package util

import (
	"errors"
	"net"
)

func IsIPAddr(ip string) bool {
	i := net.ParseIP(ip)
	return i != nil
}

func IsLocalIPAddr(ip string) bool {
	i := net.ParseIP(ip)
	if i == nil {
		return false
	}
	return IsLocalIP(i)
}

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
}

var ErrorInvalidIPV4Format = errors.New("invalid ipv4 format")

func IPAddrToUint32(ip string) (uint32, error) {
	i := net.ParseIP(ip)
	if i == nil {
		return 0, ErrorInvalidIPV4Format
	}

	b := i.To4()
	if b == nil {
		return 0, ErrorInvalidIPV4Format
	}

	return uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24, nil
}

func Uint32ToIPAddr(i uint32) string {
	ip := make(net.IP, net.IPv4len)
	ip[0] = byte(i >> 24)
	ip[1] = byte(i >> 16)
	ip[2] = byte(i >> 8)
	ip[3] = byte(i)

	return ip.String()
}

func IPToUint32(ip net.IP) (uint32, error) {
	b := ip.To4()
	if b == nil {
		return 0, ErrorInvalidIPV4Format
	}

	return uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24, nil
}

func Uint32ToIP(i uint32) net.IP {
	ip := make(net.IP, net.IPv4len)
	ip[0] = byte(i >> 24)
	ip[1] = byte(i >> 16)
	ip[2] = byte(i >> 8)
	ip[3] = byte(i)

	return ip
}

func GetLocalIp() (string, error) {
	addrs, err := net.InterfaceAddrs()

	if err != nil {
		return "", err
	}

	for _, address := range addrs {
		// 检查ip地址判断是否回环地址
		if ipNet, ok := address.(*net.IPNet); ok && !ipNet.IP.IsLoopback() {
			if ipNet.IP.To4() != nil {
				return ipNet.IP.String(), nil
			}
		}
	}

	return "", errors.New("get local ip failed")
}