// License: GPL. For details, see LICENSE file.
package org.openstreetmap.josm.io;

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

import java.io.InputStream;
import java.util.Arrays;

import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;

import org.openstreetmap.josm.data.osm.DataSet;
import org.openstreetmap.josm.data.osm.OsmPrimitive;
import org.openstreetmap.josm.gui.progress.ProgressMonitor;

public class OsmChangeReader extends OsmReader {

    public static final String[] ACTIONS = {"create", "modify", "delete"};
    
    /**
     * constructor (for private and subclasses use only)
     *
     * @see #parseDataSet(InputStream, ProgressMonitor)
     */
    protected OsmChangeReader() {
    }
    
    /* (non-Javadoc)
     * @see org.openstreetmap.josm.io.OsmReader#parseRoot()
     */
    @Override
    protected void parseRoot() throws XMLStreamException {
        if (parser.getLocalName().equals("osmChange")) {
            parseOsmChange();
        } else {
            parseUnknown();
        }
    }

    private void parseOsmChange() throws XMLStreamException {
        String v = parser.getAttributeValue(null, "version");
        if (v == null) {
            throwException(tr("Missing mandatory attribute ''{0}''.", "version"));
        }
        if (!v.equals("0.6")) {
            throwException(tr("Unsupported version: {0}", v));
        }
        ds.setVersion(v);
        while (parser.hasNext()) {
            int event = parser.next();
            if (event == XMLStreamConstants.START_ELEMENT) {
                if (Arrays.asList(ACTIONS).contains(parser.getLocalName())) {
                    parseCommon(parser.getLocalName());
                } else {
                    parseUnknown();
                }
            } else if (event == XMLStreamConstants.END_ELEMENT) {
                return;
            }
        }
    }

    private void parseCommon(String action) throws XMLStreamException {
        while (parser.hasNext()) {
            int event = parser.next();
            if (event == XMLStreamConstants.START_ELEMENT) {
                OsmPrimitive p = null;
                if (parser.getLocalName().equals("node")) {
                    p = parseNode();
                } else if (parser.getLocalName().equals("way")) {
                    p = parseWay();
                } else if (parser.getLocalName().equals("relation")) {
                    p = parseRelation();
                } else {
                    parseUnknown();
                }
                if (p != null && action != null) {
                    if (action.equals("modify")) {
                        p.setModified(true);
                    } else if (action.equals("delete")) {
                        p.setDeleted(true);
                    }
                }
            } else if (event == XMLStreamConstants.END_ELEMENT) {
                return;
            }
        }
    }
    
    /**
     * Parse the given input source and return the dataset.
     *
     * @param source the source input stream. Must not be <code>null</code>.
     * @param progressMonitor  the progress monitor. If <code>null</code>,
     * {@link org.openstreetmap.josm.gui.progress.NullProgressMonitor#INSTANCE} is assumed
     *
     * @return the dataset with the parsed data
     * @throws IllegalDataException thrown if the an error was found while parsing the data from the source
     * @throws IllegalArgumentException thrown if source is <code>null</code>
     */
    public static DataSet parseDataSet(InputStream source, ProgressMonitor progressMonitor) throws IllegalDataException {
        return new OsmChangeReader().doParseDataSet(source, progressMonitor);
    }
}