package ip

import (
	"bufio"
	"io"
	"net"
	"os"
	"strconv"
	"strings"
)

// IP ip struct info.
type IP struct {
	Begin        uint32
	End          uint32
	ISPCode      int
	ISP          string
	CountryCode  int
	Country      string
	ProvinceCode int
	Province     string
	CityCode     int
	City         string
	DistrictCode int
	District     string
	Latitude     float64
	Longitude    float64
}

// Zone ip struct info.
type Zone struct {
	ID          int64   `json:"id"`
	Addr        string  `json:"addr"`
	ISP         string  `json:"isp"`
	Country     string  `json:"country"`
	Province    string  `json:"province"`
	City        string  `json:"city"`
	Latitude    float64 `json:"latitude"`
	Longitude   float64 `json:"longitude"`
	CountryCode int     `json:"country_code,omitempty"`
}

// List struct info list.
type List struct {
	IPs []*IP
}

// New create Xip instance and return.
func New(path string) (list *List, err error) {
	var (
		ip   *IP
		file *os.File
		line []byte
	)
	list = new(List)
	if file, err = os.Open(path); err != nil {
		return
	}
	defer file.Close()
	reader := bufio.NewReader(file)
	for {
		if line, _, err = reader.ReadLine(); err != nil {
			if err == io.EOF {
				err = nil
				break
			}
			continue
		}
		lines := strings.Fields(string(line))
		if len(lines) < 13 {
			continue
		}
		// lines[2]:country  lines[3]:province  lines[4]:city  lines[5]:unit
		if lines[3] == "香港" || lines[3] == "澳门" || lines[3] == "台湾" {
			lines[2] = lines[3]
			lines[3] = lines[4]
			lines[4] = "*"
		}
		// ex.: from 中国 中国 *  to 中国 ”“ ”“
		if lines[2] == lines[3] || lines[3] == "*" {
			lines[3] = ""
			lines[4] = ""
		} else if lines[3] == lines[4] || lines[4] == "*" {
			// ex.: from 中国 北京 北京  to 中国 北京 ”“
			lines[4] = ""
		}
		ip = &IP{
			Begin:    InetAtoN(lines[0]),
			End:      InetAtoN(lines[1]),
			Country:  lines[2],
			Province: lines[3],
			City:     lines[4],
			ISP:      lines[6],
		}
		ip.Latitude, _ = strconv.ParseFloat(lines[7], 64)
		ip.Longitude, _ = strconv.ParseFloat(lines[8], 64)
		ip.CountryCode, _ = strconv.Atoi(lines[12])
		list.IPs = append(list.IPs, ip)
	}
	return
}

// IP ip zone info by ip
func (l *List) IP(ipStr string) (ip *IP) {
	addr := InetAtoN(ipStr)
	i, j := 0, len(l.IPs)
	for i < j {
		h := i + (j-i)/2 // avoid overflow when computing h
		ip = l.IPs[h]
		// i ≤ h < j
		if addr < ip.Begin {
			j = h
		} else if addr > ip.End {
			i = h + 1
		} else {
			break
		}
	}
	return
}

// Zone get ip info from ip
func (l *List) Zone(addr string) (zone *Zone) {
	ip := l.IP(addr)
	if ip == nil {
		return
	}
	return &Zone{
		ID:          ZoneID(ip.Country, ip.Province, ip.City),
		Addr:        addr,
		ISP:         ip.ISP,
		Country:     ip.Country,
		Province:    ip.Province,
		City:        ip.City,
		Latitude:    ip.Latitude,
		Longitude:   ip.Longitude,
		CountryCode: ip.CountryCode,
	}
}

// All return ipInfos.
func (l *List) All() []*IP {
	return l.IPs
}

// ExternalIP get external ip.
func ExternalIP() (res []string) {
	inters, err := net.Interfaces()
	if err != nil {
		return
	}
	for _, inter := range inters {
		if !strings.HasPrefix(inter.Name, "lo") {
			addrs, err := inter.Addrs()
			if err != nil {
				continue
			}
			for _, addr := range addrs {
				if ipnet, ok := addr.(*net.IPNet); ok {
					if ipnet.IP.IsLoopback() || ipnet.IP.IsLinkLocalMulticast() || ipnet.IP.IsLinkLocalUnicast() {
						continue
					}
					if ip4 := ipnet.IP.To4(); ip4 != nil {
						switch true {
						case ip4[0] == 10:
							continue
						case ip4[0] == 172 && ip4[1] >= 16 && ip4[1] <= 31:
							continue
						case ip4[0] == 192 && ip4[1] == 168:
							continue
						default:
							res = append(res, ipnet.IP.String())
						}
					}
				}
			}
		}
	}
	return
}

// InternalIP get internal ip.
func InternalIP() string {
	inters, err := net.Interfaces()
	if err != nil {
		return ""
	}
	for _, inter := range inters {
		if !strings.HasPrefix(inter.Name, "lo") {
			addrs, err := inter.Addrs()
			if err != nil {
				continue
			}
			for _, addr := range addrs {
				if ipnet, ok := addr.(*net.IPNet); ok && !ipnet.IP.IsLoopback() {
					if ipnet.IP.To4() != nil {
						return ipnet.IP.String()
					}
				}
			}
		}
	}
	return ""
}

// InetAtoN conver ip addr to uint32.
func InetAtoN(s string) (sum uint32) {
	ip := net.ParseIP(s)
	if ip == nil {
		return
	}
	ip = ip.To4()
	if ip == nil {
		return
	}
	sum += uint32(ip[0]) << 24
	sum += uint32(ip[1]) << 16
	sum += uint32(ip[2]) << 8
	sum += uint32(ip[3])
	return sum
}

// InetNtoA conver uint32 to ip addr.
func InetNtoA(sum uint32) string {
	ip := make(net.IP, net.IPv4len)
	ip[0] = byte((sum >> 24) & 0xFF)
	ip[1] = byte((sum >> 16) & 0xFF)
	ip[2] = byte((sum >> 8) & 0xFF)
	ip[3] = byte(sum & 0xFF)
	return ip.String()
}