import asyncio
import io
import logging
import wave
from concurrent.futures import ThreadPoolExecutor
from functools import partial

from piper.voice import PiperVoice

from .config import settings

logger = logging.getLogger(__name__)

_voice: PiperVoice | None = None
_executor = ThreadPoolExecutor(max_workers=2)


def load_model() -> None:
    global _voice
    logger.info("Loading Piper TTS voice %s...", settings.piper_model)
    _voice = PiperVoice.load(settings.piper_model)
    logger.info("Piper TTS loaded.")


def _synthesize_sync(text: str) -> bytes:
    """Synthesize text to raw PCM 16-bit mono audio bytes."""
    assert _voice is not None, "Piper voice not loaded — call load_model() first"

    buf = io.BytesIO()
    with wave.open(buf, "wb") as wf:
        _voice.synthesize(text, wf)

    # Extract raw PCM from the WAV container
    buf.seek(0)
    with wave.open(buf, "rb") as wf:
        pcm_data = wf.readframes(wf.getnframes())

    logger.debug("Synthesized %d chars → %d bytes PCM", len(text), len(pcm_data))
    return pcm_data


async def synthesize(text: str) -> bytes:
    """Async wrapper — runs Piper in a thread pool."""
    loop = asyncio.get_running_loop()
    return await loop.run_in_executor(
        _executor,
        partial(_synthesize_sync, text),
    )