/*--------------------------------------------------------------------------
    *  Copyright 2007 utgenome.org
    *
    *  Licensed 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.
   *--------------------------------------------------------------------------*/
  //--------------------------------------
  // utgb-core Project
  //
  // RequestDispatcher.java
  // Since: Oct 4, 2007
  //
  // $URL$ 
  // $Author$
  //--------------------------------------
  package org.utgenome.gwt.utgb.server;
  
  import java.io.BufferedInputStream;
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.text.DateFormat;
  import java.text.SimpleDateFormat;
  import java.util.Calendar;
  import java.util.Date;
  import java.util.Enumeration;
  import java.util.HashMap;
  import java.util.LinkedList;
  import java.util.Locale;
  import java.util.Properties;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import javax.servlet.Filter;
  import javax.servlet.FilterChain;
  import javax.servlet.FilterConfig;
  import javax.servlet.ServletException;
  import javax.servlet.ServletRequest;
  import javax.servlet.ServletResponse;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.utgenome.UTGBException;
  import org.xerial.core.XerialException;
  import org.xerial.lens.Lens;
  import org.xerial.util.bean.BeanUtil;
  import org.xerial.util.log.Logger;
  
  /**
   * {@link RequestDispatcher} dispatches HTTP GET/POST request to appropriate action handlers.
   * 
   * see also http://trac.utgenome.org/project/UTGB/wiki/UTGBCore/RequestDispatcher
   * 
   * <h1>UTGB Request Dispatcher Mechanism</h1>
   * 
   * <h2>web.xml setting</h2>
   * 
   * Add the following description into your web.xml.
   * 
   * <li>The lines param-name=base-package, param-value=(application base) specifies the location (base package name)
   * where the RequestDispatcher? searches recursively for RequestHandler? implementations.
   * 
   * <li>With the following setting, an HTTP request, e.g., http://localhost:8989/hello.action, is mapped to the request
   * handler org.utgenome.gwt.utgb.server.app.Hello class. The upper letters are converted into the lower letters when
   * mapping the request, e.g., Hello action can be accecced via hello.action URL.
   * 
   * <li>Another example using hierarchies of actions: http://localhost:8989/admin/login.action is mapped to
   * org.utgenome.gwt.utgb.server.Login class.
   * 
   * <pre>
   *  &lt;servlet&gt;
   *  &lt;servlet-name&gt;dispatcher&lt;/servlet-name&gt;
   *  &lt;servlet-class&gt;org.utgenome.gwt.utgb.server.RequestDispatcher&lt;/servlet-class&gt;
   *  &lt;init-param&gt;
   *  &lt;param-name&gt;base-package&lt;/param-name&gt;
   *  &lt;param-value&gt;(your web application request handler base package. e.g. org.utgenome.gwt.utgb.server.app)&lt;/param-value&gt;
   *  &lt;/init-param&gt;
   *  &lt;/servlet&gt;
   * 
   *  &lt;servlet-mapping&gt;
   *  &lt;servlet-name&gt;dispatcher&lt;/servlet-name&gt;
   *  &lt;url-pattern&gt;*.action&lt;/url-pattern&gt;
   *  &lt;/servlet-mapping&gt;
   * </pre>
   * 
   * <h2>Automatic Data Binding to Request Handler</h2>
   * 
   * Hello.java class has serveral parameter values name and year:
   * 
  * <code>
  <pre>
  * public class Hello implements RequestHandler {
  * 	private String name = &quot;&quot;;
  * 	private int year = 2000;
  * 
  * 	public void handle(HttpServletRequest request, HttpServletResponse response) {
  * 		PrintWriter out = response.getWriter().println(&quot;Hello &quot; + name + &quot;(&quot; + year + &quot;)&quot;);
  * 	}
  * 
  * 	public void setName(String name) {
  * 		this.name = name;
  * 	}
  * 
  * 	public void setYear(int year) {
  * 		this.year = year;
  * 	}
  * }
  * </pre>
  </code>
  * 
  * 
  * Our {@link RequestDispatcher} automatically set these parameter values from a given HTTP request. For example, an
  * HTTP request
  * 
  * http://localhost:8989/hello.action?name=leo&year=2007
  * 
  * will invoke setName("leo") and setYear(2007) methods.
  * 
  * Note that, although the query string in the HTTP request consists of string values, our {@link BeanUtil} library
  * detects the data type to which the string should be translated by analysing the class definition. In this example,
  * the string value
  * 
  * "2007" is translated into an integer, 2007.
  * 
  * The web page result of the avobe request looks like as this:
  * 
  * <pre>
  *  Hello leo(2007)
  * </pre>
  * 
  * 
  * Alternate access method: http://localhost:8989/dispathcer?actionClass=org.utgenome .gwt.utgb.server.app.hello&
  * 
  * @author leo
  * 
  */
 public class RequestDispatcher implements Filter {
 	/**
 	 * 
 	 */
 	private static final long serialVersionUID = 1L;
 	private static Logger _logger = Logger.getLogger(RequestDispatcher.class);
 
 	private LinkedList<RequestMap> requestMapList = new LinkedList<RequestMap>();
 	private boolean isInGWTHostedMode = false;
 	private static HashMap<String, String> mimeTypes = new HashMap<String, String>();
 
 	private void initMimeTypes() {
 		if (!isInGWTHostedMode)
 			return; // no need to initialize the mime type table other than the GWT Hosted mode
 
 		// the following part is borrowed from GWTShellServlet
 		mimeTypes.put("abs", "audio/x-mpeg");
 		mimeTypes.put("ai", "application/postscript");
 		mimeTypes.put("aif", "audio/x-aiff");
 		mimeTypes.put("aifc", "audio/x-aiff");
 		mimeTypes.put("aiff", "audio/x-aiff");
 		mimeTypes.put("aim", "application/x-aim");
 		mimeTypes.put("art", "image/x-jg");
 		mimeTypes.put("asf", "video/x-ms-asf");
 		mimeTypes.put("asx", "video/x-ms-asf");
 		mimeTypes.put("au", "audio/basic");
 		mimeTypes.put("avi", "video/x-msvideo");
 		mimeTypes.put("avx", "video/x-rad-screenplay");
 		mimeTypes.put("bcpio", "application/x-bcpio");
 		mimeTypes.put("bin", "application/octet-stream");
 		mimeTypes.put("bmp", "image/bmp");
 		mimeTypes.put("body", "text/html");
 		mimeTypes.put("cdf", "application/x-cdf");
 		mimeTypes.put("cer", "application/x-x509-ca-cert");
 		mimeTypes.put("class", "application/java");
 		mimeTypes.put("cpio", "application/x-cpio");
 		mimeTypes.put("csh", "application/x-csh");
 		mimeTypes.put("css", "text/css");
 		mimeTypes.put("dib", "image/bmp");
 		mimeTypes.put("doc", "application/msword");
 		mimeTypes.put("dtd", "text/plain");
 		mimeTypes.put("dv", "video/x-dv");
 		mimeTypes.put("dvi", "application/x-dvi");
 		mimeTypes.put("eps", "application/postscript");
 		mimeTypes.put("etx", "text/x-setext");
 		mimeTypes.put("exe", "application/octet-stream");
 		mimeTypes.put("gif", "image/gif");
 		mimeTypes.put("gtar", "application/x-gtar");
 		mimeTypes.put("gz", "application/x-gzip");
 		mimeTypes.put("hdf", "application/x-hdf");
 		mimeTypes.put("hqx", "application/mac-binhex40");
 		mimeTypes.put("htc", "text/x-component");
 		mimeTypes.put("htm", "text/html");
 		mimeTypes.put("html", "text/html");
 		mimeTypes.put("hqx", "application/mac-binhex40");
 		mimeTypes.put("ief", "image/ief");
 		mimeTypes.put("jad", "text/vnd.sun.j2me.app-descriptor");
 		mimeTypes.put("jar", "application/java-archive");
 		mimeTypes.put("java", "text/plain");
 		mimeTypes.put("jnlp", "application/x-java-jnlp-file");
 		mimeTypes.put("jpe", "image/jpeg");
 		mimeTypes.put("jpeg", "image/jpeg");
 		mimeTypes.put("jpg", "image/jpeg");
 		mimeTypes.put("js", "text/javascript");
 		mimeTypes.put("jsf", "text/plain");
 		mimeTypes.put("jspf", "text/plain");
 		mimeTypes.put("kar", "audio/x-midi");
 		mimeTypes.put("latex", "application/x-latex");
 		mimeTypes.put("m3u", "audio/x-mpegurl");
 		mimeTypes.put("mac", "image/x-macpaint");
 		mimeTypes.put("man", "application/x-troff-man");
 		mimeTypes.put("me", "application/x-troff-me");
 		mimeTypes.put("mid", "audio/x-midi");
 		mimeTypes.put("midi", "audio/x-midi");
 		mimeTypes.put("mif", "application/x-mif");
 		mimeTypes.put("mov", "video/quicktime");
 		mimeTypes.put("movie", "video/x-sgi-movie");
 		mimeTypes.put("mp1", "audio/x-mpeg");
 		mimeTypes.put("mp2", "audio/x-mpeg");
 		mimeTypes.put("mp3", "audio/x-mpeg");
 		mimeTypes.put("mpa", "audio/x-mpeg");
 		mimeTypes.put("mpe", "video/mpeg");
 		mimeTypes.put("mpeg", "video/mpeg");
 		mimeTypes.put("mpega", "audio/x-mpeg");
 		mimeTypes.put("mpg", "video/mpeg");
 		mimeTypes.put("mpv2", "video/mpeg2");
 		mimeTypes.put("ms", "application/x-wais-source");
 		mimeTypes.put("nc", "application/x-netcdf");
 		mimeTypes.put("oda", "application/oda");
 		mimeTypes.put("pbm", "image/x-portable-bitmap");
 		mimeTypes.put("pct", "image/pict");
 		mimeTypes.put("pdf", "application/pdf");
 		mimeTypes.put("pgm", "image/x-portable-graymap");
 		mimeTypes.put("pic", "image/pict");
 		mimeTypes.put("pict", "image/pict");
 		mimeTypes.put("pls", "audio/x-scpls");
 		mimeTypes.put("png", "image/png");
 		mimeTypes.put("pnm", "image/x-portable-anymap");
 		mimeTypes.put("pnt", "image/x-macpaint");
 		mimeTypes.put("ppm", "image/x-portable-pixmap");
 		mimeTypes.put("ppt", "application/powerpoint");
 		mimeTypes.put("ps", "application/postscript");
 		mimeTypes.put("psd", "image/x-photoshop");
 		mimeTypes.put("qt", "video/quicktime");
 		mimeTypes.put("qti", "image/x-quicktime");
 		mimeTypes.put("qtif", "image/x-quicktime");
 		mimeTypes.put("ras", "image/x-cmu-raster");
 		mimeTypes.put("rgb", "image/x-rgb");
 		mimeTypes.put("rm", "application/vnd.rn-realmedia");
 		mimeTypes.put("roff", "application/x-troff");
 		mimeTypes.put("rtf", "application/rtf");
 		mimeTypes.put("rtx", "text/richtext");
 		mimeTypes.put("sh", "application/x-sh");
 		mimeTypes.put("shar", "application/x-shar");
 		mimeTypes.put("smf", "audio/x-midi");
 		mimeTypes.put("sit", "application/x-stuffit");
 		mimeTypes.put("snd", "audio/basic");
 		mimeTypes.put("src", "application/x-wais-source");
 		mimeTypes.put("sv4cpio", "application/x-sv4cpio");
 		mimeTypes.put("sv4crc", "application/x-sv4crc");
 		mimeTypes.put("swf", "application/x-shockwave-flash");
 		mimeTypes.put("t", "application/x-troff");
 		mimeTypes.put("tar", "application/x-tar");
 		mimeTypes.put("tcl", "application/x-tcl");
 		mimeTypes.put("tex", "application/x-tex");
 		mimeTypes.put("texi", "application/x-texinfo");
 		mimeTypes.put("texinfo", "application/x-texinfo");
 		mimeTypes.put("tif", "image/tiff");
 		mimeTypes.put("tiff", "image/tiff");
 		mimeTypes.put("tr", "application/x-troff");
 		mimeTypes.put("tsv", "text/tab-separated-values");
 		mimeTypes.put("txt", "text/plain");
 		mimeTypes.put("ulw", "audio/basic");
 		mimeTypes.put("ustar", "application/x-ustar");
 		mimeTypes.put("xbm", "image/x-xbitmap");
 		mimeTypes.put("xht", "application/xhtml+xml");
 		mimeTypes.put("xhtml", "application/xhtml+xml");
 		mimeTypes.put("xml", "text/xml");
 		mimeTypes.put("xpm", "image/x-xpixmap");
 		mimeTypes.put("xsl", "text/xml");
 		mimeTypes.put("xwd", "image/x-xwindowdump");
 		mimeTypes.put("wav", "audio/x-wav");
 		mimeTypes.put("svg", "image/svg+xml");
 		mimeTypes.put("svgz", "image/svg+xml");
 		mimeTypes.put("vsd", "application/x-visio");
 		mimeTypes.put("wbmp", "image/vnd.wap.wbmp");
 		mimeTypes.put("wml", "text/vnd.wap.wml");
 		mimeTypes.put("wmlc", "application/vnd.wap.wmlc");
 		mimeTypes.put("wmls", "text/vnd.wap.wmlscript");
 		mimeTypes.put("wmlscriptc", "application/vnd.wap.wmlscriptc");
 		mimeTypes.put("wrl", "x-world/x-vrml");
 		mimeTypes.put("Z", "application/x-compress");
 		mimeTypes.put("z", "application/x-compress");
 		mimeTypes.put("zip", "application/zip");
 	}
 
 	private String removeFirstSlash(String requestURI) {
 		if (requestURI.startsWith("/"))
 			return requestURI.substring(1);
 		else
 			return requestURI;
 	}
 
 	public static String removeGWTModuleNamePart(String requestURI) {
 		return requestURI.replaceFirst("\\/\\w+(\\.\\w+)*\\/", "");
 	}
 
 	private static Pattern invalidCharInParamKey = Pattern.compile("[.-]");
 
 	public static void setRequestParametersToHandler(RequestHandler handler, HttpServletRequest req) {
 		assert (handler != null);
 
 		// bind the parameter values to the RequestHandler
 		try {
 			Properties prop = new Properties();
 			for (Enumeration e = req.getParameterNames(); e.hasMoreElements();) {
 				String key = e.nextElement().toString();
 				Matcher m = invalidCharInParamKey.matcher(key);
 				String sanitizedKey = m.replaceAll("");
 				prop.put(sanitizedKey, req.getParameter(key));
 			}
 			if (_logger.isTraceEnabled())
 				_logger.trace(prop.toString());
 			Lens.loadMap(handler, prop);
 		}
 		catch (XerialException e) {
 			_logger.error(e);
 		}
 
 	}
 
 	public void destroy() {
 		_logger.info("destroy RequestDispatcher");
 	}
 
 	public static String getExtension(String path) {
 		int dotIndex = path.lastIndexOf(".");
 		if (dotIndex > 0) {
 			return path.substring(dotIndex + 1);
 		}
 		else
 			return "";
 	}
 
 	public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException {
 
 		HttpServletRequest req = (HttpServletRequest) request;
 		HttpServletResponse resp = (HttpServletResponse) response;
 
 		// resolve request URI
 		String requestURI = null;
 		if (isInGWTHostedMode) {
 			// in GWT-shell, we have to remove the module name prefix in the
 			// request URI.
 			requestURI = req.getRequestURI();
 			requestURI = removeGWTModuleNamePart(requestURI);
 		}
 		else
 			requestURI = removeFirstSlash(req.getServletPath());
 		_logger.trace("request URI: " + requestURI);
 
 		dispatchRequest(new RequestURI(requestURI), req, resp, filterChain);
 	}
 
 	public void dispatchRequest(RequestURI requestURI, HttpServletRequest req, HttpServletResponse resp, FilterChain filterChain) throws IOException,
 			ServletException {
 
 		for (RequestMap map : requestMapList) {
 			RequestHandler handler = map.map(requestURI, req, resp);
 			if (handler != null) {
 				req.setAttribute("actionPrefix", requestURI.getPrefix());
 				req.setAttribute("actionSuffix", requestURI.getSuffix());
 				setRequestParametersToHandler(handler, req);
 
 				// validate the request parameters
 				try {
 					handler.validate(req, resp);
 				}
 				catch (UTGBException e) {
 					_logger.error(e);
 					return;
 				}
 
 				// passes the request to the handler
 				handler.handle(req, resp);
 
 				// returns without chains the request
 				return;
 			}
 		}
 
 		// when no handler is found
 
 		// search src/main/webapp folder (in GWT hosted mode)
 		if (doGetFromSrcMainWebApp(requestURI.getURI(), req, resp))
 			return;
 
 		// when no handler is found for the requested URI, forward this
 		// request to the next chain filter
 		filterChain.doFilter(req, resp);
 	}
 
 	private static DateFormat sHttpDateFormat = new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss", Locale.US);
 
 	/**
 	 * Converts a file-style date/time into a string form that is compatible with HTTP.
 	 */
 	public static String toInternetDateFormat(long time) {
 		Date date = dateToGMT(new Date(time));
 		String dateGmt;
 		synchronized (sHttpDateFormat) {
 			dateGmt = sHttpDateFormat.format(date) + " GMT";
 		}
 		return dateGmt;
 	}
 
 	/**
 	 * Converts a local date to GMT.
 	 * 
 	 * @param date
 	 *            the date in the local time zone
 	 * @return the GMT version
 	 */
 	private static Date dateToGMT(Date date) {
 		Calendar cal = Calendar.getInstance();
 		long tzMillis = cal.get(Calendar.ZONE_OFFSET) + cal.get(Calendar.DST_OFFSET);
 		return new Date(date.getTime() - tzMillis);
 	}
 
 	private boolean doGetFromSrcMainWebApp(String requestURI, ServletRequest request, ServletResponse response) throws IOException {
 
 		if (!isInGWTHostedMode)
 			return false;
 
 		// search the resource
 		File resourceFile = new File("src/main/webapp/", requestURI);
 		if (!resourceFile.exists())
 			return false;
 
 		// Get the MIME type.
 		String mimeType = mimeTypes.get(getExtension(requestURI));
 		if (mimeType == null) {
 			mimeType = "application/octet-stream";
 		}
 
 		HttpServletResponse resp = (HttpServletResponse) response;
 		resp.setStatus(HttpServletResponse.SC_OK);
 
 		// set cache time
 		long cacheTime = 5;
 		long expires = 24 * 1000;
 		resp.setHeader("Cache-Control", "max-age=" + cacheTime);
 		String expiresString = toInternetDateFormat(expires);
 		resp.setHeader("Expires", expiresString);
 
 		// set current date
 		long now = new Date().getTime();
 		resp.setHeader("Date", toInternetDateFormat(now));
 
 		// content type
 		resp.setContentType(mimeType);
 
 		// last modified time
 		long lastModified = resourceFile.lastModified();
 		String lastModifiedStr = toInternetDateFormat(resourceFile.lastModified());
 		resp.setHeader("Last-Modified", lastModifiedStr);
 
 		// content length
 		long contentLength = resourceFile.length();
 		if (contentLength >= 0) {
 			resp.setHeader("Content-Length", Long.toString(contentLength));
 		}
 
 		// Send the bytes.
 		OutputStream out = resp.getOutputStream();
 		BufferedInputStream in = new BufferedInputStream(new FileInputStream(resourceFile));
 		byte[] buf = new byte[1024];
 		int bytesRead = 0;
 		while ((bytesRead = in.read(buf)) >= 0) {
 			out.write(buf, 0, bytesRead);
 		}
 		in.close();
 		return true;
 	}
 
 	public static boolean isGWTHostedMode() {
 		return Boolean.parseBoolean(System.getProperty("gwt-hosted-mode"));
 	}
 
 	public void init(FilterConfig config) throws ServletException {
 		_logger.info("initializing RequestDispatcher");
 
 		isInGWTHostedMode = isGWTHostedMode();
 
 		if (isInGWTHostedMode) {
 			_logger.info("GWT Hosted Mode");
 			initMimeTypes();
 		}
 
 		initRequestMap();
 	}
 
 	public void initRequestMap() {
 		addRequestMap(new DefaultRequestMap());
 	}
 
 	public void addRequestMap(RequestMap map) {
 		requestMapList.add(map);
 	}
 
 }