package main

import (
	"fmt"
	"net"
	"time"
)

// LatencyInfo 延迟信息
type LatencyInfo struct {
	ClientToServer float64            `json:"clientToServer"` // 客户端到服务器延迟（ms），由前端计算
	External       map[string]string `json:"external"`        // 外部网站延迟
}

// checkExternalLatency 检测外部网站延迟
func checkExternalLatency(host string, timeout time.Duration) string {
	start := time.Now()
	
	// 尝试 TCP 连接 80 端口
	conn, err := net.DialTimeout("tcp", host+":80", timeout)
	if err != nil {
		// 如果 80 端口失败，尝试 443 (HTTPS)
		conn, err = net.DialTimeout("tcp", host+":443", timeout)
		if err != nil {
			return "超时"
		}
	}
	defer conn.Close()
	
	latency := time.Since(start).Milliseconds()
	
	// 检查是否超时（超过超时时间的一半就认为可能有问题）
	if latency > timeout.Milliseconds()/2 {
		return "超时"
	}
	
	return fmt.Sprintf("%d ms", latency)
}

// readExternalLatencies 读取外部网站延迟
func readExternalLatencies() map[string]string {
	latencies := make(map[string]string)
	timeout := 3 * time.Second

	// 检测百度
	latencies["baidu.com"] = checkExternalLatency("baidu.com", timeout)

	// 检测谷歌
	latencies["google.com"] = checkExternalLatency("google.com", timeout)

	// 检测 GitHub
	latencies["github.com"] = checkExternalLatency("github.com", timeout)

	return latencies
}