"""

* the vregistry handle various type of objects interacting

  together. The vregistry handle registration of dynamically loaded

  objects and provide a convenient api access to those objects

  according to a context

* to interact with the vregistry, object should inherit from the

  VObject abstract class

* the registration procedure is delegated to a registerer. Each

  registerable vobject must defines its registerer class using the

  __registerer__ attribute.  A registerer is instantianted at

  registration time after what the instance is lost

* the selection procedure has been generalized by delegating to a

  selector, which is responsible to score the vobject according to the

  current state (req, rset, row, col). At the end of the selection, if

  a vobject class has been found, an instance of this class is

  returned. The selector is instantiated at vobject registration

:organization: Logilab

:copyright: 2001-2009 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

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

"""

__docformat__ = "restructuredtext en"

import sys

from os import listdir, stat

from os.path import dirname, join, realpath, split, isdir

from logging import getLogger

from cubicweb import CW_SOFTWARE_ROOT, set_log_methods

from cubicweb import RegistryNotFound, ObjectNotFound, NoSelectableObject

class vobject_helper(object):

    """object instantiated at registration time to help a wrapped

    VObject subclass

    """

    def __init__(self, registry, vobject):

        self.registry = registry

        self.vobject = vobject

        self.config = registry.config

        self.schema = registry.schema

class registerer(vobject_helper):

    """do whatever is needed at registration time for the wrapped

    class, according to current application schema and already

    registered objects of the same kind (i.e. same registry name and

    same id).

    The wrapped class may be skipped, some previously selected object

    may be kicked out... After whatever works needed, if the object or

    a transformed object is returned, it will be added to previously

    registered objects.

    """

    def __init__(self, registry, vobject):

        super(registerer, self).__init__(registry, vobject)

        self.kicked = set()

    def do_it_yourself(self, registered):

        raise NotImplementedError(str(self.vobject))

    def kick(self, registered, kicked):

        self.debug('kicking vobject %s', kicked)

        registered.remove(kicked)

        self.kicked.add(kicked.classid())

    def skip(self):

        self.debug('no schema compat, skipping %s', self.vobject)

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

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

    particular request and result set by returning a score.

    it must implement a .score_method taking a request, a result set and

    optionaly row and col arguments which return an int telling how well

    the wrapped class apply to the given request and result set. 0 score

    means that it doesn't apply.

    rset may be None. If not, row and col arguments may be optionally

    given if the registry is scoring a given row or a given cell of

    the result set (both row and col are int if provided).

    """    

    raise NotImplementedError(cls)

class autoselectors(type):

    """implements __selectors__ / __select__ compatibility layer so that:

    __select__ = chainall(classmethod(A, B, C))

    can be replaced by something like:

    __selectors__ = (A, B, C)

    """

    def __new__(mcs, name, bases, classdict):

        if '__select__' in classdict and '__selectors__' in classdict:

            raise TypeError("__select__ and __selectors__ "

                            "can't be used together")

        if '__select__' not in classdict and '__selectors__' in classdict:

            selectors = classdict['__selectors__']

            if len(selectors) > 1:

                classdict['__select__'] = classmethod(chainall(*selectors))

            else:

                classdict['__select__'] = classmethod(selectors[0])

        return super(autoselectors, mcs).__new__(mcs, name, bases, classdict)

    def __setattr__(self, attr, value):

        if attr == '__selectors__':

            self.__select__ = classmethod(chainall(*value))

        super(autoselectors, self).__setattr__(attr, value)

class VObject(object):

    """visual object, use to be handled somehow by the visual components

    registry.

    The following attributes should be set on concret vobject subclasses:

    :__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')

    :__registerer__:

      registration helper class

    :__select__:

      selection helper function

    :__selectors__:

      tuple of selectors to be chained

      (__select__ and __selectors__ are mutually exclusive)

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

    that a vobject is abstract and should not be registered

    """

    __metaclass__ = autoselectors

    # necessary attributes to interact with the registry

    id = None

    __registry__ = None

    __registerer__ = None

    __select__ = None

    @classmethod

    def registered(cls, registry):

        """called by the registry when the vobject 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 vobject is returned without any transformation.

        """

        return cls

    @classmethod

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

        """called by the registry when the vobject has been selected.

        It must return the  object that will be actually returned by the

        .select method (this may be the right hook to create an

        instance for example). By default the selected object is

        returned without any transformation.

        """

        return cls

    @classmethod

    def classid(cls):

        """returns a unique identifier for the vobject"""

        return '%s.%s' % (cls.__module__, cls.__name__)

class VRegistry(object):

    """class responsible to register, propose and select the various

    elements used to build the web interface. Currently, we have templates,

    views, actions and components.

    """

    def __init__(self, config):#, cache_size=1000):

        self.config = config

        # dictionnary of registry (themself dictionnary) by name

        self._registries = {}

        self._lastmodifs = {}

    def reset(self):

        self._registries = {}

        self._lastmodifs = {}

    def __getitem__(self, key):

        return self._registries[key]

    def get(self, key, default=None):

        return self._registries.get(key, default)

    def items(self):

        return self._registries.items()

    def values(self):

        return self._registries.values()

    def __contains__(self, key):

        return key in self._registries

    def registry(self, name):

        """return the registry (dictionary of class objects) associated to

        this name

        """

        try:

            return self._registries[name]

        except KeyError:

            raise RegistryNotFound(name), None, sys.exc_info()[-1]

    def registry_objects(self, name, oid=None):

        """returns objects registered with the given oid in the given registry.

        If no oid is given, return all objects in this registry

        """

        registry = self.registry(name)

        if oid:

            try:

                return registry[oid]

            except KeyError:

                raise ObjectNotFound(oid), None, sys.exc_info()[-1]

        else:

            result = []

            for objs in registry.values():

                result += objs

            return result

    def object_by_id(self, registry, cid, *args, **kwargs):

        """return the most specific component according to the resultset"""

        objects = self[registry][cid]

        assert len(objects) == 1, objects

        return objects[0].selected(*args, **kwargs)

    # methods for explicit (un)registration ###################################

#     def clear(self, key):

#         regname, oid = key.split('.')

#         self[regname].pop(oid, None)

    def register(self, obj, registryname=None, oid=None, clear=False):

        """base method to add an object in the registry"""

        registryname = registryname or obj.__registry__

        oid = oid or obj.id

        registry = self._registries.setdefault(registryname, {})

        if clear:

            vobjects = registry[oid] =  []

        else:

            vobjects = registry.setdefault(oid, [])

        # registered() is technically a classmethod but is not declared

        # as such because we need to compose registered in some cases

        assert not vobject in vobjects

        vobjects.append(vobject)

        try:

            vname = vobject.__name__

        except AttributeError:

            vname = vobject.__class__.__name__

        self.debug('registered vobject %s in registry %s with id %s',

                   vname, registryname, oid)

        # automatic reloading management

        self._registered['%s.%s' % (obj.__module__, oid)] = obj

    def unregister(self, obj, registryname=None):

        registryname = registryname or obj.__registry__

        registry = self.registry(registryname)

        removed_id = obj.classid()

        for registered in registry[obj.id]:

            # use classid() to compare classes because vreg will probably

            # have its own version of the class, loaded through execfile

            if registered.classid() == removed_id:

                # XXX automatic reloading management

                try:

                    registry[obj.id].remove(registered)

                except ValueError:

                    self.warning('can\'t remove %s, no id %s in the %s registry',

                                 removed_id, obj.id, registryname)

                except ValueError:

                    self.warning('can\'t remove %s, not in the %s registry with id %s',

                                 removed_id, registryname, obj.id)

#                 else:

#                     # if objects is empty, remove oid from registry

#                     if not registry[obj.id]:

#                         del regcontent[oid]                    

                break

    def register_and_replace(self, obj, replaced, registryname=None):

        if hasattr(replaced, 'classid'):

            replaced = replaced.classid()

        registryname = registryname or obj.__registry__

        registry = self.registry(registryname)

        registered_objs = registry[obj.id]

        for index, registered in enumerate(registered_objs):

            if registered.classid() == replaced:

                del registry[obj.id][index]

                break

        self.register(obj, registryname=registryname)

    # dynamic selection methods ###############################################

    def select(self, vobjects, *args, **kwargs):

        """return an instance of the most specific object according

        to parameters

        raise NoSelectableObject if not object apply

        """

        score, winners = 0, []

        for vobject in vobjects:

            vobjectscore = vobject.__select__(*args, **kwargs)

            if vobjectscore > score:

                score, winners = vobjectscore, [vobject]

            elif vobjectscore > 0 and vobjectscore == score:

                winners.append(vobject)

        if not winners:

            raise NoSelectableObject('args: %s\nkwargs: %s %s'

                                     % (args, kwargs.keys(), [repr(v) for v in vobjects]))

        if len(winners) > 1:

            if self.config.mode == 'installed':

                self.error('select ambiguity, args: %s\nkwargs: %s %s',

                           args, kwargs.keys(), [repr(v) for v in winners])

            else:

                raise Exception('select ambiguity, args: %s\nkwargs: %s %s'

                                % (args, kwargs.keys(), [repr(v) for v in winners]))

        winner = winners[0]

        # return the result of the .selected method of the vobject

        return winner.selected(*args, **kwargs)

    def possible_objects(self, registry, *args, **kwargs):

        """return an iterator on possible objects in a registry for this result set

        actions returned are classes, not instances

        """

        for vobjects in self.registry(registry).values():

            try:

                yield self.select(vobjects, *args, **kwargs)

            except NoSelectableObject:

                continue

    def select_object(self, registry, cid, *args, **kwargs):

        """return the most specific component according to the resultset"""

        return self.select(self.registry_objects(registry, cid), *args, **kwargs)

    # intialization methods ###################################################

    def register_objects(self, path, force_reload=None):

        if force_reload is None:

            force_reload = self.config.mode == 'dev'

        elif not force_reload:

            # force_reload == False usually mean modules have been reloaded

            # by another connection, so we want to update the registry

            # content even if there has been no module content modification

            self.reset()

        # need to clean sys.path this to avoid import confusion pb (i.e.

        # having the same module loaded as 'cubicweb.web.views' subpackage and

        # as views'  or 'web.views' subpackage

        # this is mainly for testing purpose, we should'nt need this in

        # production environment

        for webdir in (join(dirname(realpath(__file__)), 'web'),

                       join(dirname(__file__), 'web')):

            if webdir in sys.path:

                sys.path.remove(webdir)

        if CW_SOFTWARE_ROOT in sys.path:

            sys.path.remove(CW_SOFTWARE_ROOT)        

        # load views from each directory in the application's path

        change = False

        for fileordirectory in path:

            if isdir(fileordirectory):

                if self.read_directory(fileordirectory, force_reload):

                    change = True

            else:

                directory, filename = split(fileordirectory)

                if self.load_file(directory, filename, force_reload):

                    change = True

        if change:

            for registry, objects in self.items():

                self.debug('available in registry %s: %s', registry,

                           sorted(objects))

        return change

    def read_directory(self, directory, force_reload=False):

        """read a directory and register available views"""

        modified_on = stat(realpath(directory))[-2]

        # only read directory if it was modified

        _lastmodifs = self._lastmodifs

        if directory in _lastmodifs and modified_on <= _lastmodifs[directory]:

            return False

        self.info('loading directory %s', directory)

        for filename in listdir(directory):

            if filename[-3:] == '.py':

                try:

                    self.load_file(directory, filename, force_reload)

                except OSError:

                    # this typically happens on emacs backup files (.#foo.py)

                    self.warning('Unable to load file %s. It is likely to be a backup file',

                                 filename)

                except Exception, ex:

                    if self.config.mode in ('dev', 'test'):

                        raise

                    self.exception('%r while loading file %s', ex, filename)

        _lastmodifs[directory] = modified_on

        return True