/* *****************************************************************************
 The Open Java Unified Mapping Platform (OpenJUMP) is an extensible, interactive
 GUI for visualizing and manipulating spatial features with geometry and
 attributes. 

 Copyright (C) 2007  Revolution Systems Inc.

 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 as published by the Free Software Foundation; either version 2
 of the License, or (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

 For more information see:
 
 http://openjump.org/

 ******************************************************************************/
package org.openjump.core.ui.io.file;

import java.io.File;
import java.util.Locale;

import javax.swing.filechooser.FileFilter;

public class FileNameExtensionFilter extends FileFilter {
  // Description of this filter.
  private final String description;

  // Known extensions.
  private final String[] extensions;

  // Cached ext
  private final String[] lowerCaseExtensions;

  public FileNameExtensionFilter(String description, String extension) {
    this(description, new String[] {
      extension
    });
  }

  public FileNameExtensionFilter(String description, String[] extensions) {
    if (extensions == null || extensions.length == 0) {
      throw new IllegalArgumentException(
        "Extensions must be non-null and not empty");
    }
    this.description = description;
    this.extensions = new String[extensions.length];
    this.lowerCaseExtensions = new String[extensions.length];
    for (int i = 0; i < extensions.length; i++) {
      if (extensions[i] == null || extensions[i].length() == 0) {
        throw new IllegalArgumentException(
          "Each extension must be non-null and not empty");
      }
      this.extensions[i] = extensions[i];
      lowerCaseExtensions[i] = extensions[i].toLowerCase(Locale.ENGLISH);
    }
  }

  /**
   * Tests the specified file, returning true if the file is accepted, false
   * otherwise. True is returned if the extension matches one of the file name
   * extensions of this {@code FileFilter}, or the file is a directory.
   * 
   * @param f the {@code File} to test
   * @return true if the file is to be accepted, false otherwise
   */
  public boolean accept(File f) {
    if (f != null) {
      if (f.isDirectory()) {
        return true;
      }
      // NOTE: we tested implementations using Maps, binary search
      // on a sorted list and this implementation. All implementations
      // provided roughly the same speed, most likely because of
      // overhead associated with java.io.File. Therefor we've stuck
      // with the simple lightweight approach.
      String fileName = f.getName();
      int i = fileName.lastIndexOf('.');
      if (i > 0 && i < fileName.length() - 1) {
        String desiredExtension = fileName.substring(i + 1).toLowerCase(
          Locale.ENGLISH);
        for (String extension : lowerCaseExtensions) {
          if (desiredExtension.equals(extension)) {
            return true;
          }
        }
      }
    }
    return false;
  }

  /**
   * The description of this filter. For example: "JPG and GIF Images."
   * 
   * @return the description of this filter
   */
  public String getDescription() {
    return description;
  }

  /**
   * Returns the set of file name extensions files are tested against.
   * 
   * @return the set of file name extensions files are tested against
   */
  public String[] getExtensions() {
    String[] result = new String[extensions.length];
    System.arraycopy(extensions, 0, result, 0, extensions.length);
    return result;
  }

  /**
   * Returns a string representation of the {@code FileNameExtensionFilter}.
   * This method is intended to be used for debugging purposes, and the content
   * and format of the returned string may vary between implementations.
   * 
   * @return a string representation of this {@code FileNameExtensionFilter}
   */
  public String toString() {
    return super.toString() + "[description=" + getDescription()
      + " extensions=" + java.util.Arrays.asList(getExtensions()) + "]";
  }
}