from collections.abc import Iterable
from .abstract import (ConstSized, Container, Hashable, MutableSequence,
                       Sequence, Type, TypeRef)
from .common import Buffer, IterableType, SimpleIterableType, SimpleIteratorType
from .misc import Undefined, unliteral, Optional, NoneType
from ..typeconv import Conversion
from ..errors import TypingError
from .. import utils

class Pair(Type):
    """
    A heterogeneous pair.
    """

    def __init__(self, first_type, second_type):
        self.first_type = first_type
        self.second_type = second_type
        name = "pair<%s, %s>" % (first_type, second_type)
        super(Pair, self).__init__(name=name)

    @property
    def key(self):
        return self.first_type, self.second_type

    def unify(self, typingctx, other):
        if isinstance(other, Pair):
            first = typingctx.unify_pairs(self.first_type, other.first_type)
            second = typingctx.unify_pairs(self.second_type, other.second_type)
            if first is not None and second is not None:
                return Pair(first, second)


class BaseContainerIterator(SimpleIteratorType):
    """
    Convenience base class for some container iterators.

    Derived classes must implement the *container_class* attribute.
    """

    def __init__(self, container):
        assert isinstance(container, self.container_class), container
        self.container = container
        yield_type = container.dtype
        name = 'iter(%s)' % container
        super(BaseContainerIterator, self).__init__(name, yield_type)

    def unify(self, typingctx, other):
        cls = type(self)
        if isinstance(other, cls):
            container = typingctx.unify_pairs(self.container, other.container)
            if container is not None:
                return cls(container)

    @property
    def key(self):
        return self.container


class BaseContainerPayload(Type):
    """
    Convenience base class for some container payloads.

    Derived classes must implement the *container_class* attribute.
    """

    def __init__(self, container):
        assert isinstance(container, self.container_class)
        self.container = container
        name = 'payload(%s)' % container
        super(BaseContainerPayload, self).__init__(name)

    @property
    def key(self):
        return self.container


class Bytes(Buffer):
    """
    Type class for Python 3.x bytes objects.
    """
    mutable = False
    # Actually true but doesn't matter since bytes is immutable
    slice_is_copy = False


class ByteArray(Buffer):
    """
    Type class for bytearray objects.
    """
    slice_is_copy = True


class PyArray(Buffer):
    """
    Type class for array.array objects.
    """
    slice_is_copy = True


class MemoryView(Buffer):
    """
    Type class for memoryview objects.
    """


def is_homogeneous(*tys):
    """Are the types homogeneous?
    """
    if tys:
        first, tys = tys[0], tys[1:]
        return not any(t != first for t in tys)
    else:
        # *tys* is empty.
        return False


class BaseTuple(ConstSized, Hashable):
    """
    The base class for all tuple types (with a known size).
    """

    @classmethod
    def from_types(cls, tys, pyclass=None):
        """
        Instantiate the right tuple type for the given element types.
        """
        if pyclass is not None and pyclass is not tuple:
            # A subclass => is it a namedtuple?
            assert issubclass(pyclass, tuple)
            if hasattr(pyclass, "_asdict"):
                tys = tuple(map(unliteral, tys))
                homogeneous = is_homogeneous(*tys)
                if homogeneous:
                    return NamedUniTuple(tys[0], len(tys), pyclass)
                else:
                    return NamedTuple(tys, pyclass)
        else:
            dtype = utils.unified_function_type(tys)
            if dtype is not None:
                return UniTuple(dtype, len(tys))
            # non-named tuple
            homogeneous = is_homogeneous(*tys)
            if homogeneous:
                return cls._make_homogeneous_tuple(tys[0], len(tys))
            else:
                return cls._make_heterogeneous_tuple(tys)

    @classmethod
    def _make_homogeneous_tuple(cls, dtype, count):
        return UniTuple(dtype, count)

    @classmethod
    def _make_heterogeneous_tuple(cls, tys):
        return Tuple(tys)


class BaseAnonymousTuple(BaseTuple):
    """
    Mixin for non-named tuples.
    """

    def can_convert_to(self, typingctx, other):
        """
        Convert this tuple to another one.  Note named tuples are rejected.
        """
        if not isinstance(other, BaseAnonymousTuple):
            return
        if len(self) != len(other):
            return
        if len(self) == 0:
            return Conversion.safe
        if isinstance(other, BaseTuple):
            kinds = [typingctx.can_convert(ta, tb)
                     for ta, tb in zip(self, other)]
            if any(kind is None for kind in kinds):
                return
            return max(kinds)

    def __unliteral__(self):
        return BaseTuple.from_types([unliteral(t) for t in self])


class _HomogeneousTuple(Sequence, BaseTuple):

    @property
    def iterator_type(self):
        return UniTupleIter(self)

    def __getitem__(self, i):
        """
        Return element at position i
        """
        return self.dtype

    def __iter__(self):
        return iter([self.dtype] * self.count)

    def __len__(self):
        return self.count

    @property
    def types(self):
        return (self.dtype,) * self.count


class UniTuple(BaseAnonymousTuple, _HomogeneousTuple, Sequence):
    """
    Type class for homogeneous tuples.
    """

    def __init__(self, dtype, count):
        self.dtype = dtype
        self.count = count
        name = "%s(%s x %d)" % (
            self.__class__.__name__, dtype, count,
        )
        super(UniTuple, self).__init__(name)

    @property
    def mangling_args(self):
        return self.__class__.__name__, (self.dtype, self.count)

    @property
    def key(self):
        return self.dtype, self.count

    def unify(self, typingctx, other):
        """
        Unify UniTuples with their dtype
        """
        if isinstance(other, UniTuple) and len(self) == len(other):
            dtype = typingctx.unify_pairs(self.dtype, other.dtype)
            if dtype is not None:
                return UniTuple(dtype=dtype, count=self.count)


class UniTupleIter(BaseContainerIterator):
    """
    Type class for homogeneous tuple iterators.
    """
    container_class = _HomogeneousTuple


class _HeterogeneousTuple(BaseTuple):

    def __getitem__(self, i):
        """
        Return element at position i
        """
        return self.types[i]

    def __len__(self):
        # Beware: this makes Tuple(()) false-ish
        return len(self.types)

    def __iter__(self):
        return iter(self.types)

    @staticmethod
    def is_types_iterable(types):
        # issue 4463 - check if argument 'types' is iterable
        if not isinstance(types, Iterable):
            raise TypingError("Argument 'types' is not iterable")


class UnionType(Type):
    def __init__(self, types):
        self.types = tuple(sorted(set(types), key=lambda x:x.name))
        name = 'Union[{}]'.format(','.join(map(str, self.types)))
        super(UnionType, self).__init__(name=name)

    def get_type_tag(self, typ):
        return self.types.index(typ)


class Tuple(BaseAnonymousTuple, _HeterogeneousTuple):

    def __new__(cls, types):

        t = utils.unified_function_type(types)
        if t is not None:
            return UniTuple(dtype=t, count=len(types))

        _HeterogeneousTuple.is_types_iterable(types)

        if types and all(t == types[0] for t in types[1:]):
            return UniTuple(dtype=types[0], count=len(types))
        else:
            return object.__new__(Tuple)

    def __init__(self, types):
        self.types = tuple(types)
        self.count = len(self.types)
        self.dtype = UnionType(types)
        name = "%s(%s)" % (
            self.__class__.__name__,
            ', '.join(str(i) for i in self.types),
        )
        super(Tuple, self).__init__(name)

    @property
    def mangling_args(self):
        return self.__class__.__name__, tuple(t for t in self.types)

    @property
    def key(self):
        return self.types

    def unify(self, typingctx, other):
        """
        Unify elements of Tuples/UniTuples
        """
        # Other is UniTuple or Tuple
        if isinstance(other, BaseTuple) and len(self) == len(other):
            unified = [typingctx.unify_pairs(ta, tb)
                       for ta, tb in zip(self, other)]

            if all(t is not None for t in unified):
                return Tuple(unified)


class _StarArgTupleMixin:

    @classmethod
    def _make_homogeneous_tuple(cls, dtype, count):
        return StarArgUniTuple(dtype, count)

    @classmethod
    def _make_heterogeneous_tuple(cls, tys):
        return StarArgTuple(tys)


class StarArgTuple(_StarArgTupleMixin, Tuple):
    """To distinguish from Tuple() used as argument to a `*args`.
    """
    def __new__(cls, types):
        _HeterogeneousTuple.is_types_iterable(types)

        if types and all(t == types[0] for t in types[1:]):
            return StarArgUniTuple(dtype=types[0], count=len(types))
        else:
            return object.__new__(StarArgTuple)


class StarArgUniTuple(_StarArgTupleMixin, UniTuple):
    """To distinguish from UniTuple() used as argument to a `*args`.
    """


class BaseNamedTuple(BaseTuple):
    pass


class NamedUniTuple(_HomogeneousTuple, BaseNamedTuple):

    def __init__(self, dtype, count, cls):
        self.dtype = dtype
        self.count = count
        self.fields = tuple(cls._fields)
        self.instance_class = cls
        name = "%s(%s x %d)" % (cls.__name__, dtype, count)
        super(NamedUniTuple, self).__init__(name)

    @property
    def iterator_type(self):
        return UniTupleIter(self)

    @property
    def key(self):
        return self.instance_class, self.dtype, self.count


class NamedTuple(_HeterogeneousTuple, BaseNamedTuple):

    def __init__(self, types, cls):
        _HeterogeneousTuple.is_types_iterable(types)

        self.types = tuple(types)
        self.count = len(self.types)
        self.fields = tuple(cls._fields)
        self.instance_class = cls
        name = "%s(%s)" % (cls.__name__, ', '.join(str(i) for i in self.types))
        super(NamedTuple, self).__init__(name)

    @property
    def key(self):
        return self.instance_class, self.types


class List(MutableSequence):
    """
    Type class for (arbitrary-sized) homogeneous lists.
    """
    mutable = True

    def __init__(self, dtype, reflected=False):
        dtype = unliteral(dtype)
        self.dtype = dtype
        self.reflected = reflected
        cls_name = "reflected list" if reflected else "list"
        name = "%s(%s)" % (cls_name, self.dtype)
        super(List, self).__init__(name=name)

    def copy(self, dtype=None, reflected=None):
        if dtype is None:
            dtype = self.dtype
        if reflected is None:
            reflected = self.reflected
        return List(dtype, reflected)

    def unify(self, typingctx, other):
        if isinstance(other, List):
            dtype = typingctx.unify_pairs(self.dtype, other.dtype)
            reflected = self.reflected or other.reflected
            if dtype is not None:
                return List(dtype, reflected)

    @property
    def key(self):
        return self.dtype, self.reflected

    @property
    def iterator_type(self):
        return ListIter(self)

    def is_precise(self):
        return self.dtype.is_precise()

    def __getitem__(self, args):
        """
        Overrides the default __getitem__ from Type.
        """
        return self.dtype


class ListIter(BaseContainerIterator):
    """
    Type class for list iterators.
    """
    container_class = List


class ListPayload(BaseContainerPayload):
    """
    Internal type class for the dynamically-allocated payload of a list.
    """
    container_class = List


class Set(Container):
    """
    Type class for homogeneous sets.
    """
    mutable = True

    def __init__(self, dtype, reflected=False):
        assert isinstance(dtype, (Hashable, Undefined))
        self.dtype = dtype
        self.reflected = reflected
        cls_name = "reflected set" if reflected else "set"
        name = "%s(%s)" % (cls_name, self.dtype)
        super(Set, self).__init__(name=name)

    @property
    def key(self):
        return self.dtype, self.reflected

    @property
    def iterator_type(self):
        return SetIter(self)

    def is_precise(self):
        return self.dtype.is_precise()

    def copy(self, dtype=None, reflected=None):
        if dtype is None:
            dtype = self.dtype
        if reflected is None:
            reflected = self.reflected
        return Set(dtype, reflected)

    def unify(self, typingctx, other):
        if isinstance(other, Set):
            dtype = typingctx.unify_pairs(self.dtype, other.dtype)
            reflected = self.reflected or other.reflected
            if dtype is not None:
                return Set(dtype, reflected)


class SetIter(BaseContainerIterator):
    """
    Type class for set iterators.
    """
    container_class = Set


class SetPayload(BaseContainerPayload):
    """
    Internal type class for the dynamically-allocated payload of a set.
    """
    container_class = Set


class SetEntry(Type):
    """
    Internal type class for the entries of a Set's hash table.
    """
    def __init__(self, set_type):
        self.set_type = set_type
        name = 'entry(%s)' % set_type
        super(SetEntry, self).__init__(name)

    @property
    def key(self):
        return self.set_type


class ListType(IterableType):
    """List type
    """

    mutable = True

    def __init__(self, itemty):
        assert not isinstance(itemty, TypeRef)
        itemty = unliteral(itemty)
        if isinstance(itemty, Optional):
            fmt = 'List.item_type cannot be of type {}'
            raise TypingError(fmt.format(itemty))
        # FIXME: _sentry_forbidden_types(itemty)
        self.item_type = itemty
        self.dtype = itemty
        name = '{}[{}]'.format(
            self.__class__.__name__,
            itemty,
        )
        super(ListType, self).__init__(name)

    def is_precise(self):
        return not isinstance(self.item_type, Undefined)

    @property
    def iterator_type(self):
        return ListTypeIterableType(self).iterator_type

    @classmethod
    def refine(cls, itemty):
        """Refine to a precise list type
        """
        res = cls(itemty)
        assert res.is_precise()
        return res

    def unify(self, typingctx, other):
        """
        Unify this with the *other* list.
        """
        # If other is list
        if isinstance(other, ListType):
            if not other.is_precise():
                return self


class ListTypeIterableType(SimpleIterableType):
    """List iterable type
    """
    def __init__(self, parent):
        assert isinstance(parent, ListType)
        self.parent = parent
        self.yield_type = self.parent.item_type
        name = "list[{}]".format(self.parent.name)
        iterator_type = ListTypeIteratorType(self)
        super(ListTypeIterableType, self).__init__(name, iterator_type)


class ListTypeIteratorType(SimpleIteratorType):
    def __init__(self, iterable):
        self.parent = iterable.parent
        self.iterable = iterable
        yield_type = iterable.yield_type
        name = "iter[{}->{}]".format(iterable.parent, yield_type)
        super(ListTypeIteratorType, self).__init__(name, yield_type)


def _sentry_forbidden_types(key, value):
    # Forbids List and Set for now
    if isinstance(key, (Set, List)):
        raise TypingError('{} as key is forbidden'.format(key))
    if isinstance(value, (Set, List)):
        raise TypingError('{} as value is forbidden'.format(value))


class DictType(IterableType):
    """Dictionary type
    """
    def __init__(self, keyty, valty):
        assert not isinstance(keyty, TypeRef)
        assert not isinstance(valty, TypeRef)
        keyty = unliteral(keyty)
        valty = unliteral(valty)
        if isinstance(keyty, (Optional, NoneType)):
            fmt = 'Dict.key_type cannot be of type {}'
            raise TypingError(fmt.format(keyty))
        if isinstance(valty, (Optional, NoneType)):
            fmt = 'Dict.value_type cannot be of type {}'
            raise TypingError(fmt.format(valty))
        _sentry_forbidden_types(keyty, valty)
        self.key_type = keyty
        self.value_type = valty
        self.keyvalue_type = Tuple([keyty, valty])
        name = '{}[{},{}]'.format(
            self.__class__.__name__,
            keyty,
            valty,
        )
        super(DictType, self).__init__(name)

    def is_precise(self):
        return not any((
            isinstance(self.key_type, Undefined),
            isinstance(self.value_type, Undefined),
        ))

    @property
    def iterator_type(self):
        return DictKeysIterableType(self).iterator_type

    @classmethod
    def refine(cls, keyty, valty):
        """Refine to a precise dictionary type
        """
        res = cls(keyty, valty)
        assert res.is_precise()
        return res

    def unify(self, typingctx, other):
        """
        Unify this with the *other* dictionary.
        """
        # If other is dict
        if isinstance(other, DictType):
            if not other.is_precise():
                return self


class DictItemsIterableType(SimpleIterableType):
    """Dictionary iterable type for .items()
    """
    def __init__(self, parent):
        assert isinstance(parent, DictType)
        self.parent = parent
        self.yield_type = self.parent.keyvalue_type
        name = "items[{}]".format(self.parent.name)
        self.name = name
        iterator_type = DictIteratorType(self)
        super(DictItemsIterableType, self).__init__(name, iterator_type)


class DictKeysIterableType(SimpleIterableType):
    """Dictionary iterable type for .keys()
    """
    def __init__(self, parent):
        assert isinstance(parent, DictType)
        self.parent = parent
        self.yield_type = self.parent.key_type
        name = "keys[{}]".format(self.parent.name)
        self.name = name
        iterator_type = DictIteratorType(self)
        super(DictKeysIterableType, self).__init__(name, iterator_type)


class DictValuesIterableType(SimpleIterableType):
    """Dictionary iterable type for .values()
    """
    def __init__(self, parent):
        assert isinstance(parent, DictType)
        self.parent = parent
        self.yield_type = self.parent.value_type
        name = "values[{}]".format(self.parent.name)
        self.name = name
        iterator_type = DictIteratorType(self)
        super(DictValuesIterableType, self).__init__(name, iterator_type)


class DictIteratorType(SimpleIteratorType):
    def __init__(self, iterable):
        self.parent = iterable.parent
        self.iterable = iterable
        yield_type = iterable.yield_type
        name = "iter[{}->{}],{}".format(iterable.parent, yield_type,
                                        iterable.name)
        super(DictIteratorType, self).__init__(name, yield_type)
