##############################################################################
#
# Copyright (c) 2001, 2002 Zope Foundation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""Interface object implementation
"""
from __future__ import generators

import sys
from types import MethodType
from types import FunctionType
import warnings
import weakref

from zope.interface.exceptions import Invalid
from zope.interface.ro import ro


CO_VARARGS = 4
CO_VARKEYWORDS = 8
TAGGED_DATA = '__interface_tagged_values__'

_decorator_non_return = object()

def invariant(call):
    f_locals = sys._getframe(1).f_locals
    tags = f_locals.setdefault(TAGGED_DATA, {})
    invariants = tags.setdefault('invariants', [])
    invariants.append(call)
    return _decorator_non_return


def taggedValue(key, value):
    """Attaches a tagged value to an interface at definition time."""
    f_locals = sys._getframe(1).f_locals
    tagged_values = f_locals.setdefault(TAGGED_DATA, {})
    tagged_values[key] = value
    return _decorator_non_return


class Element(object):
    """
    Default implementation of `zope.interface.interfaces.IElement`.
    """

    # We can't say this yet because we don't have enough
    # infrastructure in place.
    #
    #implements(IElement)

    def __init__(self, __name__, __doc__=''):
        if not __doc__ and __name__.find(' ') >= 0:
            __doc__ = __name__
            __name__ = None

        self.__name__=__name__
        self.__doc__=__doc__
        self.__tagged_values = {}

    def getName(self):
        """ Returns the name of the object. """
        return self.__name__

    def getDoc(self):
        """ Returns the documentation for the object. """
        return self.__doc__

    def getTaggedValue(self, tag):
        """ Returns the value associated with 'tag'. """
        return self.__tagged_values[tag]

    def queryTaggedValue(self, tag, default=None):
        """ Returns the value associated with 'tag'. """
        return self.__tagged_values.get(tag, default)

    def getTaggedValueTags(self):
        """ Returns a list of all tags. """
        return self.__tagged_values.keys()

    def setTaggedValue(self, tag, value):
        """ Associates 'value' with 'key'. """
        self.__tagged_values[tag] = value

class SpecificationBasePy(object):

    def providedBy(self, ob):
        """Is the interface implemented by an object
        """
        spec = providedBy(ob)
        return self in spec._implied

    def implementedBy(self, cls):
        """Test whether the specification is implemented by a class or factory.

        Raise TypeError if argument is neither a class nor a callable.
        """
        spec = implementedBy(cls)
        return self in spec._implied

    def isOrExtends(self, interface):
        """Is the interface the same as or extend the given interface
        """
        return interface in self._implied

    __call__ = isOrExtends

SpecificationBase = SpecificationBasePy
try:
    from zope.interface._zope_interface_coptimizations import SpecificationBase
except ImportError:
    pass

_marker = object()
class InterfaceBasePy(object):
    """Base class that wants to be replaced with a C base :)
    """

    def __call__(self, obj, alternate=_marker):
        """Adapt an object to the interface
        """
        conform = getattr(obj, '__conform__', None)
        if conform is not None:
            adapter = self._call_conform(conform)
            if adapter is not None:
                return adapter

        adapter = self.__adapt__(obj)

        if adapter is not None:
            return adapter
        elif alternate is not _marker:
            return alternate
        else:
            raise TypeError("Could not adapt", obj, self)

    def __adapt__(self, obj):
        """Adapt an object to the reciever
        """
        if self.providedBy(obj):
            return obj

        for hook in adapter_hooks:
            adapter = hook(self, obj)
            if adapter is not None:
                return adapter


InterfaceBase = InterfaceBasePy
try:
    from zope.interface._zope_interface_coptimizations import InterfaceBase
except ImportError:
    pass


adapter_hooks = []
try:
    from zope.interface._zope_interface_coptimizations import adapter_hooks
except ImportError:
    pass


class Specification(SpecificationBase):
    """Specifications

    An interface specification is used to track interface declarations
    and component registrations.

    This class is a base class for both interfaces themselves and for
    interface specifications (declarations).

    Specifications are mutable.  If you reassign their bases, their
    relations with other specifications are adjusted accordingly.
    """

    # Copy some base class methods for speed
    isOrExtends = SpecificationBase.isOrExtends
    providedBy = SpecificationBase.providedBy

    def __init__(self, bases=()):
        self._implied = {}
        self.dependents = weakref.WeakKeyDictionary()
        self.__bases__ = tuple(bases)

    def subscribe(self, dependent):
        self.dependents[dependent] = self.dependents.get(dependent, 0) + 1

    def unsubscribe(self, dependent):
        n = self.dependents.get(dependent, 0) - 1
        if not n:
            del self.dependents[dependent]
        elif n > 0:
            self.dependents[dependent] = n
        else:
            raise KeyError(dependent)

    def __setBases(self, bases):
        # Register ourselves as a dependent of our old bases
        for b in self.__bases__:
            b.unsubscribe(self)

        # Register ourselves as a dependent of our bases
        self.__dict__['__bases__'] = bases
        for b in bases:
            b.subscribe(self)

        self.changed(self)

    __bases__ = property(

        lambda self: self.__dict__.get('__bases__', ()),
        __setBases,
        )

    def changed(self, originally_changed):
        """We, or something we depend on, have changed
        """
        try:
            del self._v_attrs
        except AttributeError:
            pass

        implied = self._implied
        implied.clear()

        ancestors = ro(self)

        try:
            if Interface not in ancestors:
                ancestors.append(Interface)
        except NameError:
            pass # defining Interface itself

        self.__sro__ = tuple(ancestors)
        self.__iro__ = tuple([ancestor for ancestor in ancestors
                              if isinstance(ancestor, InterfaceClass)
                              ])

        for ancestor in ancestors:
            # We directly imply our ancestors:
            implied[ancestor] = ()

        # Now, advise our dependents of change:
        for dependent in tuple(self.dependents.keys()):
            dependent.changed(originally_changed)


    def interfaces(self):
        """Return an iterator for the interfaces in the specification.
        """
        seen = {}
        for base in self.__bases__:
            for interface in base.interfaces():
                if interface not in seen:
                    seen[interface] = 1
                    yield interface


    def extends(self, interface, strict=True):
        """Does the specification extend the given interface?

        Test whether an interface in the specification extends the
        given interface
        """
        return ((interface in self._implied)
                and
                ((not strict) or (self != interface))
                )

    def weakref(self, callback=None):
        return weakref.ref(self, callback)

    def get(self, name, default=None):
        """Query for an attribute description
        """
        try:
            attrs = self._v_attrs
        except AttributeError:
            attrs = self._v_attrs = {}
        attr = attrs.get(name)
        if attr is None:
            for iface in self.__iro__:
                attr = iface.direct(name)
                if attr is not None:
                    attrs[name] = attr
                    break

        if attr is None:
            return default
        else:
            return attr

class InterfaceClass(Element, InterfaceBase, Specification):
    """Prototype (scarecrow) Interfaces Implementation."""

    # We can't say this yet because we don't have enough
    # infrastructure in place.
    #
    #implements(IInterface)

    def __init__(self, name, bases=(), attrs=None, __doc__=None,
                 __module__=None):

        if attrs is None:
            attrs = {}

        if __module__ is None:
            __module__ = attrs.get('__module__')
            if isinstance(__module__, str):
                del attrs['__module__']
            else:
                try:
                    # Figure out what module defined the interface.
                    # This is how cPython figures out the module of
                    # a class, but of course it does it in C. :-/
                    __module__ = sys._getframe(1).f_globals['__name__']
                except (AttributeError, KeyError): # pragma: no cover
                    pass

        self.__module__ = __module__

        d = attrs.get('__doc__')
        if d is not None:
            if not isinstance(d, Attribute):
                if __doc__ is None:
                    __doc__ = d
                del attrs['__doc__']

        if __doc__ is None:
            __doc__ = ''

        Element.__init__(self, name, __doc__)

        tagged_data = attrs.pop(TAGGED_DATA, None)
        if tagged_data is not None:
            for key, val in tagged_data.items():
                self.setTaggedValue(key, val)