package tool

import (
	"encoding/binary"
	"errors"
	"fmt"
	"net"
)

var (
	privateIPv4Blocks []*net.IPNet
	privateIPv6Blocks []*net.IPNet
)

func init() {
	// IPv4私有地址段
	for _, cidr := range []string{
		"10.0.0.0/8",     // A类私有地址
		"172.16.0.0/12",  // B类私有地址
		"192.168.0.0/16", // C类私有地址
		"169.254.0.0/16", // 链路本地地址
		"127.0.0.0/8",    // 环回地址
	} {
		_, block, _ := net.ParseCIDR(cidr)
		privateIPv4Blocks = append(privateIPv4Blocks, block)
	}

	// IPv6私有地址段
	for _, cidr := range []string{
		"fc00::/7",  // 唯一本地地址
		"fe80::/10", // 链路本地地址
		"::1/128",   // 环回地址
	} {
		_, block, _ := net.ParseCIDR(cidr)
		privateIPv6Blocks = append(privateIPv6Blocks, block)
	}
}

func IsPrivateIP(ipStr string) bool {
	ip := net.ParseIP(ipStr)
	if ip == nil {
		return false
	}

	// 处理IPv4和IPv4映射的IPv6地址
	if ip4 := ip.To4(); ip4 != nil {
		for _, block := range privateIPv4Blocks {
			if block.Contains(ip4) {
				return true
			}
		}
		return false
	}

	// 处理IPv6地址
	for _, block := range privateIPv6Blocks {
		if block.Contains(ip) {
			return true
		}
	}
	return false
}

func IP2Int(ip net.IP) uint32 {
	if ip == nil {
		return 0
	}

	ip = ip.To4()
	if ip == nil {
		return 0
	}

	return binary.BigEndian.Uint32(ip)
}

func Int2IP(ip uint32) net.IP {
	data := make(net.IP, 4)
	binary.BigEndian.PutUint32(data, ip)
	return data
}

func IPStr2Int(ipStr string) *uint32 {
	ip := IP2Int(net.ParseIP(ipStr))
	if ip == 0 {
		return nil
	}
	return &ip
}

func Int2IPStr(ip uint32) string {
	return Int2IP(ip).String()
}

func GetLastIP4(cidr string) (lastIP4 uint32, err error) {
	ip, ipNet, err := net.ParseCIDR(cidr)
	if err != nil {
		return
	}

	firstIP4 := IP2Int(ip.Mask(ipNet.Mask))
	ipNetMaskInt := binary.BigEndian.Uint32(ipNet.Mask)
	lastIP4 = firstIP4 | ^ipNetMaskInt
	return
}

func IsCIDRConflict(cidr1, cidr2 string) (conflict bool, err error) {
	_, ipNet1, err := net.ParseCIDR(cidr1)
	if err != nil {
		return
	}
	_, ipNet2, err := net.ParseCIDR(cidr2)
	if err != nil {
		return
	}

	if ipNet2.Contains(ipNet1.IP) || ipNet1.Contains(ipNet2.IP) {
		conflict = true
	}

	return
}

func GetCIDRs(startCIDR, endCIDR string, mask uint8) (cidrs []string, err error) {
	cidrs = append(cidrs, startCIDR)

	currentCIDR := startCIDR
	for {
		lastIP4, err := GetLastIP4(currentCIDR)
		if err != nil {
			return cidrs, err
		}

		nextCIDR := Int2IPStr(lastIP4+1) + fmt.Sprintf("/%d", mask)
		cidrs = append(cidrs, nextCIDR)

		conflict, err := IsCIDRConflict(nextCIDR, endCIDR)
		if err != nil {
			return cidrs, err
		}
		if conflict {
			break
		}

		currentCIDR = nextCIDR
	}

	return
}

func GetLocalIP() (ip string, err error) {
	ifaces, err := net.Interfaces()
	if err != nil {
		return
	}

	for _, iface := range ifaces {
		if iface.Name != "eth0" {
			continue
		}

		addrs, err := iface.Addrs()
		if err != nil {
			continue
		}

		for _, addr := range addrs {
			switch v := addr.(type) {
			case *net.IPNet:
				ip = v.IP.String()
				if ip == "192.168.88.88" {
					continue
				}
				return ip, err
			case *net.IPAddr:
				ip = v.IP.String()
				if ip == "192.168.88.88" {
					continue
				}
				return ip, err
			}
		}
	}

	ip = "127.0.0.1"

	return
}

func LookupIP(host string) (ip string, err error) {
	ips, err := net.LookupIP(host)
	if err != nil {
		return
	}

	for _, i := range ips {
		if ipv4 := i.To4(); ipv4 != nil {
			ip = ipv4.String()
			break
		}
	}

	return
}
func LookupIPv4(host string) (uint32, error) {
	ips, err := net.LookupIP(host)
	if err != nil {
		return 0, err
	}

	for _, i := range ips {
		if ipv4 := i.To4(); ipv4 != nil {
			return binary.BigEndian.Uint32(ipv4), nil
		}
	}

	return 0, errors.New("host not found " + host)
}

func ResolveIPv4(host string) (uint32, error) {
	addr, err := net.ResolveIPAddr("ip4", host)
	if err == nil && addr != nil {
		addrV4 := binary.BigEndian.Uint32(addr.IP.To4())

		return addrV4, err
	}

	return 0, err
}