__author__ = 'roland'


def find_paths(cls, arg, path=None, seen=None, res=None, lev=0):
    if lev == 0 and res is None:
        res = []

    if path is None:
        path = []

    if seen is None:
        seen = [cls]
    else:
        if cls in seen:
            return None

        seen.append(cls)

    for cn, c in cls.c_children.values():
        _path = path + [cn]
        if cn == arg:
            if res is not None:
                res.append(_path)
        else:
            if isinstance(c, list):
                _c = c[0]
            else:
                _c = c

            find_paths(_c, arg, _path, seen, res)

    for an, typ, mult in cls.c_attributes.values():
        if an == arg:
            if res is not None:
                res.append(path + [an])

    if lev == 0:
        return res


def set_arg(cls, arg, value):
    res = []
    for path in find_paths(cls, arg):
        x = y = {}
        for arc in path[:-1]:
            y[arc] = {}
            y = y[arc]
        y[path[-1]] = value
        res.append(x)

    return res


def add_path(tdict, path):
    """
    Create or extend an argument tree `tdict` from `path`.

    :param tdict: a dictionary representing a argument tree
    :param path: a path list
    :return: a dictionary

    Convert a list of items in a 'path' into a nested dict, where the
    second to last item becomes the key for the final item. The remaining
    items in the path become keys in the nested dict around that final pair
    of items.

    For example, for input values of:
        tdict={}
        path = ['assertion', 'subject', 'subject_confirmation',
                'method', 'urn:oasis:names:tc:SAML:2.0:cm:bearer']

        Returns an output value of:
           {'assertion': {'subject': {'subject_confirmation':
                         {'method': 'urn:oasis:names:tc:SAML:2.0:cm:bearer'}}}}

    Another example, this time with a non-empty tdict input:

        tdict={'method': 'urn:oasis:names:tc:SAML:2.0:cm:bearer'},
        path=['subject_confirmation_data', 'in_response_to', '_012345']

        Returns an output value of:
            {'subject_confirmation_data': {'in_response_to': '_012345'},
             'method': 'urn:oasis:names:tc:SAML:2.0:cm:bearer'}
    """
    t = tdict
    for step in path[:-2]:
        try:
            t = t[step]
        except KeyError:
            t[step] = {}
            t = t[step]
    t[path[-2]] = path[-1]

    return tdict


def is_set(tdict, path):
    """

    :param tdict: a dictionary representing a argument tree
    :param path: a path list
    :return: True/False if the value is set
    """
    t = tdict
    for step in path:
        try:
            t = t[step]
        except KeyError:
            return False

    if t is not None:
        return True

    return False


def get_attr(tdict, path):
    t = tdict
    for step in path:
        t = t[step]

    return t