// Derived from http://stackoverflow.com/a/3054692/250076
  public static File getRelativeFile(File targetFile, File baseFile) {
    try {
      targetFile = targetFile.getCanonicalFile();
      baseFile = baseFile.getCanonicalFile();
    } catch (IOException ignored) {
    }
    String pathSeparator = File.separator;
    String basePath = baseFile.getAbsolutePath();
    String normalizedTargetPath = normalize(targetFile.getAbsolutePath(), pathSeparator);
    String normalizedBasePath = normalize(basePath, pathSeparator);

    String[] base = normalizedBasePath.split(Pattern.quote(pathSeparator));
    String[] target = normalizedTargetPath.split(Pattern.quote(pathSeparator));

    StringBuilder common = new StringBuilder();

    int commonIndex = 0;
    while (commonIndex < target.length
        && commonIndex < base.length
        && target[commonIndex].equals(base[commonIndex])) {
      common.append(target[commonIndex]).append(pathSeparator);
      commonIndex++;
    }

    if (commonIndex == 0) {
      throw new Error(
          "No common path element found for '"
              + normalizedTargetPath
              + "' and '"
              + normalizedBasePath
              + '\'');
    }

    boolean baseIsFile = true;

    if (baseFile.exists()) {
      baseIsFile = baseFile.isFile();
    } else if (basePath.endsWith(pathSeparator)) {
      baseIsFile = false;
    }

    StringBuilder relative = new StringBuilder();

    if (base.length != commonIndex) {
      int numDirsUp = baseIsFile ? base.length - commonIndex - 1 : base.length - commonIndex;

      for (int i = 0; i < numDirsUp; i++) {
        relative.append("..").append(pathSeparator);
      }
    }
    relative.append(normalizedTargetPath.substring(common.length()));
    return new File(relative.toString());
  }
  @Nullable
  static ClassLoader createPluginClassLoader(
      @NotNull File[] classPath,
      @NotNull ClassLoader[] parentLoaders,
      @NotNull IdeaPluginDescriptor pluginDescriptor) {

    if (pluginDescriptor.getUseIdeaClassLoader()) {
      try {
        final ClassLoader loader = PluginManagerCore.class.getClassLoader();
        final Method addUrlMethod = getAddUrlMethod(loader);

        for (File aClassPath : classPath) {
          final File file = aClassPath.getCanonicalFile();
          addUrlMethod.invoke(loader, file.toURI().toURL());
        }

        return loader;
      } catch (NoSuchMethodException e) {
        e.printStackTrace();
      } catch (IOException e) {
        e.printStackTrace();
      } catch (IllegalAccessException e) {
        e.printStackTrace();
      } catch (InvocationTargetException e) {
        e.printStackTrace();
      }
    }

    PluginId pluginId = pluginDescriptor.getPluginId();
    File pluginRoot = pluginDescriptor.getPath();

    // if (classPath.length == 0) return null;
    if (isUnitTestMode()) return null;
    try {
      final List<URL> urls = new ArrayList<URL>(classPath.length);
      for (File aClassPath : classPath) {
        final File file =
            aClassPath
                .getCanonicalFile(); // it is critical not to have "." and ".." in classpath
                                     // elements
        urls.add(file.toURI().toURL());
      }
      return new PluginClassLoader(
          urls, parentLoaders, pluginId, pluginDescriptor.getVersion(), pluginRoot);
    } catch (MalformedURLException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
    return null;
  }