# copyright 2010-2013 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of CubicWeb.
#
# CubicWeb is free software: you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option)
# any later version.
#
# CubicWeb is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.
"""some basic entity adapter implementations, for interfaces used in the
framework itself.
"""

__docformat__ = "restructuredtext en"
from cubicweb import _

from itertools import chain
from warnings import warn
from hashlib import md5

from logilab.mtconverter import TransformError
from logilab.common.decorators import cached

from cubicweb import ValidationError, view, ViolatedConstraint
from cubicweb.schema import CONSTRAINTS
from cubicweb.predicates import is_instance, relation_possible, match_exception


class IEmailableAdapter(view.EntityAdapter):
    __regid__ = 'IEmailable'
    __select__ = relation_possible('primary_email') | relation_possible('use_email')

    def get_email(self):
        if getattr(self.entity, 'primary_email', None):
            return self.entity.primary_email[0].address
        if getattr(self.entity, 'use_email', None):
            return self.entity.use_email[0].address
        return None

    def allowed_massmail_keys(self):
        """returns a set of allowed email substitution keys

        The default is to return the entity's attribute list but you might
        override this method to allow extra keys.  For instance, a Person
        class might want to return a `companyname` key.
        """
        return set(rschema.type
                   for rschema, attrtype in self.entity.e_schema.attribute_definitions()
                   if attrtype.type not in ('Password', 'Bytes'))

    def as_email_context(self):
        """returns the dictionary as used by the sendmail controller to
        build email bodies.

        NOTE: the dictionary keys should match the list returned by the
        `allowed_massmail_keys` method.
        """
        return dict( (attr, getattr(self.entity, attr))
                     for attr in self.allowed_massmail_keys() )


class INotifiableAdapter(view.EntityAdapter):
    __regid__ = 'INotifiable'
    __select__ = is_instance('Any')

    def notification_references(self, view):
        """used to control References field of email send on notification
        for this entity. `view` is the notification view.

        Should return a list of eids which can be used to generate message
        identifiers of previously sent email(s)
        """
        itree = self.entity.cw_adapt_to('ITree')
        if itree is not None:
            return itree.path()[:-1]
        if view.msgid_timestamp:
            return (self.entity.eid,)
        return ()


class IFTIndexableAdapter(view.EntityAdapter):
    """standard adapter to handle fulltext indexing

    .. automethod:: cubicweb.entities.adapters.IFTIndexableAdapter.fti_containers
    .. automethod:: cubicweb.entities.adapters.IFTIndexableAdapter.get_words
    """
    __regid__ = 'IFTIndexable'
    __select__ = is_instance('Any')

    def fti_containers(self, _done=None):
        """return the list of entities to index when handling ``self.entity``

        The actual list of entities depends on ``fulltext_container`` usage
        in the datamodel definition
        """
        if _done is None:
            _done = set()
        entity = self.entity
        _done.add(entity.eid)
        containers = tuple(entity.e_schema.fulltext_containers())
        if containers:
            for rschema, role in containers:
                if role == 'object':
                    targets = getattr(entity, rschema.type)
                else:
                    targets = getattr(entity, 'reverse_%s' % rschema)
                for target in targets:
                    if target.eid in _done:
                        continue
                    for container in target.cw_adapt_to('IFTIndexable').fti_containers(_done):
                        yield container
        else:
            yield entity

    # weight in ABCD
    entity_weight = 1.0
    attr_weight = {}

    def get_words(self):
        """used by the full text indexer to get words to index

        this method should only be used on the repository side since it depends
        on the logilab.database package

        :rtype: list
        :return: the list of indexable word of this entity
        """
        from logilab.database.fti import tokenize
        # take care to cases where we're modyfying the schema
        entity = self.entity
        pending = self._cw.transaction_data.setdefault('pendingrdefs', set())
        words = {}
        for rschema in entity.e_schema.indexable_attributes():
            if (entity.e_schema, rschema) in pending:
                continue
            weight = self.attr_weight.get(rschema, 'C')
            try:
                value = entity.printable_value(rschema, format=u'text/plain')
            except TransformError:
                continue
            except Exception:
                self.exception("can't add value of %s to text index for entity %s",
                               rschema, entity.eid)
                continue
            if value:
                words.setdefault(weight, []).extend(tokenize(value))
        for rschema, role in entity.e_schema.fulltext_relations():
            if role == 'subject':
                for entity_ in getattr(entity, rschema.type):
                    merge_weight_dict(words, entity_.cw_adapt_to('IFTIndexable').get_words())
            else: # if role == 'object':
                for entity_ in getattr(entity, 'reverse_%s' % rschema.type):
                    merge_weight_dict(words, entity_.cw_adapt_to('IFTIndexable').get_words())
        return words

def merge_weight_dict(maindict, newdict):
    for weight, words in newdict.items():
        maindict.setdefault(weight, []).extend(words)

class IDownloadableAdapter(view.EntityAdapter):
    """interface for downloadable entities"""
    __regid__ = 'IDownloadable'
    __abstract__ = True

    def download_url(self, **kwargs): # XXX not really part of this interface
        """return a URL to download entity's content

        It should be a unicode object containing url-encoded ASCII."""
        raise NotImplementedError

    def download_content_type(self):
        """return MIME type (unicode) of the downloadable content"""
        raise NotImplementedError

    def download_encoding(self):
        """return encoding (unicode) of the downloadable content"""
        raise NotImplementedError

    def download_file_name(self):
        """return file name (unicode) of the downloadable content"""
        raise NotImplementedError

    def download_data(self):
        """return actual data (bytes) of the downloadable content"""
        raise NotImplementedError

# XXX should propose to use two different relations for children/parent
class ITreeAdapter(view.EntityAdapter):
    """This adapter provides a tree interface.

    It has to be overriden to be configured using the tree_relation,
    child_role and parent_role class attributes to benefit from this default
    implementation.

    This class provides the following methods:

    .. automethod: iterparents
    .. automethod: iterchildren
    .. automethod: prefixiter

    .. automethod: is_leaf
    .. automethod: is_root

    .. automethod: root
    .. automethod: parent
    .. automethod: children
    .. automethod: different_type_children
    .. automethod: same_type_children
    .. automethod: children_rql
    .. automethod: path
    """
    __regid__ = 'ITree'
    __abstract__ = True

    child_role = 'subject'
    parent_role = 'object'

    def children_rql(self):
        """Returns RQL to get the children of the entity."""
        return self.entity.cw_related_rql(self.tree_relation, self.parent_role)

    def different_type_children(self, entities=True):
        """Return children entities of different type as this entity.

        According to the `entities` parameter, return entity objects or the
        equivalent result set.
        """
        res = self.entity.related(self.tree_relation, self.parent_role,
                                  entities=entities)
        eschema = self.entity.e_schema
        if entities:
            return [e for e in res if e.e_schema != eschema]
        return res.filtered_rset(lambda x: x.e_schema != eschema, self.entity.cw_col)

    def same_type_children(self, entities=True):
        """Return children entities of the same type as this entity.

        According to the `entities` parameter, return entity objects or the
        equivalent result set.
        """
        res = self.entity.related(self.tree_relation, self.parent_role,
                                  entities=entities)
        eschema = self.entity.e_schema
        if entities:
            return [e for e in res if e.e_schema == eschema]
        return res.filtered_rset(lambda x: x.e_schema is eschema, self.entity.cw_col)

    def is_leaf(self):
        """Returns True if the entity does not have any children."""
        return len(self.children()) == 0

    def is_root(self):
        """Returns true if the entity is root of the tree (e.g. has no parent).
        """
        return self.parent() is None

    def root(self):
        """Return the root entity of the tree."""
        return self._cw.entity_from_eid(self.path()[0])

    def parent(self):
        """Returns the parent entity if any, else None (e.g. if we are on the
        root).
        """
        try:
            return self.entity.related(self.tree_relation, self.child_role,
                                       entities=True)[0]
        except (KeyError, IndexError):
            return None

    def children(self, entities=True, sametype=False):
        """Return children entities.

        According to the `entities` parameter, return entity objects or the
        equivalent result set.
        """
        if sametype:
            return self.same_type_children(entities)
        else:
            return self.entity.related(self.tree_relation, self.parent_role,
                                       entities=entities)

    def iterparents(self, strict=True):
        """Return an iterator on the parents of the entity."""
        def _uptoroot(self):
            curr = self
            while True:
                curr = curr.parent()
                if curr is None:
                    break
                yield curr
                curr = curr.cw_adapt_to('ITree')
        if not strict:
            return chain([self.entity], _uptoroot(self))
        return _uptoroot(self)

    def iterchildren(self, _done=None):
        """Return an iterator over the item's children."""
        if _done is None:
            _done = set()
        for child in self.children():
            if child.eid in _done:
                self.error('loop in %s tree: %s', child.cw_etype.lower(), child)
                continue
            yield child
            _done.add(child.eid)

    def prefixiter(self, _done=None):
        """Return an iterator over the item's descendants in a prefixed order."""
        if _done is None:
            _done = set()
        if self.entity.eid in _done:
            return
        _done.add(self.entity.eid)
        yield self.entity
        for child in self.same_type_children():
            for entity in child.cw_adapt_to('ITree').prefixiter(_done):
                yield entity

    @cached
    def path(self):
        """Returns the list of eids from the root object to this object."""
        path = []
        adapter = self
        entity = adapter.entity
        while entity is not None:
            if entity.eid in path:
                self.error('loop in %s tree: %s', entity.cw_etype.lower(), entity)
                break
            path.append(entity.eid)
            try:
                # check we are not jumping to another tree
                if (adapter.tree_relation != self.tree_relation or
                    adapter.child_role != self.child_role):
                    break
                entity = adapter.parent()
                adapter = entity.cw_adapt_to('ITree')
            except AttributeError:
                break
        path.reverse()
        return path


# error handling adapters ######################################################

from cubicweb import UniqueTogetherError

class IUserFriendlyError(view.EntityAdapter):
    __regid__ = 'IUserFriendlyError'
    __abstract__ = True

    def __init__(self, *args, **kwargs):
        self.exc = kwargs.pop('exc')
        super(IUserFriendlyError, self).__init__(*args, **kwargs)


class IUserFriendlyUniqueTogether(IUserFriendlyError):
    __select__ = match_exception(UniqueTogetherError)

    def raise_user_exception(self):
        rtypes = self.exc.rtypes
        errors = {}
        msgargs = {}
        i18nvalues = []
        for rtype in rtypes:
            errors[rtype] = _('%(KEY-rtype)s is part of violated unicity constraint')
            msgargs[rtype + '-rtype'] = rtype
            i18nvalues.append(rtype + '-rtype')
        errors[''] = _('some relations violate a unicity constraint')
        raise ValidationError(self.entity.eid, errors, msgargs=msgargs, i18nvalues=i18nvalues)


class IUserFriendlyCheckConstraint(IUserFriendlyError):
    __select__ = match_exception(ViolatedConstraint)

    def raise_user_exception(self):
        _ = self._cw._
        cstrname = self.exc.cstrname
        eschema = self.entity.e_schema
        for rschema, attrschema in eschema.attribute_definitions():
            rdef = rschema.rdef(eschema, attrschema)
            for constraint in rdef.constraints:
                if cstrname == 'cstr' + md5((eschema.type + rschema.type + constraint.type() + (constraint.serialize() or '')).encode('ascii')).hexdigest():
                    break
            else:
                continue
            break
        else:
            assert 0
        key = rschema.type + '-subject'
        msg, args = constraint.failed_message(key, self.entity.cw_edited[rschema.type])
        raise ValidationError(self.entity.eid, {key: msg}, args)