package de.intevation.flys.client.server;

import java.util.ArrayList;
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.NamedNodeMap;
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.ClientProtocolUtils;
import de.intevation.artifacts.common.utils.XMLUtils;

import de.intevation.artifacts.httpclient.exceptions.ConnectionException;
import de.intevation.artifacts.httpclient.http.HttpClient;
import de.intevation.artifacts.httpclient.http.HttpClientImpl;
import de.intevation.artifacts.httpclient.http.response.DocumentResponseHandler;

import de.intevation.flys.client.shared.exceptions.ServerException;
import de.intevation.flys.client.shared.model.AttributedTheme;
import de.intevation.flys.client.shared.model.Collection;
import de.intevation.flys.client.shared.model.CollectionItem;
import de.intevation.flys.client.shared.model.DefaultCollection;
import de.intevation.flys.client.shared.model.DefaultCollectionItem;
import de.intevation.flys.client.shared.model.DefaultFacet;
import de.intevation.flys.client.shared.model.ChartMode;
import de.intevation.flys.client.shared.model.ExportMode;
import de.intevation.flys.client.shared.model.MapMode;
import de.intevation.flys.client.shared.model.ReportMode;
import de.intevation.flys.client.shared.model.Facet;
import de.intevation.flys.client.shared.model.OutputMode;
import de.intevation.flys.client.shared.model.Recommendation;
import de.intevation.flys.client.shared.model.Theme;
import de.intevation.flys.client.shared.model.ThemeList;
import de.intevation.flys.client.client.services.DescribeCollectionService;


/**
 * This service implements a method that queries the DESCRIBE document of a
 * specific collection and returns a Collection object with the information of
 * the document.
 *
 * @author <a href="mailto:ingo.weinzierl@intevation.de">Ingo Weinzierl</a>
 */
public class DescribeCollectionServiceImpl
extends      RemoteServiceServlet
implements   DescribeCollectionService
{
    /** The error message key that is thrown if an error occured while
     * describe() a Collection.*/
    public static final String ERROR_DESCRIBE_COLLECTION =
        "error_describe_collection";

    public static final String XPATH_FACETS = "art:facets/art:facet";

    public static final String XPATH_LOADED_RECOMMENDATIONS =
        "/art:artifact-collection/art:attribute/art:loaded-recommendations/art:recommendation";


    public Collection describe(String uuid, String serverUrl, String locale)
    throws ServerException
    {
        System.out.println("DescribeCollectionServiceImpl.describe");

        Document describe = ClientProtocolUtils.newDescribeCollectionDocument(
            uuid);

        HttpClient client = new HttpClientImpl(serverUrl, locale);

        try {
            Document response = (Document) client.doCollectionAction(
                describe, uuid, new DocumentResponseHandler());

            Collection c = parseCollection(response);

            if (c == null) {
                throw new ServerException(ERROR_DESCRIBE_COLLECTION);
            }

            System.out.println("Collection successfully parsed.");

            return c;
        }
        catch (ConnectionException ce) {
            System.err.println(ce.getLocalizedMessage());
        }

        throw new ServerException(ERROR_DESCRIBE_COLLECTION);
    }


    /**
     * This method takes the DESCRIBE document of the Collections describe()
     * operation and extracts the information about the collection itself and
     * the collection items.
     *
     * @param description The DESCRIBE document of the Collections describe()
     * operation.
     *
     * @return a Collection with CollectionItems.
     */
    protected Collection parseCollection(Document description) {
        System.out.println("AddArtifactServiceImpl.parseCollection");

        if (description == null) {
            System.err.println("The DESCRIBE of the Collection is null!");
            return null;
        }

        String uuid = XMLUtils.xpathString(
            description,
            "art:artifact-collection/@art:uuid",
            ArtifactNamespaceContext.INSTANCE);

        String ttlStr = XMLUtils.xpathString(
            description,
            "art:artifact-collection/@art:ttl",
            ArtifactNamespaceContext.INSTANCE);

        if (uuid.length() == 0 || ttlStr.length() == 0) {
            System.err.println("Found an invalid Collection!");
            return null;
        }


        long ttl = -1;
        try {
            ttl = Long.valueOf(ttlStr);
        }
        catch (NumberFormatException nfe) {
            // do nothing
        }

        Map<String, ThemeList> themeList = parseThemeLists(description);
        List<Recommendation> recommended = parseRecommendations(description);

        Collection c = !themeList.isEmpty()
            ? new DefaultCollection(uuid, ttl, recommended, themeList)
            : new DefaultCollection(uuid, ttl, recommended);

        NodeList items = (NodeList) XMLUtils.xpath(
            description,
            "art:artifact-collection/art:artifacts/art:artifact",
            XPathConstants.NODESET,
            ArtifactNamespaceContext.INSTANCE);

        if (items == null || items.getLength() == 0) {
            System.out.println("No collection item found for this collection.");

            return c;
        }

        int size = items.getLength();

        for (int i = 0; i < size; i++) {
            CollectionItem item = parseCollectionItem(
                (Element)items.item(i),
                i == 0);

            if (item != null) {
                c.addItem(item);
            }
        }

        System.out.println(
            "Found " + c.getItemLength() + " collection items " +
            "for the Collection '" + c.identifier() + "'.");

        return c;
    }


    protected Map<String, ThemeList> parseThemeLists(Document description) {
        System.out.println("DescribeCollectionServiceImpl.parseThemeLists");

        NodeList lists = (NodeList) XMLUtils.xpath(
            description,
            "/art:artifact-collection/art:attribute/art:outputs/art:output",
            XPathConstants.NODESET,
            ArtifactNamespaceContext.INSTANCE);

        int num = lists != null ? lists.getLength() : 0;

        Map<String, ThemeList> themeList = new HashMap<String, ThemeList>(num);

        String uri = ArtifactNamespaceContext.NAMESPACE_URI;

        for (int i = 0; i < num; i++) {
            Element node = (Element)lists.item(i);

            String outName = node.getAttribute("name");

            if (outName.length() > 0) {
                ThemeList list = parseThemeList(node);
                if (list.getThemeCount() > 0) {
                    themeList.put(outName, list);
                }
            }
        }

        return themeList;
    }


    protected ThemeList parseThemeList(Element node) {
        System.out.println("DescribeCollectionServiceImpl.parseThemeList");

        NodeList themes = node.getElementsByTagNameNS(
            ArtifactNamespaceContext.NAMESPACE_URI,
            "facet");

        int num = themes != null ? themes.getLength() : 0;

        List<Theme> themeList = new ArrayList<Theme>(num);

        for (int i = 0; i < num; i++) {
            Theme theme = parseTheme((Element)themes.item(i));

            if (theme != null) {
                themeList.add(theme);
            }
        }

        return new ThemeList(themeList);
    }


    protected Theme parseTheme(Element ele) {
        System.out.println("DescribeCollectionServiceImpl.parseTheme");

        String uri = ArtifactNamespaceContext.NAMESPACE_URI;

        NamedNodeMap attrMap = ele.getAttributes();
        int          attrNum = attrMap != null ? attrMap.getLength() : 0;

        AttributedTheme t = new AttributedTheme();

        for (int i = 0; i < attrNum; i++) {
            Node attr = attrMap.item(i);

            String prefix = attr.getPrefix();
            String name   = attr.getNodeName().replace(prefix + ":", "");
            String value  = attr.getNodeValue();

            t.addAttr(name, value);
        }

        return t;
    }


    /**
     * This method extracts the CollectionItem from <i>node</i> with its output
     * modes. The output modes are parsed using the parseOutputModes() method.
     *
     * @param node A node that contains information about a CollectionItem.
     *
     * @return a CollectionItem.
     */
    protected CollectionItem parseCollectionItem(Element node, boolean outs) {
        System.out.println("AddArtifactServiceImpl.parseCollectionItem");

        if (node == null) {
            System.err.println("The node for parsing CollectionItem is null!");
            return null;
        }

        String uri = ArtifactNamespaceContext.NAMESPACE_URI;

        String uuid = node.getAttributeNS(uri, "uuid");
        String hash = node.getAttributeNS(uri, "hash");

        if (uuid == null || uuid.length() == 0) {
            System.err.println("Found an invalid CollectionItem!");
            return null;
        }

        List<OutputMode> modes = new ArrayList<OutputMode>();

        if (outs) {
            NodeList outputmodes = node.getElementsByTagNameNS(
                uri, "outputmodes");

            if (outputmodes.getLength() < 1) {
                return null;
            }

            Element om = (Element)outputmodes.item(0);

            modes = parseOutputModes(om);
        }

        return new DefaultCollectionItem(uuid, hash, modes);
    }


    /**
     * This method extracts the OutputModes available for a specific
     * CollectionItem and returns them as list.
     *
     * @param node The root node of the outputmodes list.
     *
     * @return a list of OutputModes.
     */
    protected List<OutputMode> parseOutputModes(Element node) {
        System.out.println("AddArtifactServiceImpl.parseOutputModes");

        if (node == null) {
            System.err.println("The node for parsing OutputModes is null!");
            return null;
        }

        String uri = ArtifactNamespaceContext.NAMESPACE_URI;

        NodeList list = node.getElementsByTagNameNS(uri, "output");

        int size = list.getLength();

        if (size == 0) {
            System.err.println("No outputmode nodes found!");
            return null;
        }

        List<OutputMode> modes = new ArrayList<OutputMode>(size);

        for (int i = 0; i < size; i++) {
            Element tmp = (Element)list.item(i);

            String name = tmp.getAttributeNS(uri, "name");
            String desc = tmp.getAttributeNS(uri, "description");
            String mime = tmp.getAttributeNS(uri, "mime-type");
            String type = tmp.getAttributeNS(uri, "type");

            if (name.length() == 0) {
                System.err.println("Found an invalid output mode.");
                continue;
            }

            OutputMode outmode = null;
            List<Facet> fs     = extractFacets(tmp);

            if (type.equals("export")) {
                outmode = new ExportMode(name, desc, mime, fs);
            }
            else if (type.equals("report")) {
                outmode = new ReportMode(name, desc, mime, fs);
            }
            else if (type.equals("chart")){
                outmode = new ChartMode(name, desc, mime, fs);
            }
            else if (type.equals("map")){
                outmode = new MapMode(name, desc, mime, fs);
            }
            else {
                System.err.println("Broken Output mode without type found.");
                continue;
            }

            modes.add(outmode);
        }

        return modes;
    }


    protected static List<Facet> extractFacets(Element outmode) {
        System.out.println("DescribeCollectionServiceImpl - extractFacets()");

        NodeList facetList = (NodeList) XMLUtils.xpath(
            outmode,
            XPATH_FACETS,
            XPathConstants.NODESET,
            ArtifactNamespaceContext.INSTANCE);

        int num = facetList != null ? facetList.getLength() : 0;

        List<Facet> facets = new ArrayList<Facet>(num);

        String uri = ArtifactNamespaceContext.NAMESPACE_URI;

        for (int i = 0; i < num; i++) {
            Element facetEl = (Element) facetList.item(i);

            String name  = facetEl.getAttributeNS(uri, "name");
            String desc  = facetEl.getAttributeNS(uri, "description");
            String index = facetEl.getAttributeNS(uri, "index");

            if (name != null && name.length() > 0 && index != null) {
                facets.add(new DefaultFacet(name, Integer.valueOf(index),desc));
            }
        }

        return facets;
    }


    public static List<Recommendation> parseRecommendations(Document doc) {
        System.out.println("DescribeCollectionServiceImpl.parseRecommendations");

        NodeList list = (NodeList) XMLUtils.xpath(
            doc,
            XPATH_LOADED_RECOMMENDATIONS,
            XPathConstants.NODESET,
            ArtifactNamespaceContext.INSTANCE);

        int num = list != null ? list.getLength() : 0;

        List<Recommendation> recs = new ArrayList<Recommendation>(num);

        String uri = ArtifactNamespaceContext.NAMESPACE_URI;

        for (int i = 0; i < num; i++) {
            Element rec = (Element) list.item(i);

            String factory = rec.getAttributeNS(uri, "factory");
            String dbids   = rec.getAttributeNS(uri, "ids");

            if (factory != null && factory.length() > 0) {
                recs.add(new Recommendation(factory, dbids));
            }
        }

        return recs;
    }
}
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