// Package proxy ...
//
// Description : 正向代理服务器
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 2022-10-08 14:26
package proxy

import (
	"git.zhangdeman.cn/zhangdeman/util"
	"io"
	"net"
	"net/http"
	"strings"
)

// Forward 正向代理主干逻辑
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 14:28 2022/10/8
func Forward(rw http.ResponseWriter, req *http.Request)  {
	// 复制请求
	proxyRequest := new(http.Request)
	*proxyRequest = *req
	if clientIP, _, err := net.SplitHostPort(proxyRequest.RemoteAddr); err == nil {
		if prior, ok := proxyRequest.Header["X-forwarded-For"]; ok {
			clientIP = strings.Join(prior, ", ")+ ", "+clientIP
		}
		proxyRequest.Header.Set("X-Forwarded-For", clientIP)
	}
	// 请求代理机器IP
	proxyIP := util.IP.GetHostIP()
	proxyRequest.Header.Set("X-Forward-Proxy-IP", proxyIP)

	// 请求目标服务
	transport := http.DefaultTransport
	res, err := transport.RoundTrip(proxyRequest)
	if nil != err {
		rw.WriteHeader(http.StatusBadGateway)
		return
	}
	// 回写客户端响应头
	for key, values := range res.Header {
		for _, v := range values {
			rw.Header().Add(key, v)
		}
	}
	// 回写客户端状态码
	rw.WriteHeader(res.StatusCode)
	// 回写响应体
	io.Copy(rw, res.Body)
	res.Body.Close()
}