package proxy

import (
	"net"
	"net/http"
	"net/http/httputil"
	"net/url"
	"strings"
	"time"
)

func CreateCustomProxyClient(target *url.URL, errFunc func(http.ResponseWriter, *http.Request, error)) *httputil.ReverseProxy {
	director := func(req *http.Request) {
		targetQuery := target.RawQuery
		req.URL.Scheme = target.Scheme
		req.URL.Host = target.Host
		req.URL.Path = singleJoiningSlash(target.Path, req.URL.Path)
		if targetQuery == "" || req.URL.RawQuery == "" {
			req.URL.RawQuery = targetQuery + req.URL.RawQuery
		} else {
			req.URL.RawQuery = targetQuery + "&" + req.URL.RawQuery
		}
		if _, ok := req.Header["User-Agent"]; !ok {
			// explicitly disable User-Agent so it's not set to default value
			req.Header.Set("User-Agent", "")
		}
	}

	//超时处理
	transport := &http.Transport{
		Proxy: http.ProxyFromEnvironment,
		DialContext: (&net.Dialer{
			Timeout:   15 * time.Second, //连接超时
			KeepAlive: 15 * time.Second, //长连接超时时间
			DualStack: true,
		}).DialContext,
		MaxIdleConns:          30,               //最大空闲连接
		IdleConnTimeout:       90 * time.Second, //空闲超时时间
		TLSHandshakeTimeout:   10 * time.Second, //tls握手超时时间
		ExpectContinueTimeout: 1 * time.Second,  //100-continue 超时时间
		MaxIdleConnsPerHost:   300,
	}

	//异常处理
	//errFunc := func(w http.ResponseWriter, r *http.Request, err error) {
	//	http.Error(w, "proxy error:", 500)
	//	logs.GInfo.Error(r.Context(), err.Error())
	//}

	reverseProxy := &httputil.ReverseProxy{
		Director:  director,
		Transport: transport,
		//ModifyResponse: change,
		ErrorHandler: errFunc}

	return reverseProxy
}

func singleJoiningSlash(a, b string) string {
	aslash := strings.HasSuffix(a, "/")
	bslash := strings.HasPrefix(b, "/")
	switch {
	case aslash && bslash:
		return a + b[1:]
	case !aslash && !bslash:
		return a + "/" + b
	}
	return a + b
}