package utils

import (
	"net"
	"net/http"
	"strings"
)

func ClientIP(r *http.Request) string {
	xForwardedFor := r.Header.Get("X-Forwarded-For")
	ip := strings.TrimSpace(strings.Split(xForwardedFor, ",")[0])
	if ip != "" {
		return ip
	}

	ip = strings.TrimSpace(r.Header.Get("X-Real-Ip"))
	if ip != "" {
		return ip
	}

	if ip, _, err := net.SplitHostPort(strings.TrimSpace(r.RemoteAddr)); err == nil {
		return ip
	}

	return ""
}

func IsLocalIPAddr(ip string) bool {
	return IsLocalIP(net.ParseIP(ip))
}

func IsLocalIP(ip net.IP) bool {
	if ip == nil {
		return false
	}
	if ip.IsLoopback() {
		return true
	}

	ip4 := ip.To4()
	if ip4 == nil {
		return false
	}

	return ip4[0] == 10 || // 10.0.0.0/8
		(ip4[0] == 172 && ip4[1] >= 16 && ip4[1] <= 31) || // 172.16.0.0/12
		(ip4[0] == 169 && ip4[1] == 254) || // 169.254.0.0/16
		(ip4[0] == 192 && ip4[1] == 168) // 192.168.0.0/16
}