package main

import (
	"bytes"
	"encoding/binary"
	"net"
	"net/http"
	"strconv"
	"strings"
)

func ip2Long(ip string) uint32 {
	var long uint32
	binary.Read(bytes.NewBuffer(net.ParseIP(ip).To4()), binary.BigEndian, &long)
	return long
}

func backtoIP4(ipInt int64) string {

	// need to do two bit shifting and “0xff” masking
	b0 := strconv.FormatInt((ipInt>>24)&0xff, 10)
	b1 := strconv.FormatInt((ipInt>>16)&0xff, 10)
	b2 := strconv.FormatInt((ipInt>>8)&0xff, 10)
	b3 := strconv.FormatInt((ipInt & 0xff), 10)
	return b0 + "." + b1 + "." + b2 + "." + b3
}

func getClientIP(r *http.Request) string {
	a := r.RemoteAddr // always be 127.0.0.1:300456 port number may vary
	s := strings.Split(a, ":")
	if s[0] == "127.0.0.1" { //loopback address
		ip := r.Header.Get("X-Forwarded-For")
		return ip
	}
	return s[0]
}

func getClientIPLong(r *http.Request) uint32 {
	s := getClientIP(r)
	return ip2Long(s)
}