/*
 * Copyright 1998-2014 University Corporation for Atmospheric Research/Unidata
 *
 *   Portions of this software were developed by the Unidata Program at the
 *   University Corporation for Atmospheric Research.
 *
 *   Access and use of this software shall impose the following obligations
 *   and understandings on the user. The user is granted the right, without
 *   any fee or cost, to use, copy, modify, alter, enhance and distribute
 *   this software, and any derivative works thereof, and its supporting
 *   documentation for any purpose whatsoever, provided that this entire
 *   notice appears in all copies of the software, derivative works and
 *   supporting documentation.  Further, UCAR requests that the user credit
 *   UCAR/Unidata in any publications that result from the use of this
 *   software or in any product that includes this software. The names UCAR
 *   and/or Unidata, however, may not be used in any advertising or publicity
 *   to endorse or promote any products or commercial entity unless specific
 *   written permission is obtained from UCAR/Unidata. The user also
 *   understands that UCAR/Unidata is not obligated to provide the user with
 *   any support, consulting, training or assistance of any kind with regard
 *   to the use, operation and performance of this software nor to provide
 *   the user with any updates, revisions, new versions or "bug fixes."
 *
 *   THIS SOFTWARE IS PROVIDED BY UCAR/UNIDATA "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 UCAR/UNIDATA BE LIABLE FOR ANY SPECIAL,
 *   INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
 *   FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
 *   NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
 *   WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE.
 */
package thredds.util.filesource;

import org.springframework.util.StringUtils;

import java.io.File;

/**
 * _more_
 *
 * @author edavis
 * @since 4.0
 */
public class BasicDescendantFileSource implements DescendantFileSource {
  //private static org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(BasicDescendantFileSource.class);

  private final String rootDirectoryPath;
  private final File rootDirectory;

  public BasicDescendantFileSource(File rootDirectory) {
    if (rootDirectory == null)
      throw new IllegalArgumentException("Root directory must not be null.");
    if (!rootDirectory.exists())
      throw new IllegalArgumentException("Root directory must exist: " + rootDirectory.getAbsolutePath() + ".");
    if (!rootDirectory.isDirectory())
      throw new IllegalArgumentException("Root directory must be a directory: " + rootDirectory.getAbsolutePath() + ".");
    this.rootDirectoryPath = StringUtils.cleanPath(rootDirectory.getAbsolutePath());
    this.rootDirectory = new File(this.rootDirectoryPath);
  }

  public BasicDescendantFileSource(String rootDirectoryPath) {
    if (rootDirectoryPath == null)
      throw new IllegalArgumentException("Root directory must not be null.");
    File file = new File(rootDirectoryPath);
    if (!file.exists())
      throw new IllegalArgumentException("Root directory must exist: " + rootDirectoryPath + ".");
    if (!file.isDirectory())
      throw new IllegalArgumentException("Root directory must be a directory: " + rootDirectoryPath + ".");

    this.rootDirectoryPath = StringUtils.cleanPath(file.getAbsolutePath());
    this.rootDirectory = new File(this.rootDirectoryPath);
  }

  /**
   * This implementation requires the path to be relative to the root
   * directory and a descendant of the root directory. It also requires the
   * relative path at each path segment to be a descendant of the root
   * directory, i.e., it cannot start with "../" or contain "../" path
   * segments such that once "normalized" it would start with "../"
   * (e.g., "dir1/../../dir2" once normalized would be "../dir2").
   *
   * @param path the relative path to the descendant File.
   * @return the descendant File represented by the given relative path or null if the path is null, not relative to the root, not a descendant, or the File doesn't exist.
   */
  public File getFile(String path) {
    if (path == null)
      return null;
    String workPath = StringUtils.cleanPath(path);
    if (workPath.startsWith("../"))
      return null;
    if (new File(workPath).isAbsolute())
      return null;

    File file = new File(this.rootDirectory, workPath);
    if (file.exists())
      return file;
    else
      return null;
  }

  public DescendantFileSource getDescendant(String relativePath) {
    File descendantFile = getFile(relativePath);
    if (descendantFile == null || !descendantFile.isDirectory())
      return null;
    return new BasicDescendantFileSource(descendantFile);
  }

  public File getRootDirectory() {
    return this.rootDirectory;
  }

  public String getRootDirectoryPath() {
    return this.rootDirectoryPath;
  }

  public boolean isDescendant(File file) {
    if (file == null)
      return false;
    String relPath = getRelativePath(file);
    return !(relPath == null || relPath.equals(""));
  }

  public boolean isDescendant(String filePath) {
    return filePath != null && isDescendant(new File(filePath));
  }

  public String getRelativePath(File file) {
    if (file == null)
      return null;
    String cleanPath = StringUtils.cleanPath(file.getAbsolutePath()).trim();
    if (cleanPath.startsWith(this.rootDirectoryPath + "/")
            && cleanPath.length() > this.rootDirectoryPath.length() + 1) {
      String relativePath = cleanPath.substring(this.rootDirectoryPath.length() + 1);
      return relativePath.trim();
    }
    return null;
  }

  public String getRelativePath(String filePath) {
    if (filePath == null)
      return null;
    return getRelativePath(new File(filePath));
  }
}