package manet

import (
	"fmt"
	"net"
	"strings"

	ma "github.com/multiformats/go-multiaddr"
)

var errIncorrectNetAddr = fmt.Errorf("incorrect network addr conversion")

// FromNetAddr converts a net.Addr type to a Multiaddr.
func FromNetAddr(a net.Addr) (ma.Multiaddr, error) {
	return defaultCodecs.FromNetAddr(a)
}

// FromNetAddr converts a net.Addr to Multiaddress.
func (cm *CodecMap) FromNetAddr(a net.Addr) (ma.Multiaddr, error) {
	if a == nil {
		return nil, fmt.Errorf("nil multiaddr")
	}
	p, err := cm.getAddrParser(a.Network())
	if err != nil {
		return nil, err
	}

	return p(a)
}

// ToNetAddr converts a Multiaddr to a net.Addr
// Must be ThinWaist. acceptable protocol stacks are:
// /ip{4,6}/{tcp, udp}
func ToNetAddr(maddr ma.Multiaddr) (net.Addr, error) {
	return defaultCodecs.ToNetAddr(maddr)
}

// ToNetAddr converts a Multiaddress to a standard net.Addr.
func (cm *CodecMap) ToNetAddr(maddr ma.Multiaddr) (net.Addr, error) {
	protos := maddr.Protocols()
	final := protos[len(protos)-1]

	p, err := cm.getMaddrParser(final.Name)
	if err != nil {
		return nil, err
	}

	return p(maddr)
}

func parseBasicNetMaddr(maddr ma.Multiaddr) (net.Addr, error) {
	network, host, err := DialArgs(maddr)
	if err != nil {
		return nil, err
	}

	switch network {
	case "tcp", "tcp4", "tcp6":
		return net.ResolveTCPAddr(network, host)
	case "udp", "udp4", "udp6":
		return net.ResolveUDPAddr(network, host)
	case "ip", "ip4", "ip6":
		return net.ResolveIPAddr(network, host)
	}

	return nil, fmt.Errorf("network not supported: %s", network)
}

// FromIP converts a net.IP type to a Multiaddr.
func FromIP(ip net.IP) (ma.Multiaddr, error) {
	switch {
	case ip.To4() != nil:
		return ma.NewMultiaddr("/ip4/" + ip.String())
	case ip.To16() != nil:
		return ma.NewMultiaddr("/ip6/" + ip.String())
	default:
		return nil, errIncorrectNetAddr
	}
}

// DialArgs is a convenience function returning arguments for use in net.Dial
func DialArgs(m ma.Multiaddr) (string, string, error) {
	// TODO: find a 'good' way to eliminate the function.
	// My preference is with a multiaddr.Format(...) function
	if !IsThinWaist(m) {
		return "", "", fmt.Errorf("%s is not a 'thin waist' address", m)
	}

	str := m.String()
	parts := strings.Split(str, "/")[1:]

	if len(parts) == 2 { // only IP
		return parts[0], parts[1], nil
	}

	network := parts[2]

	var host string
	switch parts[0] {
	case "ip4":
		network = network + "4"
		host = strings.Join([]string{parts[1], parts[3]}, ":")
	case "ip6":
		network = network + "6"
		host = fmt.Sprintf("[%s]:%s", parts[1], parts[3])
	}
	return network, host, nil
}

func parseTCPNetAddr(a net.Addr) (ma.Multiaddr, error) {
	ac, ok := a.(*net.TCPAddr)
	if !ok {
		return nil, errIncorrectNetAddr
	}

	// Get IP Addr
	ipm, err := FromIP(ac.IP)
	if err != nil {
		return nil, errIncorrectNetAddr
	}

	// Get TCP Addr
	tcpm, err := ma.NewMultiaddr(fmt.Sprintf("/tcp/%d", ac.Port))
	if err != nil {
		return nil, errIncorrectNetAddr
	}

	// Encapsulate
	return ipm.Encapsulate(tcpm), nil
}

func parseUDPNetAddr(a net.Addr) (ma.Multiaddr, error) {
	ac, ok := a.(*net.UDPAddr)
	if !ok {
		return nil, errIncorrectNetAddr
	}

	// Get IP Addr
	ipm, err := FromIP(ac.IP)
	if err != nil {
		return nil, errIncorrectNetAddr
	}

	// Get UDP Addr
	udpm, err := ma.NewMultiaddr(fmt.Sprintf("/udp/%d", ac.Port))
	if err != nil {
		return nil, errIncorrectNetAddr
	}

	// Encapsulate
	return ipm.Encapsulate(udpm), nil
}

func parseIPNetAddr(a net.Addr) (ma.Multiaddr, error) {
	ac, ok := a.(*net.IPAddr)
	if !ok {
		return nil, errIncorrectNetAddr
	}
	return FromIP(ac.IP)
}

func parseIPPlusNetAddr(a net.Addr) (ma.Multiaddr, error) {
	ac, ok := a.(*net.IPNet)
	if !ok {
		return nil, errIncorrectNetAddr
	}
	return FromIP(ac.IP)
}