"""

* the vregistry handles various types of objects interacting

  together. The vregistry handles registration of dynamically loaded

  objects and provides a convenient api to access those objects

  according to a context

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

  AppObject abstract class

* the selection procedure has been generalized by delegating to a

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

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

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

  returned. The selector is instantiated at appobject registration

: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 sys

from os import listdir, stat

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

from logging import getLogger

from warnings import warn

from logilab.common.deprecation import deprecated, class_moved

from logilab.common.logging_ext import set_log_methods

from cubicweb import CW_SOFTWARE_ROOT

from cubicweb import (RegistryNotFound, ObjectNotFound, NoSelectableObject,

                      RegistryOutOfDate)

from cubicweb.appobject import AppObject

def _toload_info(path, extrapath, _toload=None):

    """return a dictionary of <modname>: <modpath> and an ordered list of

    (file, module name) to load

    """

    from logilab.common.modutils import modpath_from_file

    if _toload is None:

        assert isinstance(path, list)

        _toload = {}, []

    for fileordir in path:

        if isdir(fileordir) and exists(join(fileordir, '__init__.py')):

            subfiles = [join(fileordir, fname) for fname in listdir(fileordir)]

            _toload_info(subfiles, extrapath, _toload)

        elif fileordir[-3:] == '.py':

            modname = '.'.join(modpath_from_file(fileordir, extrapath))

            _toload[0][modname] = fileordir

            _toload[1].append((fileordir, modname))

    return _toload

class Registry(dict):

    def __init__(self, config):

        super(Registry, self).__init__()

        self.config = config

    def __getitem__(self, name):

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

        this name

        """

        try:

            return super(Registry, self).__getitem__(name)

        except KeyError:

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

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

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

        assert not '__abstract__' in obj.__dict__

        oid = oid or obj.id

        assert oid

        if clear:

            appobjects = self[oid] =  []

        else:

            appobjects = self.setdefault(oid, [])

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

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

        appobject = obj.registered.im_func(obj, self)

        assert not appobject in appobjects, \

               'object %s is already registered' % appobject

        assert callable(appobject.__select__), appobject

        appobjects.append(appobject)

    def register_and_replace(self, obj, replaced):

        # XXXFIXME this is a duplication of unregister()

        # remove register_and_replace in favor of unregister + register

        # or simplify by calling unregister then register here

        if hasattr(replaced, 'classid'):

            replaced = replaced.classid()

        registered_objs = self.get(obj.id, ())

        for index, registered in enumerate(registered_objs):

            if registered.classid() == replaced:

                del registered_objs[index]

                break

        else:

            self.warning('trying to replace an unregistered view %s by %s',

                         replaced, obj)

        self.register(obj)

    def unregister(self, obj):

        oid = obj.classid()

        for registered in self.get(obj.id, ()):

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

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

            if registered.classid() == oid:

                # XXX automatic reloading management

                self[obj.id].remove(registered)

                break

        else:

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

                         oid, obj.id)

    def all_objects(self):

        """return a list containing all objects in this registry.

        """

        result = []

        for objs in self.values():

            result += objs

        return result

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

    def object_by_id(self, oid, *args, **kwargs):

        """return object with the given oid. Only one object is expected to be

        found.

        raise `ObjectNotFound` if not object with id <oid> in <registry>

        raise `AssertionError` if there is more than one object there

        """

        objects = self[oid]

        assert len(objects) == 1, objects

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

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

        """return the most specific object among those with the given oid

        according to the given context.

        raise `ObjectNotFound` if not object with id <oid> in <registry>

        raise `NoSelectableObject` if not object apply

        """

        return self.select_best(self[oid], *args, **kwargs)

    def select_object(self, oid, *args, **kwargs):

        """return the most specific object among those with the given oid

        according to the given context, or None if no object applies.

        """

        try:

            return self.select(oid, *args, **kwargs)

        except (NoSelectableObject, ObjectNotFound):

            return None

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

        """return an iterator on possible objects in this registry for the given

        context

        """

        for appobjects in self.itervalues():

            try:

                yield self.select_best(appobjects, *args, **kwargs)

            except NoSelectableObject:

                continue

    def select_best(self, appobjects, *args, **kwargs):

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

        to parameters

        raise `NoSelectableObject` if not object apply

        """

        if len(args) > 1:

            warn('only the request param can not be named when calling select',

                 DeprecationWarning, stacklevel=3)

        score, winners = 0, []

        for appobject in appobjects:

            appobjectscore = appobject.__select__(appobject, *args, **kwargs)

            if appobjectscore > score:

                score, winners = appobjectscore, [appobject]

            elif appobjectscore > 0 and appobjectscore == score:

                winners.append(appobject)

        if not winners:

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

                                     % (args, kwargs.keys(),

                                        [repr(v) for v in appobjects]))

        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]))

        # return the result of calling the appobject

        return winners[0](*args, **kwargs)

class VRegistry(dict):

    """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):

        super(VRegistry, self).__init__()

        self.config = config

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

        # don't use self.clear, we want to keep existing subdictionaries

        for subdict in self.itervalues():

            subdict.clear()

        self._lastmodifs = {}

    def __getitem__(self, name):

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

        this name

        """

        try:

            return super(VRegistry, self).__getitem__(name)

        except KeyError:

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

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

    @deprecated('use vreg[registry].object_by_id(oid, *args, **kwargs)')

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

        """return object in <registry>.<oid>

        raise `ObjectNotFound` if not object with id <oid> in <registry>

        raise `AssertionError` if there is more than one object there

        """

        return self[registry].object_by_id(oid)

    @deprecated('use vreg[registry].select(oid, *args, **kwargs)')

    def select(self, registry, oid, *args, **kwargs):

        """return the most specific object in <registry>.<oid> according to

        the given context

        raise `ObjectNotFound` if not object with id <oid> in <registry>

        raise `NoSelectableObject` if not object apply

        """

        return self[registry].select(oid, *args, **kwargs)

    @deprecated('use vreg[registry].select_object(oid, *args, **kwargs)')

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

        """return the most specific object in <registry>.<oid> according to

        the given context, or None if no object apply

        """

        return self[registry].select_object(oid, *args, **kwargs)

    @deprecated('use vreg[registry].possible_objects(*args, **kwargs)')

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

        """return an iterator on possible objects in <registry> for the given

        context

        """

        return self[registry].possible_objects(*args, **kwargs)

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

    # default class, when no specific class set

    REGISTRY_FACTORY = {None: Registry}

    def registry_class(self, regid):

        try:

            return self.REGISTRY_FACTORY[regid]

        except KeyError:

            return self.REGISTRY_FACTORY[None]

    def setdefault(self, regid):

        try:

            return self[regid]

        except KeyError:

            self[regid] = self.registry_class(regid)(self.config)

            return self[regid]

#     def clear(self, key):

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

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

    def register_all(self, objects, modname, butclasses=()):

        for obj in objects:

            try:

                if obj.__module__ != modname or obj in butclasses:

                    continue

                oid = obj.id

            except AttributeError:

                continue

            if oid and not '__abstract__' in obj.__dict__:

                self.register(obj)

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

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

        assert not '__abstract__' in obj.__dict__

        registryname = registryname or obj.__registry__

        registry = self.setdefault(registryname)

        registry.register(obj, oid=oid, clear=clear)

        try:

            vname = obj.__name__

        except AttributeError:

            vname = obj.__class__.__name__

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

                   vname, registryname, oid or obj.id)

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

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

        self[registryname or obj.__registry__].unregister(obj)

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

        self[registryname or obj.__registry__].register_and_replace(obj, replaced)

    # initialization methods ###################################################

    def init_registration(self, path, extrapath=None):

        # compute list of all modules that have to be loaded

        self._toloadmods, filemods = _toload_info(path, extrapath)

        # XXX is _loadedmods still necessary ? It seems like it's useful

        #     to avoid loading same module twice, especially with the

        #     _load_ancestors_then_object logic but this needs to be checked

        self._loadedmods = {}

        return filemods

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

        # 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 instance's path

        filemods = self.init_registration(path, extrapath)

        change = False

        for filepath, modname in filemods:

            if self.load_file(filepath, modname, force_reload):

                change = True

        return change

    def load_file(self, filepath, modname, force_reload=False):

        """load app objects from a python file"""

        from logilab.common.modutils import load_module_from_name

        if modname in self._loadedmods:

            return

        self._loadedmods[modname] = {}

        try:

            modified_on = stat(filepath)[-2]

        except OSError:

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

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

                         filepath)

            return False

        if filepath in self._lastmodifs:

            # only load file if it was modified

            if modified_on <= self._lastmodifs[filepath]:

                return

            # if it was modified, raise RegistryOutOfDate to reload everything

            self.info('File %s changed since last visit', filepath)

            raise RegistryOutOfDate()

        # load the module

        module = load_module_from_name(modname, use_sys=not force_reload)

        self.load_module(module)

        self._lastmodifs[filepath] = modified_on

        return True

    def load_module(self, module):

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

        if hasattr(module, 'registration_callback'):

            module.registration_callback(self)

        else:

            for objname, obj in vars(module).items():

                if objname.startswith('_'):

                    continue

                self._load_ancestors_then_object(module.__name__, obj)