# copyright 2010-2012 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/>.
"""hooks for repository sources synchronization"""

_ = unicode

from socket import gethostname

from logilab.common.decorators import clear_cache

from cubicweb import validation_error
from cubicweb.predicates import is_instance
from cubicweb.server import SOURCE_TYPES, hook

class SourceHook(hook.Hook):
    __abstract__ = True
    category = 'cw.sources'


# repo sources synchronization #################################################

class SourceAddedOp(hook.Operation):
    entity = None # make pylint happy
    def postcommit_event(self):
        self.session.repo.add_source(self.entity)

class SourceAddedHook(SourceHook):
    __regid__ = 'cw.sources.added'
    __select__ = SourceHook.__select__ & is_instance('CWSource')
    events = ('after_add_entity',)
    def __call__(self):
        try:
            sourcecls = SOURCE_TYPES[self.entity.type]
        except KeyError:
            msg = _('unknown source type')
            raise validation_error(self.entity, {('type', 'subject'): msg})
        sourcecls.check_conf_dict(self.entity.eid, self.entity.host_config,
                                  fail_if_unknown=not self._cw.vreg.config.repairing)
        SourceAddedOp(self._cw, entity=self.entity)


class SourceRemovedOp(hook.Operation):
    uri = None # make pylint happy
    def postcommit_event(self):
        self.session.repo.remove_source(self.uri)

class SourceRemovedHook(SourceHook):
    __regid__ = 'cw.sources.removed'
    __select__ = SourceHook.__select__ & is_instance('CWSource')
    events = ('before_delete_entity',)
    def __call__(self):
        if self.entity.name == 'system':
            msg = _("You cannot remove the system source")
            raise validation_error(self.entity, {None: msg})
        SourceRemovedOp(self._cw, uri=self.entity.name)


class SourceConfigUpdatedOp(hook.DataOperationMixIn, hook.Operation):

    def precommit_event(self):
        self.__processed = []
        for source in self.get_data():
            if not self.session.deleted_in_transaction(source.eid):
                conf = source.repo_source.check_config(source)
                self.__processed.append( (source, conf) )

    def postcommit_event(self):
        for source, conf in self.__processed:
            source.repo_source.update_config(source, conf)


class SourceRenamedOp(hook.LateOperation):
    oldname = newname = None # make pylint happy

    def precommit_event(self):
        source = self.session.repo.sources_by_uri[self.oldname]
        if source.copy_based_source:
            sql = 'UPDATE entities SET asource=%(newname)s WHERE asource=%(oldname)s'
        else:
            sql = 'UPDATE entities SET source=%(newname)s, asource=%(newname)s WHERE source=%(oldname)s'
        self.session.system_sql(sql, {'oldname': self.oldname,
                                      'newname': self.newname})

    def postcommit_event(self):
        repo = self.session.repo
        # XXX race condition
        source = repo.sources_by_uri.pop(self.oldname)
        source.uri = self.newname
        source.public_config['uri'] = self.newname
        repo.sources_by_uri[self.newname] = source
        repo._type_source_cache.clear()
        clear_cache(repo, 'source_defs')
        if not source.copy_based_source:
            repo._extid_cache.clear()
            repo._clear_planning_caches()
            for cnxset in repo.cnxsets:
                cnxset.source_cnxs[self.oldname] = cnxset.source_cnxs.pop(self.oldname)


class SourceUpdatedHook(SourceHook):
    __regid__ = 'cw.sources.configupdate'
    __select__ = SourceHook.__select__ & is_instance('CWSource')
    events = ('before_update_entity',)
    def __call__(self):
        if 'config' in self.entity.cw_edited:
            SourceConfigUpdatedOp.get_instance(self._cw).add_data(self.entity)
        if 'name' in self.entity.cw_edited:
            oldname, newname = self.entity.cw_edited.oldnewvalue('name')
            SourceRenamedOp(self._cw, oldname=oldname, newname=newname)


class SourceHostConfigUpdatedHook(SourceHook):
    __regid__ = 'cw.sources.hostconfigupdate'
    __select__ = SourceHook.__select__ & is_instance('CWSourceHostConfig')
    events = ('after_add_entity', 'after_update_entity', 'before_delete_entity',)
    def __call__(self):
        if self.entity.match(gethostname()):
            if self.event == 'after_update_entity' and \
                   not 'config' in self.entity.cw_edited:
                return
            try:
                SourceConfigUpdatedOp.get_instance(self._cw).add_data(self.entity.cwsource)
            except IndexError:
                # XXX no source linked to the host config yet
                pass


# source mapping synchronization ###############################################
#
# Expect cw_for_source/cw_schema are immutable relations (i.e. can't change from
# a source or schema to another).

class SourceMappingImmutableHook(SourceHook):
    """check cw_for_source and cw_schema are immutable relations

    XXX empty delete perms would be enough?
    """
    __regid__ = 'cw.sources.mapping.immutable'
    __select__ = SourceHook.__select__ & hook.match_rtype('cw_for_source', 'cw_schema')
    events = ('before_add_relation',)
    def __call__(self):
        if not self._cw.added_in_transaction(self.eidfrom):
            msg = _("You can't change this relation")
            raise validation_error(self.eidfrom, {self.rtype: msg})


class SourceMappingChangedOp(hook.DataOperationMixIn, hook.Operation):
    def check_or_update(self, checkonly):
        session = self.session
        # take care, can't call get_data() twice
        try:
            data = self.__data
        except AttributeError:
            data = self.__data = self.get_data()
        for schemacfg, source in data:
            if source is None:
                source = schemacfg.cwsource.repo_source
            if session.added_in_transaction(schemacfg.eid):
                if not session.deleted_in_transaction(schemacfg.eid):
                    source.add_schema_config(schemacfg, checkonly=checkonly)
            elif session.deleted_in_transaction(schemacfg.eid):
                source.del_schema_config(schemacfg, checkonly=checkonly)
            else:
                source.update_schema_config(schemacfg, checkonly=checkonly)

    def precommit_event(self):
        self.check_or_update(True)

    def postcommit_event(self):
        self.check_or_update(False)


class SourceMappingChangedHook(SourceHook):
    __regid__ = 'cw.sources.schemaconfig'
    __select__ = SourceHook.__select__ & is_instance('CWSourceSchemaConfig')
    events = ('after_add_entity', 'after_update_entity')
    def __call__(self):
        if self.event == 'after_add_entity' or (
            self.event == 'after_update_entity' and 'options' in self.entity.cw_edited):
            SourceMappingChangedOp.get_instance(self._cw).add_data(
                (self.entity, None) )

class SourceMappingDeleteHook(SourceHook):
    __regid__ = 'cw.sources.delschemaconfig'
    __select__ = SourceHook.__select__ & hook.match_rtype('cw_for_source')
    events = ('before_delete_relation',)
    def __call__(self):
        SourceMappingChangedOp.get_instance(self._cw).add_data(
            (self._cw.entity_from_eid(self.eidfrom),
             self._cw.entity_from_eid(self.eidto).repo_source) )