/*
 * 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.wicket.util.upload;

import java.io.IOException;
import java.util.List;

import javax.servlet.http.HttpServletRequest;

/**
 * <p>
 * High level API for processing file uploads.
 * </p>
 * 
 * <p>
 * This class handles multiple files per single HTML widget, sent using <code>multipart/mixed</code>
 * encoding type, as specified by <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>. Use
 * {@link #parseRequest(HttpServletRequest)} to acquire a list of
 * {@link org.apache.wicket.util.upload.FileItem}s associated with a given HTML widget.
 * </p>
 * 
 * <p>
 * How the data for individual parts is stored is determined by the factory used to create them; a
 * given part may be in memory, on disk, or somewhere else.
 * </p>
 * 
 * @author <a href="mailto:Rafal.Krzewski@e-point.pl">Rafal Krzewski</a>
 * @author <a href="mailto:dlr@collab.net">Daniel Rall</a>
 * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
 * @author <a href="mailto:jmcnally@collab.net">John McNally</a>
 * @author <a href="mailto:martinc@apache.org">Martin Cooper</a>
 * @author Sean C. Sullivan
 */
public class ServletFileUpload extends FileUpload
{

	// ---------------------------------------------------------- Class methods


	/**
	 * Utility method that determines whether the request contains multipart content.
	 * 
	 * @param request
	 *            The servlet request to be evaluated. Must be non-null.
	 * 
	 * @return <code>true</code> if the request is multipart; <code>false</code> otherwise.
	 */
	public static final boolean isMultipartContent(final HttpServletRequest request)
	{
		if (!"post".equals(request.getMethod().toLowerCase()))
		{
			return false;
		}
		String contentType = request.getContentType();
		if (contentType == null)
		{
			return false;
		}
		if (contentType.toLowerCase().startsWith(MULTIPART))
		{
			return true;
		}
		return false;
	}


	// ----------------------------------------------------------- Constructors


	/**
	 * Constructs an uninitialised instance of this class. A factory must be configured, using
	 * <code>setFileItemFactory()</code>, before attempting to parse requests.
	 * 
	 * @see FileUpload#FileUpload(FileItemFactory)
	 */
	public ServletFileUpload()
	{
		super();
	}


	/**
	 * Constructs an instance of this class which uses the supplied factory to create
	 * <code>FileItem</code> instances.
	 * 
	 * @see FileUpload#FileUpload()
	 * @param fileItemFactory
	 *            The factory to use for creating file items.
	 */
	public ServletFileUpload(final FileItemFactory fileItemFactory)
	{
		super(fileItemFactory);
	}


	// --------------------------------------------------------- Public methods


	/**
	 * Processes an <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a> compliant
	 * <code>multipart/form-data</code> stream.
	 * 
	 * @param request
	 *            The servlet request to be parsed.
	 * 
	 * @return A list of <code>FileItem</code> instances parsed from the request, in the order that
	 *         they were transmitted.
	 * 
	 * @throws FileUploadException
	 *             if there are problems reading/parsing the request or storing files.
	 */
	public List<FileItem> parseRequest(final HttpServletRequest request) throws FileUploadException
	{
		return parseRequest(new ServletRequestContext(request));
	}


	/**
	 * Processes an <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a> compliant
	 * <code>multipart/form-data</code> stream.
	 * 
	 * @param request
	 *            The servlet request to be parsed.
	 * 
	 * @return An iterator to instances of <code>FileItemStream</code> parsed from the request, in
	 *         the order that they were transmitted.
	 * 
	 * @throws FileUploadException
	 *             if there are problems reading/parsing the request or storing files.
	 * @throws IOException
	 *             An I/O error occurred. This may be a network error while communicating with the
	 *             client or a problem while storing the uploaded content.
	 */
	public FileItemIterator getItemIterator(final HttpServletRequest request)
		throws FileUploadException, IOException
	{
		return super.getItemIterator(new ServletRequestContext(request));
	}
}
