package nets

import (
	"errors"
	"net"
)

// GetHostIpv4 获取本地内网IP
func GetHostIpv4() (string, error) {
	privates, err := getAllIPV4(func(ip net.IP) bool {
		return ip.IsPrivate()
	})
	if err != nil {
		return "", err
	}
	if len(privates) == 0 {
		return "", errors.New("no private ip")
	}
	return privates[0], nil
}

func getAllIPV4(filter func(net.IP) bool) (ips []string, err error) {
	// 获取所有网卡
	addrs, err := net.InterfaceAddrs()
	if err != nil {
		return
	}

	for _, addr := range addrs {
		// 这个网络地址是IP地址: ipv4, ipv6
		ipNet, isIpNet := addr.(*net.IPNet)
		if isIpNet && !ipNet.IP.IsLoopback() {
			// 跳过IPV6
			if ipNet.IP.To4() != nil {
				if filter(ipNet.IP) {
					ips = append(ips, ipNet.IP.String())
				}
			}
		}
	}
	return
}