source: osm/applications/editors/josm/plugins/utilsplugin/src/UtilsPlugin/MergeNodesAction.java@ 5419

package UtilsPlugin;

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

import java.util.ArrayList;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Collection;
import java.util.Collections;

import java.awt.event.ActionEvent;

import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.data.osm.OsmPrimitive;
import org.openstreetmap.josm.data.osm.Node;
import org.openstreetmap.josm.data.osm.Way;
import org.openstreetmap.josm.data.osm.visitor.CollectBackReferencesVisitor;
import org.openstreetmap.josm.data.coor.EastNorth;
import org.openstreetmap.josm.gui.MapFrame;
import org.openstreetmap.josm.plugins.Plugin;
import org.openstreetmap.josm.actions.JosmAction;
import org.openstreetmap.josm.command.Command;
import org.openstreetmap.josm.command.AddCommand;
import org.openstreetmap.josm.command.DeleteCommand;
import org.openstreetmap.josm.command.ChangeCommand;
import org.openstreetmap.josm.command.SequenceCommand;

import javax.swing.AbstractAction;
import javax.swing.JOptionPane;

class MergeNodesAction extends JosmAction {
        public MergeNodesAction() {
                super(tr("Merge nodes"), "mergenodes",
                        tr("Merge nodes"), 0, 0, true);
        }

        public void actionPerformed(ActionEvent e) {
                Collection<OsmPrimitive> sel = Main.ds.getSelected();
                HashSet<Node> nodes = new HashSet<Node>();

                for (OsmPrimitive osm : sel)
                        if (osm instanceof Node)
                                nodes.add((Node)osm);
                if (nodes.size() < 2) {
                        JOptionPane.showMessageDialog(Main.parent,
                                tr("Must select at least two nodes."));
                        return;
                }

                // Find the node with the lowest ID.
                // We're gonna keep our 3-digit node ids.
                Node target = null;
                for (Node n : nodes) {
                        if (target == null || target.id == 0 || n.id < target.id) {
                                target = n;
                        }
                }

                Collection<Command> cmds = new LinkedList<Command>();

                Node newTarget = new Node(target);

                // Don't place the merged node on one of the former nodes.
                // Place it right there in the middle.
                double x = 0, y = 0;
                for (Node n : nodes) {
                        x += n.eastNorth.east();
                        y += n.eastNorth.north();
                }
                newTarget.eastNorth = new EastNorth(
                        x / nodes.size(), y / nodes.size());

                cmds.add(new ChangeCommand(target, newTarget));

                HashSet<Node> delNodes = new HashSet<Node>(nodes);
                delNodes.remove(target);
                cmds.add(new DeleteCommand(delNodes));

                for (Way w : Main.ds.ways) {
                        if (w.deleted || w.incomplete) continue;

                        boolean affected = false;
                        for (Node n : nodes) {
                                if (w.nodes.contains(n)) {
                                        affected = true;
                                        break;
                                }
                        }
                        if (!affected) continue;

                        // Replace the old nodes with the merged one
                        Way wnew = new Way(w);
                        for (int i = 0; i < wnew.nodes.size(); i++) {
                                if (nodes.contains(wnew.nodes.get(i))) {
                                        wnew.nodes.set(i, target);
                                }
                        }

                        // Remove duplicates
                        Node lastN = null;
                        for (int i = wnew.nodes.size() - 1; i >= 0; i--) {
                                Node n = wnew.nodes.get(i);
                                if (lastN == n) wnew.nodes.remove(i);
                                lastN = n;
                        }

                        if (wnew.nodes.size() < 2) {
                                CollectBackReferencesVisitor backRefV =
                                        new CollectBackReferencesVisitor(Main.ds, false);
                                backRefV.visit(w);
                                if (!backRefV.data.isEmpty()) {
                                        JOptionPane.showMessageDialog(Main.parent,
                                                tr("Cannot merge nodes: " +
                                                        "Would have to delete a way that is still used."));
                                        return;
                                }

                                cmds.add(new DeleteCommand(Collections.singleton(w)));
                        } else {
                                cmds.add(new ChangeCommand(w, wnew));
                        }
                }

                Main.main.undoRedo.add(new SequenceCommand(tr("Merge Nodes"), cmds));
                Main.ds.setSelected(newTarget);
                Main.map.repaint();
        }
}