--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pdf/src/main/java/digilib/servlet/PDFCache.java	Tue Apr 26 20:24:31 2011 +0200
@@ -0,0 +1,327 @@
+package digilib.servlet;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.util.concurrent.Future;
+
+import javax.servlet.RequestDispatcher;
+import javax.servlet.ServletConfig;
+import javax.servlet.ServletContext;
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.apache.log4j.Logger;
+
+import digilib.image.DocuImage;
+import digilib.pdf.PDFFileWorker;
+import digilib.util.DigilibJobCenter;
+
+/**
+ * A class for handling user requests for pdf documents made from digilib images.  
+ * 
+ * If a document does not already exist, it will be enqueued for generation; if it does exist, it is sent
+ * to the user.
+ * 
+ * @author cmielack
+ *
+ */
+
+@SuppressWarnings("serial")
+public class PDFCache extends HttpServlet {
+
+    public static String version = "0.3a";
+
+    /** logger for accounting requests */
+    protected static Logger accountlog = Logger.getLogger("account.pdf.request");
+
+    /** gengeral logger for this class */
+    protected static Logger logger = Logger.getLogger("digilib.pdfcache");
+
+    /** logger for authentication related */
+    protected static Logger authlog = Logger.getLogger("digilib.pdf.auth");
+
+	private DigilibConfiguration dlConfig = null;
+	
+	public static String instanceKey = "digilib.servlet.PDFCache";
+	
+	private DigilibJobCenter<File> pdfJobCenter = null;
+	
+	private DigilibJobCenter<DocuImage> pdfImageJobCenter = null;
+	
+	private File cache_directory = new File("cache");  
+	
+	private File temp_directory = new File("pdf_temp");
+	
+	private static String JSP_WIP = "/pdf/wip.jsp";
+	
+	private static String JSP_ERROR = "/pdf/error.jsp";
+	
+	/** document status.
+	 *  DONE: document exists in cache
+	 *  WIP: document is "work in progress"
+	 *  NONEXISTENT: document does not exist in cache and is not in progress
+	 *  ERROR: an error occurred while processing the request
+	 */
+	public static enum PDFStatus {DONE, WIP, NONEXISTENT, ERROR};
+
+	
+	public void init(ServletConfig config) throws ServletException {
+		super.init(config);
+		
+        System.out.println("***** Digital Image Library Image PDF-Cache Servlet (version "
+                + version + ") *****");
+        // say hello in the log file
+        logger.info("***** Digital Image Library Image PDF-Cache Servlet (version "
+                + version + ") *****");
+
+		ServletContext context = getServletContext();
+		dlConfig = (DigilibConfiguration) context.getAttribute("digilib.servlet.configuration");
+		if (dlConfig == null) {
+			// no Configuration
+			throw new ServletException("No Configuration!");
+		}
+	
+		String temp_fn = dlConfig.getAsString("pdf-temp-dir");
+		temp_directory = new File(temp_fn);
+		if (!temp_directory.exists()) {
+			// try to create
+			temp_directory.mkdirs();
+		} else {
+	        // rid the temporary directory of possible incomplete document files
+	        emptyDirectory(temp_directory);
+		}
+		if (!temp_directory.isDirectory()) {
+		    throw new ServletException("Configuration error: problem with pdf-temp-dir="+temp_fn);
+		}
+        
+		String cache_fn = dlConfig.getAsString("pdf-cache-dir");
+       	cache_directory = new File(cache_fn);
+		if (!cache_directory.exists()) {
+			// try to create
+			cache_directory.mkdirs();
+		}
+        if (!cache_directory.isDirectory()) {
+            throw new ServletException("Configuration error: problem with pdf-cache-dir="+cache_fn);
+        }
+
+        pdfJobCenter = (DigilibJobCenter<File>) dlConfig.getValue("servlet.worker.pdfexecutor");
+        pdfImageJobCenter = (DigilibJobCenter<DocuImage>) dlConfig.getValue("servlet.worker.pdfimageexecutor");
+        
+		// register this instance globally
+		context.setAttribute(instanceKey, this);
+		
+	}
+	
+    /* (non-Javadoc)
+     * @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
+     */
+    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException {
+        accountlog.info("GET from " + request.getRemoteAddr());
+        this.processRequest(request, response);
+    }
+
+
+    /* (non-Javadoc)
+     * @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
+     */
+    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException {
+        accountlog.info("POST from " + request.getRemoteAddr());
+        this.processRequest(request, response);
+    }
+    
+	/** 
+	 * clean up any broken and unfinished files from the temporary directory.
+	 */
+	public void emptyDirectory(File dir){
+		File[] temp_files = dir.listFiles();
+		for (File f: temp_files){
+			f.delete();
+		}
+	}
+	
+	
+	public void processRequest(HttpServletRequest request,
+			HttpServletResponse response) throws ServletException {
+
+        if (dlConfig == null) {
+            logger.error("ERROR: No Configuration!");
+            throw new ServletException("NO VALID digilib CONFIGURATION!");
+        }
+
+        String docid = "";
+	    try {
+		// evaluate request ( make a PDFJobDeclaration , get the DocumentId)
+		PDFRequest pdfji = new PDFRequest(request, dlConfig); 
+		
+		docid = pdfji.getDocumentId();
+		
+		// if some invalid data has been entered ...
+		if(!pdfji.checkValidity()) {
+			notifyUser(PDFStatus.ERROR, docid, request, response);
+			return;
+		}
+		
+		PDFStatus status = getStatus(docid);
+		
+        if (status == PDFStatus.NONEXISTENT) {
+        	// not there -- start creation
+            try {
+				createNewPdfDocument(pdfji, docid);
+	            notifyUser(status, docid, request, response);
+	            return;
+			} catch (FileNotFoundException e) {
+				// error in pdf creation
+                logger.error(e.getMessage());
+				notifyUser(PDFStatus.ERROR, docid, request, response);
+				return;
+			}
+        } else if (status == PDFStatus.DONE) {
+        	// pdf created -- send it
+            try {
+                ServletOps.sendFile(getCacheFile(docid), "application/pdf", getDownloadFilename(pdfji), response, logger);
+                return;
+            } catch (Exception e) {
+            	// sending didn't work
+                logger.error(e.getMessage());
+                return;
+            }
+        } else {
+        	// should be work in progress
+            notifyUser(status, docid, request, response);
+            return;
+        }
+	    } catch (Exception e) {
+            // error in pdf creation
+            logger.error(e.getMessage());
+            notifyUser(PDFStatus.ERROR, docid, request, response);
+            return;
+	    }
+	}
+
+    /**
+     * depending on the documents status, redirect the user to the appropriate
+     * waiting or download page.
+     * 
+     * @param status
+     * @param documentid
+     * @param request
+     * @param response
+     */
+    public void notifyUser(PDFStatus status, String documentid,
+            HttpServletRequest request, HttpServletResponse response) {
+
+        String jsp = null;
+
+        if (status == PDFStatus.NONEXISTENT) {
+            // tell the user that the document has to be created before he/she
+            // can download it
+            logger.debug("PDFCache: " + documentid + " has STATUS_NONEXISTENT.");
+            jsp = JSP_WIP;
+        } else if (status == PDFStatus.WIP) {
+            logger.debug("PDFCache: " + documentid + " has STATUS_WIP.");
+            jsp = JSP_WIP;
+
+            // TODO: estimate remaining work time
+            // TODO: tell the user he/she has to wait
+        } else if (status == PDFStatus.DONE) {
+            logger.debug("PDFCache: " + documentid + " has STATUS_DONE.");
+        } else {
+            logger.debug("PDFCache: " + documentid + " has STATUS_ERROR.");
+            jsp = JSP_ERROR;
+        }
+
+        try {
+            // forward to the relevant jsp
+            ServletContext context = getServletContext();
+            RequestDispatcher dispatch = context.getRequestDispatcher(jsp);
+            dispatch.forward(request, response);
+        } catch (ServletException e) {
+            logger.debug(e.getMessage());
+            e.printStackTrace();
+        } catch (IOException e) {
+            logger.debug(e.getMessage());
+            e.printStackTrace();
+        }
+
+    }
+
+	
+	/** check the status of the document corresponding to the documentid */
+	public PDFStatus getStatus(String documentid){
+		// looks into the cache and temp directory in order to find out the status of the document
+		File cached = getCacheFile(documentid);
+		File wip = getTempFile(documentid);
+		if(cached.exists()){
+			return PDFStatus.DONE;
+		} else if (wip.exists()){
+			return PDFStatus.WIP;
+		} else {
+			return PDFStatus.NONEXISTENT;
+		}
+	}
+
+	/** 
+	 * create new thread for pdf generation.
+	 * 
+	 * @param pdfji
+	 * @param filename
+	 * @return 
+	 * @throws FileNotFoundException 
+	 */
+	public Future<File> createNewPdfDocument(PDFRequest pdfji, String filename) throws FileNotFoundException{
+		// start new worker
+		File tempf = this.getTempFile(filename);
+		File finalf = this.getCacheFile(filename);
+		PDFFileWorker job = new PDFFileWorker(dlConfig, tempf, finalf, pdfji, pdfImageJobCenter);
+		// start job
+		Future<File> jobTicket = pdfJobCenter.submit(job);
+		return jobTicket;
+	}
+	
+	
+	/**
+	 * generate the filename the user is going to receive the pdf as
+	 * 
+	 * @param pdfji
+	 * @return
+	 */
+	public String getDownloadFilename(PDFRequest pdfji){
+		// filename example: digilib_example_pgs1-3.pdf
+		String filename;
+		filename =  "digilib_";
+		filename += pdfji.getAsString("fn");
+		filename += "_pgs" + pdfji.getAsString("pgs");
+		filename += ".pdf";
+		
+		return filename;
+	}
+		
+	public File getCacheDirectory(){
+		return cache_directory;
+	}
+	
+	public File getTempDirectory(){
+		return temp_directory;
+	}
+	
+	/** 
+	 * returns a File object based on filename in the temp directory.
+	 * @param filename
+	 * @return
+	 */
+	public File getTempFile(String filename) {
+	    return new File(temp_directory, filename);
+	}
+
+	/** 
+     * returns a File object based on filename in the cache directory.
+     * @param filename
+     * @return
+     */
+    public File getCacheFile(String filename) {
+        return new File(cache_directory, filename);
+    }
+}