package gboat2.base.bridge;
   
   import gboat2.base.bridge.exception.DefaultGboatNestedException;
   import gboat2.base.bridge.model.UserSession;
   import gboat2.base.bridge.util.json.JsonUtil;
   
   import java.io.PrintWriter;
   
   import javax.servlet.ServletContext;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import javax.servlet.http.HttpSession;
  
  import org.apache.commons.io.IOUtils;
  import org.apache.struts2.ServletActionContext;
  
  /**
   * 整个平台的上下文，提供一些通用的常规工具方法
   * @date 2013-12-4
   * @author hemw
   * @since 2.1.2-SNAPSHOT
   */
  public class GboatAppContext implements GboatAppConstants{
  
      /**
       * 返回web应用的根目录的绝对路径: eg: D:\apache-tomcat-7.0.23\webapps\G2\
       * 
       * @return web应用的根目录的绝对路径,如果因为某些原因未找到，则返回null
       */
      public static String getWebRootPath() {
          String path = System.getProperty(WEBAPP_ROOT_KEY);
          if (null == path) {
              path = ServletActionContext.getServletContext().getRealPath("/");
          }
          return path;
      }
  
      /**
       * @return HTTP 请求的 Servlet 上下文实例
       */
      public static ServletContext getServletContext(){
          return ServletActionContext.getServletContext();
      }
      
      /**
       * @return HTTP 请求实例
       */
      public static HttpServletRequest getRequest(){
          return ServletActionContext.getRequest();
      }
      
      /**
       * @return HTTP 响应实例
       */
      public static HttpServletResponse getResponse(){
          return ServletActionContext.getResponse();
      }
      
      /**
       * @return HTTP 请求的会话 Session 实例
       */
      public static HttpSession getSession(){
          return getRequest().getSession();
      }
      
      /**
       * 根据 session 中的 key 获取对应的值
       * @param name 保存在 session 中的 key
       * @return session 中对应的值
       */
      public static Object getSessionAttr(String name){
          return getSession().getAttribute(name);
      }
      
      /**
       * @return 用户 Session 实例
       * @since 2.1.2
       */
      public static UserSession getUserSession() {
          return getUserSession(null);
      }
      
      /**
       * 用户 Session 实例
       * @param request
       * @return
       */
      public static UserSession getUserSession(HttpServletRequest request){
          if(request == null) {
              request = getRequest();
          }
          
  		Object userSessionObj = request.getSession().getAttribute(UserSession.USER_SESSION_KEY);
  		if (userSessionObj instanceof UserSession) 
  		    return (UserSession) userSessionObj;
  
  		return null;
  	}
      
     /**
      * @return 客户端的 IP 地址
      */
     public static String getRemoteAddr() {
         HttpServletRequest request = getRequest();
         String ip = request.getHeader("x-forwarded-for");
         // 判断是否为反向代理,多级反向代理的话，X-Forwarded-For的值并不止一个，而是一串IP值
         // 是取X-Forwarded-For中第一个非unknown的有效IP字符串
         if (ip != null && !"".equals(ip) && !"unknown".equalsIgnoreCase(ip)) {
             String[] tempArray = ip.split(",");
             for (int i = 0; i < tempArray.length; i++) {
                 if (!"unknown".equalsIgnoreCase(tempArray[i])) {
                     ip = tempArray[i].replaceAll("\\s", "");
                     break;
                 }
             }
         }
         
         if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
             ip = request.getHeader("Proxy-Client-IP");
         }
         
         if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
             ip = request.getHeader("WL-Proxy-Client-IP");
         }
         
         if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
             ip = request.getRemoteAddr();
         }
         
         return ip;
     }
 
     /**
      * 向前台输出响应信息<br>
      * 注意: 方法最后会调用HttpServletResponse.getWriter.close()
      * @param obj 要输出到前台的响应对象
      */
     public static void output(Object obj) {
         output(obj, null);
     }
     
     /**
      * 向前台输出响应信息<br>
      * 注意: 方法最后会调用HttpServletResponse.getWriter.close()
      * @param obj 要输出到前台的响应对象
      */
     public static void output(Object obj, HttpServletResponse response) {
         if (obj == null)
             throw new IllegalArgumentException("向前台输出的响应信息不能为 null");
 
         if(response == null) {
             response = getResponse();
         }
         response.setContentType(CT_PLAIN_UTF8);
         PrintWriter out = null;
         try {
             out = response.getWriter();
             if (obj instanceof CharSequence) { // 如果是字符串，则直接输出
                 out.print(obj);
             } else {
                 String objClass = obj.getClass().getName();
                 if ("net.sf.json.JSONObject".equals(objClass)
                         || "net.sf.json.JSONArray".equals(objClass)) { // 为了兼容低版本使用的 net.sf.json 包 
                     out.print(obj);
                 } else { // 输出 Json 格式字符串
                     JsonUtil.object2Json(out, obj);
                 }
             }
             out.flush();
         } catch (Exception e) {
             throw new DefaultGboatNestedException("向前台输出响应信息 [" + obj + "] 失败。", e);
         } finally {
             IOUtils.closeQuietly(out);
             out = null;
         }
     }
 }