package ai.yue.library.web.config.argument.resolver;

import java.io.IOException;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.filter.OncePerRequestFilter;

import ai.yue.library.base.constant.Constant;
import lombok.extern.slf4j.Slf4j;

/**
 * RepeatedlyReadServletRequestWrapper过滤器
 * <p>传递输入流可反复读取的HttpServletRequest
 * <p>OncePerRequestFilter是在一次外部请求中只过滤一次。对于服务器内部之间的forward等请求，不会再次执行过滤方法。
 * 
 * @author ylyue
 * @since 2020年9月3日
 */
@Slf4j
public class RepeatedlyReadServletRequestFilter extends OncePerRequestFilter {
	
	private static final String PARAM_TRANSMIT = Constant.PREFIX + "Param-Transmit";
	
	@Override
	protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
			throws ServletException, IOException {
		log.debug("传递输入流可反复读取的HttpServletRequest ...");
		
		/*
		 * 在request被包装之前，先进行一次参数解析处理，避免后续出现使用未包装的request导致：FileUploadException: Stream closed.
		 * 如：调用 request#getParts() 将使用已解析过的结果（parse multipart content and store the parts）.
		 */
		request.getParameter(PARAM_TRANSMIT);
		
		ServletRequest requestWrapper = new RepeatedlyReadServletRequestWrapper(request);
		filterChain.doFilter(requestWrapper, response);
	}
	
}