/**
    * Copyright 2005-2014 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.rice.kew.notes.web;
  
  import org.apache.log4j.Logger;
  import org.kuali.rice.coreservice.framework.CoreFrameworkServiceLocator;
  import org.kuali.rice.kew.api.WorkflowRuntimeException;
  import org.kuali.rice.kew.doctype.SecuritySession;
  import org.kuali.rice.kew.notes.Attachment;
  import org.kuali.rice.kew.notes.service.NoteService;
  import org.kuali.rice.kew.routeheader.DocumentRouteHeaderValue;
  import org.kuali.rice.kew.service.KEWServiceLocator;
  import org.kuali.rice.kew.api.KewApiConstants;
  import org.kuali.rice.krad.UserSession;
  import org.kuali.rice.krad.util.KRADConstants;
  
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import java.io.BufferedInputStream;
  import java.io.BufferedOutputStream;
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  
  
  
  
  /**
   * A servlet which can be used to retrieve attachments from Notes.
   * 
   * @author Kuali Rice Team (rice.collab@kuali.org)
   */
  public class AttachmentServlet extends HttpServlet {
  	
  	private static final long serialVersionUID = -1918858512573502697L;
  	public static final String ATTACHMENT_ID_KEY = "attachmentId";
  
  	// TODO This should probably be put into KewApiConstants when contributed back
  	// to Rice 1.0.3
  	private static final Logger LOG = Logger.getLogger(AttachmentServlet.class);
  			
  	@Override
  	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  		String attachmentId = request.getParameter(ATTACHMENT_ID_KEY);
  		if (attachmentId == null) {
  			throw new ServletException("No 'attachmentId' was specified.");
  		}
  		
  		boolean secureChecks = false;
  		String secureAttachmentsParam = null;
  		try {
  			secureAttachmentsParam = CoreFrameworkServiceLocator.getParameterService().getParameterValueAsString(KewApiConstants.KEW_NAMESPACE, "All", KewApiConstants.SECURE_ATTACHMENTS_PARAM);
  		} catch (Exception e) {
  			LOG.info("Attempted to retrieve parameter value, but could not. Defaulting to unsecured attachment retrieval. " + e.getMessage());
  		}
  		if (secureAttachmentsParam != null && secureAttachmentsParam.equals("Y")) {
  			secureChecks = true;
  		}
  		try {
  			UserSession userSession = (UserSession) request.getSession().getAttribute(KRADConstants.USER_SESSION_KEY);
  			if (userSession != null) {// If we can get a valid userSession object off the Http request...
  				
  				NoteService noteService = KEWServiceLocator.getNoteService(); 
  				Attachment attachment = noteService.findAttachment(attachmentId);
  				File file = noteService.findAttachmentFile(attachment);
  				
  				DocumentRouteHeaderValue routeHeader = KEWServiceLocator.getRouteHeaderService().getRouteHeader(noteService.getNoteByNoteId(attachment.getNoteId()).getDocumentId());
  				
  				if(!secureChecks || routeHeader != null){// If we can get a valid routeHeader based on the requested attachment ID
  					boolean authorized = KEWServiceLocator.getDocumentSecurityService().routeLogAuthorized(userSession.getPrincipalId(), routeHeader, new SecuritySession(userSession.getPrincipalId()));
                      boolean customAttributeAuthorized = false;
                      if(routeHeader.getCustomNoteAttribute() != null){
                          routeHeader.getCustomNoteAttribute().setUserSession(userSession);
                          customAttributeAuthorized = routeHeader.getCustomNoteAttribute().isAuthorizedToRetrieveAttachments();
                      }                    
                      if(!secureChecks || (authorized && customAttributeAuthorized)){//If this user can see this document, they can get the attachment(s)						
                      	response.setContentLength((int)file.length());
  						response.setContentType(attachment.getMimeType());
  						response.setHeader("Content-disposition", "attachment; filename=\"" + attachment.getFileName() + "\"");
  						FileInputStream attachmentFile = new FileInputStream(file);
  						BufferedInputStream inputStream = new BufferedInputStream(attachmentFile);
  						OutputStream outputStream = new BufferedOutputStream(response.getOutputStream());
  
 						try {
 							int c;
 							while ((c = inputStream.read()) != -1) {
 								outputStream.write(c);
 							}
 						} finally {
 							inputStream.close();
 						}
 						outputStream.close();
 					} else {// Throw a forbidden page back, they were not approved by DocumentSecurityService
 						LOG.error("Attempt to access attachmentId:"+ attachmentId + " from documentId:" + routeHeader.getDocumentId() + " from unauthorized user: " + userSession.getPrincipalId());
 						response.sendError(HttpServletResponse.SC_FORBIDDEN);
 						return;
 					}
 				} else {// Throw a not found, couldn't get a valid routeHeader
 					LOG.error("Caught Null Pointer trying to determine routeHeader for requested attachmentId:" + attachmentId);
 					response.sendError(HttpServletResponse.SC_NOT_FOUND);
 					return;
 				}
 			} else {// Throw a bad request, we couldn't find a valid user session
 				LOG.error("Attempt to access attachmentId:" + attachmentId + " with invalid UserSession");
 				response.sendError(HttpServletResponse.SC_BAD_REQUEST);
 				return;
 			}
 		} catch (Exception e) {// Catch any error, log it. Send a not found, and throw up the exception.
 			LOG.error("Problem retrieving requested attachmentId:" + attachmentId, e);
 			throw new WorkflowRuntimeException(e);
 		}
 	}
 	@Override
 	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 		doPost(request, response);
 	}	
 	
 }