"""
The module contains vendored copies of a couple of classes from collections.abc
(python standard library) with one fundamental change:

 * The Mapping class does not have a __metaclass__ = ABCMeta set
   because this causes performance issues on IronPython 2.7.x

See these issues for more details:
 - https://github.com/compas-dev/compas/issues/562
 - https://github.com/compas-dev/compas/issues/649
"""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import compas

if compas.PY2:
    import collections as stdlib_collections
else:
    import collections.abc as stdlib_collections


class Mapping(object):
    __slots__ = ()

    """A Mapping is a generic container for associating key/value
    pairs.
    This class provides concrete generic implementations of all
    methods except for __getitem__, __iter__, and __len__.
    """

    def get(self, key, default=None):
        """D.get(k[,d]) => D[k] if k in D, else d.  d defaults to None."""
        try:
            return self[key]
        except KeyError:
            return default

    def __contains__(self, key):
        try:
            self[key]
        except KeyError:
            return False
        else:
            return True

    def keys(self):
        """D.keys() => a set-like object providing a view on D's keys"""
        return stdlib_collections.KeysView(self)

    def items(self):
        """D.items() => a set-like object providing a view on D's items"""
        return stdlib_collections.ItemsView(self)

    def values(self):
        """D.values() => an object providing a view on D's values"""
        return stdlib_collections.ValuesView(self)

    def __eq__(self, other):
        if not isinstance(other, (Mapping, stdlib_collections.Mapping)):
            return NotImplemented
        return dict(self.items()) == dict(other.items())

    __reversed__ = None


class MutableMapping(Mapping):

    __slots__ = ()

    """A MutableMapping is a generic container for associating
    key/value pairs.
    This class provides concrete generic implementations of all
    methods except for __getitem__, __setitem__, __delitem__,
    __iter__, and __len__.
    """

    __marker = object()

    def pop(self, key, default=__marker):
        """D.pop(k[,d]) => v, remove specified key and return the corresponding value.
        If key is not found, d is returned if given, otherwise KeyError is raised.
        """
        try:
            value = self[key]
        except KeyError:
            if default is self.__marker:
                raise
            return default
        else:
            del self[key]
            return value

    def popitem(self):
        """D.popitem() => (k, v), remove and return some (key, value) pair
        as a 2-tuple; but raise KeyError if D is empty.
        """
        try:
            key = next(iter(self))
        except StopIteration:
            raise KeyError
        value = self[key]
        del self[key]
        return key, value

    def clear(self):
        """D.clear() => None.  Remove all items from D."""
        try:
            while True:
                self.popitem()
        except KeyError:
            pass

    def update(*args, **kwargs):
        """D.update([E, ]**F) => None.  Update D from mapping/iterable E and F.

        If E present and has a .keys() method, does: for k in E: D[k] = E[k]
        If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v
        In either case, this is followed by: for k, v in F.items(): D[k] = v
        """
        if not args:
            raise TypeError("'update' of 'MutableMapping' object needs an argument")
        self = args[0]
        args = args[1:]
        if len(args) > 1:
            raise TypeError("update expected at most 1 arguments, got %d" % len(args))
        if args:
            other = args[0]
            if isinstance(other, (Mapping, stdlib_collections.Mapping)):
                for key in other:
                    self[key] = other[key]
            elif hasattr(other, "keys"):
                for key in other.keys():
                    self[key] = other[key]
            else:
                for key, value in other:
                    self[key] = value
            for key, value in kwargs.items():
                self[key] = value

    def setdefault(self, key, default=None):
        """D.setdefault(k[,d]) => D.get(k,d), also set D[k]=d if k not in D"""
        try:
            return self[key]
        except KeyError:
            self[key] = default
        return default
