--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gwt-client/src/main/java/org/dive4elements/river/client/server/WQInfoServiceImpl.java	Thu Apr 25 15:23:37 2013 +0200
@@ -0,0 +1,207 @@
+package org.dive4elements.river.client.server;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.List;
+
+import javax.xml.xpath.XPathConstants;
+
+import org.w3c.dom.Document;
+import org.w3c.dom.Element;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+
+import org.apache.log4j.Logger;
+
+import com.google.gwt.user.server.rpc.RemoteServiceServlet;
+
+import org.dive4elements.artifacts.common.ArtifactNamespaceContext;
+import org.dive4elements.artifacts.common.utils.XMLUtils;
+
+import org.dive4elements.artifacts.httpclient.exceptions.ConnectionException;
+import org.dive4elements.artifacts.httpclient.http.HttpClient;
+import org.dive4elements.artifacts.httpclient.http.HttpClientImpl;
+
+import org.dive4elements.river.client.shared.exceptions.ServerException;
+import org.dive4elements.river.client.client.services.WQInfoService;
+import org.dive4elements.river.client.shared.model.WQInfoObject;
+import org.dive4elements.river.client.shared.model.WQInfoObjectImpl;
+
+
+/**
+ * @author <a href="mailto:ingo.weinzierl@intevation.de">Ingo Weinzierl</a>
+ */
+public class WQInfoServiceImpl
+extends      RemoteServiceServlet
+implements   WQInfoService
+{
+    private static final Logger logger =
+        Logger.getLogger(WQInfoServiceImpl.class);
+
+    public static final String ERROR_NO_WQINFO_FOUND =
+        "error_no_wqinfo_found";
+
+    public static final String XPATH_WQS = "art:service/art:mainvalues/art:mainvalue";
+
+
+    public WQInfoObject[] getWQInfo(
+        String locale,
+        String river,
+        double from,
+        double to)
+    throws ServerException
+    {
+        logger.info("WQInfoServiceImpl.getWQInfo");
+
+        String url = getServletContext().getInitParameter("server-url");
+
+        Document doc = XMLUtils.newDocument();
+
+        XMLUtils.ElementCreator ec = new XMLUtils.ElementCreator(
+            doc,
+            ArtifactNamespaceContext.NAMESPACE_URI,
+            ArtifactNamespaceContext.NAMESPACE_PREFIX);
+
+        Element mainvalues = ec.create("mainvalues");
+        Element riverEl = ec.create("river");
+        Element startEl = ec.create("start");
+        Element endEl   = ec.create("end");
+
+        riverEl.setTextContent(river);
+        startEl.setTextContent(Double.valueOf(from).toString());
+        endEl.setTextContent(Double.valueOf(to).toString());
+
+        mainvalues.appendChild(riverEl);
+        mainvalues.appendChild(startEl);
+        mainvalues.appendChild(endEl);
+
+        doc.appendChild(mainvalues);
+
+        HttpClient client = new HttpClientImpl(url, locale);
+
+        try {
+            Document result = client.callService(url, "mainvalues", doc);
+
+            logger.debug("Extract wq info objects now.");
+            WQInfoObject[] objects = extractWQInfoObjects(result);
+
+            if (objects.length > 0) {
+                return objects;
+            }
+        }
+        catch (ConnectionException ce) {
+            logger.error(ce, ce);
+        }
+
+        throw new ServerException(ERROR_NO_WQINFO_FOUND);
+    }
+
+
+    /**
+     * Extracts all wq info objects from <i>result</i> document.
+     *
+     * @param result The document retrieved by the server.
+     *
+     * @return a list of WQInfoObjects.
+     */
+    protected WQInfoObject[] extractWQInfoObjects(Document result)
+    throws    ServerException
+    {
+        NodeList list = (NodeList) XMLUtils.xpath(
+            result,
+            XPATH_WQS,
+            XPathConstants.NODESET,
+            ArtifactNamespaceContext.INSTANCE);
+
+        if (list == null || list.getLength() == 0) {
+            logger.warn("No wq info found.");
+
+            throw new ServerException(ERROR_NO_WQINFO_FOUND);
+        }
+
+        boolean debug = logger.isDebugEnabled();
+
+        int num = list.getLength();
+        if (debug) {
+            logger.debug("Response contains " + num + " objects.");
+        }
+
+        List<WQInfoObject> objects =
+            new ArrayList<WQInfoObject>(num);
+
+        for (int i = 0; i < num; i++) {
+            WQInfoObject obj = buildWQInfoObject(list.item(i));
+
+            if (obj != null) {
+                objects.add(obj);
+            }
+        }
+
+        if (debug) {
+            logger.debug("Retrieved " + objects.size() + " wq values");
+        }
+
+        WQInfoObject [] array = (WQInfoObject[])
+            objects.toArray(new WQInfoObject[objects.size()]);
+
+        Arrays.sort(array, WQ_INFO_OBJECT_CMP);
+
+        return array;
+    }
+
+    public static final Comparator<WQInfoObject> WQ_INFO_OBJECT_CMP =
+        new Comparator<WQInfoObject>() {
+            @Override
+            public int compare(WQInfoObject a, WQInfoObject b) {
+
+                // Descending by type: Qs before Ds
+                int cmp = a.getType().compareTo(b.getType());
+                if (cmp < 0) return +1;
+                if (cmp > 0) return -1;
+
+                // Ascending by value
+                double diff = a.getValue() - b.getValue();
+                if (diff < 0d) return -1;
+                if (diff > 0d) return +1;
+                return 0;
+            }
+        };
+
+    /**
+     * Extracts information for a single wq info object and intializes an
+     * WQInfoObject with them.
+     *
+     * @param node The node that contains the information.
+     *
+     * @return a valid WQInfoObject.
+     */
+    protected static WQInfoObject buildWQInfoObject(Node node) {
+
+        String name = XMLUtils.xpathString(
+            node, "@name", ArtifactNamespaceContext.INSTANCE);
+
+        String type = XMLUtils.xpathString(
+            node, "@type", ArtifactNamespaceContext.INSTANCE);
+
+        String value = XMLUtils.xpathString(
+            node, "@value", ArtifactNamespaceContext.INSTANCE);
+
+        if (name != null && type != null) {
+            try {
+                return new WQInfoObjectImpl(
+                    name,
+                    type,
+                    new Double(value));
+            }
+            catch (NumberFormatException nfe) {
+                logger.warn(nfe.getLocalizedMessage());
+            }
+        }
+
+        logger.warn("Invalid wq info object found.");
+
+        return null;
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :