/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package org.apache.oodt.cas.product.rss;

//JDK imports
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import java.util.List;
import java.util.Date;
import java.util.Iterator;
import java.util.logging.Logger;
import java.util.logging.Level;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import java.io.File;
import java.io.FileNotFoundException;
import java.net.MalformedURLException;
import java.net.URL;
import java.text.SimpleDateFormat;
import java.text.ParseException;

//OODT imports
import static org.apache.oodt.cas.product.rss.RSSConfigMetKeys.RSS_TRANSFER_CONF_KEY;
import org.apache.oodt.cas.filemgr.structs.exceptions.CatalogException;
import org.apache.oodt.cas.filemgr.structs.exceptions.DataTransferException;
import org.apache.oodt.cas.filemgr.structs.exceptions.ConnectionException;
import org.apache.oodt.cas.filemgr.structs.FileTransferStatus;
import org.apache.oodt.cas.filemgr.system.XmlRpcFileManagerClient;
import org.apache.oodt.commons.xml.XMLUtils;
import org.apache.oodt.cas.metadata.Metadata;
import org.apache.oodt.cas.metadata.util.PathUtils;
import org.apache.oodt.commons.util.DateConvert;

/**
 * @author mattmann
 * @version $Revision$
 * 
 * <p>
 * A Servlet that supports the <a
 * href="http://feedvalidator.org/docs/rss2.html">RSS 2.0</a> specification for
 * delivering Product Transfer Feeds.
 * </p>
 * 
 */
public class RSSProductTransferServlet extends HttpServlet {

    /* serial Version UID */
    private static final long serialVersionUID = -7983832512818339079L;

    /* our client to the file manager */
    private static XmlRpcFileManagerClient fClient = null;

    /* RSS config */
    private RSSConfig rssconf;

    /* our log stream */
    private Logger LOG = Logger.getLogger(RSSProductTransferServlet.class
            .getName());

    public static final String COPYRIGHT_BOILER_PLATE = "Copyright 2010: Apache Software Foundation";

    public static final String RSS_FORMAT_STR = "E, dd MMM yyyy HH:mm:ss z";

    public static final SimpleDateFormat dateFormatter = new SimpleDateFormat(
            RSS_FORMAT_STR);

    /**
     * <p>
     * Default Constructor
     * </p>.
     */
    public RSSProductTransferServlet() {
    }

    /**
     * Initializes the servlet.
     */
    public void init(ServletConfig config) throws ServletException {
        super.init(config);

        String fileManagerUrl = null;
        try {
          fileManagerUrl = PathUtils.replaceEnvVariables(config.getServletContext().getInitParameter(
              "filemgr.url") );
        } catch (Exception e) {
          throw new ServletException("Failed to get filemgr url : " + e.getMessage(), e);
        }        
        if (fileManagerUrl == null) {
            // try the default port
            fileManagerUrl = "http://localhost:9000";
        }

        fClient = null;

        try {
            fClient = new XmlRpcFileManagerClient(new URL(fileManagerUrl));
        } catch (MalformedURLException e) {
            LOG.log(Level.SEVERE,
                    "Unable to initialize file manager url in RSS Servlet: [url="
                            + fileManagerUrl + "], Message: " + e.getMessage());
        } catch (ConnectionException e) {
            LOG.log(Level.SEVERE,
                    "Unable to initialize file manager url in RSS Servlet: [url="
                            + fileManagerUrl + "], Message: " + e.getMessage());
        }

        try
        {
          rssconf = RSSConfigReader.readConfig(new File(PathUtils
              .replaceEnvVariables(config.getServletContext().getInitParameter(
                  (RSS_TRANSFER_CONF_KEY)))));
        }
        catch (FileNotFoundException e)
        {
          throw new ServletException(e);
        }
    }

    public void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, java.io.IOException {
        doIt(req, resp);
    }

    public void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, java.io.IOException {
        doIt(req, resp);
    }

    public void doIt(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, java.io.IOException {
        List currentTransfers = null;

        try {
            currentTransfers = fClient.getCurrentFileTransfers();
        } catch (DataTransferException e) {
            e.printStackTrace();
            LOG.log(Level.WARNING,
                    "Exception getting current transfers from file manager: Message: "
                            + e.getMessage());
            return;
        }

        String requestUrl = req.getRequestURL().toString();
        String base = requestUrl.substring(0, requestUrl.lastIndexOf('/'));

        if (currentTransfers != null && currentTransfers.size() > 0) {
            String channelDesc = "Current Files Being Transferred to the File Manager";

            try {

                DocumentBuilderFactory factory = DocumentBuilderFactory
                        .newInstance();
                factory.setNamespaceAware(true);
                Document doc = factory.newDocumentBuilder().newDocument();

                Element rss = XMLUtils.addNode(doc, doc, "rss");
                XMLUtils.addAttribute(doc, rss, "version", "2.0");

                // add namespace attributes from config file to rss tag
                for (RSSNamespace namespace : rssconf.getNamespaces())
                {
                  XMLUtils.addAttribute(doc, rss,
                      "xmlns:" + namespace.getPrefix(), namespace.getUri());
                }

                Element channel = XMLUtils.addNode(doc, rss, "channel");

                XMLUtils.addNode(doc, channel, "title",
                        "File Manager Transfers");
                XMLUtils.addNode(doc, channel, "link", base
                        + "/viewTransfers");
                XMLUtils.addNode(doc, channel, "description", channelDesc);

                String buildPubDate = dateFormatter.format(new Date());

                XMLUtils.addNode(doc, channel, "language", "en-us");
                XMLUtils.addNode(doc, channel, "copyright",
                        COPYRIGHT_BOILER_PLATE);
                XMLUtils.addNode(doc, channel, "pubDate", buildPubDate);
                XMLUtils.addNode(doc, channel, "category", "data transfer");
                XMLUtils.addNode(doc, channel, "generator", "CAS File Manager");
                XMLUtils.addNode(doc, channel, "lastBuildDate", buildPubDate);

                for (Iterator i = currentTransfers.iterator(); i.hasNext();) {
                    FileTransferStatus status = (FileTransferStatus) i.next();

                    Element item = XMLUtils.addNode(doc, channel, "item");

                    XMLUtils.addNode(doc, item, "title", status
                            .getParentProduct().getProductName());
                    XMLUtils.addNode(doc, item, "description", status
                            .getParentProduct().getProductType().getName());
                    XMLUtils.addNode(doc, item, "link", base
                            + "/viewTransfer?ref="
                            + status.getFileRef().getOrigReference() + "&size="
                            + status.getFileRef().getFileSize());

                    Metadata m = null;

                    try {
                        m = fClient.getMetadata(status.getParentProduct());

                        String productReceivedTime = m
                                .getMetadata("CAS.ProductReceivedTime");
                        Date receivedTime = null;

                        try {
                            receivedTime = DateConvert
                                    .isoParse(productReceivedTime);
                        } catch (ParseException ignore) {
                        }

                        if (receivedTime != null) {
                            XMLUtils.addNode(doc, item, "pubDate",
                                    dateFormatter.format(receivedTime));
                        }

                        // set product transfer metadata
                        m.addMetadata("BytesTransferred",
                          "" + status.getBytesTransferred());
                        m.addMetadata("TotalBytes",
                          "" + status.getFileRef().getFileSize());
                        m.addMetadata("PercentComplete",
                          "" + status.computePctTransferred());

                    } catch (CatalogException ignore) {
                    }

                    // add additional elements from the RSSConfig
                    for (RSSTag tag : rssconf.getTags()) {
                      item.appendChild(RSSUtils.emitRSSTag(tag, m, doc, item));
                    }

                }

                DOMSource source = new DOMSource(doc);
                TransformerFactory transFactory = TransformerFactory
                        .newInstance();
                Transformer transformer = transFactory.newTransformer();
                transformer.setOutputProperty("indent", "yes");
                StreamResult result = new StreamResult(resp.getOutputStream());
                resp.setContentType("text/xml");
                transformer.transform(source, result);

            } catch (ParserConfigurationException e) {
                throw new ServletException(e);
            } catch (TransformerException e) {
                throw new ServletException(e);
            }

        }

    }

}