"""Logic for applying validations to an image."""

from PIL import Image

from constants import errors
from constants import image_standards
from src import image_validator


class InvalidImageError(Exception):
    """Exception class for image validation errors."""

    def __init__(self, message, code):
        """Init."""
        Exception.__init__(self, message)
        self._code = code

    @property
    def code(self):
        """Error code."""
        return self._code


def validate_image(
    *,
    file_contents
):
    """Validate the contents of an image.

    Args:
        file_contents (io.BytesIO): Image file contents.

    Returns:
        bool: True if validation is successful.
    Raises:
        Exception: If a validation fails.
    """
    file_contents.seek(0)
    image = Image.open(file_contents)

    if not image_validator.validate_mode(image.mode):
        raise InvalidImageError(
            message=errors.ERROR_MESSAGES[errors.IMAGE_INVALID_MODE_CODE].format(mode=image.mode),
            code=errors.IMAGE_INVALID_MODE_CODE
        )

    if not image_validator.validate_is_opaque(image):
        raise InvalidImageError(
            message=errors.ERROR_MESSAGES[errors.IMAGE_NOT_OPAQUE_CODE],
            code=errors.IMAGE_NOT_OPAQUE_CODE
        )

    width, height = image.size

    validation_result = image_validator.validate_dimensions(
        width=width,
        height=height,
    )

    if validation_result != image_standards.VALID_DIMENSIONS_CODE:
        raise InvalidImageError(
            message=errors.ERROR_MESSAGES[validation_result],
            code=validation_result
        )

    return True