"""PCM helpers for Bonvoice media (from test_bonvoice/audio_utils.py)."""

import audioop
import wave
from pathlib import Path

TARGET_RATE = 8000
CHUNK_SIZE = 320


def wav_to_pcm8000_mono(path: str | Path) -> bytes:
    path = Path(path)
    with wave.open(str(path), "rb") as wf:
        channels = wf.getnchannels()
        sample_width = wf.getsampwidth()
        frame_rate = wf.getframerate()
        pcm = wf.readframes(wf.getnframes())

    if sample_width != 2:
        raise ValueError(f"Expected 16-bit audio, got {sample_width * 8}-bit")

    if channels == 2:
        pcm = audioop.tomono(pcm, 2, 0.5, 0.5)
    elif channels != 1:
        raise ValueError(f"Unsupported channel count: {channels}")

    if frame_rate != TARGET_RATE:
        pcm, _ = audioop.ratecv(pcm, 2, 1, frame_rate, TARGET_RATE, None)

    return pcm


def chunk_pcm(pcm: bytes, chunk_size: int = CHUNK_SIZE) -> list[bytes]:
    chunks: list[bytes] = []
    for i in range(0, len(pcm), chunk_size):
        chunk = pcm[i : i + chunk_size]
        if len(chunk) < chunk_size:
            chunk = chunk + b"\x00" * (chunk_size - len(chunk))
        chunks.append(chunk)
    return chunks