from typing import Union, Callable, Any
import operator

from inspect import signature, Parameter


class ModelFactory:

    @staticmethod
    def create_from_list(funcs: list, left=None, func_order=None, param_len=None, left_cnt=None):
        if func_order is None:
            func_order = []

        if param_len is None:
            param_len = []

        for func in funcs:
            if not func['active']:
                continue

            func_order.append(func['cnt'])
            param_len.append(len(func['func'].params))

            if func['children']:
                right, _, _ = ModelFactory.create_from_list(func['children'], left=func['func'], left_cnt=func['pos'],
                                                            func_order=func_order, param_len=param_len)
                right_cnt = None
            else:
                right = func['func']
                right_cnt = func['pos']

            if left is None:
                left = right
                left_cnt = right_cnt
            else:
                left = MultiModel(left, right, func['op'],
                                  left_idx=left_cnt, right_idx=right_cnt)

        return left, func_order, param_len


class MultiModel:
    op_repr = {operator.add: ' + ', operator.mul: ' * ', operator.sub: ' - ', operator.truediv: ' / '}
    str_op = {'+': operator.add, '*': operator.mul, '-': operator.sub, '/': operator.truediv}
    int_op = {0: operator.add, 1: operator.mul, 2: operator.sub, 3: operator.truediv}

    def __init__(self, left: Any, right: Any, op: Union[str, Callable, int] = '+', left_idx=0, right_idx=1):
        self._left = left
        self._right = right

        self._op = None

        if isinstance(op, str):
            self._op = MultiModel.str_op.get(op, None)
        elif isinstance(op, int):
            self._op = MultiModel.int_op.get(op, None)
        elif isinstance(op, Callable):
            self._op = op

        if self._op is None:
            raise ValueError('Invalid binary operator.')

        self.name = '('
        self.params = []
        self.bounds = []
        self._kwargs_right = {}
        self._kwargs_left = {}
        self._fun_kwargs = {}

        # mapping kwargs to kwargs of underlying functions
        self._ext_int_kw = {}

        self._get_parameter(left, 'l', left_idx)
        self._param_left = len(left.params)

        try:
            self.name += MultiModel.op_repr[self._op]
        except KeyError:
            self.name += str(op)

        self._get_parameter(right, 'r', right_idx)
        self.name += ')'

        self._param_len = len(self.params)

    def __str__(self):
        return self.name

    def _get_parameter(self, func, pos, idx):
        kw_dict = {'l': self._kwargs_left, 'r': self._kwargs_right}[pos]

        if isinstance(func, MultiModel):
            strcnt = ''
            kw_dict.update(func.fun_kwargs)
            self._fun_kwargs.update({k: v for k, v in kw_dict.items()})
            self._ext_int_kw.update({k: k for k in kw_dict.keys()})

        else:
            temp_dic = {k: v.default for k, v in signature(func.func).parameters.items()
                        if v.default is not Parameter.empty}

            for k, v in temp_dic.items():
                key_ = '%s_%d' % (k, idx)
                kw_dict[key_] = v
                self._fun_kwargs[key_] = v
                self._ext_int_kw[key_] = k

            strcnt = '(%d)' % idx

        self.params += [pp+strcnt for pp in func.params]
        self.name += func.name + strcnt

        try:
            self.bounds.extend(func.bounds)
        except AttributeError:
            self.bounds.extend([(None, None)]*len(func.params))

    def _left_arguments(self, *args, **kwargs):
        kw_left = {k_int: kwargs[k_ext] for k_ext, k_int in self._ext_int_kw.items() if k_ext in self._kwargs_left}
        pl = args[:self._param_left]

        return pl, kw_left

    def _right_arguments(self, *args, **kwargs):
        kw_right = {k_int: kwargs[k_ext] for k_ext, k_int in self._ext_int_kw.items() if k_ext in self._kwargs_right}
        pr = args[self._param_left:self._param_len]

        return pr, kw_right

    def func(self, x, *args, **kwargs):
        pl, kw_left = self._left_arguments(*args, **kwargs)
        l_func = self._left.func(x, *pl, **kw_left)

        pr, kw_right = self._right_arguments(*args, **kwargs)
        r_func = self._right.func(x, *pr, **kw_right)

        return self._op(l_func, r_func)

    def left_func(self, x, *args, **kwargs):
        return self._left.func(x, *args, **kwargs)

    def right_func(self, x, *args, **kwargs):
        return self._right.func(x, *args, **kwargs)

    @property
    def fun_kwargs(self):
        return self._fun_kwargs

    def subs(self, x, *args, **kwargs):
        """ Iterator over all sub-functions (depth-first and left-to-right) """
        pl, kw_left = self._left_arguments(*args, **kwargs)
        if isinstance(self._left, MultiModel):
            yield from self._left.subs(x, *pl, **kw_left)
        else:
            yield self._left.func(x, *pl, **kw_left)

        pr, kw_right = self._right_arguments(*args, **kwargs)
        if isinstance(self._right, MultiModel):
            yield from self._right.subs(x, *pr, **kw_right)
        else:
            yield self._right.func(x, *pr, **kw_right)