# copyright 2010-2014 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

"""

import StringIO

from os.path import exists

from datetime import datetime, timedelta

from six.moves.urllib.parse import urlparse

from six.moves.urllib.request import Request, build_opener, HTTPCookieProcessor

from six.moves.urllib.error import HTTPError

from lxml import etree

from cubicweb import RegistryNotFound, ObjectNotFound, ValidationError, UnknownEid

from cubicweb.server.repository import preprocess_inlined_relations

from cubicweb.server.sources import AbstractSource

from cubicweb.appobject import AppObject

class DataFeedSource(AbstractSource):

    use_cwuri_as_url = 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,

          }),

        ('max-lock-lifetime',

         {'type' : 'time',

          'default': '1h',

          'help': ('Maximum time allowed for a synchronization to be run. '

                   'Exceeded that time, the synchronization will be considered '

                   'as having failed and not properly released the lock, hence '

                   'it won\'t be considered'),

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

          }),

        ('delete-entities',

         {'type' : 'yn',

          'default': False,

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

                   'external source be deleted?'),

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

          }),

        ('logs-lifetime',

         {'type': 'time',

          'default': '10d',

          'help': ('Time before logs from datafeed imports are deleted.'),

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

          }),

        ('http-timeout',

         {'type': 'time',

          'default': '1min',

          'help': ('Timeout of HTTP GET requests, when synchronizing a source.'),

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

          }),

        ('use-cwuri-as-url',

         {'type': 'yn',

          'default': None, # explicitly unset

          'help': ('Use cwuri (i.e. external URL) for link to the entity '

                   'instead of its local URL.'),

          'group': 'datafeed-source', 'level': 1,

          }),

        )

    def check_config(self, source_entity):

        """check configuration of source entity"""

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

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

            _ = source_entity._cw._

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

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

        return typed_config

    def _entity_update(self, source_entity):

        super(DataFeedSource, self)._entity_update(source_entity)

        self.parser_id = source_entity.parser

        self.latest_retrieval = source_entity.latest_retrieval

    def update_config(self, source_entity, typed_config):

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

        properly typed with defaults set

        """

        super(DataFeedSource, self).update_config(source_entity, typed_config)

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

        self.max_lock_lifetime = timedelta(seconds=typed_config['max-lock-lifetime'])

        self.http_timeout = typed_config['http-timeout']

        # if typed_config['use-cwuri-as-url'] is set, we have to update

        # use_cwuri_as_url attribute and public configuration dictionary

        # accordingly

        if typed_config['use-cwuri-as-url'] is not None:

            self.use_cwuri_as_url = typed_config['use-cwuri-as-url']

            self.public_config['use-cwuri-as-url'] = self.use_cwuri_as_url

    def init(self, activated, source_entity):

        super(DataFeedSource, self).init(activated, source_entity)

        self.parser_id = source_entity.parser

        self.load_mapping(source_entity._cw)

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

        if self.parser_id is None:

            self.warning('No parser defined on source %r', self)

            raise ObjectNotFound()

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

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

    def load_mapping(self, cnx):

        self.mapping = {}

        self.mapping_idx = {}

        try:

            parser = self._get_parser(cnx)

        except (RegistryNotFound, ObjectNotFound):

            return # no parser yet, don't go further

        self._load_mapping(cnx, 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, cnx):

        self.latest_retrieval = datetime.utcnow()

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

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

        cnx.commit()

    def acquire_synchronization_lock(self, cnx):

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

        # 'SELECT FOR UPDATE'

        now = datetime.utcnow()

        if not cnx.execute(

            'SET X in_synchronization %(now)s WHERE X eid %(x)s, '

            'X in_synchronization NULL OR X in_synchronization < %(maxdt)s',

            {'x': self.eid, 'now': now, 'maxdt': now - self.max_lock_lifetime}):

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

            cnx.commit()

            return False

        cnx.commit()

        return True

    def release_synchronization_lock(self, cnx):

        cnx.execute('SET X in_synchronization NULL WHERE X eid %(x)s',

                    {'x': self.eid})

        cnx.commit()

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

        """Launch synchronization of the source if needed.

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

        connection.

        """

        if not force and self.fresh():

            return {}

        if not self.acquire_synchronization_lock(cnx):

            return {}

        try:

            return self._pull_data(cnx, force, raise_on_error)

        finally:

            cnx.rollback() # rollback first in case there is some dirty

                           # transaction remaining

            self.release_synchronization_lock(cnx)

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

        importlog = self.init_import_log(cnx)

        myuris = self.source_cwuris(cnx)

        try:

            parser = self._get_parser(cnx, sourceuris=myuris, import_log=importlog)

        except ObjectNotFound:

            return {}

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

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

        else:

            parser.handle_deletion(self.config, cnx, myuris)

        self.update_latest_retrieval(cnx)

        stats = parser.stats

        if stats.get('created'):

            importlog.record_info('added %s entities' % len(stats['created']))

        if stats.get('updated'):

            importlog.record_info('updated %s entities' % len(stats['updated']))

        importlog.write_log(cnx, end_timestamp=self.latest_retrieval)

        cnx.commit()

        return 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 IOError as exc:

                if raise_on_error:

                    raise

                parser.import_log.record_error(

                    'could not pull data while processing %s: %s'

                    % (url, exc))

                error = True

            except Exception as exc:

                if raise_on_error:

                    raise

                self.exception('error while processing %s: %s',

                               url, exc)

                error = True

        return error

    def before_entity_insertion(self, cnx, 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(

            cnx, lid, etype, eid, sourceparams)

        entity.cw_edited['cwuri'] = lid.decode('utf-8')

        entity.cw_edited.set_defaults()

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

        return entity

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

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

        inserted in the system table.

        """

        relations = preprocess_inlined_relations(cnx, entity)

        if cnx.is_hook_category_activated('integrity'):

            entity.cw_edited.check(creation=True)

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

        entity.cw_edited.saved = entity._cw_is_saved = True

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

        # call hooks for inlined relations

        call_hooks = self.repo.hm.call_hooks

        if self.should_call_hooks:

            for attr, value in relations:

                call_hooks('before_add_relation', cnx,

                           eidfrom=entity.eid, rtype=attr, eidto=value)

                call_hooks('after_add_relation', cnx,

                           eidfrom=entity.eid, rtype=attr, eidto=value)

    def source_cwuris(self, cnx):

        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((self.decode_extid(uri), (eid, type))

                    for uri, eid, type in cnx.system_sql(sql).fetchall())

    def init_import_log(self, cnx, **kwargs):

        dataimport = cnx.create_entity('CWDataImport', cw_import_of=self,

                                           start_timestamp=datetime.utcnow(),

                                           **kwargs)

        dataimport.init()

        return dataimport

class DataFeedParser(AppObject):

    __registry__ = 'parsers'

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

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

        self.source = source

        self.sourceuris = sourceuris

        self.import_log = import_log

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

    def normalize_url(self, url):

        """Normalize an url by looking if there is a replacement for it in

        `cubicweb.sobjects.URL_MAPPING`.

        This dictionary allow to redirect from one host to another, which may be

        useful for example in case of test instance using production data, while

        you don't want to load the external source nor to hack your `/etc/hosts`

        file.

        """

        # local import mandatory, it's available after registration

        from cubicweb.sobjects import URL_MAPPING

        for mappedurl in URL_MAPPING:

            if url.startswith(mappedurl):

                return url.replace(mappedurl, URL_MAPPING[mappedurl], 1)

        return url

    def retrieve_url(self, url):

        """Return stream linked by the given url:

        * HTTP urls will be normalized (see :meth:`normalize_url`)

        * handle file:// URL

        * other will be considered as plain content, useful for testing purpose

        For http URLs, it will try to find a cwclientlib config entry

        (if available) and use it as requester.

        """

        purl = urlparse(url)

        if purl.scheme == 'file':

            return URLLibResponseAdapter(open(url[7:]), url)

        url = self.normalize_url(url)

        # first, try to use cwclientlib if it's available and if the

        # url matches a configuration entry in ~/.config/cwclientlibrc

        try:

            from cwclientlib import cwproxy_for

            # parse url again since it has been normalized

            cnx = cwproxy_for(url)

            cnx.timeout = self.source.http_timeout

            self.source.info('Using cwclientlib for %s' % url)

            resp = cnx.get(url)

            resp.raise_for_status()

            return URLLibResponseAdapter(StringIO.StringIO(resp.text), url)

        except (ImportError, ValueError, EnvironmentError) as exc:

            # ImportError: not available

            # ValueError: no config entry found

            # EnvironmentError: no cwclientlib config file found

            self.source.debug(str(exc))

        # no chance with cwclientlib, fall back to former implementation

        if purl.scheme in ('http', 'https'):

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

            req = Request(url)

            return _OPENER.open(req, timeout=self.source.http_timeout)

        # url is probably plain content

        return URLLibResponseAdapter(StringIO.StringIO(url), url)

    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.