source: josm/src/org/openstreetmap/josm/actions/CombineWayAction.java@ 290

package org.openstreetmap.josm.actions;

import static org.openstreetmap.josm.tools.I18n.tr;

import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;
import java.util.Map.Entry;

import javax.swing.Box;
import javax.swing.JComboBox;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;

import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.command.ChangeCommand;
import org.openstreetmap.josm.command.Command;
import org.openstreetmap.josm.command.DeleteCommand;
import org.openstreetmap.josm.command.SequenceCommand;
import org.openstreetmap.josm.data.SelectionChangedListener;
import org.openstreetmap.josm.data.osm.DataSet;
import org.openstreetmap.josm.data.osm.OsmPrimitive;
import org.openstreetmap.josm.data.osm.Way;
import org.openstreetmap.josm.tools.GBC;

/**
 * Combines multiple ways into one.
 * 
 * @author Imi
 */
public class CombineWayAction extends JosmAction implements SelectionChangedListener {

        public CombineWayAction() {
                super(tr("Combine Way"), "combineway", tr("Combine several ways into one."), KeyEvent.VK_C, KeyEvent.CTRL_MASK | KeyEvent.SHIFT_MASK, true);
                DataSet.listeners.add(this);
        }

        public void actionPerformed(ActionEvent event) {
                Collection<OsmPrimitive> selection = Main.ds.getSelected();
                LinkedList<Way> selectedWays = new LinkedList<Way>();
                
                for (OsmPrimitive osm : selection)
                        if (osm instanceof Way)
                                selectedWays.add((Way)osm);

                if (selectedWays.size() < 2) {
                        JOptionPane.showMessageDialog(Main.parent, tr("Please select at least two ways to combine."));
                        return;
                }

                // collect properties for later conflict resolving
                Map<String, Set<String>> props = new TreeMap<String, Set<String>>();
                for (Way w : selectedWays) {
                        for (Entry<String,String> e : w.entrySet()) {
                                if (!props.containsKey(e.getKey()))
                                        props.put(e.getKey(), new TreeSet<String>());
                                props.get(e.getKey()).add(e.getValue());
                        }
                }
                
                Way oldWay = selectedWays.poll();
                Way newWay = new Way(oldWay);
                LinkedList<Command> cmds = new LinkedList<Command>();
                
                for (Way w : selectedWays)
                        newWay.segments.addAll(w.segments);
                
                // display conflict dialog
                Map<String, JComboBox> components = new HashMap<String, JComboBox>();
                JPanel p = new JPanel(new GridBagLayout());
                for (Entry<String, Set<String>> e : props.entrySet()) {
                        if (e.getValue().size() > 1) {
                                JComboBox c = new JComboBox(e.getValue().toArray());
                                c.setEditable(true);
                                p.add(new JLabel(e.getKey()), GBC.std());
                                p.add(Box.createHorizontalStrut(10), GBC.std());
                                p.add(c, GBC.eol());
                                components.put(e.getKey(), c);
                        } else
                                newWay.put(e.getKey(), e.getValue().iterator().next());
                }
                if (!components.isEmpty()) {
                        int answer = JOptionPane.showConfirmDialog(Main.parent, p, tr("Enter values for all conflicts."), JOptionPane.OK_CANCEL_OPTION);
                        if (answer != JOptionPane.OK_OPTION)
                                return;
                        for (Entry<String, JComboBox> e : components.entrySet())
                                newWay.put(e.getKey(), e.getValue().getEditor().getItem().toString());
                }

                cmds.add(new DeleteCommand(selectedWays));
                cmds.add(new ChangeCommand(oldWay, newWay));
                Main.main.editLayer().add(new SequenceCommand(tr("Combine {0} ways", selectedWays.size()), cmds));
                Main.ds.setSelected(oldWay);
        }

        /**
         * Enable the "Combine way" menu option if more then one way is selected
         */
        public void selectionChanged(Collection<? extends OsmPrimitive> newSelection) {
                boolean first = false;
                for (OsmPrimitive osm : newSelection) {
                        if (osm instanceof Way) {
                                if (first) {
                                        setEnabled(true);
                                        return;
                                }
                                first = true;
                        }
                }
                setEnabled(false);
        }
}