// Package ip provides IP address helpers.
package ip

import (
	"net"
	"strconv"

	"github.com/gogf/gf/v2/errors/gerror"
	"github.com/gogf/gf/v2/net/gipv4"
)

// IsValid reports whether s is a valid IPv4 address.
func IsValid(s string) bool {
	return gipv4.Validate(s)
}

// LocalIP returns the first non-loopback IPv4 address of this host.
func LocalIP() (string, error) {
	addrs, err := net.InterfaceAddrs()
	if err != nil {
		return "", gerror.Wrap(err, `net.InterfaceAddrs failed`)
	}
	for _, addr := range addrs {
		if ipNet, ok := addr.(*net.IPNet); ok {
			if ipv4 := ipNet.IP.To4(); ipv4 != nil && !ipv4.IsLoopback() {
				return ipv4.String(), nil
			}
		}
	}
	return "", nil
}

// IsInternal reports whether s is a private/internal IPv4 address
// (private ranges, loopback or link-local).
func IsInternal(s string) bool {
	parsed := net.ParseIP(s)
	if parsed == nil || parsed.To4() == nil {
		return false
	}
	return parsed.IsPrivate() || parsed.IsLoopback() || parsed.IsLinkLocalUnicast()
}

// ToLong converts an IPv4 string to its uint32 representation
// (big-endian, same as inet_aton).
func ToLong(s string) (uint32, error) {
	ipv4 := net.ParseIP(s).To4()
	if ipv4 == nil {
		return 0, gerror.Newf(`invalid IPv4 address: %s`, s)
	}
	return uint32(ipv4[0])<<24 | uint32(ipv4[1])<<16 | uint32(ipv4[2])<<8 | uint32(ipv4[3]), nil
}

// ToString converts a uint32 IPv4 value to its dotted-decimal string.
func ToString(v uint32) string {
	return strconv.Itoa(int(v>>24)) + "." +
		strconv.Itoa(int(v>>16&0xFF)) + "." +
		strconv.Itoa(int(v>>8&0xFF)) + "." +
		strconv.Itoa(int(v&0xFF))
}