package com.walker.web;

import com.walker.infrastructure.core.NamedThreadLocal;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 可获得请求对象的上下文环境</p>
 * 通过线程绑定<code>HttpServletRequest</code>让<code>Action</code>层获得请求支持。
 * @author shikeying
 * @date 2013-10-1
 *
 */
public abstract class RequestAwareContext {
	
	/* 因为界面中用户可能频繁恶意刷新，因此在tomcat等中间件中，会存在多个请求
	 * 重复使用线程池中的某个线程，造成重复绑定。
	 * 所以设置此参数，控制是否允许重复绑定，同时后续还要解决重复提交的问题。
	 * 2014-6-30 时克英 */
//	private static boolean requestOverride = false;

	private static boolean requestOverride = true;

	public static boolean isRequestOverride() {
		return requestOverride;
	}

	/**
	 * 是否允许线程局部变量的覆盖，默认不允许。</br>
	 * 注意：在系统中该方法只能被调用一次，即：初始化调用。
	 * @param requestOverride
	 */
	public static void setRequestOverride(boolean requestOverride) {
		RequestAwareContext.requestOverride = requestOverride;
	}

	private static final NamedThreadLocal<HttpServletRequest> requestLocals
		= new NamedThreadLocal<HttpServletRequest>("walker_request_threadlocal");
	
	private static final NamedThreadLocal<HttpServletResponse> responseLocals
	= new NamedThreadLocal<HttpServletResponse>("walker_response_threadlocal");
	
	/**
	 * 设置当前线程绑定的请求对象<code>HttpServletRequest</code>。<br>
	 * 当前某些环境会出现恶意刷新界面时，tomcat线程池重复绑定的情况，可以通过捕获异常提示用户。
	 * @throws BindRequestRepeatException 当不允许重复绑定线程变量时，出现重复绑定会抛出异常
	 * @param request
	 */
	public static void setCurrentRequest(HttpServletRequest request){
		HttpServletRequest _r = requestLocals.get();
		if(_r != null){
			if(!isRequestOverride())
				throw new BindRequestRepeatException("request can't be binded repeatly! request = " + _r);
			else {
				// 如果允许覆盖
				requestLocals.remove();
			}
		}
		requestLocals.set(request);
	}
	
	public static HttpServletRequest getCurrentRequest(){
		return requestLocals.get();
	}
	
	public static void clearCurrentRequest(){
		requestLocals.remove();
	}
	
	public static void setCurrentResponse(HttpServletResponse response){
		HttpServletResponse _r = responseLocals.get();
		if(_r != null)
			throw new IllegalStateException("response can't be binded repeatly! response = " + _r);
		responseLocals.set(response);
	}
	
	public static HttpServletResponse getCurrentResponse(){
		return responseLocals.get();
	}
	
	public static void clearCurrentResponse(){
		responseLocals.remove();
	}
	
	public static class BindRequestRepeatException extends IllegalStateException{
		/**
		 *
		 */
		private static final long serialVersionUID = -7221718348573512540L;

		public BindRequestRepeatException(){
			super("request can't be binded repeatly!");
		}

		public BindRequestRepeatException(String msg){
			super(msg);
		}

		public BindRequestRepeatException(String msg, Throwable cause){
			super(msg, cause);
		}
	}
}