Deaf_Transcription_Service/bridge/bridge.py

#!/usr/bin/env python3
"""
bridge.py — Church Live Transcription Bridge

Streams microphone audio to WhisperLiveKit (ws://localhost:8000/asr),
receives transcription + speaker diarization, buffers sentences, and
publishes rolling 3-line JSON to Mosquitto MQTT for the e-ink display.

Start WhisperLiveKit with:
    wlk --model large-v3 --language en --diarization

Run this script:
    python bridge.py
"""

import asyncio
import json
import re
import textwrap
import threading
import time
from collections import Counter
from pathlib import Path

import numpy as np
import paho.mqtt.client as mqtt
import sounddevice as sd
import websockets

# ── Configuration ─────────────────────────────────────────────────────────────

MQTT_HOST        = "localhost"
MQTT_PORT        = 1883
MQTT_TOPIC_TEXT  = "display/text"
MQTT_TOPIC_CLEAR = "display/clear"

WS_URL      = "ws://localhost:8000/asr"
SAMPLE_RATE = 16000
CHANNELS    = 1
BLOCKSIZE   = 4096          # ~256 ms per chunk at 16 kHz

SENTENCE_TIMEOUT = 4.0      # seconds of silence before forcing a flush
MAX_LINE_CHARS   = 38       # characters per line (~24pt font at 800 px wide)
DISPLAY_LINES    = 3

# Set to a device index (integer) to force a specific microphone.
# Leave as None to use the Windows default input device.
# Run bridge.py once to see available device indices printed at startup.
AUDIO_DEVICE: int | None = None

SPEAKERS_FILE = Path(__file__).parent / "speakers.json"

DEFAULT_SPEAKERS: dict[str, str] = {
    "SPEAKER_00": "Pastor",
    "SPEAKER_01": "Reader",
    "SPEAKER_02": "Guest",
    "SPEAKER_03": "Choir",
}

# ── Speaker persistence ───────────────────────────────────────────────────────

def _load_speakers() -> dict[str, str]:
    if SPEAKERS_FILE.exists():
        try:
            data = json.loads(SPEAKERS_FILE.read_text(encoding="utf-8"))
            if isinstance(data, dict):
                return data
        except (json.JSONDecodeError, OSError):
            pass
    # First run — seed with defaults and save
    _write_speakers(DEFAULT_SPEAKERS)
    return dict(DEFAULT_SPEAKERS)


def _write_speakers(names: dict[str, str]) -> None:
    try:
        SPEAKERS_FILE.write_text(
            json.dumps(names, indent=2, ensure_ascii=False),
            encoding="utf-8",
        )
    except OSError as exc:
        print(f"[Speakers] Save failed: {exc}")


# ── State ─────────────────────────────────────────────────────────────────────

class BridgeState:
    """All mutable state, protected by a single lock."""

    def __init__(self):
        self._lock                         = threading.Lock()
        self.speaker_names: dict[str, str] = _load_speakers()
        self._seen: set[str]               = set(self.speaker_names)
        self._current_speaker: str | None  = None
        self._speaker_changed              = False
        self._text_buffer                  = ""
        self._display: list[str]           = [""] * DISPLAY_LINES
        self._last_final_time              = time.monotonic()

    # ── Speaker name management ───────────────────────────────────────────────

    def set_speaker_name(self, speaker_id: str, name: str) -> None:
        with self._lock:
            self.speaker_names[speaker_id] = name.strip()
            self._seen.add(speaker_id)
            _write_speakers(self.speaker_names)

    def delete_speaker(self, speaker_id: str) -> None:
        with self._lock:
            self.speaker_names.pop(speaker_id, None)
            self._seen.discard(speaker_id)
            _write_speakers(self.speaker_names)

    def seen_speakers_snapshot(self) -> set[str]:
        with self._lock:
            return set(self._seen)

    def _resolve(self, speaker_id: str | None) -> str | None:
        if not speaker_id:
            return None
        return self.speaker_names.get(speaker_id, speaker_id)

    # ── Text ingestion ────────────────────────────────────────────────────────

    def push_final(self, text: str, speaker_id: str | None, mqtt_client: mqtt.Client) -> None:
        """Accept a finalised segment; flush on sentence boundary or speaker change."""
        with self._lock:
            if speaker_id:
                self._seen.add(speaker_id)

            resolved = self._resolve(speaker_id)
            if resolved != self._current_speaker:
                if self._text_buffer:
                    self._flush(mqtt_client)
                self._current_speaker = resolved
                self._speaker_changed = True

            sep = " " if self._text_buffer else ""
            self._text_buffer += sep + text.strip()
            self._last_final_time = time.monotonic()

            if _is_sentence_end(text):
                self._flush(mqtt_client)

    def maybe_timeout_flush(self, mqtt_client: mqtt.Client) -> None:
        with self._lock:
            if self._text_buffer and (time.monotonic() - self._last_final_time) > SENTENCE_TIMEOUT:
                self._flush(mqtt_client)

    def _flush(self, mqtt_client: mqtt.Client) -> None:
        """Word-wrap buffer → rolling display → publish. Must hold lock."""
        text = self._text_buffer.strip()
        self._text_buffer = ""
        if not text:
            return

        new_lines: list[str] = []
        if self._speaker_changed and self._current_speaker:
            new_lines.append(f"[{self._current_speaker.upper()}]")
            self._speaker_changed = False

        new_lines.extend(textwrap.wrap(text, MAX_LINE_CHARS) or [""])
        self._display.extend(new_lines)
        self._display = self._display[-DISPLAY_LINES:]
        while len(self._display) < DISPLAY_LINES:
            self._display.insert(0, "")

        payload = json.dumps({"lines": list(self._display)})
        mqtt_client.publish(MQTT_TOPIC_TEXT, payload)
        print(f"[Display] {self._display}")

    def clear(self, mqtt_client: mqtt.Client) -> None:
        with self._lock:
            self._display         = [""] * DISPLAY_LINES
            self._text_buffer     = ""
            self._current_speaker = None
            self._speaker_changed = False
        mqtt_client.publish(MQTT_TOPIC_CLEAR, "")
        print("[Display] Cleared")


# ── Helpers ───────────────────────────────────────────────────────────────────

def _is_sentence_end(text: str) -> bool:
    return bool(re.search(r'[.!?…]\s*$', text.strip()))


def _extract_speaker(data: dict) -> str | None:
    if "speaker" in data:
        return data["speaker"] or None
    words = data.get("words", [])
    if words:
        ids = [w.get("speaker") for w in words if w.get("speaker")]
        if ids:
            return Counter(ids).most_common(1)[0][0]
    return None


# ── MQTT ──────────────────────────────────────────────────────────────────────

def build_mqtt_client() -> mqtt.Client:
    client = mqtt.Client(mqtt.CallbackAPIVersion.VERSION2)

    def on_connect(client, userdata, flags, rc, props):
        print("[MQTT] Connected" if rc == 0 else f"[MQTT] Failed: {rc}")

    def on_disconnect(client, userdata, flags, rc, props):
        print(f"[MQTT] Disconnected ({rc}), will reconnect...")

    client.on_connect    = on_connect
    client.on_disconnect = on_disconnect
    client.reconnect_delay_set(min_delay=1, max_delay=30)
    client.connect_async(MQTT_HOST, MQTT_PORT)
    client.loop_start()
    return client


# ── WebSocket + audio pipeline ────────────────────────────────────────────────

async def _sender(ws, queue: asyncio.Queue) -> None:
    while not queue.empty():
        queue.get_nowait()
    while True:
        chunk = await queue.get()
        await ws.send(chunk)


async def _receiver(ws, state: BridgeState, mqtt_client: mqtt.Client) -> None:
    async for message in ws:
        try:
            data = json.loads(message)
        except (json.JSONDecodeError, TypeError):
            continue

        text     = (data.get("text") or data.get("buffer_transcription") or "").strip()
        is_final = data.get("is_final", False) or data.get("end_of_segment", False)
        speaker  = _extract_speaker(data)

        if is_final and text:
            print(f"[Whisper] ({speaker or '?'}) {text}")
            state.push_final(text, speaker, mqtt_client)


async def _flusher(state: BridgeState, mqtt_client: mqtt.Client) -> None:
    while True:
        await asyncio.sleep(1.0)
        state.maybe_timeout_flush(mqtt_client)


async def _speaker_reloader(state: BridgeState) -> None:
    """Reload speakers.json every 5 s so admin UI changes take effect live."""
    last_mtime = 0.0
    while True:
        await asyncio.sleep(5.0)
        try:
            mtime = SPEAKERS_FILE.stat().st_mtime
            if mtime != last_mtime:
                fresh = _load_speakers()
                with state._lock:
                    state.speaker_names = fresh
                last_mtime = mtime
                print("[Bridge] Speaker names reloaded from disk")
        except OSError:
            pass


def _choose_audio_device() -> int | None:
    """
    List all input devices and return the index to use.
    Prefers AUDIO_DEVICE if set, otherwise the system default,
    otherwise the first device with input channels.
    """
    try:
        devices   = sd.query_devices()
        default_in = sd.default.device[0]  # may be -1 if unset
    except Exception as exc:
        print(f"[Audio] Cannot query devices: {exc}")
        return None

    print("[Audio] Available input devices:")
    input_devices: list[tuple[int, str]] = []
    for i, dev in enumerate(devices):
        if dev["max_input_channels"] > 0:
            marker = "  ← default" if i == default_in else ""
            print(f"  [{i}] {dev['name']}{marker}")
            input_devices.append((i, dev["name"]))

    if not input_devices:
        print("[Audio] ERROR: No input devices found. Connect a microphone and restart.")
        return None

    # Explicit override from config
    if AUDIO_DEVICE is not None:
        print(f"[Audio] Using configured device [{AUDIO_DEVICE}]")
        return AUDIO_DEVICE

    # System default (if valid)
    if default_in >= 0:
        print(f"[Audio] Using default input device [{default_in}]")
        return default_in

    # Fall back to first available input
    idx, name = input_devices[0]
    print(f"[Audio] No system default set — using [{idx}] {name}")
    print("[Audio] To choose a different device, set AUDIO_DEVICE in bridge.py")
    return idx


async def audio_ws_loop(state: BridgeState, mqtt_client: mqtt.Client) -> None:
    audio_queue: asyncio.Queue[bytes] = asyncio.Queue(maxsize=120)
    loop = asyncio.get_running_loop()

    def audio_callback(indata: np.ndarray, frames: int, time_info, status) -> None:
        if status:
            print(f"[Audio] {status}")
        chunk = indata.tobytes()
        def _put():
            try:
                audio_queue.put_nowait(chunk)
            except asyncio.QueueFull:
                pass
        loop.call_soon_threadsafe(_put)

    device = _choose_audio_device()
    if device is None:
        print("[Audio] No input device available — audio pipeline cannot start.")
        return

    with sd.InputStream(
        device=device,
        samplerate=SAMPLE_RATE,
        channels=CHANNELS,
        dtype="int16",
        blocksize=BLOCKSIZE,
        callback=audio_callback,
    ):
        flusher   = asyncio.create_task(_flusher(state, mqtt_client))
        reloader  = asyncio.create_task(_speaker_reloader(state))
        try:
            while True:
                try:
                    print(f"[WS] Connecting to {WS_URL} ...")
                    async with websockets.connect(WS_URL, max_size=2**23) as ws:
                        print("[WS] Connected")
                        send_t = asyncio.create_task(_sender(ws, audio_queue))
                        recv_t = asyncio.create_task(_receiver(ws, state, mqtt_client))
                        done, pending = await asyncio.wait(
                            [send_t, recv_t], return_when=asyncio.FIRST_COMPLETED
                        )
                        for t in pending:
                            t.cancel()
                        for t in done:
                            if not t.cancelled() and (exc := t.exception()):
                                print(f"[WS] Task error: {exc}")
                except (websockets.ConnectionClosed, OSError, ConnectionRefusedError) as exc:
                    print(f"[WS] {exc}  — retrying in 3 s...")
                    await asyncio.sleep(3)
        finally:
            flusher.cancel()
            reloader.cancel()


def run_async_loop(state: BridgeState, mqtt_client: mqtt.Client) -> None:
    asyncio.run(audio_ws_loop(state, mqtt_client))


# ── Entry point ───────────────────────────────────────────────────────────────

def main() -> None:
    state       = BridgeState()
    mqtt_client = build_mqtt_client()

    ws_thread = threading.Thread(
        target=run_async_loop, args=(state, mqtt_client), daemon=True
    )
    ws_thread.start()
    print(f"[Bridge] Speaker names loaded from {SPEAKERS_FILE}")
    print("[Bridge] Audio pipeline running — speaker admin at http://localhost:8001")
    print("[Bridge] Close this window to quit")

    try:
        ws_thread.join()
    except KeyboardInterrupt:
        pass


if __name__ == "__main__":
    main()