {
                  if (sb.length() != 0) {
                      sb.append(File.separatorChar);
                  }
                  first = false;
              } else {
                  sb.append(File.separatorChar);
              }
              
              sb.append(pathToRelativize.get(i));
          }
  
          if (sb.length() == 0) {
              return ".";
          }
  
          return sb.toString();
      }
  
      private static List<String> getPathComponents(File file) {
          ArrayList<String> path = new ArrayList<String>();
  
          while (file != null) {
              File parentFile = file.getParentFile();
  
              if (parentFile == null) {
                  path.add(file.getPath());
              } else {
                  path.add(file.getName());
              }
  
              file = parentFile;
          }
  
          return Lists.reverse(path);
      }
  }
  