"""Base class for entity objects manipulated in clients

:organization: Logilab

:copyright: 2001-2010 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"

from warnings import warn

from logilab.common import interface

from logilab.common.compat import all

from logilab.common.decorators import cached

from logilab.common.deprecation import deprecated

from logilab.mtconverter import TransformData, TransformError, xml_escape

from rql import parse

from rql.utils import rqlvar_maker

from cubicweb import Unauthorized, typed_eid

from cubicweb.rset import ResultSet

from cubicweb.selectors import yes

from cubicweb.appobject import AppObject

from cubicweb.rqlrewrite import RQLRewriter

from cubicweb.schema import RQLVocabularyConstraint, RQLConstraint, bw_normalize_etype

from cubicweb.common.uilib import printable_value, soup2xhtml

from cubicweb.common.mixins import MI_REL_TRIGGERS

from cubicweb.common.mttransforms import ENGINE

_marker = object()

def greater_card(rschema, subjtypes, objtypes, index):

    for subjtype in subjtypes:

        for objtype in objtypes:

            card = rschema.rproperty(subjtype, objtype, 'cardinality')[index]

            if card in '+*':

                return card

    return '1'

_MODE_TAGS = set(('link', 'create'))

_CATEGORY_TAGS = set(('primary', 'secondary', 'generic', 'generated')) # , 'metadata'))

try:

    from cubicweb.web import formwidgets, uicfg

    def _dispatch_rtags(tags, rtype, role, stype, otype):

        for tag in tags:

            if tag in _MODE_TAGS:

                uicfg.actionbox_appearsin_addmenu.tag_relation(

                    (stype, rtype, otype, role), tag == 'create')

            elif tag in _CATEGORY_TAGS:

                uicfg.autoform_section.tag_relation((stype, rtype, otype, role),

                                                    tag)

            elif tag == 'inlineview':

                uicfg.autoform_is_inlined.tag_relation((stype, rtype, otype, role), True)

            else:

                raise ValueError(tag)

except ImportError:

    _dispatch_rtags = None

def _get_etype(bases, classdict):

    try:

        return classdict['id']

    except KeyError:

        for base in bases:

            etype = getattr(base, 'id', None)

            if etype and etype != 'Any':

                return etype

def _get_defs(attr, name, bases, classdict):

    try:

        yield name, classdict.pop(attr)

    except KeyError:

        for base in bases:

            try:

                value = getattr(base, attr)

                delattr(base, attr)

                yield base.__name__, value

            except AttributeError:

                continue

class _metaentity(type):

    """this metaclass sets the relation tags on the entity class

    and deals with the `widgets` attribute

    """

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

        # collect baseclass' rtags

        etype = _get_etype(bases, classdict)

        if etype and _dispatch_rtags is not None:

            for name, rtags in _get_defs('__rtags__', name, bases, classdict):

                warn('%s: __rtags__ is deprecated' % name, DeprecationWarning)

                for relation, tags in rtags.iteritems():

                    # tags must become an iterable

                    if isinstance(tags, basestring):

                        tags = (tags,)

                    # relation must become a 3-uple (rtype, targettype, role)

                    if isinstance(relation, basestring):

                        _dispatch_rtags(tags, relation, 'subject', etype, '*')

                        _dispatch_rtags(tags, relation, 'object', '*', etype)

                    elif len(relation) == 1: # useful ?

                        _dispatch_rtags(tags, relation[0], 'subject', etype, '*')

                        _dispatch_rtags(tags, relation[0], 'object', '*', etype)

                    elif len(relation) == 2:

                        rtype, ttype = relation

                        ttype = bw_normalize_etype(ttype) # XXX bw compat

                        _dispatch_rtags(tags, rtype, 'subject', etype, ttype)

                        _dispatch_rtags(tags, rtype, 'object', ttype, etype)

                    elif len(relation) == 3:

                        rtype, ttype, role = relation

                        ttype = bw_normalize_etype(ttype)

                        if role == 'subject':

                            _dispatch_rtags(tags, rtype, 'subject', etype, ttype)

                        else:

                            _dispatch_rtags(tags, rtype, 'object', ttype, etype)

                    else:

                        raise ValueError('bad rtag definition (%r)' % (relation,))

            for name, widgets in _get_defs('widgets', name, bases, classdict):

                warn('%s: widgets is deprecated' % name, DeprecationWarning)

                for rtype, wdgname in widgets.iteritems():

                    if wdgname in ('URLWidget', 'EmbededURLWidget', 'RawDynamicComboBoxWidget'):

                        warn('%s widget is deprecated' % wdgname, DeprecationWarning)

                        continue

                    if wdgname == 'StringWidget':

                        wdgname = 'TextInput'

                    widget = getattr(formwidgets, wdgname)

                    assert hasattr(widget, 'render')

                    uicfg.autoform_field_kwargs.tag_subject_of(

                        (etype, rtype, '*'), {'widget': widget})

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

class Entity(AppObject, dict):

    """an entity instance has e_schema automagically set on

    the class and instances has access to their issuing cursor.

    A property is set for each attribute and relation on each entity's type

    class. Becare that among attributes, 'eid' is *NEITHER* stored in the

    dict containment (which acts as a cache for other attributes dynamically

    fetched)

    :type e_schema: `cubicweb.schema.EntitySchema`

    :ivar e_schema: the entity's schema

    :type rest_var: str

    :cvar rest_var: indicates which attribute should be used to build REST urls

                    If None is specified, the first non-meta attribute will

                    be used

    :type skip_copy_for: list

    :cvar skip_copy_for: a list of relations that should be skipped when copying

                         this kind of entity. Note that some relations such

                         as composite relations or relations that have '?1' as object

                         cardinality are always skipped. 

    """

    __metaclass__ = _metaentity

    __registry__ = 'etypes'

    __select__ = yes()

    # class attributes that must be set in class definition

    id = None

    rest_attr = None

    fetch_attrs = None

    skip_copy_for = ('in_state',)

    # class attributes set automatically at registration time

    e_schema = None

    MODE_TAGS = set(('link', 'create'))

    CATEGORY_TAGS = set(('primary', 'secondary', 'generic', 'generated')) # , 'metadata'))

    @classmethod

    def __initialize__(cls):

        """initialize a specific entity class by adding descriptors to access

        entity type's attributes and relations

        """

        etype = cls.id

        assert etype != 'Any', etype

        cls.e_schema = eschema = cls.schema.eschema(etype)

        for rschema, _ in eschema.attribute_definitions():

            if rschema.type == 'eid':

                continue

            setattr(cls, rschema.type, Attribute(rschema.type))

        mixins = []

        for rschema, _, role in eschema.relation_definitions():

            if (rschema, role) in MI_REL_TRIGGERS:

                mixin = MI_REL_TRIGGERS[(rschema, role)]

                if not (issubclass(cls, mixin) or mixin in mixins): # already mixed ?

                    mixins.append(mixin)

                for iface in getattr(mixin, '__implements__', ()):

                    if not interface.implements(cls, iface):

                        interface.extend(cls, iface)

            if role == 'subject':

                setattr(cls, rschema.type, SubjectRelation(rschema))

            else:

                attr = 'reverse_%s' % rschema.type

                setattr(cls, attr, ObjectRelation(rschema))

        if mixins:

            # see etype class instantation in cwvreg.ETypeRegistry.etype_class method:

            # due to class dumping, cls is the generated top level class with actual

            # user class as (only) parent. Since we want to be able to override mixins

            # method from this user class, we have to take care to insert mixins after that

            # class

            #

            # note that we don't plug mixins as user class parent since it causes pb

            # with some cases of entity classes inheritance.

            mixins.insert(0, cls.__bases__[0])

            mixins += cls.__bases__[1:]

            cls.__bases__ = tuple(mixins)

            cls.info('plugged %s mixins on %s', mixins, cls)

    @classmethod

    def fetch_rql(cls, user, restriction=None, fetchattrs=None, mainvar='X',

                  settype=True, ordermethod='fetch_order'):

        """return a rql to fetch all entities of the class type"""

        restrictions = restriction or []

        if settype:

            restrictions.append('%s is %s' % (mainvar, cls.id))

        if fetchattrs is None:

            fetchattrs = cls.fetch_attrs

        selection = [mainvar]

        orderby = []

        # start from 26 to avoid possible conflicts with X

        varmaker = rqlvar_maker(index=26)

        cls._fetch_restrictions(mainvar, varmaker, fetchattrs, selection,

                                orderby, restrictions, user, ordermethod)

        rql = 'Any %s' % ','.join(selection)

        if orderby:

            rql +=  ' ORDERBY %s' % ','.join(orderby)

        rql += ' WHERE %s' % ', '.join(restrictions)

        return rql

    @classmethod

    def _fetch_restrictions(cls, mainvar, varmaker, fetchattrs,

                            selection, orderby, restrictions, user,

                            ordermethod='fetch_order', visited=None):

        eschema = cls.e_schema

        if visited is None:

            visited = set((eschema.type,))

        elif eschema.type in visited:

            # avoid infinite recursion

            return

        else:

            visited.add(eschema.type)

        _fetchattrs = []

        for attr in fetchattrs:

            try:

                rschema = eschema.subjrels[attr]

            except KeyError:

                cls.warning('skipping fetch_attr %s defined in %s (not found in schema)',

                            attr, cls.id)

                continue

            if not user.matching_groups(rschema.get_groups('read')):

                continue

            var = varmaker.next()

            selection.append(var)

            restriction = '%s %s %s' % (mainvar, attr, var)

            restrictions.append(restriction)

            if not rschema.final:

                # XXX this does not handle several destination types

                desttype = rschema.objects(eschema.type)[0]

                card = rschema.rproperty(eschema, desttype, 'cardinality')[0]

                if card not in '?1':

                    cls.warning('bad relation %s specified in fetch attrs for %s',

                                 attr, cls)

                    selection.pop()

                    restrictions.pop()

                    continue

                # XXX we need outer join in case the relation is not mandatory

                # (card == '?')  *or if the entity is being added*, since in

                # that case the relation may still be missing. As we miss this

                # later information here, systematically add it.

                restrictions[-1] += '?'

                destcls = cls.vreg['etypes'].etype_class(desttype)

                destcls._fetch_restrictions(var, varmaker, destcls.fetch_attrs,

                                            selection, orderby, restrictions,

                                            user, ordermethod, visited=visited)

            orderterm = getattr(cls, ordermethod)(attr, var)

            if orderterm:

                orderby.append(orderterm)

        return selection, orderby, restrictions

    @classmethod

    @cached

    def parent_classes(cls):

        parents = [cls.vreg['etypes'].etype_class(e.type)

                   for e in cls.e_schema.ancestors()]

        parents.append(cls.vreg['etypes'].etype_class('Any'))

        return parents

    @classmethod

    @cached

    def _rest_attr_info(cls):

        mainattr, needcheck = 'eid', True

        if cls.rest_attr:

            mainattr = cls.rest_attr

            needcheck = not cls.e_schema.has_unique_values(mainattr)

        else:

            for rschema in cls.e_schema.subject_relations():

                if rschema.final and rschema != 'eid' and cls.e_schema.has_unique_values(rschema):

                    mainattr = str(rschema)

                    needcheck = False

                    break

        if mainattr == 'eid':

            needcheck = False

        return mainattr, needcheck

    def __init__(self, req, rset=None, row=None, col=0):

        AppObject.__init__(self, req, rset, row, col)

        dict.__init__(self)

        self._related_cache = {}

        if rset is not None:

            self.eid = rset[row][col]

        else:

            self.eid = None

        self._is_saved = True

    def __repr__(self):

        return '<Entity %s %s %s at %s>' % (

            self.e_schema, self.eid, self.keys(), id(self))

    def __nonzero__(self):

        return True

    def __hash__(self):

        return id(self)

    def __cmp__(self, other):

        raise NotImplementedError('comparison not implemented for %s' % self.__class__)

    def pre_add_hook(self):

        """hook called by the repository before doing anything to add the entity

        (before_add entity hooks have not been called yet). This give the

        occasion to do weird stuff such as autocast (File -> Image for instance).

        This method must return the actual entity to be added.

        """

        return self

    def set_eid(self, eid):

        self.eid = self['eid'] = eid

    def has_eid(self):

        """return True if the entity has an attributed eid (False

        meaning that the entity has to be created

        """

        try:

            typed_eid(self.eid)

            return True

        except (ValueError, TypeError):

            return False

    def is_saved(self):

        """during entity creation, there is some time during which the entity

        has an eid attributed though it's not saved (eg during before_add_entity

        hooks). You can use this method to ensure the entity has an eid *and* is

        saved in its source.

        """

        return self.has_eid() and self._is_saved

    @cached

    def metainformation(self):

        res = dict(zip(('type', 'source', 'extid'), self.req.describe(self.eid)))

        res['source'] = self.req.source_defs()[res['source']]

        return res

    def clear_local_perm_cache(self, action):

        for rqlexpr in self.e_schema.get_rqlexprs(action):

            self.req.local_perm_cache.pop((rqlexpr.eid, (('x', self.eid),)), None)

    def check_perm(self, action):

        self.e_schema.check_perm(self.req, action, self.eid)

    def has_perm(self, action):

        return self.e_schema.has_perm(self.req, action, self.eid)