"""This module contains image validation methods."""
import numpy as np

from constants import errors
from constants import image_standards


def validate_dimensions(*, width, height):
    """Check image dimensions for cover images.

    Args:
        width (int): Image width.
        height (int): Image height.

    Returns:
        str: The result of image dimensions validation.
             Error code in case of an error

    """
    if width != height:
        return errors.IMAGE_WRONG_ASPECT_RATIO_CODE
    if width < image_standards.MIN_IMAGE_DIMENSION:
        return errors.IMAGE_TOO_SMALL_DIMENSIONS_CODE
    if width > image_standards.MAX_IMAGE_DIMENSION:
        return errors.IMAGE_TOO_LARGE_DIMENSIONS_CODE
    return image_standards.VALID_DIMENSIONS_CODE


def validate_mode(mode):
    """Check image mode.

    https://pillow.readthedocs.io/en/5.2.x/handbook/concepts.html#concept-modes

    Args:
        mode (str): image mode value

    Returns:
        bool: True if mode is valid, False otherwise
    """
    return mode in image_standards.VALID_MODES


def validate_is_opaque(image):
    """Check if an image is fully opaque.

    Args:
        image (PIL.Image.Image): Image to check.

    Returns:
        bool: True if image is fully opaque, False otherwise.
    """
    if image.mode in image_standards.VALID_MODES_WITHOUT_ALPHA_CHANNEL:
        return True

    if image.mode in image_standards.VALID_MODES_WITH_ALPHA_CHANNEL - {'RGBA'}:
        image = image.convert('RGBA')

    np_img = np.array(image)

    return np.all(np_img[:, :, 3] == 255)