/*

  * Copyright 2004-2011 the Seasar Foundation and the Others.

  *

  * 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.

  */

 package org.seasar.teeda.core.util;

 import java.io.IOException;

 import java.lang.reflect.Method;

 import java.util.Enumeration;

 import java.util.Iterator;

 import javax.faces.FacesException;

 import javax.faces.application.ViewHandler;

 import javax.faces.context.ExternalContext;

 import javax.faces.context.FacesContext;

 import javax.servlet.RequestDispatcher;

 import javax.servlet.ServletException;

 import javax.servlet.ServletRequest;

 import javax.servlet.ServletResponse;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 import javax.servlet.http.HttpSession;

 import org.seasar.framework.log.Logger;

 import org.seasar.framework.util.AssertionUtil;

 import org.seasar.framework.util.Disposable;

 import org.seasar.framework.util.DisposableUtil;

 import org.seasar.framework.util.EnumerationIterator;

 import org.seasar.framework.util.MethodUtil;

 import org.seasar.teeda.core.JsfConstants;

 import org.seasar.teeda.core.resolver.RedirectUrlResolver;

 /**

  * @author shot

  * @author manhole

  */

 public class ServletExternalContextUtil {

     private static Logger logger = Logger

             .getLogger(ServletExternalContextUtil.class);

     private static final String CONTENT_TYPE = "Content-Type";

     private static final String CHARSET_HEADER = "charset=";

     private static final int CHARSET_HEADER_LENGTH = CHARSET_HEADER.length();

     private static RedirectUrlResolver resolver = null;

     private static boolean resolverInited = false;

     static {

         DisposableUtil.add(new Disposable() {

             public void dispose() {

                 resolver = null;

                 resolverInited = false;

             }

         });

     }

     private ServletExternalContextUtil() {

     }

     public static void setCharacterEncoding(ServletRequest request) {

         Method characterEncodingMethod = getCharacterEncodingMethodFromRequest();

         if (characterEncodingMethod == null) {

             return;

         }

         if (!isHttpServletRequest(request)) {

             // No getHeader(), no getSession() if it is not HttpServletRequest.

             // So, do nothing.

             return;

         }

         HttpServletRequest httpServletRequest = (HttpServletRequest) request;

         String contentType = httpServletRequest.getHeader(CONTENT_TYPE);

         String encoding = getEncodingFromContentType(contentType);

         if (encoding == null) {

             encoding = getEncodingFromSession(httpServletRequest);

         }

         if (encoding == null || "null".equals(encoding)) {

             return;

         }

         MethodUtil.invoke(characterEncodingMethod, httpServletRequest,

                 new Object[] { encoding });

     }

     public static boolean setCharacterEncoding(ServletResponse response) {

         Method characterEncodingMethod = getCharacterEncodingMethodFromResponse();

         if (characterEncodingMethod == null

                 && (!isHttpServletResponse(response))) {

             return false;

         }

         HttpServletResponse httpServletResponse = (HttpServletResponse) response;

         String contentType = httpServletResponse.getContentType();

         String encoding = getEncodingFromContentType(contentType);

         if (encoding == null) {

             return false;

         }

         MethodUtil.invoke(characterEncodingMethod, httpServletResponse,

                 new Object[] { encoding });

         return true;

     }

     public static boolean isHttpServletRequest(ServletRequest request) {

         return (request != null) && (request instanceof HttpServletRequest);

     }

     public static boolean isHttpServletResponse(ServletResponse response) {

         return (response != null) && (response instanceof HttpServletResponse);

     }

     public static String getEncodingFromContentType(String contentType) {

         if (contentType == null) {

             return null;

         }

         String encoding = null;

         int found = contentType.indexOf(CHARSET_HEADER);

         if (found == 0) {

             encoding = contentType.substring(CHARSET_HEADER_LENGTH);

         } else if (found >= 1) {

             char charBefore = contentType.charAt(found - 1);

             if (charBefore == ';' || Character.isWhitespace(charBefore)) {

                 encoding = contentType.substring(found + CHARSET_HEADER_LENGTH);

             }

         }

         return encoding;

     }

     public static String getEncodingFromSession(

             HttpServletRequest servletRequest) {

         String encoding = null;

         HttpSession session = servletRequest.getSession(false);

         if (session != null) {

             encoding = (String) session

                     .getAttribute(ViewHandler.CHARACTER_ENCODING_KEY);

         }

         return encoding;

     }

     public static void dispatch(String path, ServletRequest request,

             ServletResponse response) throws IOException {

         AssertionUtil.assertNotNull("path is null.", path);

         RequestDispatcher dispatcher = request.getRequestDispatcher(path);

         try {

             dispatcher.forward(request, response);

         } catch (ServletException e) {

             if (e.getMessage() != null) {

                 throw new FacesException(e.getMessage(), e);

             }

             throw new FacesException(e);

         }

     }

     public static Iterator getLocales(Enumeration locales) {

         return new EnumerationIterator(locales);

     }

     public static Iterator getRequestParameterNames(Enumeration paramNames) {

         return new EnumerationIterator(paramNames);

     }

     public static void redirect(String url, ServletRequest request,

             ServletResponse response) throws IOException {

         HttpServletResponse httpResponse = (HttpServletResponse) response;

         FacesContext context = FacesContext.getCurrentInstance();

         if (!resolverInited) {

             if (DIContainerUtil.hasContainer()) {

                 resolver = (RedirectUrlResolver) DIContainerUtil

                         .getComponentNoException(RedirectUrlResolver.class);

             }

             resolverInited = true;

         }

         if (resolver != null) {

             HttpServletRequest httpRequest = (HttpServletRequest) request;

             url = resolver.resolveUrl(url, context, httpRequest, httpResponse);

         }

         httpResponse.sendRedirect(url);

         if (context != null) {

             context.responseComplete();

         } else {

             logger

                     .info("[ServletExternalContextUtil.redirect] facesContext is null.");

         }

     }

     private static Method getCharacterEncodingMethodFromRequest() {

         try {

             Class clazz = ServletRequest.class;

             return clazz.getMethod("setCharacterEncoding",

                     new Class[] { String.class });

         } catch (Exception e) {

             logger.log(e);

             return null;

         }

     }

     private static Method getCharacterEncodingMethodFromResponse() {

         try {

             Class clazz = ServletResponse.class;

             return clazz.getMethod("setCharacterEncoding",

                     new Class[] { String.class });

         } catch (Exception e) {

             logger.log(e);

             return null;

         }

     }

     public static HttpServletRequest getRequest(ExternalContext externalContext) {

         return (HttpServletRequest) externalContext.getRequest();

     }

     public static HttpServletResponse getResponse(

             ExternalContext externalContext) {

         return (HttpServletResponse) externalContext.getResponse();

     }

     public static boolean isGet(ExternalContext externalContext) {

         return getRequest(externalContext).getMethod().equals("GET");

     }

     public static boolean isPost(ExternalContext externalContext) {

         return getRequest(externalContext).getMethod().equals("POST");

     }

     public static void storeErrorInfoToAttribute(final ServletRequest request,

             final Throwable exception) {

         AssertionUtil.assertNotNull("request", request);

         AssertionUtil.assertNotNull("exception", exception);

         request.setAttribute(JsfConstants.ERROR_EXCEPTION, exception);

         request.setAttribute(JsfConstants.ERROR_EXCEPTION_TYPE, exception

                 .getClass());

         request

                 .setAttribute(JsfConstants.ERROR_MESSAGE, exception

                         .getMessage());

     }

 }