# -*- coding: utf-8 -*-
"""
Viper Log Encoding
==================

Defines the *Viper Log* encoding:

-   :func:`colour.models.log_encoding_ViperLog`
-   :func:`colour.models.log_decoding_ViperLog`

See Also
--------
`RGB Colourspaces Jupyter Notebook
<http://nbviewer.jupyter.org/github/colour-science/colour-notebooks/\
blob/master/notebooks/models/rgb.ipynb>`_

References
----------
-   :cite:`SonyImageworks2012a` : Sony Imageworks. (2012). make.py. Retrieved
    November 27, 2014, from https://github.com/imageworks/OpenColorIO-Configs/\
blob/master/nuke-default/make.py
"""

from __future__ import division, unicode_literals

import numpy as np

from colour.utilities import from_range_1, to_domain_1

__author__ = 'Colour Developers'
__copyright__ = 'Copyright (C) 2013-2020 - Colour Developers'
__license__ = 'New BSD License - https://opensource.org/licenses/BSD-3-Clause'
__maintainer__ = 'Colour Developers'
__email__ = 'colour-developers@colour-science.org'
__status__ = 'Production'

__all__ = ['log_encoding_ViperLog', 'log_decoding_ViperLog']


def log_encoding_ViperLog(x):
    """
    Defines the *Viper Log* log encoding curve / opto-electronic transfer
    function.

    Parameters
    ----------
    x : numeric or array_like
        Linear data :math:`x`.

    Returns
    -------
    numeric or ndarray
        Non-linear data :math:`y`.

    Notes
    -----

    +------------+-----------------------+---------------+
    | **Domain** | **Scale - Reference** | **Scale - 1** |
    +============+=======================+===============+
    | ``x``      | [0, 1]                | [0, 1]        |
    +------------+-----------------------+---------------+

    +------------+-----------------------+---------------+
    | **Range**  | **Scale - Reference** | **Scale - 1** |
    +============+=======================+===============+
    | ``y``      | [0, 1]                | [0, 1]        |
    +------------+-----------------------+---------------+

    References
    ----------
    :cite:`SonyImageworks2012a`

    Examples
    --------
    >>> log_encoding_ViperLog(0.18)  # doctest: +ELLIPSIS
    0.6360080...
    """

    x = to_domain_1(x)

    y = (1023 + 500 * np.log10(x)) / 1023

    return from_range_1(y)


def log_decoding_ViperLog(y):
    """
    Defines the *Viper Log* log decoding curve / electro-optical transfer
    function.

    Parameters
    ----------
    y : numeric or array_like
        Non-linear data :math:`y`.

    Returns
    -------
    numeric or ndarray
        Linear data :math:`x`.

    Notes
    -----

    +------------+-----------------------+---------------+
    | **Domain** | **Scale - Reference** | **Scale - 1** |
    +============+=======================+===============+
    | ``y``      | [0, 1]                | [0, 1]        |
    +------------+-----------------------+---------------+

    +------------+-----------------------+---------------+
    | **Range**  | **Scale - Reference** | **Scale - 1** |
    +============+=======================+===============+
    | ``x``      | [0, 1]                | [0, 1]        |
    +------------+-----------------------+---------------+

    References
    ----------
    :cite:`SonyImageworks2012a`

    Examples
    --------
    >>> log_decoding_ViperLog(0.636008067010413)  # doctest: +ELLIPSIS
    0.1799999...
    """

    y = to_domain_1(y)

    x = 10 ** ((1023 * y - 1023) / 500)

    return from_range_1(x)
