package de.intevation.flys.artifacts.services;

import java.io.InputStream;
import java.io.IOException;

import java.sql.Connection;
import java.sql.SQLException;

import org.w3c.dom.Document;

import org.apache.log4j.Logger;

import java.util.Map;
import java.util.HashMap;

import de.intevation.artifacts.CallMeta;
import de.intevation.artifacts.ServiceFactory;

import de.intevation.artifactdatabase.DefaultService;

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

import de.intevation.artifacts.common.ArtifactNamespaceContext;

import de.intevation.flys.artifacts.services.meta.Builder;

import de.intevation.flys.backend.SessionHolder;

import org.hibernate.Session;

import org.hibernate.jdbc.Work;

public class MetaDataService
extends      DefaultService
{
    private static Logger log = Logger.getLogger(MetaDataService.class);

    public static final String XPATH_RIVER = "/art:river/text()";

    public static final String META_DATA_TEMPLATE = "/metadata/template.xml";

    protected Builder builder;

    public MetaDataService() {
    }

    protected static Map<String, Object> extractParameters(Document data) {
        HashMap<String, Object> parameters = new HashMap<String, Object>();

        String river = XMLUtils.xpathString(
            data, XPATH_RIVER, ArtifactNamespaceContext.INSTANCE);

        if (river == null || (river = river.trim()).length() == 0) {
            river = "%"; // matches all rivers
        }

        parameters.put("river", river);

        return parameters;
    }

    @Override
    public Document process(
        Document data,
        Object   globalContext,
        CallMeta callMeta
    ) {
        log.debug("MetaDataService.process");

        final Document result = XMLUtils.newDocument();

        if (builder == null) {
            log.error("MetaDataService is not setup properly.");
            return result;
        }

        final Map<String, Object> parameters = extractParameters(data);

        Session session = SessionHolder.acquire();
        try {
            session.doWork(new Work() {
                @Override
                public void execute(Connection connection)
                throws SQLException
                {
                    log.debug("MetaDataService.execute");
                    builder.build(connection, result, parameters);
                }
            });
        }
        finally {
            session.close();
            SessionHolder.release();
        }

        return result;
    }

    @Override
    public void setup(ServiceFactory factory, Object globalContext) {
        log.debug("MetaDataService.setup");

        InputStream in = getClass().getResourceAsStream(META_DATA_TEMPLATE);

        if (in == null) {
            log.error("cannot get template resource");
            return;
        }

        try {
            Document template = XMLUtils.parseDocument(in);
            if (template == null) {
                log.error("cannot parse meta data template");
            }
            else {
                builder = new Builder(template);
            }
        }
        finally {
            try {
                in.close();
            }
            catch (IOException ioe) {
                log.error(ioe);
            }
        }
    }
}
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