"""PCM 归一化与 WAV 封装。"""

from __future__ import annotations

import array

import pytest

from app.services.audio_wav import (
    WavDecodeError,
    normalize_pcm_s16le_for_baidu,
    pcm_s16le_to_wav_bytes,
    wav_bytes_to_pcm16k_mono_s16le,
)


def test_normalize_boosts_quiet_pcm() -> None:
    samples = array.array("h", [50, -80, 30] * 500)
    pcm = samples.tobytes()
    out = normalize_pcm_s16le_for_baidu(pcm)
    arr = array.array("h")
    arr.frombytes(out)
    assert max(abs(x) for x in arr) > max(abs(x) for x in samples)


def test_normalize_skips_loud_pcm() -> None:
    samples = array.array("h", [15000, -14000])
    pcm = samples.tobytes()
    out = normalize_pcm_s16le_for_baidu(pcm)
    assert out == pcm


def test_pcm_wav_roundtrip_is_valid_wav() -> None:
    pcm = array.array("h", [100, -200, 300] * 100).tobytes()
    wav = pcm_s16le_to_wav_bytes(pcm)
    back = wav_bytes_to_pcm16k_mono_s16le(wav)
    assert len(back) == len(pcm)
    assert max(abs(x) for x in array.array("h", back)) >= max(
        abs(x) for x in array.array("h", pcm)
    )


def test_pcm_s16le_to_wav_empty_raises() -> None:
    with pytest.raises(WavDecodeError):
        pcm_s16le_to_wav_bytes(b"")