"""Plugin: voice STT/TTS for Mumble channels.

Listens for voice audio via pymumble's sound callback, buffers PCM per
user, transcribes via Whisper STT on silence, and provides TTS playback
via Piper.  Commands: !listen, !say.
"""

from __future__ import annotations

import asyncio
import io
import json
import logging
import threading
import time
import urllib.request
import wave

from derp.http import urlopen as _urlopen
from derp.plugin import command

log = logging.getLogger(__name__)

# -- Constants ---------------------------------------------------------------

_SAMPLE_RATE = 48000
_CHANNELS = 1
_SAMPLE_WIDTH = 2  # s16le = 2 bytes per sample

_SILENCE_GAP = 1.5      # seconds of silence before flushing
_MIN_DURATION = 0.5      # discard utterances shorter than this
_MAX_DURATION = 30.0     # cap buffer at this many seconds
_MIN_BYTES = int(_MIN_DURATION * _SAMPLE_RATE * _SAMPLE_WIDTH)
_MAX_BYTES = int(_MAX_DURATION * _SAMPLE_RATE * _SAMPLE_WIDTH)
_FLUSH_INTERVAL = 0.5    # flush monitor poll interval
_MAX_SAY_LEN = 500       # max characters for !say

_WHISPER_URL = "http://192.168.129.9:8080/inference"
_PIPER_URL = "http://192.168.129.9:5100/"

# -- Per-bot state -----------------------------------------------------------


def _ps(bot):
    """Per-bot plugin runtime state."""
    cfg = getattr(bot, "config", {}).get("voice", {})
    return bot._pstate.setdefault("voice", {
        "listen": False,
        "trigger": cfg.get("trigger", ""),
        "buffers": {},          # {username: bytearray}
        "last_ts": {},          # {username: float monotonic}
        "flush_task": None,
        "lock": threading.Lock(),
        "silence_gap": cfg.get("silence_gap", _SILENCE_GAP),
        "whisper_url": cfg.get("whisper_url", _WHISPER_URL),
        "piper_url": cfg.get("piper_url", _PIPER_URL),
        "_listener_registered": False,
    })


# -- Helpers -----------------------------------------------------------------


def _is_mumble(bot) -> bool:
    """Check if bot supports voice streaming."""
    return hasattr(bot, "stream_audio")


def _pcm_to_wav(pcm: bytes) -> bytes:
    """Wrap raw s16le 48kHz mono PCM in a WAV container."""
    buf = io.BytesIO()
    with wave.open(buf, "wb") as wf:
        wf.setnchannels(_CHANNELS)
        wf.setsampwidth(_SAMPLE_WIDTH)
        wf.setframerate(_SAMPLE_RATE)
        wf.writeframes(pcm)
    return buf.getvalue()


# -- STT: Sound listener (pymumble thread) ----------------------------------


def _on_voice(bot, user, sound_chunk):
    """Buffer incoming voice PCM per user.  Runs on pymumble thread."""
    ps = _ps(bot)
    if not ps["listen"] and not ps["trigger"]:
        return
    try:
        name = user["name"]
    except (KeyError, TypeError):
        name = None
    if not name or name == bot.nick:
        return
    pcm = sound_chunk.pcm
    if not pcm:
        return
    with ps["lock"]:
        if name not in ps["buffers"]:
            ps["buffers"][name] = bytearray()
        buf = ps["buffers"][name]
        buf.extend(pcm)
        if len(buf) > _MAX_BYTES:
            ps["buffers"][name] = bytearray(buf[-_MAX_BYTES:])
        ps["last_ts"][name] = time.monotonic()


# -- STT: Whisper transcription ---------------------------------------------


def _transcribe(ps, pcm: bytes) -> str:
    """POST PCM (as WAV) to Whisper and return transcribed text.  Blocking."""
    wav_data = _pcm_to_wav(pcm)
    boundary = "----derp_voice_boundary"
    body = (
        f"--{boundary}\r\n"
        f'Content-Disposition: form-data; name="file"; filename="audio.wav"\r\n'
        f"Content-Type: audio/wav\r\n\r\n"
    ).encode() + wav_data + (
        f"\r\n--{boundary}\r\n"
        f'Content-Disposition: form-data; name="response_format"\r\n\r\n'
        f"json\r\n--{boundary}--\r\n"
    ).encode()
    req = urllib.request.Request(ps["whisper_url"], data=body, method="POST")
    req.add_header("Content-Type", f"multipart/form-data; boundary={boundary}")
    resp = _urlopen(req, timeout=30, proxy=False)
    data = json.loads(resp.read())
    resp.close()
    return data.get("text", "").strip()


# -- STT: Flush monitor (asyncio background task) ---------------------------


async def _flush_monitor(bot):
    """Poll for silence gaps and transcribe completed utterances."""
    ps = _ps(bot)
    loop = asyncio.get_running_loop()
    try:
        while ps["listen"] or ps["trigger"]:
            await asyncio.sleep(_FLUSH_INTERVAL)
            now = time.monotonic()
            to_flush: list[tuple[str, bytes]] = []

            with ps["lock"]:
                for name in list(ps["last_ts"]):
                    elapsed = now - ps["last_ts"][name]
                    if elapsed >= ps["silence_gap"] and name in ps["buffers"]:
                        pcm = bytes(ps["buffers"].pop(name))
                        del ps["last_ts"][name]
                        to_flush.append((name, pcm))

            for name, pcm in to_flush:
                if len(pcm) < _MIN_BYTES:
                    continue
                try:
                    text = await loop.run_in_executor(
                        None, _transcribe, ps, pcm,
                    )
                except Exception:
                    log.exception("voice: transcription failed for %s", name)
                    continue
                if not text or text.strip("., ") == "":
                    continue

                trigger = ps["trigger"]
                if trigger and text.lower().startswith(trigger.lower()):
                    remainder = text[len(trigger):].strip()
                    if remainder:
                        log.info("voice: trigger from %s: %s", name, remainder)
                        bot._spawn(
                            _tts_play(bot, remainder), name="voice-tts",
                        )
                    continue

                if ps["listen"]:
                    log.info("voice: %s said: %s", name, text)
                    await bot.action("0", f"heard {name} say: {text}")
    except asyncio.CancelledError:
        pass
    except Exception:
        log.exception("voice: flush monitor error")


# -- TTS: Piper fetch + playback --------------------------------------------


def _fetch_tts(piper_url: str, text: str) -> str | None:
    """POST text to Piper TTS and save the WAV response.  Blocking."""
    import tempfile
    try:
        payload = json.dumps({"text": text}).encode()
        req = urllib.request.Request(
            piper_url, data=payload, method="POST",
        )
        req.add_header("Content-Type", "application/json")
        resp = _urlopen(req, timeout=30, proxy=False)
        data = resp.read()
        resp.close()
        if not data:
            return None
        tmp = tempfile.NamedTemporaryFile(
            suffix=".wav", prefix="derp_tts_", delete=False,
        )
        tmp.write(data)
        tmp.close()
        return tmp.name
    except Exception:
        log.exception("voice: TTS fetch failed")
        return None


async def _tts_play(bot, text: str):
    """Fetch TTS audio and play it via stream_audio."""
    from pathlib import Path

    ps = _ps(bot)
    loop = asyncio.get_running_loop()
    wav_path = await loop.run_in_executor(
        None, _fetch_tts, ps["piper_url"], text,
    )
    if wav_path is None:
        return
    try:
        done = asyncio.Event()
        await bot.stream_audio(str(wav_path), volume=1.0, on_done=done)
        await done.wait()
    finally:
        Path(wav_path).unlink(missing_ok=True)


# -- Listener lifecycle -----------------------------------------------------


def _ensure_listener(bot):
    """Register the sound listener callback (idempotent)."""
    ps = _ps(bot)
    if ps["_listener_registered"]:
        return
    if not hasattr(bot, "_sound_listeners"):
        return
    bot._sound_listeners.append(lambda user, chunk: _on_voice(bot, user, chunk))
    ps["_listener_registered"] = True
    log.info("voice: registered sound listener")


def _ensure_flush_task(bot):
    """Start the flush monitor if not running."""
    ps = _ps(bot)
    task = ps.get("flush_task")
    if task and not task.done():
        return
    ps["flush_task"] = bot._spawn(
        _flush_monitor(bot), name="voice-flush-monitor",
    )


def _stop_flush_task(bot):
    """Cancel the flush monitor."""
    ps = _ps(bot)
    task = ps.get("flush_task")
    if task and not task.done():
        task.cancel()
    ps["flush_task"] = None


# -- Commands ----------------------------------------------------------------


@command("listen", help="Voice: !listen [on|off] -- toggle STT", tier="admin")
async def cmd_listen(bot, message):
    """Toggle voice-to-text transcription."""
    if not _is_mumble(bot):
        await bot.reply(message, "Voice is Mumble-only")
        return

    ps = _ps(bot)
    parts = message.text.split()
    if len(parts) < 2:
        state = "on" if ps["listen"] else "off"
        trigger = ps["trigger"]
        info = f"Listen: {state}"
        if trigger:
            info += f" | Trigger: {trigger}"
        await bot.reply(message, info)
        return

    sub = parts[1].lower()
    if sub == "on":
        ps["listen"] = True
        _ensure_listener(bot)
        _ensure_flush_task(bot)
        await bot.reply(message, "Listening for voice")
    elif sub == "off":
        ps["listen"] = False
        if not ps["trigger"]:
            with ps["lock"]:
                ps["buffers"].clear()
                ps["last_ts"].clear()
            _stop_flush_task(bot)
        await bot.reply(message, "Stopped listening")
    else:
        await bot.reply(message, "Usage: !listen [on|off]")


@command("say", help="Voice: !say <text> -- text-to-speech")
async def cmd_say(bot, message):
    """Speak text aloud via Piper TTS."""
    if not _is_mumble(bot):
        await bot.reply(message, "Voice is Mumble-only")
        return

    parts = message.text.split(None, 1)
    if len(parts) < 2:
        await bot.reply(message, "Usage: !say <text>")
        return

    text = parts[1].strip()
    if len(text) > _MAX_SAY_LEN:
        await bot.reply(message, f"Text too long (max {_MAX_SAY_LEN} chars)")
        return

    bot._spawn(_tts_play(bot, text), name="voice-tts")


# -- Plugin lifecycle --------------------------------------------------------


async def on_connected(bot) -> None:
    """Re-register listener after reconnect; play TTS greeting on first join."""
    if not _is_mumble(bot):
        return
    ps = _ps(bot)

    # TTS greeting on first connect
    greet = bot.config.get("mumble", {}).get("greet")
    if greet and not ps.get("_greeted"):
        ps["_greeted"] = True
        # Wait for audio subsystem to be ready
        for _ in range(20):
            if bot._is_audio_ready():
                break
            await asyncio.sleep(0.5)
        bot._spawn(_tts_play(bot, greet), name="voice-greet")

    if ps["listen"] or ps["trigger"]:
        _ensure_listener(bot)
        _ensure_flush_task(bot)