/*
 * Copyright 2010 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 java.awt;

import java.awt.peer.*;
import java.io.IOException;
import java.io.ObjectInputStream;
import sun.awt.AWTAccessor;

/**
 * The <code>DirectoryDialog</code> class displays a dialog window from which
 * the user can select a directory.
 * <p>
 * It is a modal dialog, that blocks the rest of the application until the user
 * has chosen a file.
 * </p>
 * 
 * @author Costantino Cerbo (c.cerbo@gmail.com)
 * @since 1.7
 */
public class DirectoryDialog extends Dialog {

    static {
        AWTAccessor
                .setDirectoryDialogAccessor(new AWTAccessor.DirectoryDialogAccessor() {

                    public void setDirectory(DirectoryDialog directoryDialog,
                            String directory) {
                        directoryDialog.dir = ("".equals(directory)) ? null
                                : directory;
                    }
                });
    }

    static {
        /* ensure that the necessary native libraries are loaded */
        Toolkit.loadLibraries();
        GraphicsEnvironment.isHeadless();
    }
    /*
     * The string specifying the directory to display in the file dialog. This
     * variable may be <code>null</code>.
     * 
     * @serial
     * 
     * @see getDirectory()
     * 
     * @see setDirectory()
     */
    private String dir;

    /**
     * Creates a dialog for selecting a directory. The title of the file dialog
     * is initially empty.
     * 
     * @param parent
     *            the owner of the dialog
     * @since 1.7
     */
    public DirectoryDialog(Frame parent) {
        super(parent, true);
    }

    /**
     * Creates a dialog for selecting a directory.
     * 
     * @param parent
     *            the owner of the dialog
     * @param title
     *            the title of the dialog
     * @since 1.7
     */
    public DirectoryDialog(Frame parent, String title) {
        super(parent, title, true);
    }

    /**
     * Creates a dialog for selecting a directory. The title of the file dialog
     * is initially empty.
     * 
     * @param parent
     *            the owner of the dialog
     * @since 1.7
     */
    public DirectoryDialog(Dialog parent) {
        super(parent, "", true);
    }

    /**
     * Creates a dialog for selecting a directory.
     * 
     * @param parent
     *            the owner of the dialog
     * @param title
     *            the title of the dialog
     * @since 1.7
     */
    public DirectoryDialog(Dialog parent, String title) {
        super(parent, title, true);
    }

    /**
     * Gets the directory of this file dialog.
     * 
     * @return the (potentially <code>null</code> or invalid) directory of this
     *         <code>FileDialog</code>
     * @see java.awt.FileDialog#setDirectory
     */
    public String getDirectory() {
        return dir;
    }

    /**
     * Sets the directory of this file dialog window to be the specified
     * directory. Specifying a <code>null</code> or an invalid directory implies
     * an implementation-defined default. This default will not be realized,
     * however, until the user has selected a file. Until this point,
     * <code>getDirectory()</code> will return the value passed into this
     * method.
     * <p>
     * Specifying "" as the directory is exactly equivalent to specifying
     * <code>null</code> as the directory.
     * 
     * @param dir
     *            the specified directory
     * @see java.awt.DirectoryDialog#getDirectory
     */
    public void setDirectory(String dir) {
        this.dir = (dir != null && dir.equals("")) ? null : dir;
        if (peer != null) {
            ((DirectoryDialogPeer) this.peer).setDirectory(this.dir);
        }
    }

    /**
     * Creates the file dialog's peer. The peer allows us to change the look of
     * the file dialog without changing its functionality.
     */
    @Override
    public void addNotify() {
        synchronized (getTreeLock()) {
            if (parent != null && parent.getPeer() == null) {
                parent.addNotify();
            }
            if (peer == null) {
                peer = getToolkit().createDirectoryDialog(this);
            }
            super.addNotify();
        }
    }

    /**
     * Returns a string representing the state of this <code>FileDialog</code>
     * window. This method is intended to be used only for debugging purposes,
     * and the content and format of the returned string may vary between
     * implementations. The returned string may be empty but may not be
     * <code>null</code>.
     * 
     * @return the parameter string of this file dialog window
     */
    @Override
    protected String paramString() {
        String str = super.paramString();
        str += ",dir= " + dir;
        return str;
    }

    /**
     * Reads the <code>ObjectInputStream</code> and performs a backwards
     * compatibility check by converting either a <code>dir</code> or a
     * <code>file</code> equal to an empty string to <code>null</code>.
     * 
     * @param s
     *            the <code>ObjectInputStream</code> to read
     */
    private void readObject(ObjectInputStream s) throws ClassNotFoundException,
            IOException {
        s.defaultReadObject();
    }
}