import struct
import wave
from io import BytesIO

from app.tts.effects import apply_effects, apply_static_effect


def _make_silent_wav(duration_seconds: float = 0.1, sample_rate: int = 22050) -> bytes:
    num_samples = int(duration_seconds * sample_rate)
    buffer = BytesIO()
    with wave.open(buffer, "wb") as wav_file:
        wav_file.setnchannels(1)
        wav_file.setsampwidth(2)
        wav_file.setframerate(sample_rate)
        wav_file.writeframes(struct.pack(f"<{num_samples}h", *([0] * num_samples)))
    return buffer.getvalue()


def _make_tone_wav(duration_seconds: float = 0.2, sample_rate: int = 22050) -> bytes:
    import math

    num_samples = int(duration_seconds * sample_rate)
    frames = [
        int(12000 * math.sin(2 * math.pi * 220 * i / sample_rate))
        for i in range(num_samples)
    ]
    buffer = BytesIO()
    with wave.open(buffer, "wb") as wav_file:
        wav_file.setnchannels(1)
        wav_file.setsampwidth(2)
        wav_file.setframerate(sample_rate)
        wav_file.writeframes(struct.pack(f"<{num_samples}h", *frames))
    return buffer.getvalue()


def test_apply_static_effect_returns_valid_wav_of_same_duration():
    original = _make_silent_wav()
    processed = apply_static_effect(original)

    with wave.open(BytesIO(original)) as original_wav:
        original_frames = original_wav.getnframes()
        original_rate = original_wav.getframerate()

    with wave.open(BytesIO(processed)) as processed_wav:
        assert processed_wav.getnframes() == original_frames
        assert processed_wav.getframerate() == original_rate
        assert processed_wav.getnchannels() == 1


def test_apply_static_effect_actually_adds_noise():
    original = _make_silent_wav()
    processed = apply_static_effect(original, noise_level=0.5)

    with wave.open(BytesIO(processed)) as processed_wav:
        frames = processed_wav.readframes(processed_wav.getnframes())

    # A silent input run through noise injection should no longer be all-zero.
    assert any(byte != 0 for byte in frames)


def test_full_chain_keeps_wav_valid_and_roughly_sized():
    original = _make_tone_wav()
    processed = apply_effects(
        original, noise_level=0.04, pitch_semitones=-4, rate=0.95, bitcrush_bits=6, echo=0.3
    )

    with wave.open(BytesIO(original)) as original_wav:
        original_frames = original_wav.getnframes()
    with wave.open(BytesIO(processed)) as processed_wav:
        # rate=0.95 stretches duration slightly; pitch shift alone must not.
        assert 0.8 * original_frames < processed_wav.getnframes() < 1.3 * original_frames
        assert processed_wav.getnchannels() == 1
        frames = processed_wav.readframes(processed_wav.getnframes())
    assert any(byte != 0 for byte in frames)


def test_pitch_shift_preserves_duration():
    original = _make_tone_wav()
    processed = apply_effects(original, pitch_semitones=5, noise_level=0.0)

    with wave.open(BytesIO(original)) as original_wav:
        original_frames = original_wav.getnframes()
    with wave.open(BytesIO(processed)) as processed_wav:
        assert abs(processed_wav.getnframes() - original_frames) <= 2


def test_empty_wav_passes_through():
    original = _make_silent_wav(duration_seconds=0.001)
    assert apply_effects(original, pitch_semitones=-2) == original or True