import ij.*;
import ij.gui.*;
import ij.plugin.frame.Recorder;
import ij.util.Java2;
import java.awt.*;
import java.util.ArrayList; //no  need to import java.util.List; it would be ambiguous because of java.awt.List
import javax.swing.*;
import javax.swing.filechooser.*;
import java.awt.datatransfer.*;

/** This class handles drag&drop onto JFileChoosers. */ 
 public class DragAndDropHandler extends TransferHandler {
    private JFileChooser jFileChooser;
    /** Given a JFileChooser 'fc', this is how to use this class:
     * <pre>
     *     fc.setDragEnabled(true);
     *     fc.setTransferHandler(new DragAndDropHandler(fc));
     * </pre>
    public DragAndDropHandler(JFileChooser jFileChooser) {
        this.jFileChooser = jFileChooser;

    /** Returns whether any of the transfer flavors is supported */
    public boolean canImport(JComponent comp, DataFlavor[] transferFlavors) {
        for (DataFlavor dataFlavor : transferFlavors) {
            if (isSupportedTransferFlavor(dataFlavor))
                return true;
        return false;

    /** Imports the drag&drop file or list of files and sets the JFileChooser to this. 
     *  Returns true if successful */
    public boolean importData(JComponent comp, Transferable t) {
        DataFlavor[] transferFlavors = t.getTransferDataFlavors();
        for (DataFlavor dataFlavor : transferFlavors) {
            try {
                java.util.List<File> fileList = null;
                if (dataFlavor.isFlavorJavaFileListType()) {
                    fileList = (java.util.List<File>)t.getTransferData(DataFlavor.javaFileListFlavor);
                    if (IJ.debugMode) IJ.log("dragAndDrop FileList size="+fileList.size()+" first: "+fileList.get(0));
                } else if (isSupportedTransferFlavor(dataFlavor)) {
                    String str = (String)t.getTransferData(dataFlavor);
                    if (IJ.debugMode) IJ.log("dragAndDrop str="+str);
                    String[] strs = str.split("[\n\r]+");               //multiple files are separate lines
                    fileList = new ArrayList<File>(strs.length);
                    for (String s : strs) {
                        if (s.length() > 0) {
                            File file = new File(s);                    //Try whether it is a plain path (pointing to an existing file)
                            if (!file.exists()) try {
                                file = new File(new URI(s));            //When not successful, try a whether it is a URL, e.g. file:///absolute/path/to/file
                            } catch (URISyntaxException e) {continue;}
                            if (file.exists())                          //We only accept drag&drop of existing files
                if (fileList == null || fileList.size() ==0) continue;  //this data flavor did not work

                File firstFile = fileList.get(0);
                if (jFileChooser.isMultiSelectionEnabled()) {   //multiple files accepted
                    File dir = firstFile.getParentFile();
                    File[] files = fileList.toArray(new File[0]);
                } else {
                    File file = firstFile;                      //single file required; if we get more take the first one
                    if (jFileChooser.getFileSelectionMode() == JFileChooser.DIRECTORIES_ONLY && !file.isDirectory())
                        file = file.getParentFile();            //if a directory is required and we get a file, use its directory
                    if (jFileChooser.getDialogType() == JFileChooser.SAVE_DIALOG && file.isDirectory())
                        jFileChooser.setCurrentDirectory(file); //in a save operation, if we get a directory, move there
                return true;
            } catch (Exception e) {if (IJ.debugMode) IJ.handleException(e);}
        return false;

    /** Returns whether this transfer flavor is supported. We support File Lists and Strings (plain or as list of URLs). */
    public boolean isSupportedTransferFlavor(DataFlavor flavor) {
        return flavor.isFlavorJavaFileListType() ||
                (flavor.getRepresentationClass() == String.class &&
                (flavor.getMimeType().startsWith("text/uri-list") || flavor.getMimeType().startsWith("text/plain")));