/*
    * FCKeditor - The text editor for Internet - http://www.fckeditor.net
    * Copyright (C) 2004-2010 Frederico Caldeira Knabben
    * 
    * == BEGIN LICENSE ==
    * 
    * Licensed under the terms of any of the following licenses at your
    * choice:
    * 
   *  - GNU General Public License Version 2 or later (the "GPL")
   *    http://www.gnu.org/licenses/gpl.html
   * 
   *  - GNU Lesser General Public License Version 2.1 or later (the "LGPL")
   *    http://www.gnu.org/licenses/lgpl.html
   * 
   *  - Mozilla Public License Version 1.1 or later (the "MPL")
   *    http://www.mozilla.org/MPL/MPL-1.1.html
   * 
   * == END LICENSE ==
   */
  package net.fckeditor.connector;
  
  import java.io.IOException;
  import java.util.List;
  
  import javax.servlet.ServletContext;
  import javax.servlet.http.HttpServletRequest;
  
  import net.fckeditor.connector.exception.FolderAlreadyExistsException;
  import net.fckeditor.connector.exception.InvalidCurrentFolderException;
  import net.fckeditor.connector.exception.InvalidNewFolderNameException;
  import net.fckeditor.connector.exception.ReadException;
  import net.fckeditor.connector.exception.WriteException;
  import net.fckeditor.handlers.Command;
  import net.fckeditor.handlers.PropertiesLoader;
  import net.fckeditor.handlers.RequestCycleHandler;
  import net.fckeditor.handlers.ResourceType;
  import net.fckeditor.requestcycle.Context;
  import net.fckeditor.requestcycle.ThreadLocalData;
  import net.fckeditor.response.GetResponse;
  import net.fckeditor.response.UploadResponse;
  import net.fckeditor.tool.Utils;
  import net.fckeditor.tool.UtilsFile;
  import net.fckeditor.tool.UtilsResponse;
  
  import org.apache.commons.fileupload.FileItem;
  import org.apache.commons.fileupload.FileItemFactory;
  import org.apache.commons.fileupload.FileUploadException;
  import org.apache.commons.fileupload.disk.DiskFileItemFactory;
  import org.apache.commons.fileupload.servlet.ServletFileUpload;
  import org.apache.commons.io.FilenameUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * File Browser request dispatcher. This class is the validating and managing
   * instance between the {@link ConnectorServlet connector servlet} and the
   * {@link Connector connector}. It receives the requests, parses the parameters,
   * validates/sanitizes them and mandates them to the connector. After the
   * connector has processed the request, this dispatcher passes the response back
   * to the connector servlet. More over, it intercepts all
   * {@link net.fckeditor.connector.exception specified exceptions} from a
   * connector and emits appropriate (localized) messages to the user. The
   * exceptions won't be logged, they simply indicate the connector state.
   * 
   * @version $Id: Dispatcher.java 4785 2009-12-21 20:10:28Z mosipov $
   */
  public class Dispatcher {
  	private static final Logger logger = LoggerFactory.getLogger(Dispatcher.class);
  	private Connector connector;
  
  	/**
  	 * Initializes this dispatcher. It initializes the connector internally.
  	 * Called at connector servlet {@link ConnectorServlet#init()
  	 * initialization}.
  	 * 
  	 * @param servletContext
  	 *            reference to the {@link ServletContext} in which the caller is
  	 *            running
  	 * @throws Exception
  	 *             if the dispatcher initialization fails due to some reason
  	 */
  	Dispatcher(final ServletContext servletContext) throws Exception {	
  		// try to instantiate the Connector object
  		String className = PropertiesLoader.getConnectorImpl();
  		if (Utils.isEmpty(className))
  			logger.error("Empty Connector implementation class name provided");
  		else {
  			try {
  				Class<?> clazz = Class.forName(className);
  				connector = (Connector) clazz.newInstance();
  				logger.info("Connector initialized to {}", className);
  			} catch (Throwable e) {
  				logger.error("Connector implementation {} could not be instantiated", className);
  				throw new RuntimeException("Connector implementation " + className + " could not be instantiated", e); //$NON-NLS-1$
  			}
  		}
  		connector.init(servletContext);
  	}
 
 	/**
 	 * Called by the connector servlet to handle a {@code GET} request. In
 	 * particular, it handles the {@link Command#GET_FOLDERS GetFolders},
 	 * {@link Command#GET_FOLDERS_AND_FILES GetFoldersAndFiles} and
 	 * {@link Command#CREATE_FOLDER CreateFolder} commands.
 	 * 
 	 * @param request
 	 *            the current request instance
 	 * @return the get response instance associated with this request
 	 */
 	GetResponse doGet(final HttpServletRequest request) {
 		logger.debug("Entering Dispatcher#doGet");
 		
 		Context context = ThreadLocalData.getContext();
 		context.logBaseParameters();
 		
 		GetResponse getResponse = null;
 		// check parameters
 		if (!Command.isValidForGet(context.getCommandStr()))
 			getResponse = GetResponse.getInvalidCommandError();
 		else if (!ResourceType.isValidType(context.getTypeStr()))
 			getResponse = GetResponse.getInvalidResourceTypeError();
 		else if (!UtilsFile.isValidPath(context.getCurrentFolderStr()))
 			getResponse = GetResponse.getInvalidCurrentFolderError();
 		else {
 			
 			// in contrast to doPost the referrer has to send an explicit type
 			ResourceType type = context.getResourceType();
 			Command command = context.getCommand();
 			
 			// check permissions for user action
 			if ((command.equals(Command.GET_FOLDERS) || command.equals(Command.GET_FOLDERS_AND_FILES))
 					&& !RequestCycleHandler.isGetResourcesEnabled(request))
 				getResponse = GetResponse.getGetResourcesDisabledError();
 			else if (command.equals(Command.CREATE_FOLDER) && !RequestCycleHandler.isCreateFolderEnabled(request))
 				getResponse = GetResponse.getCreateFolderDisabledError();
 			else {
 				// make the connector calls, catch its exceptions and generate
 				// the proper response object
 				try {
 					if (command.equals(Command.CREATE_FOLDER)) {
 						String newFolderNameStr = request
 								.getParameter("NewFolderName");
 						logger.debug("Parameter NewFolderName: {}",
 								newFolderNameStr);				
 						String sanitizedNewFolderNameStr = UtilsFile
 								.sanitizeFolderName(newFolderNameStr);
 						if (Utils.isEmpty(sanitizedNewFolderNameStr))
 							getResponse = GetResponse
 									.getInvalidNewFolderNameError();
 						else {
 							logger.debug(
 									"Parameter NewFolderName (sanitized): {}",
 									sanitizedNewFolderNameStr);
 							connector.createFolder(type, context
 									.getCurrentFolderStr(),
 									sanitizedNewFolderNameStr);
 							getResponse = GetResponse.getOK();
 						}
 					} else if (command.equals(Command.GET_FOLDERS)
 							|| command
 									.equals(Command.GET_FOLDERS_AND_FILES)) {
 						String url = UtilsResponse.getUrl(RequestCycleHandler
 								.getUserFilesPath(request), type, context
 								.getCurrentFolderStr());
 						getResponse = getFoldersAndOrFiles(command, type, context
 								.getCurrentFolderStr(), url);
 					}
 				} catch (InvalidCurrentFolderException e) {
 					getResponse = GetResponse.getInvalidCurrentFolderError();
 				} catch (InvalidNewFolderNameException e) {
 					getResponse = GetResponse.getInvalidNewFolderNameError();
 				} catch (FolderAlreadyExistsException e) {
 					getResponse = GetResponse.getFolderAlreadyExistsError();
 				} catch (WriteException e) {
 					getResponse = GetResponse.getCreateFolderWriteError();
 				} catch (ReadException e) {
 					getResponse = GetResponse.getGetResourcesReadError();
 				}
 			}
 		}
 		
 		logger.debug("Exiting Dispatcher#doGet");
 		return getResponse;
 	}
 	
 	/**
 	 * Returns get response for the {@code GetFolders*} commands. This is simply
 	 * a helper method.
 	 * 
 	 * @param command
 	 *            the current command, should be only GetFolders or
 	 *            GetFoldersAndFiles
 	 * @param the
 	 *            current resource type
 	 * @param currentFolder
 	 *            the current folder
 	 * @param constructedUrl
 	 *            the final URL
 	 * @return the get response instance associated with this request
 	 * @throws InvalidCurrentFolderException
 	 *             if the current folder name is invalid or does not exist
 	 *             within the underlying backend
 	 * @throws ReadException
 	 *             if the file attributes and/or folder names could not be read
 	 *             due to some reason
 	 */
 	private GetResponse getFoldersAndOrFiles(final Command command,
 			final ResourceType type, final String currentFolder,
 			final String constructedUrl) throws InvalidCurrentFolderException,
 			ReadException {
 		GetResponse getResponse = new GetResponse(command, type,
 				currentFolder, constructedUrl);
 		getResponse.setFolders(connector.getFolders(type, currentFolder));
 		if (command.equals(Command.GET_FOLDERS_AND_FILES))
 			getResponse.setFiles(connector.getFiles(type, currentFolder));
 		return getResponse;
 	}
 
 	/**
 	 * Called by the connector servlet to handle a {@code POST} request. In
 	 * particular, it handles the {@link Command#FILE_UPLOAD FileUpload} and
 	 * {@link Command#QUICK_UPLOAD QuickUpload} commands.
 	 * 
 	 * @param request
 	 *            the current request instance
 	 * @return the upload response instance associated with this request
 	 */
 	UploadResponse doPost(final HttpServletRequest request) {
 		logger.debug("Entering Dispatcher#doPost");
 		
 		Context context = ThreadLocalData.getContext();
 		context.logBaseParameters();
 		
 		UploadResponse uploadResponse = null;
 		// check permissions for user actions
 		if (!RequestCycleHandler.isFileUploadEnabled(request))
 			uploadResponse = UploadResponse.getFileUploadDisabledError();
 		// check parameters  
 		else if (!Command.isValidForPost(context.getCommandStr()))
 			uploadResponse = UploadResponse.getInvalidCommandError();
 		else if (!ResourceType.isValidType(context.getTypeStr()))
 			uploadResponse = UploadResponse.getInvalidResourceTypeError();
 		else if (!UtilsFile.isValidPath(context.getCurrentFolderStr()))
 			uploadResponse = UploadResponse.getInvalidCurrentFolderError();
 		else {
 
 			// call the Connector#fileUpload
 			ResourceType type = context.getDefaultResourceType();
 			FileItemFactory factory = new DiskFileItemFactory();
 			ServletFileUpload upload = new ServletFileUpload(factory);
 			try {
 				List<FileItem> items = upload.parseRequest(request);
 				// We upload just one file at the same time
 				FileItem uplFile = items.get(0);
 				// Some browsers transfer the entire source path not just the
 				// filename
 				String fileName = FilenameUtils.getName(uplFile.getName());
 				logger.debug("Parameter NewFile: {}", fileName);
 				// check the extension
 				if (type.isDeniedExtension(FilenameUtils.getExtension(fileName)))
 					uploadResponse = UploadResponse.getInvalidFileTypeError();
 				// Secure image check (can't be done if QuickUpload)
 				else if (type.equals(ResourceType.IMAGE)
 						&& PropertiesLoader.isSecureImageUploads()
 						&& !UtilsFile.isImage(uplFile.getInputStream())) {
 					uploadResponse = UploadResponse.getInvalidFileTypeError();
 				} else {
 					String sanitizedFileName = UtilsFile
 							.sanitizeFileName(fileName);
 					logger.debug("Parameter NewFile (sanitized): {}",
 							sanitizedFileName);
 					String newFileName = connector.fileUpload(type, context
 							.getCurrentFolderStr(), sanitizedFileName, uplFile
 							.getInputStream());
 					String fileUrl = UtilsResponse.fileUrl(RequestCycleHandler
 							.getUserFilesPath(request), type, context
 							.getCurrentFolderStr(), newFileName);
 
 					if (sanitizedFileName.equals(newFileName))
 						uploadResponse = UploadResponse.getOK(fileUrl);
 					else {
 						uploadResponse = UploadResponse.getFileRenamedWarning(fileUrl, newFileName);
 						logger.debug("Parameter NewFile (renamed): {}",
 								newFileName);
 					}
 				}
 				
 				uplFile.delete();
 			} catch (InvalidCurrentFolderException e) {
 				uploadResponse = UploadResponse.getInvalidCurrentFolderError();
 			} catch (WriteException e) {
 				uploadResponse = UploadResponse.getFileUploadWriteError();
 			} catch (IOException e) {
 				uploadResponse = UploadResponse.getFileUploadWriteError();
 			} catch (FileUploadException e) {
 				uploadResponse = UploadResponse.getFileUploadWriteError();
 			}
 		}
 		
 		logger.debug("Exiting Dispatcher#doPost");
 		return uploadResponse;
 	}
 	
 }