GitPathResolver.java

/*
 * Copyright (C) 2008-2022 Mycila (mathieu.carbou@gmail.com)
 *
 * 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.mycila.maven.plugin.license.git;

import java.io.File;

/**
 * A utility to transform native {@link File} paths to the form expected by jGit - i.e. relative to git working tree
 * root directory and delimited by {@code '/'}.
 *
 * @author <a href="mailto:ppalaga@redhat.com">Peter Palaga</a>
 */
public class GitPathResolver {

  /**
   * The path separator expected by jGit.
   */
  private static final char CANONICAL_PATH_SEPARATOR = '/';

  /**
   * The file path separator used by the current platform, usually {@value File#separatorChar}.
   */
  private final char nativePathSeparator;

  /**
   * The native path to the root directory of the current git repository working tree.
   */
  private final String repositoryRootDir;

  public GitPathResolver(String repositoryRootDir) {
    this(repositoryRootDir, File.separatorChar);
  }

  /**
   * Default visibility for testing purposes.
   *
   * @param repositoryRootDir
   * @param nativePathSeparator
   */
  GitPathResolver(String repositoryRootDir, char nativePathSeparator) {
    super();
    this.repositoryRootDir = repositoryRootDir.charAt(repositoryRootDir.length() - 1) == nativePathSeparator ? repositoryRootDir
        : repositoryRootDir + nativePathSeparator;
    this.nativePathSeparator = nativePathSeparator;
  }

  /**
   * With default visibility to be testable.
   *
   * @param absoluteNativePath
   * @return
   */
  String relativize(String absoluteNativePath) {
    if (!absoluteNativePath.startsWith(repositoryRootDir)) {
      throw new RuntimeException("Cannot relativize path '" + absoluteNativePath + "' to directory '"
          + repositoryRootDir + "'");
    }
    String result = absoluteNativePath.substring(repositoryRootDir.length());
    if (nativePathSeparator != CANONICAL_PATH_SEPARATOR) {
      result = result.replace(nativePathSeparator, CANONICAL_PATH_SEPARATOR);
    }
    return result;
  }

  /**
   * Return a string representing the supplied {@code path} path relative to git working tree root directory and
   * delimited by {@code '/'}.
   *
   * @param path the path to relativize
   * @return the relativized path
   */
  public String relativize(File path) {
    return relativize(path.getAbsolutePath());
  }

}