# copyright 2010-2016 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 warnings import warn

from io import BytesIO

from os.path import exists

from datetime import datetime, timedelta

from functools import partial

from http.cookiejar import CookieJar

from urllib.parse import urlparse

from urllib.request import Request, build_opener, HTTPCookieProcessor

from urllib.error import HTTPError

from pytz import utc

from lxml import etree

from cubicweb import ObjectNotFound, ValidationError, SourceException, _

from cubicweb.server.sources import AbstractSource

from cubicweb.appobject import AppObject

class DataFeedSource(AbstractSource):

    use_cwuri_as_url = True

    options = (

        ('synchronize',

          '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',

          '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',

          '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',

          'default': False,

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

                   'external source be deleted? Handling of this parameter '

                   "will depend on source's parser."),

          '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',

          '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:

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

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

        return typed_config

    def init(self, source_entity):

        super(DataFeedSource, self).init(source_entity)

        self.parser_id = source_entity.parser

        self.latest_retrieval = source_entity.latest_retrieval

        typed_config = self.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 _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 fresh(self):

        if self.latest_retrieval is None:

            return False

        return datetime.now(tz=utc) < (self.latest_retrieval + self.synchro_interval)

    def update_latest_retrieval(self, cnx):

        self.latest_retrieval = datetime.now(tz=utc)

        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.now(tz=utc)

        maxdt = now - self.max_lock_lifetime

        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': maxdt}):

            cnx.commit()

            raise SourceException("a concurrent synchronization is already running")

        cnx.commit()

    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, sync=True, **kwargs):

        """Launch synchronization of the source if needed.

        If `sync` is false, the method return immediatly a dictionnary containing the import log's

        eid, and the actual synchronization is done asynchronously. If `sync` is True, return some

        imports statistics (e.g. number of created and updated entities).

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

        """

        if not force and self.fresh():

            return {}

        try:

            self.acquire_synchronization_lock(cnx)

        except SourceException as exc:

            if force:

                raise

            self.error(str(exc))

            return {}

        try:

            if kwargs.get('async') is not None:

                warn('[3.27] `async` is reserved keyword in py3.7 use `sync` param instead',

                     DeprecationWarning)

                sync = not kwargs['async']

            if sync:

                return self._pull_data(cnx, force, raise_on_error)

            else:

                return self._async_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 _async_pull_data(self, cnx, force, raise_on_error):

        import_log = cnx.create_entity('CWDataImport', cw_import_of=self)

        cnx.commit()  # commit the import log creation before starting the synchronize task

        def _synchronize_source(repo, source_eid, import_log_eid):

            with repo.internal_cnx() as cnx:

                source = repo.source_by_eid(source_eid)

                source._pull_data(cnx, force, raise_on_error, import_log_eid=import_log_eid)

        sync = partial(_synchronize_source, cnx.repo, self.eid, import_log.eid)

        cnx.repo.threaded_task(sync)

        return {'import_log_eid': import_log.eid}

    def _pull_data(self, cnx, force=False, raise_on_error=False, import_log_eid=None):

        importlog = self.init_import_log(cnx, import_log_eid)

        try:

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

        except ObjectNotFound:

            msg = 'failed to load parser for %s'

            importlog.record_error(msg % ('source "%s"' % self.uri))

            self.error(msg, self)

            stats = {}

        else:

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

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

            stats = parser.stats

        self.update_latest_retrieval(cnx)

        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 init_import_log(self, cnx, import_log_eid=None, **kwargs):

        if import_log_eid is None:

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

                                           start_timestamp=datetime.now(tz=utc),

                                           **kwargs)

        else:

            import_log = cnx.entity_from_eid(import_log_eid)

            import_log.cw_set(start_timestamp=datetime.now(tz=utc), **kwargs)

        cnx.commit()  # make changes visible

        import_log.init()

        return import_log

class DataFeedParser(AppObject):

    __registry__ = 'parsers'

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

        super(DataFeedParser, self).__init__(cnx)

        self.source = source

        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(BytesIO(resp.content), 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(BytesIO(url.encode('ascii')), url)

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

        error = False

        for url in urls:

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

            try:

                if self.process(url, raise_on_error):

                    error = True

            except IOError as exc:

                if raise_on_error:

                    raise

                self.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.import_log.record_error(str(exc))

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

                               url, exc)

                error = True

        return error

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

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

        raise NotImplementedError

    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)

    def notify_checked(self, entity):

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

    def is_deleted(self, extid, etype, eid):

        """return True if the entity of given external id, entity type and eid

        is actually deleted. Always return True by default, put more sensible

        stuff in sub-classes.

        """

        return True

    def update_if_necessary(self, entity, attrs):

        entity.complete(tuple(attrs))

        # check modification date and compare attribute values to only update

        # what's actually needed

        self.notify_checked(entity)

        mdate = attrs.get('modification_date')

        if not mdate or mdate > entity.modification_date:

            if attrs:

                entity.cw_set(**attrs)

                self.notify_updated(entity)

class DataFeedXMLParser(DataFeedParser):

    def parse(self, url):

        stream = self.retrieve_url(url)

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

    def parse_etree(self, document):

        return [(document,)]

    def process_item(self, *args, **kwargs):

        raise NotImplementedError

    def is_deleted(self, extid, etype, eid):

        if extid.startswith('file://'):