package tunnel

import (
	"errors"
	"io"
)

type Manager struct {
	Tunnel        io.ReadWriter
	Connections   map[ID]*Connection
	incoming      chan *DataFrame
	outgoing      chan *DataFrame
	accept        chan *DataFrame
	closed        chan bool
	newConnection chan *Connection
	delConnection chan *Connection
}

func NewManager(tun io.ReadWriter) *Manager {
	return &Manager{
		Tunnel:        tun,
		Connections:   make(map[ID]*Connection),
		incoming:      make(chan *DataFrame, 1024),
		outgoing:      make(chan *DataFrame, 1024),
		accept:        make(chan *DataFrame, 1024),
		newConnection: make(chan *Connection),
		delConnection: make(chan *Connection),
	}
}

func (m *Manager) Run() {
	for {
		select {
		case <-m.closed:
			return
		case df := <-m.incoming:
			go df.Encode(m.Tunnel)
		case connection := <-m.newConnection:
			m.Connections[connection.ID] = connection
		case connection := <-m.delConnection:
			connection.Close()
			delete(m.Connections, connection.ID)
		default:
			go m.onReceive()
		}
	}
}

func (m *Manager) onReceive() {
	df := new(DataFrame)
	df.Decode(m.Tunnel)
	switch df.Type {
	case TypeRequest:
		m.accept <- df
	case TypeClosed:
		connection, ok := m.Connections[df.ID]
		if ok {
			m.delConnection <- connection
		}
	case TypeNormal:
		connection, ok := m.Connections[df.ID]
		if ok {
			connection.RX = m.outgoing
			m.outgoing <- df
		}
	}
}

func (m *Manager) Connect() (*Connection, error) {
	df := &DataFrame{
		ID:   NewID(),
		Type: TypeRequest,
	}
	connection := &Connection{
		ID: df.ID,
		TX: m.incoming,
	}
	m.newConnection <- connection
	m.incoming <- df

	df = <-connection.RX
	if df.Type != TypeConnected {

		return nil, errors.New("failed to connect")
	}
	return connection, nil
}

func (m *Manager) Accept() (*Connection, error) {
	df := <-m.accept
	if df.Type != TypeRequest {
		return nil, errors.New("failed to accept")
	}
	connection := &Connection{
		ID: df.ID,
		TX: m.incoming,
	}
	m.newConnection <- connection

	df.Type = TypeConnected
	m.incoming <- df

	return connection, nil
}

func (m *Manager) Close() error {
	defer close(m.closed)
	defer close(m.accept)
	defer close(m.incoming)
	defer close(m.outgoing)
	for _, connection := range m.Connections {
		connection.Close()
	}
	m.closed <- true
	return nil
}