/**
 * Alipay.com Inc.
 * Copyright (c) 2004-2014 All Rights Reserved.
 */
package com.alipay.servlet.gateway;

import com.alipay.api.AlipayApiException;
import com.alipay.api.AlipayConstants;
import com.alipay.api.internal.util.AlipaySignature;
import com.alipay.api.internal.util.StringUtils;
import com.alipay.constants.AlipayServiceEnvConstants;
import com.alipay.dispatcher.Dispatcher;
import com.alipay.executor.ActionExecutor;
import com.alipay.util.LogUtil;
import com.alipay.util.RequestUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Map;

/**
 * 开发者网关，支付宝所有主动和开发者的交互会经过此网关进入开发者系统(配置在开放平台的应用网关)
 * 
 * @author taixu.zqq
 * @version $Id: GatewayServlet.java, v 0.1 2014年7月22日 下午5:59:55 taixu.zqq Exp $
 */
public class GatewayServlet extends HttpServlet {

    private final static Logger logger = LoggerFactory.getLogger(GatewayServlet.class);


    /**
     * 
     */
    private static final long serialVersionUID = 1210436705188940602L;

    /** 
     * @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
     */
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException,
                                                                              IOException {
        logger.info("enter ali GatewayServlet  req {} ",req);
        this.doPost(req, resp);
        logger.info("enter ali GatewayServlet end ");
    }

    /**
     * 网关处理
     * 
     * @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
                                                                                   throws ServletException,
                                                                                   IOException {
        logger.info("enter ali GatewayServlet post ");
        //支付宝响应消息  
        String responseMsg = "";

        //1. 解析请求参数
        Map<String, String> params = RequestUtil.getRequestParams(request);

        //打印本次请求日志，开发者自行决定是否需要
        LogUtil.log("支付宝请求串", params.toString());

        try {
            //2. 验证签名
            this.verifySign(params);

            //3. 获取业务执行器   根据请求中的 service, msgType, eventType, actionParam 确定执行器
            ActionExecutor executor = Dispatcher.getExecutor(params);

            //4. 执行业务逻辑
            responseMsg = executor.execute();

        } 
        catch (AlipayApiException alipayApiException) {
            //开发者可以根据异常自行进行处理
            alipayApiException.printStackTrace();
            logger.error("enter ali GatewayServlet post  error {} ",alipayApiException);

        } 
        catch (Exception exception) {
            //开发者可以根据异常自行进行处理
            exception.printStackTrace();
            logger.error("enter ali GatewayServlet post exception {}  ",exception);

        } finally {
            //5. 响应结果加签及返回
            try {
                //对响应内容加签
                responseMsg = encryptAndSign(responseMsg,
                    AlipayServiceEnvConstants.ALIPAY_PUBLIC_KEY,
                    AlipayServiceEnvConstants.PRIVATE_KEY, AlipayServiceEnvConstants.CHARSET,
                    false, true, AlipayServiceEnvConstants.SIGN_TYPE);

                //http 内容应答
                response.reset();
                response.setContentType("text/xml;charset=GBK");
                PrintWriter printWriter = response.getWriter();
                printWriter.print(responseMsg);
                response.flushBuffer();

                //开发者自行决定是否要记录，视自己需求
                LogUtil.log("开发者响应串", responseMsg);

            } catch (AlipayApiException alipayApiException) {
                //开发者可以根据异常自行进行处理
                alipayApiException.printStackTrace();
                logger.error("enter ali GatewayServlet post exception {}  ",alipayApiException);
            }
        }
    }

    /**
     * 验签
     * 
     * @param
     * @return
     */
    private void verifySign(Map<String, String> params) throws AlipayApiException {

		if (!AlipaySignature.rsaCheckV2(params, AlipayServiceEnvConstants.ALIPAY_PUBLIC_KEY,
				AlipayServiceEnvConstants.SIGN_CHARSET, AlipayServiceEnvConstants.SIGN_TYPE)) {
			throw new AlipayApiException("verify sign fail.");
		}
    }
    
    
	public static String encryptAndSign(String bizContent, String alipayPublicKey, String cusPrivateKey, String charset,
			boolean isEncrypt, boolean isSign, String signType) throws AlipayApiException {
		StringBuilder sb = new StringBuilder();
		if (StringUtils.isEmpty(charset)) {
			charset = AlipayConstants.CHARSET_GBK;
		}
		sb.append("<?xml version=\"1.0\" encoding=\"" + charset + "\"?>");
		if (isEncrypt) {// 加密
			sb.append("<alipay>");
			String encrypted = AlipaySignature.rsaEncrypt(bizContent, alipayPublicKey, charset);
			sb.append("<response>" + encrypted + "</response>");
			sb.append("<encryption_type>AES</encryption_type>");
			if (isSign) {
				String sign = AlipaySignature.rsaSign(encrypted, cusPrivateKey, charset, signType);
				sb.append("<sign>" + sign + "</sign>");
				sb.append("<sign_type>");
				sb.append(signType);
				sb.append("</sign_type>");
			}
			sb.append("</alipay>");
		} else if (isSign) {// 不加密，但需要签名
			sb.append("<alipay>");
			sb.append("<response>" + bizContent + "</response>");
			String sign = AlipaySignature.rsaSign(bizContent, cusPrivateKey, charset, signType);
			sb.append("<sign>" + sign + "</sign>");
			sb.append("<sign_type>");
			sb.append(signType);
			sb.append("</sign_type>");
			sb.append("</alipay>");
		} else {// 不加密，不加签
			sb.append(bizContent);
		}
		return sb.toString();
	}

}