package tunnel

import (
	"errors"
	"io"
	"time"

	"github.com/micro/go-micro/transport"
	"github.com/micro/go-micro/util/log"
)

// session is our pseudo session for transport.Socket
type session struct {
	// the tunnel id
	tunnel string
	// the channel name
	channel string
	// the session id based on Micro.Tunnel-Session
	session string
	// closed
	closed chan bool
	// remote addr
	remote string
	// local addr
	local string
	// send chan
	send chan *message
	// recv chan
	recv chan *message
	// wait until we have a connection
	wait chan bool
	// if the discovery worked
	discovered bool
	// if the session was accepted
	accepted bool
	// outbound marks the session as outbound dialled connection
	outbound bool
	// lookback marks the session as a loopback on the inbound
	loopback bool
	// if the session is multicast
	multicast bool
	// if the session is broadcast
	broadcast bool
	// the timeout
	timeout time.Duration
	// the link on which this message was received
	link string
	// the error response
	errChan chan error
}

// message is sent over the send channel
type message struct {
	// type of message
	typ string
	// tunnel id
	tunnel string
	// channel name
	channel string
	// the session id
	session string
	// outbound marks the message as outbound
	outbound bool
	// loopback marks the message intended for loopback
	loopback bool
	// whether to send as multicast
	multicast bool
	// broadcast sets the broadcast type
	broadcast bool
	// the link to send the message on
	link string
	// transport data
	data *transport.Message
	// the error channel
	errChan chan error
}

func (s *session) Remote() string {
	return s.remote
}

func (s *session) Local() string {
	return s.local
}

func (s *session) Id() string {
	return s.session
}

func (s *session) Channel() string {
	return s.channel
}

// Open will fire the open message for the session. This is called by the dialler.
func (s *session) Open() error {
	msg := &message{
		typ:       "open",
		tunnel:    s.tunnel,
		channel:   s.channel,
		session:   s.session,
		outbound:  s.outbound,
		loopback:  s.loopback,
		multicast: s.multicast,
		link:      s.link,
		errChan:   s.errChan,
	}

	// send open message
	s.send <- msg

	// wait for an error response for send
	select {
	case err := <-msg.errChan:
		if err != nil {
			return err
		}
	case <-s.closed:
		return io.EOF
	}

	// we don't wait on multicast
	if s.multicast {
		s.accepted = true
		return nil
	}

	// now wait for the accept
	select {
	case msg = <-s.recv:
		if msg.typ != "accept" {
			log.Debugf("Received non accept message in Open %s", msg.typ)
			return errors.New("failed to connect")
		}
		// set to accepted
		s.accepted = true
		// set link
		s.link = msg.link
	case <-time.After(s.timeout):
		return ErrDialTimeout
	case <-s.closed:
		return io.EOF
	}

	return nil
}

// Accept sends the accept response to an open message from a dialled connection
func (s *session) Accept() error {
	msg := &message{
		typ:       "accept",
		tunnel:    s.tunnel,
		channel:   s.channel,
		session:   s.session,
		outbound:  s.outbound,
		loopback:  s.loopback,
		multicast: s.multicast,
		link:      s.link,
		errChan:   s.errChan,
	}

	// send the accept message
	select {
	case <-s.closed:
		return io.EOF
	case s.send <- msg:
		return nil
	}

	// wait for send response
	select {
	case err := <-s.errChan:
		if err != nil {
			return err
		}
	case <-s.closed:
		return io.EOF
	}

	return nil
}

// Announce sends an announcement to notify that this session exists. This is primarily used by the listener.
func (s *session) Announce() error {
	msg := &message{
		typ:       "announce",
		tunnel:    s.tunnel,
		channel:   s.channel,
		session:   s.session,
		outbound:  s.outbound,
		loopback:  s.loopback,
		multicast: s.multicast,
	}

	select {
	case s.send <- msg:
		return nil
	case <-s.closed:
		return io.EOF
	}
}

// Send is used to send a message
func (s *session) Send(m *transport.Message) error {
	select {
	case <-s.closed:
		return io.EOF
	default:
		// no op
	}

	// make copy
	data := &transport.Message{
		Header: make(map[string]string),
		Body:   m.Body,
	}

	for k, v := range m.Header {
		data.Header[k] = v
	}

	// append to backlog
	msg := &message{
		typ:       "session",
		tunnel:    s.tunnel,
		channel:   s.channel,
		session:   s.session,
		outbound:  s.outbound,
		loopback:  s.loopback,
		multicast: s.multicast,
		data:      data,
		// specify the link on which to send this
		// it will be blank for dialled sessions
		link: s.link,
		// error chan
		errChan: s.errChan,
	}

	// if not multicast then set link
	if !s.multicast {
		msg.link = s.link
	}

	log.Debugf("Appending %+v to send backlog", msg)
	// send the actual message
	s.send <- msg

	// wait for an error response
	select {
	case err := <-msg.errChan:
		return err
	case <-s.closed:
		return io.EOF
	}

	return nil
}

// Recv is used to receive a message
func (s *session) Recv(m *transport.Message) error {
	select {
	case <-s.closed:
		return errors.New("session is closed")
	default:
		// no op
	}
	// recv from backlog
	msg := <-s.recv

	// check the error if one exists
	select {
	case err := <-msg.errChan:
		return err
	default:
	}

	log.Debugf("Received %+v from recv backlog", msg)
	// set message
	*m = *msg.data
	// return nil
	return nil
}

// Close closes the session by sending a close message
func (s *session) Close() error {
	select {
	case <-s.closed:
		// no op
	default:
		close(s.closed)

		// append to backlog
		msg := &message{
			typ:       "close",
			tunnel:    s.tunnel,
			channel:   s.channel,
			session:   s.session,
			outbound:  s.outbound,
			loopback:  s.loopback,
			multicast: s.multicast,
			link:      s.link,
		}

		// send the close message
		select {
		case s.send <- msg:
		default:
		}
	}

	return nil
}