/*

 * Copyright 2006 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package javax.swing.filechooser;

import java.io.File;

import java.util.Locale;

/**

 * An implementation of {@code FileFilter} that filters using a

 * specified set of extensions. The extension for a file is the

 * portion of the file name after the last ".". Files whose name does

 * not contain a "." have no file name extension. File name extension

 * comparisons are case insensitive.

 * <p>

 * The following example creates a

 * {@code FileNameExtensionFilter} that will show {@code jpg} files:

 * <pre>

 * FileFilter filter = new FileNameExtensionFilter("JPEG file", "jpg", "jpeg");

 * JFileChooser fileChooser = ...;

 * fileChooser.addChoosableFileFilter(filter);

 * </pre>

 *

 * @see FileFilter

 * @see javax.swing.JFileChooser#setFileFilter

 * @see javax.swing.JFileChooser#addChoosableFileFilter

 * @see javax.swing.JFileChooser#getFileFilter

 *

 * @since 1.6

 */

public final class FileNameExtensionFilter extends FileFilter {

    // Description of this filter.

    private final String description;

    // Known extensions.

    private final String[] extensions;

    // Cached ext

    private final String[] lowerCaseExtensions;

    /**

     * Creates a {@code FileNameExtensionFilter} with the specified

     * description and file name extensions. The returned {@code

     * FileNameExtensionFilter} will accept all directories and any

     * file with a file name extension contained in {@code extensions}.

     *

     * @param description textual description for the filter, may be

     *                    {@code null}

     * @param extensions the accepted file name extensions

     * @throws IllegalArgumentException if extensions is {@code null}, empty,

     *         contains {@code null}, or contains an empty string

     * @see #accept

     */

    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()) + "]";

    }

}