#    _____           ______  _____
#  / ____/    /\    |  ____ |  __ \
# | |        /  \   | |__   | |__) | Caer - Modern Computer Vision
# | |       / /\ \  |  __|  |  _  /  Languages: Python, C, C++, Cuda
# | |___   / ____ \ | |____ | | \ \  http://github.com/jasmcaus/caer
#  \_____\/_/    \_ \______ |_|  \_\

# Licensed under the MIT License <http://opensource.org/licenses/MIT>
# SPDX-License-Identifier: MIT
# Copyright (c) 2020-2021 The Caer Authors <http://github.com/jasmcaus>


import cv2 as cv

from ..coreten import Tensor, to_tensor
from ._constants import BGR2RGB, BGR2GRAY, BGR2HSV, BGR2LAB, BGR2HLS, BGR2YUV, BGR2LUV

__all__ = [
    "bgr2gray",
    "bgr2hsv",
    "bgr2lab",
    "bgr2rgb",
    "bgr2hls",
    "bgr2yuv",
    "bgr2luv",
]


def _is_bgr_image(tens):
    # tens = to_tensor(tens)
    # return tens.is_bgr()
    return len(tens.shape) == 3 and tens.shape[-1] == 3


def bgr2rgb(tens: Tensor) -> Tensor:
    r"""
        Converts a BGR Tensor to its RGB version.

    Args:
        tens (Tensor): Valid BGR Tensor

    Returns:
        RGB Tensor of shape ``(height, width, channels)``

    Raises:
        ValueError: If `tens` is not of shape 3

    """
    if not _is_bgr_image(tens):
        raise ValueError(
            f"Tensor of shape 3 expected. Found shape {len(tens.shape)}. "
            "This function converts a BGR Tensor to its RGB counterpart"
        )

    img = cv.cvtColor(tens, BGR2RGB)
    return to_tensor(img, cspace="rgb")


def bgr2gray(tens: Tensor) -> Tensor:
    r"""
        Converts a BGR Tensor to its Grayscale version.

    Args:
        tens (Tensor): Valid BGR Tensor

    Returns:
        Grayscale Tensor of shape ``(height, width, channels)``

    Raises:
        ValueError: If `tens` is not of shape 3

    """
    if not _is_bgr_image(tens):
        raise ValueError(
            f"Tensor of shape 3 expected. Found shape {len(tens.shape)}. "
            "This function converts a BGR Tensor to its Grayscale counterpart"
        )

    tens = to_tensor(tens)
    tens._nullprt()  # raises a ValueError if we're dealing with a Foreign Tensor with illegal `.cspace` value

    img = cv.cvtColor(tens, BGR2GRAY)
    return to_tensor(img, cspace="gray")


def bgr2hsv(tens: Tensor) -> Tensor:
    r"""
        Converts a BGR Tensor to its HSV version.

    Args:
        tens (Tensor): Valid BGR Tensor

    Returns:
        HSV Tensor of shape ``(height, width, channels)``

    Raises:
        ValueError: If `tens` is not of shape 3

    """
    if not _is_bgr_image(tens):
        raise ValueError(
            f"Tensor of shape 3 expected. Found shape {len(tens.shape)}. "
            "This function converts a BGR Tensor to its HSV counterpart"
        )

    img = cv.cvtColor(tens, BGR2HSV)
    return to_tensor(img, cspace="hsv")


def bgr2lab(tens: Tensor) -> Tensor:
    r"""
        Converts a BGR Tensor to its LAB version.

    Args:
        tens (Tensor): Valid BGR Tensor

    Returns:
        LAB Tensor of shape ``(height, width, channels)``

    Raises:
        ValueError: If `tens` is not of shape 3

    """
    if not _is_bgr_image(tens):
        raise ValueError(
            f"Tensor of shape 3 expected. Found shape {len(tens.shape)}. "
            "This function converts a BGR Tensor to its LAB counterpart"
        )

    img = cv.cvtColor(tens, BGR2LAB)
    return to_tensor(img, cspace="lab")


def bgr2hls(tens: Tensor) -> Tensor:
    r"""
        Converts a BGR Tensor to its HLS version.

    Args:
        tens (Tensor): Valid BGR Tensor

    Returns:
        HLS Tensor of shape ``(height, width, channels)``

    Raises:
        ValueError: If `tens` is not of shape 3

    """
    if not _is_bgr_image(tens):
        raise ValueError(
            f"Tensor of shape 3 expected. Found shape {len(tens.shape)}. "
            "This function converts a BGR Tensor to its HLS counterpart"
        )

    img = cv.cvtColor(tens, BGR2HLS)
    return to_tensor(img, cspace="hls")


def bgr2yuv(tens: Tensor) -> Tensor:
    r"""
        Converts a BGR Tensor to its YUV version.

    Args:
        tens (Tensor): Valid BGR Tensor

    Returns:
        YUV Tensor of shape ``(height, width, channels)``

    Raises:
        ValueError: If `tens` is not of shape 3

    """
    if not _is_bgr_image(tens):
        raise ValueError(
            f"Tensor of shape 3 expected. Found shape {len(tens.shape)}. "
            "This function converts a BGR Tensor to its YUV counterpart"
        )

    img = cv.cvtColor(tens, BGR2YUV)
    return to_tensor(img, cspace="yuv")


def bgr2luv(tens: Tensor) -> Tensor:
    r"""
        Converts a BGR Tensor to its LUV version.

    Args:
        tens (Tensor): Valid BGR Tensor

    Returns:
        YUV Tensor of shape ``(height, width, channels)``

    Raises:
        ValueError: If `tens` is not of shape 3

    """
    if not _is_bgr_image(tens):
        raise ValueError(
            f"Tensor of shape 3 expected. Found shape {len(tens.shape)}. "
            "This function converts a BGR Tensor to its LUV counterpart"
        )

    img = cv.cvtColor(tens, BGR2LUV)
    return to_tensor(img, cspace="luv")
