##############################################################################
#
# Copyright (c) 2004 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.
#
##############################################################################
"""Adapter management
"""
import weakref

from zope.interface import implementer
from zope.interface import providedBy
from zope.interface import Interface
from zope.interface import ro
from zope.interface.interfaces import IAdapterRegistry

from zope.interface._compat import _normalize_name
from zope.interface._compat import STRING_TYPES

_BLANK = u''

class BaseAdapterRegistry(object):

    # List of methods copied from lookup sub-objects:
    _delegated = ('lookup', 'queryMultiAdapter', 'lookup1', 'queryAdapter',
                  'adapter_hook', 'lookupAll', 'names',
                  'subscriptions', 'subscribers')

    # All registries maintain a generation that can be used by verifying
    # registries
    _generation = 0

    def __init__(self, bases=()):

        # The comments here could be improved. Possibly this bit needs
        # explaining in a separate document, as the comments here can
        # be quite confusing. /regebro

        # {order -> {required -> {provided -> {name -> value}}}}
        # Here "order" is actually an index in a list, "required" and
        # "provided" are interfaces, and "required" is really a nested
        # key.  So, for example:
        # for order == 0 (that is, self._adapters[0]), we have:
        #   {provided -> {name -> value}}
        # but for order == 2 (that is, self._adapters[2]), we have:
        #   {r1 -> {r2 -> {provided -> {name -> value}}}}
        #
        self._adapters = []

        # {order -> {required -> {provided -> {name -> [value]}}}}
        # where the remarks about adapters above apply
        self._subscribers = []

        # Set, with a reference count, keeping track of the interfaces
        # for which we have provided components:
        self._provided = {}

        # Create ``_v_lookup`` object to perform lookup.  We make this a
        # separate object to to make it easier to implement just the
        # lookup functionality in C.  This object keeps track of cache
        # invalidation data in two kinds of registries.

        #   Invalidating registries have caches that are invalidated
        #     when they or their base registies change.  An invalidating
        #     registry can only have invalidating registries as bases.
        #     See LookupBaseFallback below for the pertinent logic.

        #   Verifying registies can't rely on getting invalidation messages,
        #     so have to check the generations of base registries to determine
        #     if their cache data are current.  See VerifyingBasePy below
        #     for the pertinent object.
        self._createLookup()

        # Setting the bases causes the registries described above
        # to be initialized (self._setBases -> self.changed ->
        # self._v_lookup.changed).

        self.__bases__ = bases

    def _setBases(self, bases):
        self.__dict__['__bases__'] = bases
        self.ro = ro.ro(self)
        self.changed(self)

    __bases__ = property(lambda self: self.__dict__['__bases__'],
                         lambda self, bases: self._setBases(bases),
                         )

    def _createLookup(self):
        self._v_lookup = self.LookupClass(self)
        for name in self._delegated:
            self.__dict__[name] = getattr(self._v_lookup, name)

    def changed(self, originally_changed):
        self._generation += 1
        self._v_lookup.changed(originally_changed)

    def register(self, required, provided, name, value):
        if not isinstance(name, STRING_TYPES):
            raise ValueError('name is not a string')
        if value is None:
            self.unregister(required, provided, name, value)
            return

        required = tuple(map(_convert_None_to_Interface, required))
        name = _normalize_name(name)
        order = len(required)
        byorder = self._adapters
        while len(byorder) <= order:
            byorder.append({})
        components = byorder[order]
        key = required + (provided,)

        for k in key:
            d = components.get(k)
            if d is None:
                d = {}
                components[k] = d
            components = d

        if components.get(name) is value:
            return

        components[name] = value

        n = self._provided.get(provided, 0) + 1
        self._provided[provided] = n
        if n == 1:
            self._v_lookup.add_extendor(provided)

        self.changed(self)

    def registered(self, required, provided, name=_BLANK):
        required = tuple(map(_convert_None_to_Interface, required))
        name = _normalize_name(name)
        order = len(required)
        byorder = self._adapters
        if len(byorder) <= order:
            return None

        components = byorder[order]
        key = required + (provided,)

        for k in key:
            d = components.get(k)
            if d is None:
                return None
            components = d

        return components.get(name)

    def unregister(self, required, provided, name, value=None):
        required = tuple(map(_convert_None_to_Interface, required))
        order = len(required)
        byorder = self._adapters
        if order >= len(byorder):
            return False
        components = byorder[order]
        key = required + (provided,)

        # Keep track of how we got to `components`:
        lookups = []
        for k in key:
            d = components.get(k)
            if d is None:
                return
            lookups.append((components, k))
            components = d

        old = components.get(name)
        if old is None:
            return
        if (value is not None) and (old is not value):
            return

        del components[name]
        if not components:
            # Clean out empty containers, since we don't want our keys
            # to reference global objects (interfaces) unnecessarily.
            # This is often a problem when an interface is slated for
            # removal; a hold-over entry in the registry can make it
            # difficult to remove such interfaces.
            for comp, k in reversed(lookups):
                d = comp[k]
                if d:
                    break
                else:
                    del comp[k]
            while byorder and not byorder[-1]:
                del byorder[-1]
        n = self._provided[provided] - 1
        if n == 0:
            del self._provided[provided]
            self._v_lookup.remove_extendor(provided)
        else:
            self._provided[provided] = n

        self.changed(self)

    def subscribe(self, required, provided, value):
        required = tuple(map(_convert_None_to_Interface, required))
        name = _BLANK
        order = len(required)
        byorder = self._subscribers
        while len(byorder) <= order:
            byorder.append({})
        components = byorder[order]
        key = required + (provided,)

        for k in key:
            d = components.get(k)
            if d is None:
                d = {}
                components[k] = d
            components = d

        components[name] = components.get(name, ()) + (value, )

        if provided is not None:
            n = self._provided.get(provided, 0) + 1
            self._provided[provided] = n
            if n == 1:
                self._v_lookup.add_extendor(provided)

        self.changed(self)

    def unsubscribe(self, required, provided, value=None):
        required = tuple(map(_convert_None_to_Interface, required))
        order = len(required)
        byorder = self._subscribers
        if order >= len(byorder):
            return
        components = byorder[order]
        key = required + (provided,)

        # Keep track of how we got to `components`:
        lookups = []
        for k in key:
            d = components.get(k)
            if d is None:
                return
            lookups.append((components, k))
            components = d

        old = components.get(_BLANK)
        if not old:
            # this is belt-and-suspenders against the failure of cleanup below
            return  # pragma: no cover

        if value is None:
            new = ()
        else:
            new = tuple([v for v in old if v != value])

        if new == old:
            return

        if new:
            components[_BLANK] = new
        else:
            # Instead of setting components[_BLANK] = new, we clean out
            # empty containers, since we don't want our keys to
            # reference global objects (interfaces) unnecessarily.  This
            # is often a problem when an interface is slated for
            # removal; a hold-over entry in the registry can make it
            # difficult to remove such interfaces.
            del components[_BLANK]
            for comp, k in reversed(lookups):
                d = comp[k]
                if d:
                    break
                else:
                    del comp[k]
            while byorder and not byorder[-1]:
                del byorder[-1]

        if provided is not None:
            n = self._provided[provided] + len(new) - len(old)
            if n == 0:
                del self._provided[provided]
                self._v_lookup.remove_extendor(provided)

        self.changed(self)

    # XXX hack to fake out twisted's use of a private api.  We need to get them
    # to use the new registed method.
    def get(self, _): # pragma: no cover
        class XXXTwistedFakeOut:
            selfImplied = {}
        return XXXTwistedFakeOut


_not_in_mapping = object()
class LookupBaseFallback(object):

    def __init__(self):
        self._cache = {}
        self._mcache = {}
        self._scache = {}

    def changed(self, ignored=None):
        self._cache.clear()
        self._mcache.clear()
        self._scache.clear()

    def _getcache(self, provided, name):
        cache = self._cache.get(provided)
        if cache is None:
            cache = {}
            self._cache[provided] = cache
        if name:
            c = cache.get(name)
            if c is None:
                c = {}
                cache[name] = c
            cache = c
        return cache

    def lookup(self, required, provided, name=_BLANK, default=None):
        if not isinstance(name, STRING_TYPES):
            raise ValueError('name is not a string')
        cache = self._getcache(provided, name)
        required = tuple(required)
        if len(required) == 1:
            result = cache.get(required[0], _not_in_mapping)
        else:
            result = cache.get(tuple(required), _not_in_mapping)

        if result is _not_in_mapping:
            result = self._uncached_lookup(required, provided, name)
            if len(required) == 1:
                cache[required[0]] = result
            else:
                cache[tuple(required)] = result

        if result is None:
            return default