"""
Antialiasing and feathering
"""

import numpy as np
import cv2


def apply_antialiasing(mask: np.ndarray, feather_amount: float = 0.0) -> np.ndarray:
    """
    Apply Gaussian blur for antialiasing/feathering.
    
    Args:
        mask: Binary mask (0-255)
        feather_amount: Amount of feathering to apply (0.0 = no blur, max 100.0)
        
    Returns:
        Smoothed mask (0-255)
    """
    # If feather_amount is 0 or invalid, return mask unchanged
    if feather_amount <= 0.0 or not isinstance(feather_amount, (int, float)) or not np.isfinite(feather_amount):
        return mask
    
    # Clamp feather_amount to valid range
    feather_amount = float(np.clip(feather_amount, 0.0, 100.0))
    
    # Calculate kernel size: 6 * sigma + 1, ensure it's odd and >= 3
    kernel_size = int(6 * feather_amount + 1)
    if kernel_size % 2 == 0:
        kernel_size += 1
    kernel_size = max(3, kernel_size)  # Minimum kernel size for cv2.GaussianBlur
    
    # Use feather_amount as sigma
    sigma = float(feather_amount)
    
    return cv2.GaussianBlur(mask, (kernel_size, kernel_size), sigma)