package proxy

import (
	"fmt"
	"net/http"
	"net/http/httputil"
	"net/url"
)

// New 创建指向 WMS 后端的反向代理。
// 请求侧保留 Method/Body/Header(含 Cookie、Authorization)；
// 响应头默认全量透传（含滑动续签的 X-Renewed-Token，由 WMS 写入）。
func New(upstream string) *httputil.ReverseProxy {
	target, err := url.Parse(upstream)
	if err != nil {
		panic(fmt.Sprintf("Upstream 配置非法: %v", err))
	}
	rp := httputil.NewSingleHostReverseProxy(target)
	origDirector := rp.Director
	rp.Director = func(req *http.Request) {
		origDirector(req)
		req.Host = target.Host
	}
	rp.ErrorHandler = func(w http.ResponseWriter, r *http.Request, err error) {
		http.Error(w, "WMS 服务不可达: "+err.Error(), http.StatusBadGateway)
	}
	return rp
}