import numpy as np
import pytest

scipy_signal = pytest.importorskip("scipy.signal")

from client.audio import resample_24k_to_16k


def test_length_and_dtype():
    frame = np.zeros(1920, dtype=np.int16)
    out = resample_24k_to_16k(frame)
    assert out.shape == (1280,)
    assert out.dtype == np.int16


def test_constant_signal_stays_constant():
    frame = np.full(1920, 1000, dtype=np.int16)
    out = resample_24k_to_16k(frame)
    # poly resample of a constant is the same constant up to filter ringing
    assert np.abs(out.astype(int).mean() - 1000) < 5


def test_silence_in_silence_out():
    frame = np.zeros(1920, dtype=np.int16)
    out = resample_24k_to_16k(frame)
    assert int(np.max(np.abs(out))) == 0


def test_sine_peak_frequency_preserved():
    # 1 kHz sine at 24 kHz: 80 ms = 80 cycles.
    t = np.arange(1920) / 24_000.0
    sig = (8000 * np.sin(2 * np.pi * 1000 * t)).astype(np.int16)
    out = resample_24k_to_16k(sig)
    # 1 kHz in a 1280-sample 16 kHz window is bin (1000 / 16000) * 1280 = 80.
    spec = np.abs(np.fft.rfft(out.astype(np.float32)))
    peak = int(np.argmax(spec))
    assert abs(peak - 80) <= 1


def test_zero_length_input_raises():
    with pytest.raises(ValueError):
        resample_24k_to_16k(np.zeros(0, dtype=np.int16))


def test_wrong_dtype_rejected():
    with pytest.raises(TypeError):
        resample_24k_to_16k(np.zeros(1920, dtype=np.float32))