package server

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

	"git.magicany.cc/black1552/gf-common/log"
	"github.com/gogf/gf/v2/net/ghttp"
	"github.com/gogf/gf/v2/os/gctx"
)

// hasProtocol 检查字符串是否包含协议前缀
func hasProtocol(s string) bool {
	return strings.HasPrefix(s, "http://") ||
		strings.HasPrefix(s, "https://") ||
		strings.HasPrefix(s, "ws://") ||
		strings.HasPrefix(s, "wss://")
}

// BuildRequest 反向代理请求到指定主机
// 自动支持所有 HTTP 方法及 WebSocket 连接
func BuildRequest(r *ghttp.Request, host string) {
	// 自动添加协议前缀
	targetHost := host
	if !hasProtocol(host) {
		// 根据请求判断协议：WebSocket 用 ws，普通 HTTP 用 http
		if r.Header.Get("Upgrade") == "websocket" {
			targetHost = "ws://" + host
		} else {
			targetHost = "http://" + host
		}
	}

	targetURL, err := url.Parse(targetHost)
	if err != nil {
		log.Error(gctx.New(), "parse target host error:", err)
		r.Response.WriteStatus(http.StatusInternalServerError)
		r.Response.Write([]byte("Invalid target host"))
		return
	}

	proxy := httputil.NewSingleHostReverseProxy(targetURL)

	// 自定义 Director 来设置目标 URL，保留原始请求的所有参数
	proxy.Director = func(req *http.Request) {
		req.URL.Scheme = targetURL.Scheme
		req.URL.Host = targetURL.Host
		req.URL.Path = r.URL.Path
		req.URL.RawQuery = r.URL.RawQuery
		// 保留原始 Host 头
		req.Host = r.Host
	}

	// 错误处理
	proxy.ErrorHandler = func(w http.ResponseWriter, req *http.Request, err error) {
		log.Error(gctx.New(), "proxy error:", err)
		w.WriteHeader(http.StatusBadGateway)
		w.Write([]byte("Bad Gateway"))
	}
	proxy.ModifyResponse = func(resp *http.Response) error {
		// 获取原始响应的 Header
		for k, v := range resp.Header {
			r.Response.Header().Set(k, v[0])
		}
		return nil
	}
	// ServeHTTP 会自动处理 WebSocket 升级和所有 HTTP 方法
	// 使用 RawWriter() 获取原始的 http.ResponseWriter，避免 gf 框架的封装影响
	proxy.ServeHTTP(r.Response.RawWriter(), r.Request)
	r.Response.WriteJson(r.Response.RawWriter())
}