# copyright 2010-2011 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/>.

"""datafeed sources: copy data from an external data stream into the system

database

"""

from __future__ import with_statement

import urllib2

import StringIO

from datetime import datetime, timedelta

from base64 import b64decode

from cookielib import CookieJar

from lxml import etree

from cubicweb import RegistryNotFound, ObjectNotFound, ValidationError, UnknownEid

from cubicweb.server.sources import AbstractSource

from cubicweb.appobject import AppObject

class DataFeedSource(AbstractSource):

    copy_based_source = True

    options = (

        ('synchronize',

         {'type' : 'yn',

          'default': True,

          'help': ('Is the repository responsible to automatically import '

                   'content from this source? '

                   'You should say yes unless you don\'t want this behaviour '

                   'or if you use a multiple repositories setup, in which '

                   'case you should say yes on one repository, no on others.'),

          'group': 'datafeed-source', 'level': 2,

          }),

        ('synchronization-interval',

         {'type' : 'time',

          'default': '5min',

          'help': ('Interval in seconds between synchronization with the '

                   'external source (default to 5 minutes, must be >= 1 min).'),

          'group': 'datafeed-source', 'level': 2,

          }),

        ('delete-entities',

         {'type' : 'yn',

          'default': True,

          'help': ('Should already imported entities not found anymore on the '

                   'external source be deleted?'),

          'group': 'datafeed-source', 'level': 2,

          }),

        )

    def __init__(self, repo, source_config, eid=None):

        AbstractSource.__init__(self, repo, source_config, eid)

        self.update_config(None, self.check_conf_dict(eid, source_config))

    def check_config(self, source_entity):

        """check configuration of source entity"""

        typedconfig = super(DataFeedSource, self).check_config(source_entity)

        if typedconfig['synchronization-interval'] < 60:

            _ = source_entity._cw._

            msg = _('synchronization-interval must be greater than 1 minute')

            raise ValidationError(source_entity.eid, {'config': msg})

        return typedconfig

    def _entity_update(self, source_entity):

        source_entity.complete()

        self.parser_id = source_entity.parser

        self.latest_retrieval = source_entity.latest_retrieval

        self.urls = [url.strip() for url in source_entity.url.splitlines()

                     if url.strip()]

    def update_config(self, source_entity, typedconfig):

        """update configuration from source entity. `typedconfig` is config

        properly typed with defaults set

        """

        self.synchro_interval = timedelta(seconds=typedconfig['synchronization-interval'])

        if source_entity is not None:

            self._entity_update(source_entity)

        self.config = typedconfig

    def init(self, activated, source_entity):

        if activated:

            self._entity_update(source_entity)

        self.parser_id = source_entity.parser

        self.load_mapping(source_entity._cw)

    def _get_parser(self, session, **kwargs):

        return self.repo.vreg['parsers'].select(

            self.parser_id, session, source=self, **kwargs)

    def load_mapping(self, session):

        self.mapping = {}

        self.mapping_idx = {}

        try:

            parser = self._get_parser(session)

        except (RegistryNotFound, ObjectNotFound):

            return # no parser yet, don't go further

        self._load_mapping(session, parser=parser)

    def add_schema_config(self, schemacfg, checkonly=False, parser=None):

        """added CWSourceSchemaConfig, modify mapping accordingly"""

        if parser is None:

            parser = self._get_parser(schemacfg._cw)

        parser.add_schema_config(schemacfg, checkonly)

    def del_schema_config(self, schemacfg, checkonly=False, parser=None):

        """deleted CWSourceSchemaConfig, modify mapping accordingly"""

        if parser is None:

            parser = self._get_parser(schemacfg._cw)

        parser.del_schema_config(schemacfg, checkonly)

    def fresh(self):

        if self.latest_retrieval is None:

            return False

        return datetime.utcnow() < (self.latest_retrieval + self.synchro_interval)

    def update_latest_retrieval(self, session):

        self.latest_retrieval = datetime.utcnow()

        session.execute('SET X latest_retrieval %(date)s WHERE X eid %(x)s',

                        {'x': self.eid, 'date': self.latest_retrieval})

    def acquire_synchronization_lock(self, session):

        # XXX race condition until WHERE of SET queries is executed using

        # 'SELECT FOR UPDATE'

        if not session.execute('SET X synchronizing TRUE WHERE X eid %(x)s, X synchronizing FALSE',

                               {'x': self.eid}):

            self.error('concurrent synchronization detected, skip pull')

            session.commit(free_cnxset=False)

            return False

        session.commit(free_cnxset=False)

        return True

    def release_synchronization_lock(self, session):

        session.execute('SET X synchronizing FALSE WHERE X eid %(x)s',

                        {'x': self.eid})

        session.commit()

    def pull_data(self, session, force=False, raise_on_error=False):

        """Launch synchronization of the source if needed.

        This method is responsible to handle commit/rollback on the given

        session.

        """

        if not force and self.fresh():

            return {}

        if not self.acquire_synchronization_lock(session):

            return {}

        try:

            with session.transaction(free_cnxset=False):

                return self._pull_data(session, force, raise_on_error)

        finally:

            self.release_synchronization_lock(session)

    def _pull_data(self, session, force=False, raise_on_error=False):

        if self.config['delete-entities']:

            myuris = self.source_cwuris(session)

        else:

            myuris = None

        parser = self._get_parser(session, sourceuris=myuris)

        if self.process_urls(parser, self.urls, raise_on_error):

            self.warning("some error occured, don't attempt to delete entities")

        elif self.config['delete-entities'] and myuris:

            byetype = {}

            for eid, etype in myuris.values():

                byetype.setdefault(etype, []).append(str(eid))

            self.error('delete %s entities %s', self.uri, byetype)

            for etype, eids in byetype.iteritems():

                session.execute('DELETE %s X WHERE X eid IN (%s)'

                                % (etype, ','.join(eids)))

        self.update_latest_retrieval(session)

        return parser.stats

    def process_urls(self, parser, urls, raise_on_error=False):

        error = False

        for url in urls:

            self.info('pulling data from %s', url)

            try:

                if parser.process(url, raise_on_error):

                    error = True

            except Exception, exc:

                if raise_on_error:

                    raise

                self.error('could not pull data while processing %s: %s',

                           url, exc)

                error = True

        return error

    def before_entity_insertion(self, session, lid, etype, eid, sourceparams):

        """called by the repository when an eid has been attributed for an

        entity stored here but the entity has not been inserted in the system

        table yet.

        This method must return the an Entity instance representation of this

        entity.

        """

        entity = super(DataFeedSource, self).before_entity_insertion(

            session, lid, etype, eid, sourceparams)

        entity.cw_edited['cwuri'] = unicode(lid)

        entity.cw_edited.set_defaults()

        sourceparams['parser'].before_entity_copy(entity, sourceparams)

        # avoid query to search full-text indexed attributes

        for attr in entity.e_schema.indexable_attributes():

            entity.cw_edited.setdefault(attr, u'')

        return entity

    def after_entity_insertion(self, session, lid, entity, sourceparams):

        """called by the repository after an entity stored here has been

        inserted in the system table.

        """

        if session.is_hook_category_activated('integrity'):

            entity.cw_edited.check(creation=True)

        self.repo.system_source.add_entity(session, entity)

        entity.cw_edited.saved = entity._cw_is_saved = True

        sourceparams['parser'].after_entity_copy(entity, sourceparams)

    def source_cwuris(self, session):

        sql = ('SELECT extid, eid, type FROM entities, cw_source_relation '

               'WHERE entities.eid=cw_source_relation.eid_from '

               'AND cw_source_relation.eid_to=%s' % self.eid)

        return dict((b64decode(uri), (eid, type))

                    for uri, eid, type in session.system_sql(sql))

class DataFeedParser(AppObject):

    __registry__ = 'parsers'

    def __init__(self, session, source, sourceuris=None, **kwargs):

        super(DataFeedParser, self).__init__(session, **kwargs)

        self.source = source

        self.sourceuris = sourceuris

        self.stats = {'created': set(),

                      'updated': set()}

    def add_schema_config(self, schemacfg, checkonly=False):

        """added CWSourceSchemaConfig, modify mapping accordingly"""

        msg = schemacfg._cw._("this parser doesn't use a mapping")

        raise ValidationError(schemacfg.eid, {None: msg})

    def del_schema_config(self, schemacfg, checkonly=False):

        """deleted CWSourceSchemaConfig, modify mapping accordingly"""

        msg = schemacfg._cw._("this parser doesn't use a mapping")

        raise ValidationError(schemacfg.eid, {None: msg})

    def extid2entity(self, uri, etype, **sourceparams):

        """return an entity for the given uri. May return None if it should be

        skipped

        """

        # if cwsource is specified and repository has a source with the same

        # name, call extid2eid on that source so entity will be properly seen as

        # coming from this source

        source = self._cw.repo.sources_by_uri.get(

            sourceparams.pop('cwsource', None), self.source)

        sourceparams['parser'] = self

        eid = source.extid2eid(str(uri), etype, self._cw,

                               sourceparams=sourceparams)

        if eid < 0:

            # entity has been moved away from its original source

            #

            # Don't give etype to entity_from_eid so we get UnknownEid if the

            # entity has been removed

            try:

                entity = self._cw.entity_from_eid(-eid)

            except UnknownEid:

                return None

            self.notify_updated(entity) # avoid later update from the source's data

            return entity

        if self.sourceuris is not None:

            self.sourceuris.pop(str(uri), None)

        return self._cw.entity_from_eid(eid, etype)

    def process(self, url, partialcommit=True):

        """main callback: process the url"""

        raise NotImplementedError

    def before_entity_copy(self, entity, sourceparams):

        raise NotImplementedError

    def after_entity_copy(self, entity, sourceparams):

        self.stats['created'].add(entity.eid)

    def created_during_pull(self, entity):

        return entity.eid in self.stats['created']

    def updated_during_pull(self, entity):

        return entity.eid in self.stats['updated']

    def notify_updated(self, entity):

        return self.stats['updated'].add(entity.eid)

class DataFeedXMLParser(DataFeedParser):

    def process(self, url, raise_on_error=False, partialcommit=True):

        """IDataFeedParser main entry point"""

        try:

            parsed = self.parse(url)

        except Exception, ex:

            if raise_on_error:

                raise

            self.source.error(str(ex))

            return True

        error = False

        for args in parsed:

            try:

                self.process_item(*args)

                if partialcommit:

                    # commit+set_cnxset instead of commit(free_cnxset=False) to let

                    # other a chance to get our connections set

                    self._cw.commit()

                    self._cw.set_cnxset()

            except ValidationError, exc:

                if raise_on_error:

                    raise

                if partialcommit:

                    self.source.error('Skipping %s because of validation error %s' % (args, exc))

                    self._cw.rollback()

                    self._cw.set_cnxset()

                    error = True

                else:

                    raise

        return error

    def parse(self, url):

        if url.startswith('http'):

            from cubicweb.sobjects.parsers import HOST_MAPPING

            for mappedurl in HOST_MAPPING:

                if url.startswith(mappedurl):

                    url = url.replace(mappedurl, HOST_MAPPING[mappedurl], 1)

                    break

            self.source.info('GET %s', url)

            stream = _OPENER.open(url)

        elif url.startswith('file://'):

            stream = open(url[7:])

        else:

            stream = StringIO.StringIO(url)

        return self.parse_etree(etree.parse(stream).getroot())

    def parse_etree(self, document):

        return [(document,)]

    def process_item(self, *args):

        raise NotImplementedError

# use a cookie enabled opener to use session cookie if any

_OPENER = urllib2.build_opener()

try:

    from logilab.common import urllib2ext

    _OPENER.add_handler(urllib2ext.HTTPGssapiAuthHandler())

except ImportError: # python-kerberos not available

    pass

_OPENER.add_handler(urllib2.HTTPCookieProcessor(CookieJar()))