"""Check unpacking non-sequences in assignments. """

# pylint: disable=too-few-public-methods, invalid-name, attribute-defined-outside-init, unused-variable, no-absolute-import
# pylint: disable=using-constant-test, no-init
from os import rename as nonseq_func
from functional.unpacking import nonseq
from six import with_metaclass

__revision__ = 0

# Working

class Seq(object):
    """ sequence """
    def __init__(self):
        self.items = range(2)

    def __getitem__(self, item):
        return self.items[item]

    def __len__(self):
        return len(self.items)

class Iter(object):
    """ Iterator """
    def __iter__(self):
        for number in range(2):
            yield number

def good_unpacking():
    """ returns should be unpackable """
    if True:
        return [1, 2]
    else:
        return (3, 4)

def good_unpacking2():
    """ returns should be unpackable """
    return good_unpacking()

class MetaIter(type):
    "metaclass that makes classes that use it iterables"
    def __iter__(cls):
        return iter((1, 2))

class IterClass(with_metaclass(MetaIter)):
    "class that is iterable (and unpackable)"

class AbstrClass(object):
    "abstract class"
    pair = None

    def setup_pair(self):
        "abstract method"
        raise NotImplementedError

    def __init__(self):
        "error should not be emitted because setup_pair is abstract"
        self.setup_pair()
        x, y = self.pair

a, b = [1, 2]
a, b = (1, 2)
a, b = set([1, 2])
a, b = {1: 2, 2: 3}
a, b = "xy"
a, b = Seq()
a, b = Iter()
a, b = (number for number in range(2))
a, b = good_unpacking()
a, b = good_unpacking2()
a, b = IterClass

# Not working
class NonSeq(object):
    """ does nothing """

def bad_unpacking():
    """ one return isn't unpackable """
    if True:
        return None
    return [1, 2]

a, b = NonSeq() # [unpacking-non-sequence]
a, b = ValueError # [unpacking-non-sequence]
a, b = None # [unpacking-non-sequence]
a, b = 1 # [unpacking-non-sequence]
a, b = nonseq # [unpacking-non-sequence]
a, b = nonseq() # [unpacking-non-sequence]
a, b = bad_unpacking() # [unpacking-non-sequence]
a, b = nonseq_func # [unpacking-non-sequence]

class ClassUnpacking(object):
    """ Check unpacking as instance attributes. """

    def test(self):
        """ test unpacking in instance attributes. """

        self.a, self.b = 1, 2
        self.a, self.b = {1: 2, 2: 3}
        self.a, self.b = "xy"
        self.a, c = "xy"
        c, self.a = good_unpacking()
        self.a, self.b = Iter()

        self.a, self.b = NonSeq() # [unpacking-non-sequence]
        self.a, self.b = ValueError # [unpacking-non-sequence]
        self.a, self.b = bad_unpacking() # [unpacking-non-sequence]
        self.a, c = nonseq_func # [unpacking-non-sequence]