# Copyright CNRS/Inria/UNS
# Contributor(s): Eric Debreuve (since 2019), Morgane Nadal (2020)
#
# eric.debreuve@cnrs.fr
#
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import numpy as nmpy

from brick.type.base import array_t


def ImageVerification(image: array_t, channel: str, /) -> array_t:
    """
    Verification of the dimension of the image and of the coherence with the entered 'channel' parameter.
    """
    if nmpy.amax(image) == nmpy.amin(image):
        raise ValueError("The input image should not be constant.")

    # Verification of the dimension of the image and its coherence with the parameters (channel)
    elif image.ndim == 3:
        if channel is not None:
            print(
                "Warning: The image has only 3 dimensions. Give the channel the value None in the parameters."
            )
        return image

    elif image.ndim == 4:
        if channel == "R" or channel == "G" or channel == "B":
            # not changed into if --channel in 'RGB'-- because if channel='RG' => True.
            print("MULTIPLE CHANNELS: ", channel, " specified in the parameters.")

            image = image[:, :, :, "RGB".find(channel)]

            # The obtained image must not be constant
            if image.max() == image.min():
                raise ValueError(
                    "The input image should not be constant. Verify the channel parameter."
                )

            return image

        else:
            raise ValueError(
                "The image has multiple color channels. Error in the value of the parameter channel."
            )

    elif image.ndim != 4 and image.ndim != 3:
        raise ValueError(
            f"The image dimensions are not correct: {image.ndim}, instead of 3 or 4."
        )