package netLayer

import (
	"math/rand"
	"net"
	"net/url"
	"strconv"
	"strings"
	"unsafe"
)

// Atyp, for vless and vmess; 注意与 trojan和socks5的区别，trojan和socks5的相同含义的值是1，3，4
const (
	AtypIP4    byte = 1
	AtypDomain byte = 2
	AtypIP6    byte = 3
)

// Addr represents a address that you want to access by proxy. Either Name or IP is used exclusively.
// Addr完整地表示了一个 传输层的目标，同时用 Network 字段 来记录网络层协议名
// Addr 还可以用Dial 方法直接进行拨号
type Addr struct {
	Name string // domain name, 或者 unix domain socket 的 文件路径
	IP   net.IP
	Port int
	//IsUDP bool

	Network string
}

func RandPortStr() string {
	return strconv.Itoa(rand.Intn(60000) + 4096)
}

func GetRandLocalAddr() string {
	return "0.0.0.0:" + RandPortStr()
}

func NewAddrFromUDPAddr(addr *net.UDPAddr) *Addr {
	return &Addr{
		IP:      addr.IP,
		Port:    addr.Port,
		Network: "udp",
	}
}

//addrStr格式一般为 host:port 的格式；如果不含冒号，将直接认为该字符串是域名或文件名
func NewAddr(addrStr string) (*Addr, error) {
	if !strings.Contains(addrStr, ":") {
		//unix domain socket, 或者域名默认端口的情况
		return &Addr{Name: addrStr}, nil
	}

	host, portStr, err := net.SplitHostPort(addrStr)
	if err != nil {
		return nil, err
	}
	if host == "" {
		host = "127.0.0.1"
	}
	port, err := strconv.Atoi(portStr)

	a := &Addr{Port: port}
	if ip := net.ParseIP(host); ip != nil {
		a.IP = ip
	} else {
		a.Name = host
	}
	return a, nil
}

// 如 tcp://127.0.0.1:443
func NewAddrByURL(addrStr string) (*Addr, error) {

	u, err := url.Parse(addrStr)
	if err != nil {
		return nil, err
	}

	addrStr = u.Host

	host, portStr, err := net.SplitHostPort(addrStr)
	if err != nil {
		return nil, err
	}
	if host == "" {
		host = "127.0.0.1"
	}
	port, err := strconv.Atoi(portStr)

	a := &Addr{Port: port}
	if ip := net.ParseIP(host); ip != nil {
		a.IP = ip
	} else {
		a.Name = host
	}

	a.Network = u.Scheme

	return a, nil
}

// Return host:port string
func (a *Addr) String() string {
	if a.Network == "unix" {
		return a.Name
	} else {
		port := strconv.Itoa(a.Port)
		if a.IP == nil {
			return net.JoinHostPort(a.Name, port)
		}
		return net.JoinHostPort(a.IP.String(), port)
	}

}

func (a *Addr) UrlString() string {
	str := a.String()

	return a.Network + "://" + str
}

func (a *Addr) ToUDPAddr() *net.UDPAddr {
	if a.Network != "udp" {
		return nil
	}
	ua, err := net.ResolveUDPAddr("udp", a.String())
	if err != nil {
		return nil
	}
	return ua
}

// Returned host string
func (a *Addr) HostStr() string {
	if a.IP == nil {
		return a.Name
	}
	return a.IP.String()
}

func (addr *Addr) Dial() (net.Conn, error) {
	//log.Println("Dial called", addr, addr.Network)

	switch addr.Network {
	case "":
		return net.Dial("tcp", addr.String())

	case "udp":
		return DialUDP(addr.ToUDPAddr())
	default:
		return net.Dial(addr.Network, addr.String())

	}

}

// Returned address bytes and type
func (a *Addr) AddressBytes() ([]byte, byte) {
	var addr []byte
	var atyp byte

	if a.IP != nil {
		if ip4 := a.IP.To4(); ip4 != nil {
			addr = make([]byte, net.IPv4len)
			atyp = AtypIP4
			copy(addr[:], ip4)
		} else {
			addr = make([]byte, net.IPv6len)
			atyp = AtypIP6
			copy(addr[:], a.IP)
		}
	} else {
		if len(a.Name) > 255 {
			return nil, 0
		}
		addr = make([]byte, 1+len(a.Name))
		atyp = AtypDomain
		addr[0] = byte(len(a.Name))
		copy(addr[1:], a.Name)
	}

	return addr, atyp
}

// ParseAddr parses the address in string s
func ParseStrToAddr(s string) (atyp byte, addr []byte, port_uint16 uint16, err error) {

	var host string
	var portStr string

	host, portStr, err = net.SplitHostPort(s)
	if err != nil {
		return
	}

	if ip := net.ParseIP(host); ip != nil {
		if ip4 := ip.To4(); ip4 != nil {
			addr = make([]byte, net.IPv4len)
			atyp = AtypIP4
			copy(addr[:], ip4)
		} else {
			addr = make([]byte, net.IPv6len)
			atyp = AtypIP6
			copy(addr[:], ip)
		}
	} else {
		if len(host) > 255 {
			return
		}
		addr = make([]byte, 1+len(host))
		atyp = AtypDomain
		addr[0] = byte(len(host))
		copy(addr[1:], host)
	}

	var portUint64 uint64
	portUint64, err = strconv.ParseUint(portStr, 10, 16)
	if err != nil {
		return
	}

	port_uint16 = uint16(portUint64)

	return
}

func UDPAddr2Byte(addr *net.UDPAddr) [6]byte {
	ip := addr.IP.To4()

	port := uint16(addr.Port)

	var allByte [6]byte
	abs := allByte[:]
	copy(abs, ip)
	copy(abs[4:], (*(*[2]byte)(unsafe.Pointer(&port)))[:])

	return allByte
}