package de.intevation.flys.client.server;

import java.util.List;
import java.util.ArrayList;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import com.google.gwt.user.server.rpc.RemoteServiceServlet;

import de.intevation.artifacts.common.ArtifactNamespaceContext;

import de.intevation.artifacts.common.utils.XMLUtils;

import de.intevation.flys.client.shared.exceptions.ServerException;

import de.intevation.flys.client.client.services.MetaDataService;

import de.intevation.artifacts.httpclient.exceptions.ConnectionException;

import de.intevation.artifacts.httpclient.http.HttpClient;
import de.intevation.artifacts.httpclient.http.HttpClientImpl;

import de.intevation.flys.client.shared.model.DataCageTree;
import de.intevation.flys.client.shared.model.DataCageNode;

public class MetaDataServiceImpl
extends      RemoteServiceServlet
implements   MetaDataService
{
    public static final String ERROR_NO_META_DATA_FOUND =
        "error_no_meta_data_found";

    public DataCageTree getMetaData(String url, String locale, String river) 
    throws ServerException
    {
        System.out.println("MetaDataService.getDistanceInfo");

        Document doc = XMLUtils.newDocument();

        XMLUtils.ElementCreator ec = new XMLUtils.ElementCreator(
            doc,
            ArtifactNamespaceContext.NAMESPACE_URI,
            ArtifactNamespaceContext.NAMESPACE_PREFIX);

        Element riverEl = ec.create("river");

        riverEl.setTextContent(river);

        doc.appendChild(riverEl);

        HttpClient client = new HttpClientImpl(url, locale);

        try {
            return convert(client.callService(url, "metadata", doc));
        }
        catch (ConnectionException ce) {
            System.err.println(ce.getLocalizedMessage());
        }

        throw new ServerException(ERROR_NO_META_DATA_FOUND);
    }

    protected static DataCageNode convert(Node node) {
        String name = node.getLocalName();
        DataCageNode dvn = new DataCageNode(name);
        NodeList children = node.getChildNodes();
        for (int i = 0, N = children.getLength(); i < N; ++i) {
            dvn.addChild(convert(children.item(i)));
        }
        return dvn;
    }

    protected static DataCageTree convert(Document document) {
        ArrayList<DataCageNode> roots = new ArrayList<DataCageNode>();
        NodeList nodes = document.getChildNodes();
        for (int i = 0, N = nodes.getLength(); i < N; ++i) {
            Node node = nodes.item(i);
            if (node.getNodeType() == Node.ELEMENT_NODE) {
                roots.add(convert(nodes.item(i)));
            }
        }
        return new DataCageTree(roots.get(0));
    }
}
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