package main

import (
	"crypto/ed25519"
	"crypto/rand"
	"crypto/x509"
	"encoding/binary"
	"encoding/pem"
	"flag"
	"fmt"
	"os"
	"os/signal"
	"syscall"
	"time"

	"git.metznet.ca/MetzNet/go-ncurses"
	"git.metznet.ca/MetzNet/pnyx"
	"github.com/gen2brain/malgo"
	"github.com/google/uuid"
	"github.com/hraban/opus"
)

var decoders = map[pnyx.PeerID]chan[]byte{}
var encoder *opus.Encoder
var sample_rate int = 0

func set_sample_rate(audio_data chan []int16, new_sample_rate int) error {
  sample_rate = new_sample_rate

  var err error
  encoder, err = opus.NewEncoder(new_sample_rate, 1, opus.AppVoIP)
  if err != nil {
    return err
  }

  for peer_id, decoder_chan := range(decoders) {
    if decoder_chan != nil {
      decoder_chan <- nil
    }
    new_chan := make(chan[]byte, 1000)
    decoders[peer_id] = new_chan
    go handle_peer_decode(audio_data, peer_id, decoders[peer_id], sample_rate)
  }
  return nil
}

func handle_peer_decode(audio_data chan []int16, peer_id pnyx.PeerID, decode_chan chan[]byte, sample_rate int){
  decoder, err := opus.NewDecoder(sample_rate, 1)
  if err != nil {
    panic(err)
  }

  running := true
  missed := 0
  for running {
    select {
    case <-time.After(20*time.Millisecond):
      missed += 1

      if missed > 100 {
        decode_chan <- <- decode_chan
      }

      pcm := make([]int16, sample_rate/50)
      err := decoder.DecodePLC(pcm)
      if err != nil {
        panic(err)
      }
      audio_data <- pcm

    case data := <-decode_chan:
      missed = 0
      if data == nil {
        running = false
      } else {
        pcm := make([]int16, sample_rate/50*2)
        written, err := decoder.Decode(data, pcm)
        if err != nil {
          panic(err)
        }
        audio_data <- pcm[:written]
      }
    }
  }
}

func mixer(data_chan chan []int16, speaker_chan chan []int16) {
  var samples []int16 = nil
  for true {
    if samples == nil {
      samples = <- data_chan
    } else {
      select {
      case new_samples := <- data_chan:
        for i, sample := range(new_samples) {
          samples[i] += sample
        }
      case speaker_chan <- samples:
        samples = nil
      }
    }
  }
}

func setup_audio(mic chan []byte, speaker chan []int16) (*malgo.AllocatedContext, *malgo.Device, *malgo.Device) {
  ctx, err := malgo.InitContext(nil, malgo.ContextConfig{}, nil)
  if err != nil {
    panic(err)
  }

	infos, err := ctx.Devices(malgo.Playback)
	if err != nil {
    panic(err)
	}

  var playback_device *malgo.DeviceInfo = nil
	for _, info := range infos {
    if info.IsDefault != 0 {
      full, err := ctx.DeviceInfo(malgo.Playback, info.ID, malgo.Shared)
      if err != nil {
        panic(err)
      }
      playback_device = &full
    }
	}

  if playback_device == nil {
    panic("No default playback device")
  }

	infos, err = ctx.Devices(malgo.Capture)
	if err != nil {
    panic(err)
	}

  var capture_device *malgo.DeviceInfo = nil
	for _, info := range infos {
    if info.IsDefault != 0 {
      full, err := ctx.DeviceInfo(malgo.Capture, info.ID, malgo.Shared)
      if err != nil {
        panic(err)
      }
      capture_device = &full
    }
	}

  if capture_device == nil {
    panic("No default capture device")
  }

  inDeviceConfig := malgo.DefaultDeviceConfig(malgo.Capture)
	inDeviceConfig.Capture.Format = malgo.FormatS16
	inDeviceConfig.Capture.Channels = 1
  inDeviceConfig.Capture.DeviceID = capture_device.ID.Pointer()
	inDeviceConfig.SampleRate = 48000
  inDeviceConfig.PeriodSizeInFrames = 960
	inDeviceConfig.Alsa.NoMMap = 1
  inDeviceConfig.Capture.ShareMode = malgo.Shared

  outDeviceConfig := malgo.DefaultDeviceConfig(malgo.Playback)
	outDeviceConfig.Playback.Format = malgo.FormatS16
	outDeviceConfig.Playback.Channels = 1
  outDeviceConfig.Playback.DeviceID = playback_device.ID.Pointer()
	outDeviceConfig.SampleRate = 48000
  outDeviceConfig.PeriodSizeInFrames = 960
	outDeviceConfig.Alsa.NoMMap = 1
  outDeviceConfig.Playback.ShareMode = malgo.Shared

  onSendFrames := func(output_samples []byte, input_samples []byte, framecount uint32) {
    select {
    case pcm := <- speaker:
      for i := 0; i < sample_rate/50; i++ {
        binary.LittleEndian.PutUint16(output_samples[i*2:], uint16(pcm[i]))
      }
    default:
    }
  }

	playbackCallbacks := malgo.DeviceCallbacks{
		Data: onSendFrames,
	}

  outDevice, err := malgo.InitDevice(ctx.Context, outDeviceConfig, playbackCallbacks)
  if err != nil {
    panic(err)
  }

  err = outDevice.Start()
  if err != nil {
    panic(err)
  }

	onRecvFrames := func(output_samples []byte, input_samples []byte, framecount uint32) {
    if encoder != nil {
      pcm := make([]int16, len(input_samples)/2)
      for i := 0; i < len(input_samples)/2; i++ {
        pcm[i] = int16(binary.LittleEndian.Uint16(input_samples[2*i:]))
      }

      data := make([]byte, len(input_samples))
      written, err := encoder.Encode(pcm, data)
      if err != nil {
        panic(err)
      }
      select {
      case mic <- data[:written]:
      default:
      }
    }
	}

	captureCallbacks := malgo.DeviceCallbacks{
		Data: onRecvFrames,
	}

	inDevice, err := malgo.InitDevice(ctx.Context, inDeviceConfig, captureCallbacks)
	if err != nil {
    panic(err)
	}

	err = inDevice.Start()
	if err != nil {
    panic(err)
	}

  return ctx, outDevice, inDevice
}

func get_private_key(path string, generate bool) ed25519.PrivateKey {
  key_file_bytes, err := os.ReadFile(path)
  if err == nil {
    key_pem, _ := pem.Decode(key_file_bytes)
    if key_pem.Type != "PRIVATE KEY" {
      panic("Key file has wrong PEM format")
    }

    private_key, err := x509.ParsePKCS8PrivateKey(key_pem.Bytes)
    if err != nil {
      panic(err)
    }

    var ok bool
    key, ok := private_key.(ed25519.PrivateKey)
    if ok == false {
      panic("Private key is not ed25519.PrivateKey")
    }
    return key
  } else if generate {
    _, key, err := ed25519.GenerateKey(rand.Reader)
    if err != nil {
      panic(err)
    }

    key_pkcs8, err := x509.MarshalPKCS8PrivateKey(key)
    if err != nil {
      panic(err)
    }

    key_pem := pem.EncodeToMemory(&pem.Block{
      Type: "PRIVATE KEY",
      Bytes: key_pkcs8,
    })

    err = os.WriteFile(path, key_pem, 0o600)
    if err != nil {
      panic(err)
    }
    return key
  } else {
    panic(fmt.Sprintf("Failed to read key from %s", path))
  }
}

func print_decoration(window, channels, body ncurses.Window, top_left string) { 
  max_y := ncurses.GetMaxY(*ncurses.CurScr)
  max_x := ncurses.GetMaxX(*ncurses.CurScr)

  ncurses.WResize(channels, max_y - 2, (max_x / 4) - 1)
  ncurses.WResize(body, max_y - 2, max_x - (max_x / 4) - 1)
  ncurses.MvWin(body, 2, (max_x / 4) + 1)

  ncurses.MvWAddStr(window, 0, 0, top_left)

  for i := 0; i < max_x; i++ {
    ncurses.MvWAddStr(window, 1, i, "═")
  }

  ncurses.MvWAddStr(window, 1, max_x/4, "╦")
  for i := 2; i < max_y; i++ {
    ncurses.MvWAddStr(window, i, max_x/4, "║")
  }

  ncurses.WRefresh(window)
  ncurses.WRefresh(channels)
  ncurses.WRefresh(body)
}

func main_loop(client *pnyx.Client, audio_data chan []int16, window ncurses.Window, packet_chan chan pnyx.Payload, user_chan chan []byte) {
  channels := ncurses.NewWin(0, 0, 2, 0)
  body := ncurses.NewWin(0, 0, 2, 0)

  print_decoration(window, channels, body, fmt.Sprintf("pnyx client %X:%X", client.Key.Public().(ed25519.PublicKey)[:2], client.Session.ID[:2]))

  for client.Active() {
    select {
    case packet := <-packet_chan:
      switch packet := packet.(type) {
      case pnyx.ChannelCommandPacket:
        if packet.Channel == pnyx.ChannelID(0) {
          if packet.Mode == pnyx.MODE_AUDIO {
            if packet.Command == pnyx.AUDIO_SET_SAMPLE_RATE {
              var new_sample_rate int
              switch pnyx.SampleRate(packet.Data[0]) {
              case pnyx.SAMPLE_RATE_24KHZ:
                new_sample_rate = 24000
              case pnyx.SAMPLE_RATE_48KHZ:
                new_sample_rate = 48000
              default:
                continue
              }

              err := set_sample_rate(audio_data, new_sample_rate)
              if err != nil {
                panic(err)
              }
            }
          }
        }
      case pnyx.PeerPacket:
        if packet.Channel == pnyx.ChannelID(0) {
          decode_chan, exists := decoders[packet.Peer]
          if exists == false {
            if sample_rate != 0 {
              decode_chan = make(chan[]byte, 1000)
              decoders[packet.Peer] = decode_chan
              go handle_peer_decode(audio_data, packet.Peer, decoders[packet.Peer], sample_rate)
              decode_chan <- packet.Data
            } else {
              decoders[packet.Peer] = nil
            }
          } else if decode_chan != nil {
            decode_chan <- packet.Data
          }
        }
      }
    case char := <-user_chan:
      ncurses.WAddStr(body,  string(char))
      ncurses.WRefresh(body)
    }
  }
}

func process_mic(client *pnyx.Client, mic chan []byte) {
  for true {
    data := <- mic
    err := client.Send(pnyx.NewDataPacket(pnyx.ChannelID(0), pnyx.MODE_AUDIO, data))
    if err != nil {
      panic(err)
    }
  }
}

func main() {
  key_file_arg := flag.String("key", "${HOME}/.pnyx.key", "Path to the private key file to load/save")
  generate_key_arg := flag.Bool("genkey", false, "Set to generate a key if none exists")
  flag.Parse()

  var audio_data = make(chan []int16, 0)
  var speaker = make(chan []int16, 0)

  go mixer(audio_data, speaker)

  var mic = make(chan []byte, 0)
  ctx, outDevice, inDevice := setup_audio(mic, speaker)

  defer ctx.Free()
  defer ctx.Uninit()
  defer outDevice.Uninit()
  defer outDevice.Stop()
  defer inDevice.Uninit()
  defer inDevice.Stop()


  user_chan := make(chan []byte, 1024)
  packet_chan := make(chan pnyx.Payload, 1024)

  key := get_private_key(os.ExpandEnv(*key_file_arg), *generate_key_arg)
  client, err := pnyx.NewClient(key, flag.Arg(0), func(payload pnyx.Payload) error {
    select {
    case packet_chan <- payload:
      return nil
    default:
      return fmt.Errorf("Channel overflow")
    }
  })
  if err != nil {
    panic(err)
  }
  
  join_packet := pnyx.NewChannelCommandPacket(uuid.New(), pnyx.ChannelID(0), pnyx.MODE_CHANNEL, pnyx.CHANNEL_COMMAND_JOIN, nil)
  err = client.Send(join_packet)
  if err != nil {
    panic(err)
  }

  get_sample_rate_packet := pnyx.NewChannelCommandPacket(uuid.New(), pnyx.ChannelID(0), pnyx.MODE_AUDIO, pnyx.AUDIO_SET_SAMPLE_RATE, []byte{byte(pnyx.SAMPLE_RATE_48KHZ)})
  err = client.Send(get_sample_rate_packet)
  if err != nil {
    panic(err)
  }

  go process_mic(client, mic)

  locale := ncurses.SetLocale(0, "")
  fmt.Printf("locale: %s\n", locale)
  
  user_chan, stdin_active := ncurses.UTF8Listener(100, os.Stdin)
  window := ncurses.InitScr()
  ret := ncurses.StartColor()
  if ret != 0 {
    panic(ret)
  }

  go main_loop(client, audio_data, window, packet_chan, user_chan)

  os_sigs := make(chan os.Signal, 1)
  signal.Notify(os_sigs, syscall.SIGINT, syscall.SIGABRT)

  <-os_sigs
  stdin_active.Store(false)
  client.Close()
  ncurses.EndWin()
}