# Copyright 2014 Pants project contributors (see CONTRIBUTORS.md).
# Licensed under the Apache License, Version 2.0 (see LICENSE).

from twitter.common.collections import OrderedSet
from twitter.common.dirutil.fileset import Fileset


def assert_list(
    obj,
    expected_type=str,
    can_be_none=True,
    default=(),
    key_arg=None,
    allowable=(list, Fileset, OrderedSet, set, tuple),
    raise_type=ValueError,
):
    """This function is used to ensure that parameters set by users in BUILD files are of acceptable
    types.

    :API: public

    :param obj           : the object that may be a list. It will pass if it is of type in allowable.
    :param expected_type : this is the expected type of the returned list contents.
    :param can_be_none   : this defines whether or not the obj can be None. If True, return default.
    :param default       : this is the default to return if can_be_none is True and obj is None.
    :param key_arg       : this is the name of the key to which obj belongs to
    :param allowable     : the acceptable types for obj. We do not want to allow any iterable (eg string).
    :param raise_type    : the error to throw if the type is not correct.
    """

    def get_key_msg(key=None):
        if key is None:
            return ""
        else:
            return "In key '{}': ".format(key)

    allowable = tuple(allowable)

    key_msg = get_key_msg(key_arg)
    val = obj
    if val is None:
        if can_be_none:
            val = list(default)
        else:
            raise raise_type(
                "{}Expected an object of acceptable type {}, received None and can_be_none is False".format(
                    key_msg, allowable
                )
            )

    if isinstance(val, allowable):
        lst = list(val)
        for e in lst:
            if not isinstance(e, expected_type):
                raise raise_type(
                    "{}Expected a list containing values of type {}, instead got a value {} of {}".format(
                        key_msg, expected_type, e, e.__class__
                    )
                )
        return lst
    else:
        raise raise_type(
            "{}Expected an object of acceptable type {}, received {} instead".format(
                key_msg, allowable, val
            )
        )