source: osm/applications/editors/josm/plugins/reltoolbox/src/relcontext/ChosenRelationComponent.java

// License: GPL. For details, see LICENSE file.
package relcontext;

import javax.swing.JLabel;

import org.openstreetmap.josm.data.osm.Relation;

/**
 * Renderer for chosen relation.
 * [Icon] na=wood U
 * key is 2-letter; type = icon; to the right — symbol of relation topology (closed, lines, broken).
 *
 * @author Zverik
 */
public class ChosenRelationComponent extends JLabel implements ChosenRelationListener {

    public ChosenRelationComponent(ChosenRelation rel) {
        super("");
        rel.addChosenRelationListener(this);
    }

    @Override
    public void chosenRelationChanged(Relation oldRelation, Relation newRelation) {
        setText(prepareText(newRelation));
        repaint();
    }

    private static final String[] TYPE_KEYS = new String[] {
            "natural", "landuse", "place", "waterway", "leisure", "amenity", "restriction", "public_transport", "route", "enforcement"
    };

    private static final String[] NAMING_TAGS = new String[] {
            "name", "place_name", "ref", "destination", "note"
    };

    protected String prepareText(Relation rel) {
        if (rel == null)
            return "";

        String type = rel.get("type");
        if (type == null || type.length() == 0) {
            type = "-";
        }

        String tag = null;
        for (int i = 0; i < TYPE_KEYS.length && tag == null; i++) {
            if (rel.hasKey(TYPE_KEYS[i])) {
                tag = TYPE_KEYS[i];
            }
        }
        if (tag != null) {
            tag = tag.substring(0, 2) + "=" + rel.get(tag);
        }

        String name = null;
        for (int i = 0; i < NAMING_TAGS.length && name == null; i++) {
            if (rel.hasKey(NAMING_TAGS[i])) {
                name = rel.get(NAMING_TAGS[i]);
            }
        }

        StringBuilder sb = new StringBuilder();
        sb.append(type.charAt(0));
        if (type.equals("boundary") && rel.hasKey("admin_level")) {
            sb.append(rel.get("admin_level"));
        }
        if (name != null) {
            sb.append(" \"").append(name).append('"');
        }
        if (tag != null) {
            sb.append("; ").append(tag);
        }
        sb.append(" (").append(rel.getMembersCount()).append(')');

        return sb.toString();
    }
}