#!/usr/bin/env python
# encoding: utf-8

from .render import tex, txt

__all__ = ['Renderable']

class Renderable(object):
    """
    A Renderable object is an object which can work with Render class. It means that it has to have attribute postfix_tokens.
    """
    STR_RENDER = tex
    DEFAULT_RENDER = tex

    @classmethod
    def set_render(cls, render):
        cls.STR_RENDER = render

    @classmethod
    def get_render(cls):
        return cls.STR_RENDER

    @classmethod
    def set_default_render(cls):
        cls.set_render(cls.DEFAULT_RENDER)

    @classmethod
    def tmp_render(cls, render=tex):
        """ Create a container in which Expression render is temporary modify

        The default temporary render is Expression in order to perform calculus inside numbers

        >>> from .expression import Expression
        >>> from .explicable import Explicable
        >>> exp = Expression("2*3/5")
        >>> print(exp)
        2 \\times \\frac{ 3 }{ 5 }
        >>> for i in exp.simplify().explain():
        ...     print(i)
        2 \\times \\frac{ 3 }{ 5 }
        \\frac{ 3 }{ 5 } \\times 2
        \\frac{ 3 \\times 2 }{ 5 }
        \\frac{ 6 }{ 5 }
        >>> with Explicable.tmp_render(txt):
        ...     for i in exp.simplify().explain():
        ...         print(i)
        2 * 3 / 5
        3 / 5 * 2
        ( 3 * 2 ) / 5
        6 / 5
        >>> for i in exp.simplify().explain():
        ...     print(i)
        2 \\times \\frac{ 3 }{ 5 }
        \\frac{ 3 }{ 5 } \\times 2
        \\frac{ 3 \\times 2 }{ 5 }
        \\frac{ 6 }{ 5 }

        # TODO: essayer de ne pas afficher ce changement de position. |lun. avril  6 17:29:56 CEST 2015

        """
        class TmpRenderEnv(object):

            def __enter__(self):
                self.old_render = Renderable.get_render()
                Renderable.set_render(render)

            def __exit__(self, type, value, traceback):
                Renderable.set_render(self.old_render)
        return TmpRenderEnv()

    def __init__(self, pstf_tokens):
        """Initiate the renderable objet

        :param pstf_tokens: the postfix list of tokens

        """
        self.postfix_tokens = pstf_tokens

    def __str__(self):
        """
        Overload str

        If you want to changer render use Expression.set_render(...) or use tmp_render context manager.
        """
        return self.STR_RENDER(self.postfix_tokens)

    def __repr__(self):
        return  "< {cls} {pstf_tokens}>".format(
                cls = str(self.__class__).split('.')[-1][:-2],
                pstf_tokens = str(self.postfix_tokens)
                )

    def __eq__(self, other):
        """ Two Renderable objects are the same if they have same postfix_tokens """
        try:
            return self.postfix_tokens == other.postfix_tokens
        except AttributeError:
            return False

    def __txt__(self):
        try:
            return txt(self.postfix_tokens)
        except AttributeError:
            return self

    def __tex__(self):
        try:
            return tex(self.postfix_tokens)
        except AttributeError:
            return self


# -----------------------------
# Reglages pour 'vim'
# vim:set autoindent expandtab tabstop=4 shiftwidth=4:
# cursor: 16 del