import json
import os
import tempfile
import numpy as np
import pytest
from pathlib import Path

from fft_analysis import io_utils


def test_load_audio_file_wav(monkeypatch):
    # Mock scipy.io.wavfile.read to return synthetic data
    import scipy.io.wavfile as wavfile

    sample_rate = 44100
    data = np.array([0, 32767, -32768], dtype=np.int16)

    def mock_read(file_path):
        assert isinstance(file_path, (str, Path))
        return sample_rate, data

    monkeypatch.setattr(wavfile, 'read', mock_read)

    arr, sr = io_utils.load_audio_file("dummy.wav")
    assert isinstance(arr, np.ndarray)
    assert sr == sample_rate
    assert np.allclose(arr, data.astype(np.float32) / np.max(np.abs(data)))


def test_load_audio_file_invalid_path():
    with pytest.raises(FileNotFoundError):
        io_utils.load_audio_file("nonexistent_path.wav")


def test_save_spectrum_to_json_and_verify(tmp_path):
    spectrum = np.array([0.1, 0.5, 0.9, 0.2])
    output_file = tmp_path / "spectrum.json"

    io_utils.save_spectrum_to_json(spectrum, str(output_file))

    assert output_file.exists()

    with open(output_file, "r", encoding="utf-8") as f:
        data = json.load(f)

    assert isinstance(data, dict)
    assert 'frequencies' in data and 'magnitudes' in data
    assert isinstance(data['frequencies'], list)
    assert isinstance(data['magnitudes'], list)
    assert len(data['frequencies']) == len(data['magnitudes']) == len(spectrum)


def test_save_spectrum_to_json_invalid_path():
    spectrum = np.array([0.1, 0.2, 0.3])
    invalid_path = "/invalid_directory/output.json"

    with pytest.raises((OSError, IOError)):
        io_utils.save_spectrum_to_json(spectrum, invalid_path)


def test_load_audio_file_normalization(monkeypatch):
    import scipy.io.wavfile as wavfile

    sample_rate = 48000
    data = np.array([0, 1000, -1000], dtype=np.int16)

    def mock_read(file_path):
        return sample_rate, data

    monkeypatch.setattr(wavfile, 'read', mock_read)

    arr, sr = io_utils.load_audio_file("file.wav")

    assert sr == sample_rate
    assert np.isclose(np.max(arr), 1.0, atol=0.01) or np.isclose(np.max(arr), 0.0)
    assert np.isclose(np.min(arr), -1.0, atol=0.01) or np.isclose(np.min(arr), 0.0)