// Copyright 2017 gf Author(https://github.com/gogf/gf). All Rights Reserved.
//
// This Source Code Form is subject to the terms of the MIT License.
// If a copy of the MIT was not distributed with this file,
// You can obtain one at https://github.com/gogf/gf.
//

package gipv4

import (
	"errors"
	"net"
	"strconv"
	"strings"
)

// GetIpArray retrieves and returns all the ip of current host.
func GetIpArray() (ips []string, err error) {
	interfaceAddr, err := net.InterfaceAddrs()
	if err != nil {
		return nil, err
	}
	for _, address := range interfaceAddr {
		ipNet, isValidIpNet := address.(*net.IPNet)
		if isValidIpNet && !ipNet.IP.IsLoopback() {
			if ipNet.IP.To4() != nil {
				ips = append(ips, ipNet.IP.String())
			}
		}
	}
	return ips, nil
}

// GetIntranetIp retrieves and returns the first intranet ip of current machine.
func GetIntranetIp() (ip string, err error) {
	ips, err := GetIntranetIpArray()
	if err != nil {
		return "", err
	}
	if len(ips) == 0 {
		return "", errors.New("no intranet ip found")
	}
	return ips[0], nil
}

// GetIntranetIpArray retrieves and returns the intranet ip list of current machine.
func GetIntranetIpArray() (ips []string, err error) {
	interFaces, e := net.Interfaces()
	if e != nil {
		return ips, e
	}
	for _, interFace := range interFaces {
		if interFace.Flags&net.FlagUp == 0 {
			// interface down
			continue
		}
		if interFace.Flags&net.FlagLoopback != 0 {
			// loopback interface
			continue
		}
		// ignore warden bridge
		if strings.HasPrefix(interFace.Name, "w-") {
			continue
		}
		addresses, e := interFace.Addrs()
		if e != nil {
			return ips, e
		}
		for _, addr := range addresses {
			var ip net.IP
			switch v := addr.(type) {
			case *net.IPNet:
				ip = v.IP
			case *net.IPAddr:
				ip = v.IP
			}

			if ip == nil || ip.IsLoopback() {
				continue
			}
			ip = ip.To4()
			if ip == nil {
				// not an ipv4 address
				continue
			}
			ipStr := ip.String()
			if IsIntranet(ipStr) {
				ips = append(ips, ipStr)
			}
		}
	}
	return ips, nil
}

// IsIntranet checks and returns whether given ip an intranet ip.
//
// Local: 127.0.0.1
// A: 10.0.0.0--10.255.255.255
// B: 172.16.0.0--172.31.255.255
// C: 192.168.0.0--192.168.255.255
func IsIntranet(ip string) bool {
	if ip == "127.0.0.1" {
		return true
	}
	array := strings.Split(ip, ".")
	if len(array) != 4 {
		return false
	}
	// A
	if array[0] == "10" || (array[0] == "192" && array[1] == "168") {
		return true
	}
	// C
	if array[0] == "192" && array[1] == "168" {
		return true
	}
	// B
	if array[0] == "172" {
		second, err := strconv.ParseInt(array[1], 10, 64)
		if err != nil {
			return false
		}
		if second >= 16 && second <= 31 {
			return true
		}
	}
	return false
}