import numpy as np


def apply_fade(audio: np.ndarray, sample_rate: int = 24000, fade_duration_ms: int = 300) -> np.ndarray:
    """Apply fade-in and fade-out to audio array.

    Args:
        audio: numpy array of audio samples
        sample_rate: audio sample rate in Hz
        fade_duration_ms: fade duration in milliseconds

    Returns:
        Audio array with fade applied
    """
    if len(audio) == 0:
        return audio

    fade_samples = int(sample_rate * fade_duration_ms / 1000)
    fade_samples = min(fade_samples, len(audio) // 4)

    if fade_samples <= 0:
        return audio

    # Create fade envelope
    fade_in = np.linspace(0, 1, fade_samples)
    fade_out = np.linspace(1, 0, fade_samples)

    # Apply fade-in
    audio[:fade_samples] *= fade_in

    # Apply fade-out
    audio[-fade_samples:] *= fade_out

    return audio