pnyx/channel.go

package pnyx

import (
	"slices"
)

type ChannelID uint32

const (
  RootChannelID ChannelID = 0

  MODE_RAW ModeID = iota

  MODE_COMMAND_DATA byte = 0x00
  MODE_COMMAND_JOIN = 0x01
  MODE_COMMAND_LEAVE = 0x02
)

type ModeID uint8
type CommandID uint8

type Channel struct {
  modes map[ModeID]Mode
}

type SendPacket struct {
  Packet *Packet
  Session SessionID
}

type Mode interface {
  // Process takes incoming packets from a session and returns a list of packets to send
  Process(*Session, *Packet) []SendPacket
}

func multiplex(session *Session, packet *Packet, sessions []SessionID) []SendPacket {
  send_packets := make([]SendPacket, len(sessions))
  for i, session_id := range(sessions) {
    if session_id == session.ID {
      continue
    }

    send_packets[i] = SendPacket{
      Packet: packet,
      Session: session_id,
    }
  }

  return send_packets
}

type RawMode struct {
  Sessions []SessionID
}

func(mode *RawMode) Process(session *Session, packet *Packet) []SendPacket {
  switch packet.Command {
  case MODE_COMMAND_JOIN:
    if slices.Contains(mode.Sessions, session.ID) == false {
      mode.Sessions = append(mode.Sessions, session.ID)
    }

  case MODE_COMMAND_LEAVE:
    idx := slices.Index(mode.Sessions, session.ID)
    if idx != -1 {
      mode.Sessions = slices.Delete(mode.Sessions, idx, idx+1)
    }

  case MODE_COMMAND_DATA:
    if slices.Contains(mode.Sessions, session.ID) {
      new_packet := &Packet{
        Channel: packet.Channel,
        Mode: packet.Mode,
        Command: MODE_COMMAND_DATA,
        Data: append(session.Peer[:], packet.Data...),
      }
      return multiplex(session, new_packet, mode.Sessions)
    }
  }
  return nil
}