package comms

import (
	"fmt"
	"github.com/hashicorp/yamux"
	"io"
	"log"
	"net"
)

type CommChannel struct {
	Peer    net.Conn
	Session *yamux.Session
}

type Role int

const (
	Agent Role = iota
	ConvergeServer
)

func NewCommChannel(role Role, wsConn io.ReadWriteCloser) (CommChannel, error) {
	var commChannel CommChannel
	switch role {
	case Agent:
		listener, err := yamux.Server(wsConn, nil)
		if err != nil {
			return CommChannel{}, err
		}
		commChannel = CommChannel{
			Peer:    nil,
			Session: listener,
		}
	case ConvergeServer:
		clientSession, err := yamux.Client(wsConn, nil)
		if err != nil {
			return CommChannel{}, err
		}
		commChannel = CommChannel{
			Peer:    nil,
			Session: clientSession,
		}
	default:
		panic(fmt.Errorf("Undefined role %d", role))
	}

	// communication from Agent to ConvergeServer

	switch role {
	case Agent:
		conn, err := commChannel.Session.OpenStream()
		commChannel.Peer = conn
		if err != nil {
			return CommChannel{}, err
		}
	case ConvergeServer:
		conn, err := commChannel.Session.Accept()
		commChannel.Peer = conn
		if err != nil {
			return CommChannel{}, err
		}
	default:
		panic(fmt.Errorf("Undefined role %d", role))
	}

	log.Println("Communication channel between agent and converge server established")
	return commChannel, nil
}