Application: gvSIG desktop

/*

 * Created on 01-oct-2005

 */

package org.gvsig.remoteClient.taskplanning.retrieving;

import java.io.File;

import java.net.MalformedURLException;

import java.util.Hashtable;

import java.util.TreeMap;

import org.gvsig.remoteClient.taskplanning.IQueue;

import org.gvsig.remoteClient.taskplanning.IRunnableTask;

/**

 * pa administrar les tasques (la hist?ria aquella

 *  de que hi haja una cola per a cada servidor)

 * @author Luis W. Sevilla (sevilla_lui@gva.es)

 */

public class RequestManager {

        private boolean debug = true;

        private static RequestManager instance;

        private TreeMap serversTable = new TreeMap();

        private RequestManager() {} // Avoid public instantiation

        public static RequestManager getInstance() {

                if (instance == null)

                        instance = new RequestManager();

                return instance;

        }

        public URLRetrieveTask addURLRequest(URLRequest request, RetrieveListener listener) {

                try {

                        // TODO canviar per a quetorne el Request antic, que la request guarde el

                        // seu estat aix? com la llista de listeners

                        File f = getPreviousDownloadedURLRequest(request);

                        if (f!=null) {

                                // The file was already requested and it is in the cache or

                                // the download is in process

                                // Overwrite the file name with the file in the cache's one.

                                request.setFileName(f.getAbsolutePath());

                                System.out.println(request.getUrl()+" is cached at '"+f.getAbsolutePath()+"'");

                                // get this server's task queue

                                RetrieveQueue serverQueue = (RetrieveQueue) getQueue(request.getHost());

                                // Look up the previous cached jobs

                                URLRetrieveTask workingTask = serverQueue.getURLPreviousRequest(request);

                                if (workingTask == null) {

                                        // Task already done. Notify listener

                                        if (debug)

                                                System.err.println("done job found: "+request.getUrl());

                                        RetrieveEvent event = new RetrieveEvent();

                                        event.setType(RetrieveEvent.REQUEST_FINISHED);

                                        listener.transferEventReceived(event);

                                } else {

                                        // The task is working yet, will register the listener

                                        // TODO no va b?... perqu? la cola va buidant-se molt r?pidament

                                        // per a fer que vaja tamb? hi hauria que registrar en cache

                                        // lo que s'est? baixant al principi de l'execute();

                                        if (debug)

                                                System.err.println("working job found: "+request.getUrl());

                                        workingTask.addRetrieveListener(listener);

                                }

                        } else {

                                // Pick an unrepeatable fileName

                                String host = request.getHost();

                                String fileName = request.getFileName();

                                File tempDir = new File(tempDirectoryPath);

                                if (!tempDir.exists())

                                        tempDir.mkdir();

                                String fileNamePrefix = tempDirectoryPath + 

                                                                                        File.separator + host + 

                                                                                        "-" ;

                                if (fileName.startsWith(fileNamePrefix))

                                        fileName = fileName.substring(fileNamePrefix.length(), fileName.length());

                                // get this server's task queue

                                RetrieveQueue serverQueue = (RetrieveQueue) getQueue(request.getHost());

                                fileName = fileNamePrefix + fileName;

                                request.setFileName(fileName);

                                // TODO

                                // jo ac? comprovaria quin protocol, m?tode, host, etc... i crearia un

                                // objecte que tractara la desc?rrega segons el m?tode que li toca.

                                // algo en plan Strategy's

                                //

                                // per exemple si fem URLRetrieveTask una abstracta i tenim

                                // 

                                // GET de tota la vida

                                // serverQueue.put(new HTTPGetRetrieveTask(request, listener));

                                //

                                // POST

                                // serverQueue.put(new HTTPPostRetrieveTask(request, listener));

                                //

                                // FTP

                                // serverQueue.put(new FTPRetrieveTask(request, listener));

                                //

                                // ????Xarxa local?????

                                // serverQueue.put(new SMBRetrieveTask(request, listener));

                                // Enqueue the request and the listener will be notified when done.

                                URLRetrieveTask task = new URLRetrieveTask(request, listener);

                                return (URLRetrieveTask) serverQueue.put(task);

                        }

                } catch (MalformedURLException e) {

                        e.printStackTrace();

                }

                return null;

        }

        private IQueue getQueue(String hostName) {

                RetrieveQueue queue = null;

                if (serversTable.containsKey(hostName))

                        queue = (RetrieveQueue) serversTable.get(hostName);

                else {

                        // crea la cola

                        queue = new RetrieveQueue(hostName);

                        // pone la cola del server en marcha.

                }

                return queue;

        }

        private Hashtable downloadedFiles;

        private final String tempDirectoryPath = System.getProperty("java.io.tmpdir")+"tmp-andami";

        /**

     * Remove an URL from the system cache. The file will remain in the file

     * system for further eventual uses.

     * @param request

     */

        public void removeURLRequest(URLRequest request) {

                if (downloadedFiles != null && downloadedFiles.containsKey(request))

                        downloadedFiles.remove(request);

        }

        /**

     * Adds an URL to the table of downloaded files for further uses. If the URL

     * already exists in the table its filePath value is updated to the new one and

     * the old file itself is removed from the file system.

     * 

     * @param url

     * @param filePath

     */

    protected void addDownloadedURLRequest(URLRequest request, String filePath){

        if (downloadedFiles==null)

            downloadedFiles = new Hashtable();

        String fileName = (String) downloadedFiles.put(request, filePath);

        if (fileName!=null){

            File f = new File(fileName);

            if (f.exists())

                f.delete();

        }

    }

    /**

     * Returns the content of this URL as a file from the file system.<br>

     * <p>

     * If the URL has been already downloaded in this session and notified 

     * to the system using the static <b>Utilities.addDownloadedURL(URL)</b>

     * method, it can be restored faster from the file system avoiding to

     * download it again.

     * </p>

     * @param url

     * @return File containing this URL's content or null if no file was found.

     */

    private File getPreviousDownloadedURLRequest(URLRequest request){

        File f = null;

        if (downloadedFiles!=null && downloadedFiles.containsKey(request)){

            String filePath = (String) downloadedFiles.get(request);

            f = new File(filePath);

        }

        return f;

    }

}