// Package main — mavwaked: always-on voice listening client.
//
// Spawns arecord(1) as a subprocess, reads 16kHz mono PCM from its stdout,
// runs an energy-based VAD over 30ms windows, and when a complete utterance
// is detected sends it as a PushToTalk frame to the voice server. The reply
// audio is played back through aplay(1).
//
// Voice activity is silero-vad when -vad-model points at the graph, and an
// energy threshold when it does not. Silero declines noise the threshold
// accepts: 0 frames against 68 to 99 on the four fixtures, measured in
// docs/evals/2026-08-09-silero-vad.md. Note that the model window is 512
// samples and the capture frame is 480, so silero.go re-chunks. This comment
// used to say the two matched, which was true of silero v4.
//
// The keyword is "Мэйвен" and it is required, when -wake-model points at the
// head (V-487 stage two). Without it anything spoken near the microphone
// becomes a turn, which the SurfaceVoice auth layer makes safe rather than
// expensive: it caps all commands at L0, no destructive acts. It does not cap
// reading, so an open gate still lets the room hear his facts read back.
// wakeword.go holds the cadence and wakefeatures.go the three models.
//
// The conn carries both directions. mavwaked sends utterances and receives
// proactive nudges on it, and it is opened at startup rather than at the first
// utterance, because mavend registers a voice session on accept. See nudge.go
// for why a nudge that is not heard is worse than one that is not delivered.
//
// While a reply is playing the capture side is muted (half-duplex): without
// it, Maven's own voice comes back in through the mic and she answers
// herself. -barge-in punches one hole in that gate — sustained energy above
// -barge-in-rms cuts playback so he can talk over her. It is off by default
// because the threshold is room-specific; see playback.go. The threshold is a
// raw frame RMS and has no reference to what the speaker actually leaks, so
// the daemon logs the mean energy of the frames it suppressed while speaking.
// Set -barge-in-rms from those numbers rather than by guessing.
//
//	usage:
//	  mavwaked                          # default ALSA device, 127.0.0.1:9100
//	  mavwaked -barge-in                # let him interrupt her mid-reply
//	  mavwaked -device hw:1,0 -addr 10.42.0.1:9100
//	  mavwaked -test file.wav           # read from file, no arecord
package main

import (
	"bufio"
	"context"
	"errors"
	"flag"
	"fmt"
	"io"
	"log"
	"os"
	"os/exec"
	"os/signal"
	"syscall"
	"time"

	"github.com/kami/maven/internal/audio"
	"github.com/kami/maven/internal/voice"
)

// Defaults.
const (
	defaultDevice   = "default"
	defaultAddr     = "127.0.0.1:9100"
	defaultLang     = "ru"
	defaultReadSize = 4096 // max PCM bytes per read from arecord (fits multiple frames)

	// defaultWakeWindowMs — how long the keyword stays good for. He says
	// "Мэйвен" and then a sentence, and the VAD does not close the utterance
	// until he stops, so this has to outlive the word by the length of what
	// follows it. It is spent on dispatch: one keyword, one turn.
	defaultWakeWindowMs = 8000
)

func main() {
	if err := run(os.Args[1:]); err != nil && !errors.Is(err, context.Canceled) {
		fmt.Fprintln(os.Stderr, "mavwaked:", err)
		os.Exit(1)
	}
}

func run(args []string) error {
	device := flag.String("device", defaultDevice, "ALSA capture device")
	addr := flag.String("addr", defaultAddr, "voice server TCP address")
	lang := flag.String("lang", defaultLang, "STT language hint (ru/en/mixed)")
	minRMS := flag.Int("min-rms", 100, "RMS floor ×10000 (e.g. 100 = 0.01)")
	speechMs := flag.Int("speech-ms", defaultSpeechMs, "min speech ms before trigger")
	silenceMs := flag.Int("silence-ms", defaultSilenceMs, "silence ms to end utterance")
	maxMs := flag.Int("max-ms", defaultMaxMs, "max utterance ms")
	testFile := flag.String("test", "", "read PCM from file instead of arecord (testing only)")
	bargeIn := flag.Bool("barge-in", false, "cut Maven off when he talks over her (needs a room-tuned -barge-in-rms)")
	bargeRMS := flag.Int("barge-in-rms", defaultBargeRMS, "RMS x10000 a frame must clear to count as barge-in")
	bargeFrames := flag.Int("barge-in-frames", defaultBargeFrames, "consecutive frames over -barge-in-rms before playback is cut")
	vadModel := flag.String("vad-model", "", "silero-vad onnx file; empty runs the energy threshold instead")
	vadThreshold := flag.Float64("vad-threshold", defaultSileroThreshold, "speech probability a frame must clear")
	onnxLib := flag.String("onnx-lib", os.Getenv("MAVEN_ONNX_LIB"), "libonnxruntime.so, needed with -vad-model")
	wakeModel := flag.String("wake-model", "", "keyword head onnx; empty ships every utterance, as before V-487")
	wakeMel := flag.String("wake-mel", "", "melspectrogram.onnx, required with -wake-model")
	wakeEmbed := flag.String("wake-embed", "", "embedding_model.onnx, required with -wake-model")
	wakeThreshold := flag.Float64("wake-threshold", defaultWakeThreshold, "score the keyword must clear")
	wakeWindowMs := flag.Int("wake-window-ms", defaultWakeWindowMs, "ms an utterance may still start after the keyword")
	flag.CommandLine.Parse(args)

	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP)
	defer stop()

	// Voice client — one conn carrying both directions. SendRequest reconnects
	// on error, and the push receiver redials on its own clock.
	vc := voice.Dial(*addr)
	defer vc.Close()

	// VAD engine. A model that will not load is logged and not fatal: the
	// energy threshold is worse, and it is a great deal better than a
	// listening client that refuses to start.
	vad := NewVAD(*minRMS, *speechMs, *silenceMs, *maxMs)
	if *vadModel != "" {
		s, err := newSileroVAD(*vadModel, *onnxLib)
		if err != nil {
			log.Printf("mavwaked: silero unavailable, energy threshold unchanged: %v", err)
		} else {
			defer s.Close()
			vad.UseSilero(s, *vadThreshold)
			log.Printf("mavwaked: silero-vad from %s, threshold %.2f", *vadModel, *vadThreshold)
		}
	}

	// Audio source.
	var src io.ReadCloser
	if *testFile != "" {
		f, err := os.Open(*testFile)
		if err != nil {
			return fmt.Errorf("open test file: %w", err)
		}
		defer f.Close()
		src = f
		log.Printf("mavwaked: reading from test file %s", *testFile)
	} else {
		arec := exec.CommandContext(ctx, "arecord",
			"-D", *device,
			"-f", "S16_LE",
			"-r", "16000",
			"-c", "1",
			"-t", "raw",
		)
		arec.Stderr = os.Stderr
		pipe, err := arec.StdoutPipe()
		if err != nil {
			return fmt.Errorf("arecord stdout pipe: %w", err)
		}
		if err := arec.Start(); err != nil {
			return fmt.Errorf("start arecord: %w", err)
		}
		src = pipe
		log.Printf("mavwaked: listening on device %s → %s", *device, *addr)

		// Ensure arecord is killed when we exit.
		go func() {
			<-ctx.Done()
			if p := arec.Process; p != nil {
				_ = p.Signal(syscall.SIGTERM)
				// Give it a moment, then force-kill.
				go func() {
					time.Sleep(2 * time.Second)
					_ = p.Kill()
				}()
			}
		}()
	}

	defer src.Close()

	var barge bargeInConfig
	if *bargeIn {
		barge = bargeInConfig{RMS: float64(*bargeRMS) / 10000.0, Frames: *bargeFrames}
		if barge.Enabled() {
			log.Printf("mavwaked: barge-in on (rms %.4f x %d frames)", barge.RMS, barge.Frames)
		} else {
			// The log used to say "barge-in on (rms 0.0000 x 5)" here and then
			// nothing happened, because Enabled needs a positive threshold.
			log.Printf("mavwaked: -barge-in was passed but rms %.4f x %d frames disables it; "+
				"both must be above zero, so barge-in is OFF",
				barge.RMS, barge.Frames)
		}
	}
	sess := newSession(vad, newAplayPlayer(), &voiceSender{vc: vc}, *lang, barge)

	// Keyword gate. A model that will not load is logged and not fatal, for
	// the same reason silero's is not: an open gate is the daemon he had
	// yesterday, and a daemon that refuses to start is not.
	if *wakeModel != "" {
		w, err := newWakeWord(*wakeMel, *wakeEmbed, *wakeModel, *onnxLib, *wakeThreshold)
		if err != nil {
			log.Printf("mavwaked: wake word unavailable, every utterance is a turn: %v", err)
		} else {
			defer w.Close()
			sess.UseWakeWord(w, time.Duration(*wakeWindowMs)*time.Millisecond)
			log.Printf("mavwaked: wake word from %s, threshold %.3f, window %dms",
				*wakeModel, *wakeThreshold, *wakeWindowMs)
		}
	}

	// Listen for nudges alongside capture. Connect eagerly so mavend has a
	// voice session before he has said anything: without one, a nudge routed
	// to voice finds nobody home and goes to the away channels instead.
	if err := vc.Connect(ctx); err != nil {
		log.Printf("mavwaked: voice server not reachable yet, retrying in background: %v", err)
	}
	go runNudgeReceiver(ctx, vc, sess)

	return captureLoop(ctx, src, sess)
}

// captureLoop reads PCM from src and hands whole frames to the session.
// Returns when ctx is done or src is exhausted.
func captureLoop(ctx context.Context, src io.Reader, sess *session) error {
	br := bufio.NewReaderSize(src, defaultReadSize)
	frameBytes := sess.vad.FrameSamples() * 2 // 480 samples × 2 bytes = 960 bytes per 30ms

	log.Printf("mavwaked: capture loop starting (frame=%d bytes, %dms)",
		frameBytes, defaultFrameMs)

	var partial []byte
	for {
		select {
		case <-ctx.Done():
			log.Printf("mavwaked: context done, stopping capture")
			return ctx.Err()
		default:
		}

		// Read exactly one frame (or wait for more data).
		buf := make([]byte, frameBytes)
		n, err := io.ReadFull(br, buf)
		if err != nil {
			if errors.Is(err, io.EOF) || errors.Is(err, io.ErrUnexpectedEOF) {
				if n > 0 {
					// Flush partial frame.
					partial = append(partial, buf[:n]...)
					if len(partial) >= frameBytes {
						if err := sess.feed(ctx, partial[:frameBytes]); err != nil {
							log.Printf("mavwaked: process frame: %v", err)
						}
						partial = partial[frameBytes:]
					}
				}
				return nil
			}
			return fmt.Errorf("read audio: %w", err)
		}

		// Include any leftover from previous partial read.
		full := buf
		if len(partial) > 0 {
			full = append(partial, buf...)
			partial = nil
		}

		if err := sess.feed(ctx, full); err != nil {
			log.Printf("mavwaked: process frame: %v", err)
		}
	}
}

// voiceSender is the production utteranceSender: one PushToTalk round-trip
// over the voice wire. SurfaceVoice (not the default SurfacePCClient that
// c.PushToTalk uses) caps everything at L0, which is what makes an accidental
// VAD trigger safe.
type voiceSender struct{ vc *voice.Client }

func (s *voiceSender) Send(ctx context.Context, utt audio.Audio, lang string) (audio.Audio, error) {
	var resp voice.PushToTalkResp
	err := s.vc.SendRequest(ctx, voice.MethodPushToTalk, voice.PushToTalkReq{
		Audio:   utt,
		Lang:    lang,
		Surface: voice.SurfaceVoice,
	}, &resp)
	if err != nil {
		return audio.Audio{}, fmt.Errorf("push-to-talk: %w", err)
	}
	log.Printf("mavwaked: reply: %q (%.2fs audio)", resp.ReplyText, resp.ReplyAudio.Duration())
	if len(resp.RoutedChannels) > 0 {
		log.Printf("mavwaked: also routed to: %v", resp.RoutedChannels)
	}
	return resp.ReplyAudio, nil
}