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"""Abstraction of OpenGL context.

It defines a way to get current OpenGL context to support multiple
OpenGL contexts.
"""

__authors__ = ["T. Vincent"]
__license__ = "MIT"
__date__ = "25/07/2016"

import contextlib


class _DEFAULT_CONTEXT(object):
    """The default value for OpenGL context"""

    pass


_context = _DEFAULT_CONTEXT
"""The current OpenGL context"""


def getCurrent():
    """Returns platform dependent object of current OpenGL context.

    This is useful to associate OpenGL resources with the context they are
    created in.

    :return: Platform specific OpenGL context
    """
    return _context


def setCurrent(context=_DEFAULT_CONTEXT):
    """Set a platform dependent OpenGL context

    :param context: Platform dependent GL context
    """
    global _context
    _context = context


@contextlib.contextmanager
def current(context):
    """Context manager setting the platform-dependent GL context

    :param context: Platform dependent GL context
    """
    previous_context = getCurrent()
    setCurrent(context)
    yield
    setCurrent(previous_context)
