from ..API.expression import Expression
from .core.random_tree import RandomTree

DEFAUTL_CONFIG = {
    "rejected": [0, 1],
    "min_max": (-10, 10),
}


def expression_generator(
    template: str,
    conditions: list[str] = [],
    global_config: dict = {},
    configs: dict = {},
):
    """Generate a random expression

    :param template: the template of the expression
    :param conditions: conditions on randomly generate variable
    :param global_config: configuration for all variables
    :param configs: configuration for each variables
    :return: Expression or Token generated

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

    """
    rd_tree = RandomTree.from_str(template)
    generated_tree = rd_tree.generate(
        conditions, dict(DEFAUTL_CONFIG, **global_config), configs
    )
    return Expression._post_processing(generated_tree)