// Package main is mavttsd — maven's tts module process.
//
// Sibling to cmd/mavsttd: same worker boundary, opposite job (synthesize vs
// transcribe). Same restart-free, key-free, fail-independent invariant.
//
// With -piper <binary> -model <onnx>: calls piper for real TTS (ru_RU
// voice at models/tts/ru_RU-irina-medium.onnx). Without flags: serves the
// stub synthesizer (200ms tone) for exercisable end-to-end testing.
//
//	$ mavttsd -socket /run/user/$UID/maven/tts.sock
//	"tts": { "socket": "/run/user/1000/maven/tts.sock", "lang": "ru" }
package main

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"log"
	"net"
	"os"
	"os/signal"
	"syscall"

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

func main() {
	if err := run(os.Args[1:]); err != nil {
		fmt.Fprintln(os.Stderr, "mavttsd:", err)
		os.Exit(1)
	}
}

func run(args []string) error {
	sock := flag.String("socket", defaultSocket("tts.sock"), "unix socket path")
	piperBin := flag.String("piper", "", "path to piper binary")
	model := flag.String("model", "", "path to piper onnx model file")
	espeakData := flag.String("espeak_data", "", "path to espeak-ng data directory")
	tashkeelModel := flag.String("tashkeel_model", "", "path to libtashkeel onnx model")

	flag.CommandLine.Parse(args)

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

	var s worker.Synthesizer
	if *piperBin != "" && *model != "" {
		s = newPiperHandler(*piperBin, *model, *espeakData, *tashkeelModel)
		log.Printf("mavttsd: using piper tts (%s, model=%s)", *piperBin, *model)
	} else {
		log.Printf("mavttsd: no piper/model specified, using stub handler")
		s = &stubHandler{}
	}

	srv := worker.NewSynthesizerServer(*sock, s)
	if err := srv.Listen(); err != nil {
		return err
	}
	defer srv.Close()
	log.Printf("mavttsd: worker listening on %s", srv.Path())

	errCh := make(chan error, 1)
	go func() { errCh <- srv.Serve() }()
	select {
	case <-ctx.Done():
		log.Printf("mavttsd: shutdown signal received")
		srv.Close()
		return nil
	case err := <-errCh:
		if err != nil && !errors.Is(err, net.ErrClosed) {
			return err
		}
		return nil
	}
}

// stubHandler — worker.Synthesizer that delegates to the tts Stub. The
// production swap replaces this struct with a silero / piper-backed handler.
type stubHandler struct{}

func (h *stubHandler) Synthesize(ctx context.Context, req worker.SynthesizeReq) (worker.SynthesizeResp, error) {
	_ = ctx
	// 200ms tone, freq keyed by first byte of text — same shape as tts.Stub,
	// kept locally so this module has zero coupling to the daemon package
	// (mavttsd running shouldn't drag stt/tts package symbols here; they're
	// siblings in the topology).
	const samples = 3200 // 200ms @ 16k
	pcm := make([]byte, samples*2)
	freq := 220.0
	if len(req.Text) > 0 {
		freq = 180.0 + float64(req.Text[0]%6)*60
	}
	for i := 0; i < samples; i++ {
		t := float64(i) / 16000.0
		v := int16(12000 * sin(2*pi*freq*t))
		pcm[i*2] = byte(v)
		pcm[i*2+1] = byte(v >> 8)
	}
	return worker.SynthesizeResp{Audio: audio.Audio{Format: audio.PCM16kMono, Bytes: pcm}}, nil
}

const pi = 3.141592653589793

// tiny stdlib-free sin approximation — keeps mavttsd out of math import.
// Adequate for a tone generator; the production model returns real audio.
func sin(x float64) float64 {
	// reduce to [-pi, +pi]
	mod := x - pi*2*float64(int(x/(pi*2)))
	if mod > pi {
		mod -= pi * 2
	} else if mod < -pi {
		mod += pi * 2
	}
	// 4-term Taylor series around 0; decent for the small amplitudes here.
	return mod - mod*mod*mod/6 + mod*mod*mod*mod*mod/120 - mod*mod*mod*mod*mod*mod*mod/5040
}

func defaultSocket(name string) string {
	if x := os.Getenv("XDG_RUNTIME_DIR"); x != "" {
		return x + "/maven/" + name
	}
	home, err := os.UserHomeDir()
	if err != nil || home == "" {
		return name
	}
	return home + "/.local/share/maven/" + name
}