package de.intevation.gnv.utils;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Date;

import javax.xml.xpath.XPathConstants;

import org.apache.log4j.Logger;

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

import de.intevation.artifactdatabase.XMLUtils;
import de.intevation.artifacts.ArtifactNamespaceContext;
import de.intevation.artifacts.CallContext;
import de.intevation.gnv.artifacts.context.GNVArtifactContext;
import de.intevation.gnv.wms.LayerInfo;

/**
 * This class provides some methods to create files storing meta information
 * about wms layers and a map service which serves these layers.
 *
 * @author <a href="mailto:ingo.weinzierl@intevation.de">Ingo Weinzierl</a>
 */
public class MetaWriter {

    private static Logger logger = Logger.getLogger(MetaWriter.class);

    public static final String NODE_MAPSERVER = "mapserver";
    public static final String NODE_SERVER    = "server";
    public static final String NODE_MAP       = "map";
    public static final String NODE_TTL       = "ttl";

    public static final String META_FILE_NAME = "meta.xml";

    public static final String XPATH_META = "/art:meta";

    /**
     * Constructor.
     */
    private MetaWriter() {
    }


    /**
     * Just create a new document and insert the root node.
     *
     * @return the meta document with necessary root node.
     */
    public static Document initMeta() {
        Document meta = XMLUtils.newDocument();
        XMLUtils.ElementCreator creator = new XMLUtils.ElementCreator(
            meta,
            ArtifactNamespaceContext.NAMESPACE_URI,
            ArtifactNamespaceContext.NAMESPACE_PREFIX);

        Element root = creator.create("meta");
        meta.appendChild(root);

        return meta;
    }

    public static boolean insertLayer(
        CallContext context,
        Document    document,
        String      name,
        String      title,
        String      data,
        String      model,
        String      type,
        String      status
    ) {
        if (document == null) {
            document = initMeta();
        }

        Node meta = (Node) XMLUtils.xpath(
            document,
            XPATH_META,
            XPathConstants.NODE,
            ArtifactNamespaceContext.INSTANCE);

        if (meta == null) {
            logger.error("No meta node was found in the given document. "
                + "Cannot insert layer!");
            return false;
        }

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

        Element layerEl  = creator.create(LayerInfo.LAYER);
        Element nameEl   = creator.create(LayerInfo.LAYER_NAME);
        Element titleEl  = creator.create(LayerInfo.LAYER_TITLE);
        Element dataEl   = creator.create(LayerInfo.LAYER_DATA);
        Element modelEl  = creator.create(LayerInfo.LAYER_MODEL);
        Element typeEl   = creator.create(LayerInfo.LAYER_TYPE);
        Element statusEl = creator.create(LayerInfo.LAYER_STATUS);

        modelEl.setTextContent(model);
        nameEl.setTextContent(name);
        titleEl.setTextContent(title);
        typeEl.setTextContent(type);
        statusEl.setTextContent(status);
        dataEl.setTextContent(data);

        layerEl.appendChild(modelEl);
        layerEl.appendChild(nameEl);
        layerEl.appendChild(titleEl);
        layerEl.appendChild(dataEl);
        layerEl.appendChild(typeEl);
        layerEl.appendChild(statusEl);

        if (logger.isDebugEnabled()) {
            logger.debug("--------------- WMS LAYER PARAMS ---------------");
            logger.debug("Name  : " + name);
            logger.debug("Title : " + title);
            logger.debug("Data  : " + data);
            logger.debug("Type  : " + type);
            logger.debug("Model : " + model);
            logger.debug("Status: " + status);
        }

        meta.appendChild(layerEl);

        return true;
    }


    /**
     * Method to write the <i>meta</i> document down to a file.
     *
     * @param path The destination of the file.
     * @param meta The xml document storing the meta information.
     */
    public static boolean writeMetaFile(String path, Document meta) {
        try {
            File metaFile = new File(path, META_FILE_NAME);

            if (metaFile.exists()) {
                logger.info("Delete old meta information file.");
                metaFile.delete();
            }

            if (!metaFile.createNewFile() || !metaFile.canWrite()) {
                logger.error("Error while writing meta file: "+metaFile.toString());
                return false;
            }

            OutputStream out = null;
            boolean success = false;
            try {
                out = new FileOutputStream(metaFile);
                success = XMLUtils.toStream(meta, out);
            }
            finally {
                if (out != null) {
                    try { out.close(); }
                    catch (IOException ioe) {}
                }
            }

            if (!success && metaFile.exists()) {
                metaFile.delete();
            }

            return success;
        }
        catch (FileNotFoundException fnfe) {
            logger.error(fnfe);
            return false;
        }
        catch (IOException ioe) {
            logger.error(ioe, ioe);
            return false;
        }
    }


    /**
     * Append meta information about the mapservice itself.
     *
     * @param callContext The CallContext object.
     * @param document The meta information document.
     * @param meta The element where the new information need to be appended to.
     */
    public static void insertAbstractMeta(
        CallContext callContext,
        Document    document
    ) {
        if (document == null) {
            document = initMeta();
        }

        Node meta = (Node) XMLUtils.xpath(
            document,
            XPATH_META,
            XPathConstants.NODE,
            ArtifactNamespaceContext.INSTANCE);

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

        GNVArtifactContext context =
            (GNVArtifactContext) callContext.globalContext();

        String server = (String)
            context.get(GNVArtifactContext.MAPSERVER_SERVER_PATH_KEY);

        String map = (String)
            context.get(GNVArtifactContext.MAPSERVER_MAP_PATH_KEY);

        Long time  = callContext.getTimeToLive();
        time       = time != null ? time + new Date().getTime() : null;
        String ttl = time != null ? time.toString() : null;

        if (logger.isDebugEnabled()) {
            logger.debug("MAPSERVER PATH: " + server);
            logger.debug("MAP PATH: " + map);
            logger.debug("TTL: " + ttl);
        }

        Element mapserver  = creator.create(NODE_MAPSERVER);
        Element serverPath = creator.create(NODE_SERVER);
        Element mapPath    = creator.create(NODE_MAP);
        Element timetolive = creator.create(NODE_TTL);

        mapPath.setTextContent(map);
        serverPath.setTextContent(server);
        timetolive.setTextContent(ttl);

        mapserver.appendChild(serverPath);
        mapserver.appendChild(mapPath);
        mapserver.appendChild(timetolive);
        meta.appendChild(mapserver);
    }
}
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