package info.ata4.util.gui;

import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.dnd.*;
import java.awt.event.HierarchyEvent;
import java.awt.event.HierarchyListener;
import java.io.*;
import java.net.URI;
import java.util.ArrayList;
import java.util.EventObject;
import java.util.List;
import java.util.TooManyListenersException;
import java.util.function.*;
import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.border.Border;

/**
 * This class makes it easy to drag and drop files from the operating
 * system to a Java program. Any <tt>java.awt.Component</tt> can be
 * dropped onto, but only <tt>javax.swing.JComponent</tt>s will indicate
 * the drop event with a changed border.
 * <p/>
 * To use this class, construct a new <tt>FileDrop</tt> by passing
 * it the target component and a <tt>Listener</tt> to receive notification
 * when file(s) have been dropped. Here is an example:
 * <p/>
 * <code><pre>
 *      JPanel myPanel = new JPanel();
 *      new FileDrop( myPanel, new FileDrop.Listener()
 *      {   public void filesDropped( java.io.File[] files )
 *          {
 *              // handle file drop
 *              ...
 *          }   // end filesDropped
 *      }); // end FileDrop.Listener
 * </pre></code>
 * <p/>
 * You can specify the border that will appear when files are being dragged by
 * calling the constructor with a <tt>javax.swing.border.Border</tt>. Only
 * <tt>JComponent</tt>s will show any indication with a border.
 * <p/>
 * You can turn on some debugging features by passing a <tt>PrintStream</tt>
 * object (such as <tt>System.out</tt>) into the full constructor. A <tt>null</tt>
 * value will result in no extra debugging information being output.
 * <p/>
 *
 * <p>I'm releasing this code into the Public Domain. Enjoy.
 * </p>
 * <p><em>Original author: Robert Harder, rharder@usa.net</em></p>
 * <p>2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.</p>
 *
 * @author  Robert Harder
 * @author  rharder@users.sf.net
 * @version 1.0.1
 */
public class FileDrop {

    private transient Border normalBorder;
    private transient DropTargetListener dropListener;
    /** Discover if the running JVM is modern enough to have drag and drop. */
    private static Boolean supportsDnD;
    // Default border color
    private static Color defaultBorderColor = new Color(0f, 0f, 1f, 0.25f);

    /**
     * Constructs a {@link FileDrop} with a default light-blue border
     * and, if <var>c</var> is a {@link java.awt.Container}, recursively
     * sets all elements contained within as drop targets, though only
     * the top level container will change borders.
     *
     * @param c Component on which files will be dropped.
     * @param listener Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(
            final Component c,
            final Consumer<File[]> listener) {
        this(null, // Logging stream
                c, // Drop target
                BorderFactory.createMatteBorder(2, 2, 2, 2, defaultBorderColor), // Drag border
                true, // Recursive
                listener);
    }   // end constructor

    /**
     * Constructor with a default border and the option to recursively set drop targets.
     * If your component is a <tt>java.awt.Container</tt>, then each of its children
     * components will also listen for drops, though only the parent will change borders.
     *
     * @param c Component on which files will be dropped.
     * @param recursive Recursively set children as drop targets.
     * @param listener Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(
            final Component c,
            final boolean recursive,
            final Consumer<File[]> listener) {
        this(null, // Logging stream
                c, // Drop target
                BorderFactory.createMatteBorder(2, 2, 2, 2, defaultBorderColor), // Drag border
                recursive, // Recursive
                listener);
    }   // end constructor

    /**
     * Constructor with a default border and debugging optionally turned on.
     * With Debugging turned on, more status messages will be displayed to
     * <tt>out</tt>. A common way to use this constructor is with
     * <tt>System.out</tt> or <tt>System.err</tt>. A <tt>null</tt> value for
     * the parameter <tt>out</tt> will result in no debugging output.
     *
     * @param out PrintStream to record debugging info or null for no debugging.
     * @param out
     * @param c Component on which files will be dropped.
     * @param listener Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(
            final PrintStream out,
            final Component c,
            final Consumer<File[]> listener) {
        this(out, // Logging stream
                c, // Drop target
                BorderFactory.createMatteBorder(2, 2, 2, 2, defaultBorderColor),
                false, // Recursive
                listener);
    }   // end constructor

    /**
     * Constructor with a default border, debugging optionally turned on
     * and the option to recursively set drop targets.
     * If your component is a <tt>java.awt.Container</tt>, then each of its children
     * components will also listen for drops, though only the parent will change borders.
     * With Debugging turned on, more status messages will be displayed to
     * <tt>out</tt>. A common way to use this constructor is with
     * <tt>System.out</tt> or <tt>System.err</tt>. A <tt>null</tt> value for
     * the parameter <tt>out</tt> will result in no debugging output.
     *
     * @param out PrintStream to record debugging info or null for no debugging.
     * @param out
     * @param c Component on which files will be dropped.
     * @param recursive Recursively set children as drop targets.
     * @param listener Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(
            final PrintStream out,
            final Component c,
            final boolean recursive,
            final Consumer<File[]> listener) {
        this(out, // Logging stream
                c, // Drop target
                BorderFactory.createMatteBorder(2, 2, 2, 2, defaultBorderColor), // Drag border
                recursive, // Recursive
                listener);
    }   // end constructor

    /**
     * Constructor with a specified border
     *
     * @param c Component on which files will be dropped.
     * @param dragBorder Border to use on <tt>JComponent</tt> when dragging occurs.
     * @param listener Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(
            final Component c,
            final Border dragBorder,
            final Consumer<File[]> listener) {
        this(
                null, // Logging stream
                c, // Drop target
                dragBorder, // Drag border
                false, // Recursive
                listener);
    }   // end constructor

    /**
     * Constructor with a specified border and the option to recursively set drop targets.
     * If your component is a <tt>java.awt.Container</tt>, then each of its children
     * components will also listen for drops, though only the parent will change borders.
     *
     * @param c Component on which files will be dropped.
     * @param dragBorder Border to use on <tt>JComponent</tt> when dragging occurs.
     * @param recursive Recursively set children as drop targets.
     * @param listener Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(
            final Component c,
            final Border dragBorder,
            final boolean recursive,
            final Consumer<File[]> listener) {
        this(
                null,
                c,
                dragBorder,
                recursive,
                listener);
    }   // end constructor

    /**
     * Constructor with a specified border and debugging optionally turned on.
     * With Debugging turned on, more status messages will be displayed to
     * <tt>out</tt>. A common way to use this constructor is with
     * <tt>System.out</tt> or <tt>System.err</tt>. A <tt>null</tt> value for
     * the parameter <tt>out</tt> will result in no debugging output.
     *
     * @param out PrintStream to record debugging info or null for no debugging.
     * @param c Component on which files will be dropped.
     * @param dragBorder Border to use on <tt>JComponent</tt> when dragging occurs.
     * @param listener Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(
            final PrintStream out,
            final Component c,
            final Border dragBorder,
            final Consumer<File[]> listener) {
        this(
                out, // Logging stream
                c, // Drop target
                dragBorder, // Drag border
                false, // Recursive
                listener);
    }   // end constructor

    /**
     * Full constructor with a specified border and debugging optionally turned on.
     * With Debugging turned on, more status messages will be displayed to
     * <tt>out</tt>. A common way to use this constructor is with
     * <tt>System.out</tt> or <tt>System.err</tt>. A <tt>null</tt> value for
     * the parameter <tt>out</tt> will result in no debugging output.
     *
     * @param out PrintStream to record debugging info or null for no debugging.
     * @param c Component on which files will be dropped.
     * @param dragBorder Border to use on <tt>JComponent</tt> when dragging occurs.
     * @param recursive Recursively set children as drop targets.
     * @param listener Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(
            final PrintStream out,
            final Component c,
            final Border dragBorder,
            final boolean recursive,
            final Consumer<File[]> listener) {

        if (supportsDnD()) {   // Make a drop listener
            dropListener = new DropTargetListener() {

                @Override
                public void dragEnter(DropTargetDragEvent evt) {
                    log(out, "FileDrop: dragEnter event.");

                    // Is this an acceptable drag event?
                    if (isDragOk(out, evt)) {
                        // If it's a Swing component, set its border
                        if (c instanceof JComponent) {
                            JComponent jc = (JComponent) c;
                            normalBorder = jc.getBorder();
                            log(out, "FileDrop: normal border saved.");
                            jc.setBorder(dragBorder);
                            log(out, "FileDrop: drag border set.");
                        }   // end if: JComponent

                        // Acknowledge that it's okay to enter
                        //evt.acceptDrag( DnDConstants.ACTION_COPY_OR_MOVE );
                        evt.acceptDrag(DnDConstants.ACTION_COPY);
                        log(out, "FileDrop: event accepted.");
                    } // end if: drag ok
                    else {   // Reject the drag event
                        evt.rejectDrag();
                        log(out, "FileDrop: event rejected.");
                    }   // end else: drag not ok
                }   // end dragEnter

                @Override
                public void dragOver(DropTargetDragEvent evt) {   // This is called continually as long as the mouse is
                    // over the drag target.
                }   // end dragOver

                @Override
                public void drop(DropTargetDropEvent evt) {
                    log(out, "FileDrop: drop event.");
                    try {   // Get whatever was dropped
                        Transferable tr = evt.getTransferable();

                        // Is it a file list?
                        if (tr.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
                            // Say we'll take it.
                            //evt.acceptDrop ( DnDConstants.ACTION_COPY_OR_MOVE );
                            evt.acceptDrop(DnDConstants.ACTION_COPY);
                            log(out, "FileDrop: file list accepted.");

                            // Get a useful list
                            List<File> fileList = (List<File>) tr.getTransferData(DataFlavor.javaFileListFlavor);

                            // Convert list to array
                            File[] filesTemp = new File[fileList.size()];
                            fileList.toArray(filesTemp);
                            final File[] files = filesTemp;

                            // Alert listener to drop.
                            if (listener != null) {
                                listener.accept(files);
                            }

                            // Mark that drop is completed.
                            evt.getDropTargetContext().dropComplete(true);
                            log(out, "FileDrop: drop complete.");
                        } // end if: file list
                        else // this section will check for a reader flavor.
                        {
                            // Thanks, Nathan!
                            // BEGIN 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.
                            DataFlavor[] flavors = tr.getTransferDataFlavors();
                            boolean handled = false;
                            for (int zz = 0; zz < flavors.length; zz++) {
                                if (flavors[zz].isRepresentationClassReader()) {
                                    // Say we'll take it.
                                    //evt.acceptDrop ( DnDConstants.ACTION_COPY_OR_MOVE );
                                    evt.acceptDrop(DnDConstants.ACTION_COPY);
                                    log(out, "FileDrop: reader accepted.");

                                    Reader reader = flavors[zz].getReaderForText(tr);

                                    BufferedReader br = new BufferedReader(reader);

                                    if (listener != null) {
                                        listener.accept(createFileArray(br, out));
                                    }

                                    // Mark that drop is completed.
                                    evt.getDropTargetContext().dropComplete(true);
                                    log(out, "FileDrop: drop complete.");
                                    handled = true;
                                    break;
                                }
                            }
                            if (!handled) {
                                log(out, "FileDrop: not a file list or reader - abort.");
                                evt.rejectDrop();
                            }
                            // END 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.
                        }   // end else: not a file list
                    } // end try
                    catch (IOException io) {
                        log(out, "FileDrop: IOException - abort:");
                        io.printStackTrace(out);
                        evt.rejectDrop();
                    } // end catch IOException
                    catch (UnsupportedFlavorException ufe) {
                        log(out, "FileDrop: UnsupportedFlavorException - abort:");
                        ufe.printStackTrace(out);
                        evt.rejectDrop();
                    } // end catch: UnsupportedFlavorException
                    finally {
                        // If it's a Swing component, reset its border
                        if (c instanceof JComponent) {
                            JComponent jc = (JComponent) c;
                            jc.setBorder(normalBorder);
                            log(out, "FileDrop: normal border restored.");
                        }   // end if: JComponent
                    }   // end finally
                }   // end drop

                @Override
                public void dragExit(DropTargetEvent evt) {
                    log(out, "FileDrop: dragExit event.");
                    // If it's a Swing component, reset its border
                    if (c instanceof JComponent) {
                        JComponent jc = (JComponent) c;
                        jc.setBorder(normalBorder);
                        log(out, "FileDrop: normal border restored.");
                    }   // end if: JComponent
                }   // end dragExit

                @Override
                public void dropActionChanged(DropTargetDragEvent evt) {
                    log(out, "FileDrop: dropActionChanged event.");
                    // Is this an acceptable drag event?
                    if (isDragOk(out, evt)) {   //evt.acceptDrag( DnDConstants.ACTION_COPY_OR_MOVE );
                        evt.acceptDrag(DnDConstants.ACTION_COPY);
                        log(out, "FileDrop: event accepted.");
                    } // end if: drag ok
                    else {
                        evt.rejectDrag();
                        log(out, "FileDrop: event rejected.");
                    }   // end else: drag not ok
                }   // end dropActionChanged
            }; // end DropTargetListener

            // Make the component (and possibly children) drop targets
            makeDropTarget(out, c, recursive);
        } // end if: supports dnd
        else {
            log(out, "FileDrop: Drag and drop is not supported with this JVM");
        }   // end else: does not support DnD
    }   // end constructor

    private static boolean supportsDnD() {   // Static Boolean
        if (supportsDnD == null) {
            try {
                Class.forName("java.awt.dnd.DnDConstants");
                supportsDnD = true;
            } // end try
            catch (Exception e) {
                supportsDnD = false;
            }   // end catch
        }   // end if: first time through
        return supportsDnD.booleanValue();
    }   // end supportsDnD
    // BEGIN 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.
    private static String ZERO_CHAR_STRING = "" + (char) 0;

    private static File[] createFileArray(BufferedReader bReader, PrintStream out) {
        try {
            List<File> list = new ArrayList<>();
            String line;
            while ((line = bReader.readLine()) != null) {
                try {
                    // kde seems to append a 0 char to the end of the reader
                    if (ZERO_CHAR_STRING.equals(line)) {
                        continue;
                    }

                    File file = new File(new URI(line));
                    list.add(file);
                } catch (Exception ex) {
                    log(out, "Error with " + line + ": " + ex.getMessage());
                }
            }

            return (File[]) list.toArray(new File[list.size()]);
        } catch (IOException ex) {
            log(out, "FileDrop: IOException");
        }
        return new File[0];
    }
    // END 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.

    private void makeDropTarget(final PrintStream out, final Component c, boolean recursive) {
        // Make drop target
        final DropTarget dt = new DropTarget();
        try {
            dt.addDropTargetListener(dropListener);
        } // end try
        catch (TooManyListenersException e) {
            e.printStackTrace();
            log(out, "FileDrop: Drop will not work due to previous error. Do you have another listener attached?");
        }   // end catch

        // Listen for hierarchy changes and remove the drop target when the parent gets cleared out.
        c.addHierarchyListener(new HierarchyListener() {

            @Override
            public void hierarchyChanged(HierarchyEvent evt) {
                log(out, "FileDrop: Hierarchy changed.");
                Component parent = c.getParent();
                if (parent == null) {
                    c.setDropTarget(null);
                    log(out, "FileDrop: Drop target cleared from component.");
                } // end if: null parent
                else {
                    new DropTarget(c, dropListener);
                    log(out, "FileDrop: Drop target added to component.");
                }   // end else: parent not null
            }   // end hierarchyChanged
        }); // end hierarchy listener
        if (c.getParent() != null) {
            new DropTarget(c, dropListener);
        }

        if (recursive && (c instanceof Container)) {
            // Get the container
            Container cont = (Container) c;

            // Get it's components
            Component[] comps = cont.getComponents();

            // Set it's components as listeners also
            for (int i = 0; i < comps.length; i++) {
                makeDropTarget(out, comps[i], recursive);
            }
        }   // end if: recursively set components as listener
    }   // end dropListener

    /** Determine if the dragged data is a file list. */
    private boolean isDragOk(final PrintStream out, final DropTargetDragEvent evt) {
        boolean ok = false;

        // Get data flavors being dragged
        DataFlavor[] flavors = evt.getCurrentDataFlavors();

        // See if any of the flavors are a file list
        int i = 0;
        while (!ok && i < flavors.length) {
            // BEGIN 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.
            // Is the flavor a file list?
            final DataFlavor curFlavor = flavors[i];
            if (curFlavor.equals(DataFlavor.javaFileListFlavor)
                    || curFlavor.isRepresentationClassReader()) {
                ok = true;
            }
            // END 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.
            i++;
        }   // end while: through flavors

        // If logging is enabled, show data flavors
        if (out != null) {
            if (flavors.length == 0) {
                log(out, "FileDrop: no data flavors.");
            }
            for (i = 0; i < flavors.length; i++) {
                log(out, flavors[i].toString());
            }
        }   // end if: logging enabled

        return ok;
    }   // end isDragOk

    /** Outputs <tt>message</tt> to <tt>out</tt> if it's not null. */
    private static void log(PrintStream out, String message) {   // Log message if requested
        if (out != null) {
            out.println(message);
        }
    }   // end log

    /**
     * Removes the drag-and-drop hooks from the component and optionally
     * from the all children. You should call this if you add and remove
     * components after you've set up the drag-and-drop.
     * This will recursively unregister all components contained within
     * <var>c</var> if <var>c</var> is a {@link java.awt.Container}.
     *
     * @param c The component to unregister as a drop target
     * @since 1.0
     */
    public static boolean remove(Component c) {
        return remove(null, c, true);
    }   // end remove

    /**
     * Removes the drag-and-drop hooks from the component and optionally
     * from the all children. You should call this if you add and remove
     * components after you've set up the drag-and-drop.
     *
     * @param out Optional {@link java.io.PrintStream} for logging drag and drop messages
     * @param c The component to unregister
     * @param recursive Recursively unregister components within a container
     * @since 1.0
     */
    public static boolean remove(PrintStream out, Component c, boolean recursive) {   // Make sure we support dnd.
        if (supportsDnD()) {
            log(out, "FileDrop: Removing drag-and-drop hooks.");
            c.setDropTarget(null);
            if (recursive && (c instanceof Container)) {
                Component[] comps = ((Container) c).getComponents();
                for (int i = 0; i < comps.length; i++) {
                    remove(out, comps[i], recursive);
                }
                return true;
            } // end if: recursive
            else {
                return false;
            }
        } // end if: supports DnD
        else {
            return false;
        }
    }   // end remove


    /* ********  I N N E R   C L A S S  ******** */
    /**
     * This is the event that is passed to the
     * {@link FileDropListener#filesDropped filesDropped(...)} method in
     * your {@link FileDropListener} when files are dropped onto
     * a registered drop target.
     *
     * <p>I'm releasing this code into the Public Domain. Enjoy.</p>
     *
     * @author  Robert Harder
     * @author  rob@iharder.net
     * @version 1.2
     */
    public static class Event extends EventObject {

        private File[] files;

        /**
         * Constructs an {@link Event} with the array
         * of files that were dropped and the
         * {@link FileDrop} that initiated the event.
         *
         * @param files The array of files that were dropped
         * @source The event source
         * @since 1.1
         */
        public Event(File[] files, Object source) {
            super(source);
            this.files = files;
        }   // end constructor

        /**
         * Returns an array of files that were dropped on a
         * registered drop target.
         *
         * @return array of files that were dropped
         * @since 1.1
         */
        public File[] getFiles() {
            return files;
        }   // end getFiles
    }   // end inner class Event

    /* ********  I N N E R   C L A S S  ******** */
    /**
     * At last an easy way to encapsulate your custom objects for dragging and dropping
     * in your Java programs!
     * When you need to create a {@link java.awt.datatransfer.Transferable} object,
     * use this class to wrap your object.
     * For example:
     * <pre><code>
     *      ...
     *      MyCoolClass myObj = new MyCoolClass();
     *      Transferable xfer = new TransferableObject( myObj );
     *      ...
     * </code></pre>
     * Or if you need to know when the data was actually dropped, like when you're
     * moving data out of a list, say, you can use the {@link TransferableObject.Fetcher}
     * inner class to return your object Just in Time.
     * For example:
     * <pre><code>
     *      ...
     *      final MyCoolClass myObj = new MyCoolClass();
     *
     *      TransferableObject.Fetcher fetcher = new TransferableObject.Fetcher()
     *      {   public Object getObject(){ return myObj; }
     *      }; // end fetcher
     *
     *      Transferable xfer = new TransferableObject( fetcher );
     *      ...
     * </code></pre>
     *
     * The {@link java.awt.datatransfer.DataFlavor} associated with
     * {@link TransferableObject} has the representation class
     * <tt>net.iharder.dnd.TransferableObject.class</tt> and MIME type
     * <tt>application/x-net.iharder.dnd.TransferableObject</tt>.
     * This data flavor is accessible via the static
     * {@link #DATA_FLAVOR} property.
     *
     *
     * <p>I'm releasing this code into the Public Domain. Enjoy.</p>
     *
     * @author  Robert Harder
     * @author  rob@iharder.net
     * @version 1.2
     */
    public static class TransferableObject implements Transferable {

        /**
         * The MIME type for {@link #DATA_FLAVOR} is
         * <tt>application/x-net.iharder.dnd.TransferableObject</tt>.
         *
         * @since 1.1
         */
        public final static String MIME_TYPE = "application/x-net.iharder.dnd.TransferableObject";
        /**
         * The default {@link java.awt.datatransfer.DataFlavor} for
         * {@link TransferableObject} has the representation class
         * <tt>net.iharder.dnd.TransferableObject.class</tt>
         * and the MIME type
         * <tt>application/x-net.iharder.dnd.TransferableObject</tt>.
         *
         * @since 1.1
         */
        public final static DataFlavor DATA_FLAVOR =
                new DataFlavor(FileDrop.TransferableObject.class, MIME_TYPE);
        private Fetcher fetcher;
        private Object data;
        private DataFlavor customFlavor;

        /**
         * Creates a new {@link TransferableObject} that wraps <var>data</var>.
         * Along with the {@link #DATA_FLAVOR} associated with this class,
         * this creates a custom data flavor with a representation class
         * determined from <code>data.getClass()</code> and the MIME type
         * <tt>application/x-net.iharder.dnd.TransferableObject</tt>.
         *
         * @param data The data to transfer
         * @since 1.1
         */
        public TransferableObject(Object data) {
            this.data = data;
            this.customFlavor = new DataFlavor(data.getClass(), MIME_TYPE);
        }   // end constructor

        /**
         * Creates a new {@link TransferableObject} that will return the
         * object that is returned by <var>fetcher</var>.
         * No custom data flavor is set other than the default
         * {@link #DATA_FLAVOR}.
         *
         * @see Fetcher
         * @param fetcher The {@link Fetcher} that will return the data object
         * @since 1.1
         */
        public TransferableObject(Fetcher fetcher) {
            this.fetcher = fetcher;
        }   // end constructor

        /**
         * Creates a new {@link TransferableObject} that will return the
         * object that is returned by <var>fetcher</var>.
         * Along with the {@link #DATA_FLAVOR} associated with this class,
         * this creates a custom data flavor with a representation class <var>dataClass</var>
         * and the MIME type
         * <tt>application/x-net.iharder.dnd.TransferableObject</tt>.
         *
         * @see Fetcher
         * @param dataClass The {@link java.lang.Class} to use in the custom data flavor
         * @param fetcher The {@link Fetcher} that will return the data object
         * @since 1.1
         */
        public TransferableObject(Class dataClass, Fetcher fetcher) {
            this.fetcher = fetcher;
            this.customFlavor = new DataFlavor(dataClass, MIME_TYPE);
        }   // end constructor

        /**
         * Returns the custom {@link java.awt.datatransfer.DataFlavor} associated
         * with the encapsulated object or <tt>null</tt> if the {@link Fetcher}
         * constructor was used without passing a {@link java.lang.Class}.
         *
         * @return The custom data flavor for the encapsulated object
         * @since 1.1
         */
        public DataFlavor getCustomDataFlavor() {
            return customFlavor;
        }   // end getCustomDataFlavor


        /* ********  T R A N S F E R A B L E   M E T H O D S  ******** */
        /**
         * Returns a two- or three-element array containing first
         * the custom data flavor, if one was created in the constructors,
         * second the default {@link #DATA_FLAVOR} associated with
         * {@link TransferableObject}, and third the
         * {@link java.awt.datatransfer.DataFlavor.stringFlavor}.
         *
         * @return An array of supported data flavors
         * @since 1.1
         */
        @Override
        public DataFlavor[] getTransferDataFlavors() {
            if (customFlavor != null) {
                return new DataFlavor[]{customFlavor,
                            DATA_FLAVOR,
                            DataFlavor.stringFlavor
                        };  // end flavors array
            } else {
                return new DataFlavor[]{DATA_FLAVOR,
                            DataFlavor.stringFlavor
                        };  // end flavors array
            }
        }   // end getTransferDataFlavors

        /**
         * Returns the data encapsulated in this {@link TransferableObject}.
         * If the {@link Fetcher} constructor was used, then this is when
         * the {@link Fetcher#getObject getObject()} method will be called.
         * If the requested data flavor is not supported, then the
         * {@link Fetcher#getObject getObject()} method will not be called.
         *
         * @param flavor The data flavor for the data to return
         * @return The dropped data
         * @since 1.1
         */
        @Override
        public Object getTransferData(DataFlavor flavor)
                throws UnsupportedFlavorException, IOException {
            // Native object
            if (flavor.equals(DATA_FLAVOR)) {
                return fetcher == null ? data : fetcher.getObject();
            }

            // String
            if (flavor.equals(DataFlavor.stringFlavor)) {
                return fetcher == null ? data.toString() : fetcher.getObject().toString();
            }

            // We can't do anything else
            throw new UnsupportedFlavorException(flavor);
        }   // end getTransferData

        /**
         * Returns <tt>true</tt> if <var>flavor</var> is one of the supported
         * flavors. Flavors are supported using the <code>equals(...)</code> method.
         *
         * @param flavor The data flavor to check
         * @return Whether or not the flavor is supported
         * @since 1.1
         */
        @Override
        public boolean isDataFlavorSupported(DataFlavor flavor) {
            // Native object
            if (flavor.equals(DATA_FLAVOR)) {
                return true;
            }

            // String
            if (flavor.equals(DataFlavor.stringFlavor)) {
                return true;
            }

            // We can't do anything else
            return false;
        }   // end isDataFlavorSupported


        /* ********  I N N E R   I N T E R F A C E   F E T C H E R  ******** */
        /**
         * Instead of passing your data directly to the {@link TransferableObject}
         * constructor, you may want to know exactly when your data was received
         * in case you need to remove it from its source (or do anyting else to it).
         * When the {@link #getTransferData getTransferData(...)} method is called
         * on the {@link TransferableObject}, the {@link Fetcher}'s
         * {@link #getObject getObject()} method will be called.
         *
         * @author Robert Harder
         * @copyright 2001
         * @version 1.1
         * @since 1.1
         */
        public static interface Fetcher {

            /**
             * Return the object being encapsulated in the
             * {@link TransferableObject}.
             *
             * @return The dropped object
             * @since 1.1
             */
            public abstract Object getObject();
        }   // end inner interface Fetcher
    }   // end class TransferableObject
}   // end class FileDrop

