"""Spectrogram DSP tests (synthetic signals, no ffmpeg)."""

from __future__ import annotations

import numpy as np

from extractors.features import spectrogram


def test_compute_features_on_tone():
    sr = 16_000
    t = np.linspace(0, 1.0, sr, endpoint=False)
    pcm = 0.5 * np.sin(2 * np.pi * 440 * t).astype(np.float32)
    feats = spectrogram.compute_features(pcm, sr)
    assert feats["sample_rate"] == sr
    assert abs(feats["duration_s"] - 1.0) < 0.01
    assert feats["spectral_centroid_hz_mean"] > 0
    assert feats["discontinuities_s"] == []


def test_detects_energy_discontinuity():
    sr = 16_000
    quiet = np.full(sr // 2, 0.001, dtype=np.float32)
    loud = (0.6 * np.sin(2 * np.pi * 300 * np.linspace(0, 0.5, sr // 2))).astype(
        np.float32
    )
    pcm = np.concatenate([quiet, loud])
    feats = spectrogram.compute_features(pcm, sr)
    assert len(feats["discontinuities_s"]) >= 1


def test_empty_signal():
    feats = spectrogram.compute_features(np.array([], dtype=np.float32), 16_000)
    assert feats["frames"] == 0