/* Copyright (C) 2011, 2012, 2013 by Bundesanstalt für Gewässerkunde
 * Software engineering by Intevation GmbH
 *
 * This file is Free Software under the GNU AGPL (>=v3)
 * and comes with ABSOLUTELY NO WARRANTY! Check out the
 * documentation coming with Dive4Elements River for details.
 */

package org.dive4elements.river.artifacts;

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

import javax.xml.xpath.XPathConstants;

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

import org.dive4elements.artifacts.Artifact;
import org.dive4elements.artifacts.ArtifactNamespaceContext;
import org.dive4elements.artifacts.CallContext;
import org.dive4elements.artifacts.Hook;

import org.dive4elements.artifacts.common.utils.XMLUtils;
import org.dive4elements.artifacts.common.utils.XMLUtils.ElementCreator;

import org.dive4elements.artifactdatabase.state.Output;

import org.dive4elements.river.artifacts.datacage.Recommendations;

/** Monitors collection changes. */
public class CollectionMonitor implements Hook {

    public static final String XPATH_RESULT = "/art:result";


    @Override
    public void setup(Node cfg) {
    }


    @Override
    public void execute(Artifact artifact, CallContext context, Document doc) {
        D4EArtifact flys = (D4EArtifact) artifact;

        Element result = (Element) XMLUtils.xpath(
            doc,
            XPATH_RESULT,
            XPathConstants.NODE,
            ArtifactNamespaceContext.INSTANCE);

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

        Element recommended = creator.create("recommended-artifacts");
        result.appendChild(recommended);

        String[] outs              = extractOutputNames(flys, context);
        Map<String, Object> params = getNoneUserSpecificParameters(flys, context);

        Recommendations rec = Recommendations.getInstance();

        // TODO For newer official-lines recommendations we actually
        // need user-id (null here).
        rec.recommend(flys, null, outs, params, recommended);
    }


    /**
     * Get outputnames from current state (only the ones for which
     * facets exist).
     */
    public static String[] extractOutputNames(
        D4EArtifact flys,
        CallContext  context)
    {
        if (flys instanceof ChartArtifact) {
            return new String[0];
        }

        List<Output> outs = flys.getCurrentOutputs(context);

        int num = outs == null ? 0 : outs.size();

        String[] names = new String[num];

        for (int i = 0; i < num; i++) {
            names[i] = outs.get(i).getName();
        }

        return names;
    }


    /**
     * Creates Map from Strings "recommended" to "true".
     */
    protected Map<String, Object> getNoneUserSpecificParameters(
        D4EArtifact flys,
        CallContext  context)
    {
        Map<String, Object> params = new HashMap<String, Object>(1);
        params.put("recommended", "true");

        return params;
    }
}
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