from ..API.expression import Expression
from ..core.tree import Tree

def expression():
    """ Generate a random expression """
    pass

@classmethod
def random(
    cls,
    template,
    conditions=[],
    rejected=[0],
    min_max=(-10, 10),
    variables_scope={},
    shuffle=False,
):
    """ Initiate randomly the expression

    :param template: the template of the expression
    :param conditions: conditions on randomly generate variable
    :param rejected: Values to reject for all random variables
    :param min_max: Min and max value for all random variables
    :param variables_scope: Dictionnary for each random varaibles to fic rejected and min_max
    :param shuffle: allowing to shuffle the tree
    :returns: TODO

    :example:
    >>> e = Expression.random("{a}/{a*k}")
    >>> e # doctest: +SKIP
    <Exp: -3 / -15>
    >>> e = Expression.random("{a}/{a*k} - 3*{b}", variables_scope={'a':{'min_max':(10, 30)}})
    >>> e # doctest: +SKIP
    <Exp: 18 / 108 - 3 * 9>
    >>> e = Expression.random("{a}*x + {b}*x + 3", ["a>b"], rejected=[0, 1])
    >>> ee = e.simplify()
    >>> print(e) # doctest: +SKIP
    10x - 6x + 3
    >>> print(ee) # doctest: +SKIP
    4x + 3

    """
    rd_t = Tree.from_str(template)
    leafs = extract_rdleaf(rd_t)
    rd_varia = extract_rv(leafs)
    generated = random_generator(
        rd_varia, conditions, rejected, min_max, variables_scope
    )
    computed = compute_leafs(leafs, generated)
    t = replace_rdleaf(rd_t, computed).map_on_leaf(moify)

    if shuffle:
        raise NotImplemented("Can't suffle expression yet")

    return cls._post_processing(t)