"""
IPT Colourspace
===============

Define the *IPT* colourspace transformations and correlate computations.

-   :func:`colour.XYZ_to_IPT`
-   :func:`colour.IPT_to_XYZ`
-   :func:`colour.IPT_hue_angle`

References
----------
-   :cite:`Fairchild2013y` : Fairchild, M. D. (2013). IPT Colourspace. In
    Color Appearance Models (3rd ed., pp. 6197-6223). Wiley. ISBN:B00DAYO8E2
"""

from __future__ import annotations

from functools import partial

import numpy as np

from colour.algebra import spow
from colour.hints import (  # noqa: TC001
    Domain1,
    NDArrayFloat,
    Range1,
    Range360,
)
from colour.models import Iab_to_XYZ, XYZ_to_Iab
from colour.utilities import as_float, from_range_degrees, to_domain_1, tsplit

__author__ = "Colour Developers"
__copyright__ = "Copyright 2013 Colour Developers"
__license__ = "BSD-3-Clause - https://opensource.org/licenses/BSD-3-Clause"
__maintainer__ = "Colour Developers"
__email__ = "colour-developers@colour-science.org"
__status__ = "Production"

__all__ = [
    "MATRIX_IPT_XYZ_TO_LMS",
    "MATRIX_IPT_LMS_TO_XYZ",
    "MATRIX_IPT_LMS_P_TO_IPT",
    "MATRIX_IPT_IPT_TO_LMS_P",
    "XYZ_to_IPT",
    "IPT_to_XYZ",
    "IPT_hue_angle",
]

MATRIX_IPT_XYZ_TO_LMS: NDArrayFloat = np.array(
    [
        [0.4002, 0.7075, -0.0807],
        [-0.2280, 1.1500, 0.0612],
        [0.0000, 0.0000, 0.9184],
    ]
)
"""*CIE XYZ* tristimulus values to normalised cone responses matrix."""

MATRIX_IPT_LMS_TO_XYZ: NDArrayFloat = np.linalg.inv(MATRIX_IPT_XYZ_TO_LMS)
"""Normalised cone responses to *CIE XYZ* tristimulus values matrix."""

MATRIX_IPT_LMS_P_TO_IPT: NDArrayFloat = np.array(
    [
        [0.4000, 0.4000, 0.2000],
        [4.4550, -4.8510, 0.3960],
        [0.8056, 0.3572, -1.1628],
    ]
)
"""Normalised non-linear cone responses to *IPT* colourspace matrix."""

MATRIX_IPT_IPT_TO_LMS_P: NDArrayFloat = np.linalg.inv(MATRIX_IPT_LMS_P_TO_IPT)
"""*IPT* colourspace to normalised non-linear cone responses matrix."""


def XYZ_to_IPT(XYZ: Domain1) -> Range1:
    """
    Convert from *CIE XYZ* tristimulus values to *IPT* colourspace.

    Parameters
    ----------
    XYZ
        *CIE XYZ* tristimulus values.

    Returns
    -------
    :class:`numpy.ndarray`
        *IPT* colourspace array.

    Notes
    -----
    +------------+-----------------------+-----------------+
    | **Domain** | **Scale - Reference** | **Scale - 1**   |
    +============+=======================+=================+
    | ``XYZ``    | 1                     | 1               |
    +------------+-----------------------+-----------------+

    +------------+-----------------------+-----------------+
    | **Range**  | **Scale - Reference** | **Scale - 1**   |
    +============+=======================+=================+
    | ``IPT``    | 1                     | 1               |
    +------------+-----------------------+-----------------+

    -   Input *CIE XYZ* tristimulus values must be adapted to
        *CIE Standard Illuminant D Series* *D65*.

    References
    ----------
    :cite:`Fairchild2013y`

    Examples
    --------
    >>> XYZ = np.array([0.20654008, 0.12197225, 0.05136952])
    >>> XYZ_to_IPT(XYZ)  # doctest: +ELLIPSIS
    array([ 0.3842619...,  0.3848730...,  0.1888683...])
    """

    return XYZ_to_Iab(
        XYZ,
        partial(spow, p=0.43),
        MATRIX_IPT_XYZ_TO_LMS,
        MATRIX_IPT_LMS_P_TO_IPT,
    )


def IPT_to_XYZ(IPT: Domain1) -> Range1:
    """
    Convert from *IPT* colourspace to *CIE XYZ* tristimulus values.

    Parameters
    ----------
    IPT
        *IPT* colourspace array.

    Returns
    -------
    :class:`numpy.ndarray`
        *CIE XYZ* tristimulus values.

    Notes
    -----
    +------------+-----------------------+-----------------+
    | **Domain** | **Scale - Reference** | **Scale - 1**   |
    +============+=======================+=================+
    | ``IPT``    | 1                     | 1               |
    +------------+-----------------------+-----------------+

    +------------+-----------------------+-----------------+
    | **Range**  | **Scale - Reference** | **Scale - 1**   |
    +============+=======================+=================+
    | ``XYZ``    | 1                     | 1               |
    +------------+-----------------------+-----------------+

    -   Output *CIE XYZ* tristimulus values are adapted to
        *CIE Standard Illuminant D Series* *D65*.

    References
    ----------
    :cite:`Fairchild2013y`

    Examples
    --------
    >>> IPT = np.array([0.38426191, 0.38487306, 0.18886838])
    >>> IPT_to_XYZ(IPT)  # doctest: +ELLIPSIS
    array([ 0.2065400...,  0.1219722...,  0.0513695...])
    """

    return Iab_to_XYZ(
        IPT,
        partial(spow, p=1 / 0.43),
        MATRIX_IPT_IPT_TO_LMS_P,
        MATRIX_IPT_LMS_TO_XYZ,
    )


def IPT_hue_angle(IPT: Domain1) -> Range360:
    """
    Compute the hue angle in degrees from the *IPT* colourspace array.

    Parameters
    ----------
    IPT
        *IPT* colourspace array.

    Returns
    -------
    :class:`numpy.ndarray`
        Hue angle in degrees.

    Notes
    -----
    +------------+-----------------------+-----------------+
    | **Domain** | **Scale - Reference** | **Scale - 1**   |
    +============+=======================+=================+
    | ``IPT``    | 1                     | 1               |
    +------------+-----------------------+-----------------+

    +------------+-----------------------+-----------------+
    | **Range**  | **Scale - Reference** | **Scale - 1**   |
    +============+=======================+=================+
    | ``hue``    | 360                   | 1               |
    +------------+-----------------------+-----------------+

    References
    ----------
    :cite:`Fairchild2013y`

    Examples
    --------
    >>> IPT = np.array([0.96907232, 1, 1.12179215])
    >>> IPT_hue_angle(IPT)  # doctest: +ELLIPSIS
    48.2852074...
    """

    _I, P, T = tsplit(to_domain_1(IPT))

    hue = np.degrees(np.arctan2(T, P)) % 360

    return as_float(from_range_degrees(hue))