package hopp

import "net"
import "context"
import "crypto/tls"
import "github.com/quic-go/quic-go"

// Listener is an object which listens for incoming HOPP connections.
type Listener interface {
	// Accept waits for and returns the next connection to the listener.
	Accept() (Conn, error)
	// Close closes the listener. Any blocked Accept operations will be
	// unblocked and return errors.
	Close() error
	// Addr returns the listener's network address.
	Addr() net.Addr
}

// Listen listens for incoming HOPP connections. The network must be one of
// "quic", "quic4", (IPv4-only) "quic6" (IPv6-only), or "unix".
func Listen(network, address string) (Listener, error) {
	switch network {
	case "quic", "quic4", "quic6": return ListenQUIC(network, address, nil)
	case "unix":                   return ListenUnix(network, address)
	default:                       return nil, ErrUnknownNetwork
	}
}

// ListenQUIC listens for incoming HOPP connections using QUIC as a transport.
// The network must be one of "quic", "quic4", (IPv4-only) or "quic6"
// (IPv6-only).
func ListenQUIC(network, address string, tlsConf *tls.Config) (Listener, error) {
	tlsConf   = tlsConfig(tlsConf)
	quicConf := quicConfig()
	udpNetwork, err := quicNetworkToUDPNetwork(network)
	if err != nil { return nil, err }
	addr, err := net.ResolveUDPAddr(udpNetwork, address)
	if err != nil { return nil, err }
	udpListener, err := net.ListenUDP(udpNetwork, addr)
	if err != nil { return nil, err }
	quicListener, err := quic.Listen(udpListener, tlsConf, quicConf)
	if err != nil { return nil, err }
	return &listenerQUIC {
		underlying: quicListener,
	}, nil
}

// ListenUnix listens for incoming HOPP connections using a Unix domain socket
// as a transport. The network must be "unix".
func ListenUnix(network, address string) (Listener, error) {
	if network != "unix" { return nil, ErrUnknownNetwork }
	addr, err := net.ResolveUnixAddr(network, address)
	if err != nil { return nil, err }
	unixListener, err := net.ListenUnix(network, addr)
	if err != nil { return nil, err }
	return &listenerUnix {
		underlying: unixListener,
	}, nil
}

type listenerQUIC struct {
	underlying *quic.Listener
}

func (this *listenerQUIC) Accept() (Conn, error) {
	conn, err := this.underlying.Accept(context.Background())
	if err != nil { return nil, err }
	return AdaptB(quicMultiConn { underlying: conn }), nil
}

func (this *listenerQUIC) Close() error {
	return this.underlying.Close()
}

func (this *listenerQUIC) Addr() net.Addr {
	return this.underlying.Addr()
}

type listenerUnix struct {
	underlying *net.UnixListener
}

func (this *listenerUnix) Accept() (Conn, error) {
	conn, err := this.underlying.Accept()
	if err != nil { return nil, err }
	return AdaptA(conn, ServerSide), nil
}

func (this *listenerUnix) Close() error {
	return this.underlying.Close()
}

func (this *listenerUnix) Addr() net.Addr {
	return this.underlying.Addr()
}