package utils

import (
	"crypto/md5" //nolint
	"encoding/hex"
	"net"
	"net/http"
	"strings"

	log "github.com/sirupsen/logrus"
)

// GenerateClientIDFromRequest generates a client id from the provided request.
func GenerateClientIDFromRequest(req *http.Request) string {
	ipAddress := GetIPAddressFromRequest(req)
	clientID := ipAddress + req.UserAgent()

	// Create a MD5 hash of this ip + useragent
	b := md5.Sum([]byte(clientID)) // nolint
	return hex.EncodeToString(b[:])
}

// GetIPAddressFromRequest returns the IP address from a http request.
func GetIPAddressFromRequest(req *http.Request) string {
	ipAddressString := req.RemoteAddr
	xForwardedFor := req.Header.Get("X-FORWARDED-FOR")
	if xForwardedFor != "" {
		clientIpString := strings.Split(xForwardedFor, ", ")[0]

		// If the IP has a prefix of ::ffff: then it's an IPv4 address.
		// Strip the prefix so we can parse it as an IPv4 address.
		clientIpString = strings.TrimPrefix(clientIpString, "::ffff:")

		if strings.Contains(clientIpString, ":") {
			ip, _, err := net.SplitHostPort(clientIpString)
			if err != nil {
				log.Errorln(err)
				return ""
			}
			return ip
		}
		return clientIpString
	}
	ip, _, err := net.SplitHostPort(ipAddressString)
	if err != nil {
		log.Errorln(err)
		return ""
	}

	return ip
}