// Copyright (C) 2020 Finogeeks Co., Ltd
//
// This program is free software: you can redistribute it and/or  modify
// it under the terms of the GNU Affero General Public License, version 3,
// as published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package external

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

func GetRemoteIP(r *http.Request) string {
	xRealIP := r.Header.Get("X-Real-Ip")
	xForwardedFor := r.Header.Get("X-Forwarded-For")

	// If both empty, return IP from remote address
	if xRealIP == "" && xForwardedFor == "" {
		var remoteIP string

		// If there are colon in remote address, remove the port number
		// otherwise, return remote address as is
		if strings.ContainsRune(r.RemoteAddr, ':') {
			remoteIP, _, _ = net.SplitHostPort(r.RemoteAddr)
		} else {
			remoteIP = r.RemoteAddr
		}

		return remoteIP
	}

	for _, address := range strings.Split(xForwardedFor, ",") {
		return strings.TrimSpace(address)
	}

	// If nothing succeed, return X-Real-IP
	return xRealIP
}