"""Base class for dynamically loaded objects accessible through the vregistry.

You'll also find some convenience classes to build selectors.

:organization: Logilab

:copyright: 2001-2009 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.

:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr

:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses

"""

__docformat__ = "restructuredtext en"

import types

from logging import getLogger

from logilab.common.decorators import classproperty

from logilab.common.deprecation import deprecated

from logilab.common.logging_ext import set_log_methods

from cubicweb import Unauthorized, NoSelectableObject

# selector base classes and operations ########################################

def objectify_selector(selector_func):

    """convenience decorator for simple selectors where a class definition

    would be overkill::

        @objectify_selector

        def yes(cls, *args, **kwargs):

            return 1

    """

    return type(selector_func.__name__, (Selector,),

                {'__call__': lambda self, *args, **kwargs: selector_func(*args, **kwargs)})

def _instantiate_selector(selector):

    """ensures `selector` is a `Selector` instance

    NOTE: This should only be used locally in build___select__()

    XXX: then, why not do it ??

    """

    if isinstance(selector, types.FunctionType):

        return objectify_selector(selector)()

    if isinstance(selector, type) and issubclass(selector, Selector):

        return selector()

    return selector

class Selector(object):

    """base class for selector classes providing implementation

    for operators ``&`` and ``|``

    This class is only here to give access to binary operators, the

    selector logic itself should be implemented in the __call__ method

    a selector is called to help choosing the correct object for a

    particular context by returning a score (`int`) telling how well

    the class given as first argument apply to the given context.

    0 score means that the class doesn't apply.

    """

    @property

    def func_name(self):

        # backward compatibility

        return self.__class__.__name__

    def search_selector(self, selector):

        """search for the given selector or selector instance in the selectors

        tree. Return it of None if not found

        """

        if self is selector:

            return self

        if isinstance(selector, type) and isinstance(self, selector):

            return self

        return None

    def __str__(self):

        return self.__class__.__name__

    def __and__(self, other):

        return AndSelector(self, other)

    def __rand__(self, other):

        return AndSelector(other, self)

    def __or__(self, other):

        return OrSelector(self, other)

    def __ror__(self, other):

        return OrSelector(other, self)

    def __invert__(self):

        return NotSelector(self)

    # XXX (function | function) or (function & function) not managed yet

    def __call__(self, cls, *args, **kwargs):

        return NotImplementedError("selector %s must implement its logic "

                                   "in its __call__ method" % self.__class__)

class MultiSelector(Selector):

    """base class for compound selector classes"""

    def __init__(self, *selectors):

        self.selectors = self.merge_selectors(selectors)

    def __str__(self):

        return '%s(%s)' % (self.__class__.__name__,

                           ','.join(str(s) for s in self.selectors))

    @classmethod

    def merge_selectors(cls, selectors):

        """deal with selector instanciation when necessary and merge

        multi-selectors if possible:

        AndSelector(AndSelector(sel1, sel2), AndSelector(sel3, sel4))

        ==> AndSelector(sel1, sel2, sel3, sel4)

        """

        merged_selectors = []

        for selector in selectors:

            try:

                selector = _instantiate_selector(selector)

            except:

                pass

            #assert isinstance(selector, Selector), selector

            if isinstance(selector, cls):

                merged_selectors += selector.selectors

            else:

                merged_selectors.append(selector)

        return merged_selectors

    def search_selector(self, selector):

        """search for the given selector or selector instance in the selectors

        tree. Return it of None if not found

        """

        for childselector in self.selectors:

            if childselector is selector:

                return childselector

            found = childselector.search_selector(selector)

            if found is not None:

                return found

        return None

class AndSelector(MultiSelector):

    """and-chained selectors (formerly known as chainall)"""

    def __call__(self, cls, *args, **kwargs):

        score = 0

        for selector in self.selectors:

            partscore = selector(cls, *args, **kwargs)

            if not partscore:

                return 0

            score += partscore

        return score

class OrSelector(MultiSelector):

    """or-chained selectors (formerly known as chainfirst)"""

    def __call__(self, cls, *args, **kwargs):

        for selector in self.selectors:

            partscore = selector(cls, *args, **kwargs)

            if partscore:

                return partscore

        return 0

class NotSelector(Selector):

    """negation selector"""

    def __init__(self, selector):

        self.selector = selector

    def __call__(self, cls, *args, **kwargs):

        score = self.selector(cls, *args, **kwargs)

        return int(not score)

    def __str__(self):

        return 'NOT(%s)' % super(NotSelector, self).__str__()

class yes(Selector):

    """return arbitrary score

    default score of 0.5 so any other selector take precedence

    """

    def __init__(self, score=0.5):

        self.score = score

    def __call__(self, *args, **kwargs):

        return self.score

# the base class for all appobjects ############################################

class AppObject(object):

    """This is the base class for CubicWeb application objects which are

    selected according to a context (usually at least a request and a result

    set).

    Concrete application objects classes are designed to be loaded by the

    vregistry and should be accessed through it, not by direct instantiation.

    The following attributes should be set on concret appobject classes:

    :__registry__:

      name of the registry for this object (string like 'views',

      'templates'...)

    :id:

      object's identifier in the registry (string like 'main',

      'primary', 'folder_box')

    :__select__:

      class'selector

    Moreover, the `__abstract__` attribute may be set to True to indicate

    that a appobject is abstract and should not be registered.

    At registration time, the following attributes are set on the class:

    :vreg:

      the instance's registry

    :schema:

      the instance's schema

    :config:

      the instance's configuration

    At selection time, the following attributes are set on the instance:

    :req:

      current request

    :rset:

      context result set or None

    :row:

      if a result set is set and the context is about a particular cell in the

      result set, and not the result set as a whole, specify the row number we

      are interested in, else None

    :col:

      if a result set is set and the context is about a particular cell in the

      result set, and not the result set as a whole, specify the col number we

      are interested in, else None

    """

    __registry__ = None

    id = None

    __select__ = yes()

    @classmethod

    def __registered__(cls, registry):

        """called by the registry when the appobject has been registered.

        It must return the object that will be actually registered (this may be

        the right hook to create an instance for example). By default the

        appobject is returned without any transformation.

        """

        cls.build___select__()

        cls.vreg = registry.vreg

        pdefs = getattr(cls, 'cw_property_defs', {})

        for propid, pdef in pdefs.items():

            pdef = pdef.copy() # may be shared

            pdef['default'] = getattr(cls, propid, pdef['default'])

            pdef['sitewide'] = getattr(cls, 'site_wide', pdef.get('sitewide'))

            registry.vreg.register_property(cls._cwpropkey(propid), **pdef)

        return cls

    def __init__(self, req=None, rset=None, row=None, col=None, **extra):

        super(AppObject, self).__init__()

        self.req = req

        self.rset = rset

        self.row = row

        self.col = col

        self.extra_kwargs = extra

    def view(self, __vid, rset=None, __fallback_oid=None, __registry='views',

             **kwargs):

        """shortcut to self.vreg.view method avoiding to pass self.req"""

        return self.vreg[__registry].render(__vid, self.req, __fallback_oid,

                                            rset=rset, **kwargs)

    # persistent class properties ##############################################

    #

    # optional `cw_property_defs` dict on a class defines available persistent

    # properties for this class:

    #

    # * key: id of the property (the actual CWProperty key is build using

    #        <registry name>.<obj id>.<property id>

    # * value: tuple (property type, vocabfunc, default value, property description)

    #         possible types are those used by `logilab.common.configuration`

    #

    # notice that when it exists multiple objects with the same id (adaptation,

    # overriding) only the first encountered definition is considered, so those

    # objects can't try to have different default values for instance.

    #

    # you can then access to a property value using self.cw_propval, where self

    # is an instance of class

    @classmethod

    def _cwpropkey(cls, propid):

        """return cw property key for the property of the given id for this

        class

        """

        return '%s.%s.%s' % (cls.__registry__, cls.id, propid)

    def cw_propval(self, propid):

        """return cw property value associated to key

        <cls.__registry__>.<cls.id>.<propid>

        """

        return self.req.property_value(self._cwpropkey(propid))

    # deprecated ###############################################################

    @classproperty

    @deprecated('[3.4] use __select__ and & or | operators')

    def __selectors__(cls):

        selector = cls.__select__

        if isinstance(selector, AndSelector):

            return tuple(selector.selectors)

        if not isinstance(selector, tuple):

            selector = (selector,)

        return selector

    @property

    @deprecated('[3.5] use req.vreg')

    def vreg(self):

        return self.req.vreg

    @property

    @deprecated('[3.5] use req.vreg.schema')

    def schema(self):

        return self.req.vreg.schema

    @property

    @deprecated('[3.5] use req.vreg.config')

    def config(self):

        return self.req.vreg.config

    @deprecated('[3.5] use req.varmaker')

    def initialize_varmaker(self):

        self.varmaker = self.req.varmaker

    @deprecated('[3.5] use req.get_cache')

    def get_cache(self, cachename):

        return self.req.get_cache(cachename)

    @deprecated('[3.5] use req.build_url')

    def build_url(self, *args, **kwargs):

        return self.req.build_url(*args, **kwargs)

    @deprecated('[3.5] use rset.limited_rql')

    def limited_rql(self):

        return self.rset.limited_rql()

    @deprecated('[3.5] use self.rset.complete_entity(row,col) instead')

    def complete_entity(self, row, col=0, skip_bytes=True):

        return self.rset.complete_entity(row, col, skip_bytes)

    @deprecated('[3.5] use self.rset.get_entity(row,col) instead')

    def entity(self, row, col=0):

        return self.rset.get_entity(row, col)

    @deprecated('[3.5] use req.user_rql_callback')

    def user_rql_callback(self, args, msg=None):

        return self.req.user_rql_callback(args, msg)

    @deprecated('[3.5] use req.user_callback')

    def user_callback(self, cb, args, msg=None, nonify=False):

        return self.req.user_callback(cb, args, msg, nonify)

    @deprecated('[3.5] use req.format_date')

    def format_date(self, date, date_format=None, time=False):

        return self.req.format_date(date, date_format, time)

    @deprecated('[3.5] use req.format_timoe')

    def format_time(self, time):

        return self.req.format_time(time)

    @deprecated('[3.5] use req.format_float')

    def format_float(self, num):

        return self.req.format_float(num)

    @deprecated('[3.5] use req.parse_datetime')

    def parse_datetime(self, value, etype='Datetime'):

        return self.req.parse_datetime(value, etype)

    @deprecated('[3.5] use self.cw_propval')

    def propval(self, propid):

        return self.req.property_value(self._cwpropkey(propid))

set_log_methods(AppObject, getLogger('cubicweb.appobject'))