# -*- coding: utf-8 -*-
#########################################################################
#
# Copyright (C) 2016 OSGeo
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
#########################################################################

import os
from lxml import etree
from django.conf import settings
from ConfigParser import SafeConfigParser
from owslib.iso import MD_Metadata
from pycsw import server
from geonode.catalogue.backends.generic import CatalogueBackend as GenericCatalogueBackend
from geonode.catalogue.backends.generic import METADATA_FORMATS
from shapely.geometry.base import ReadingError

true_value = 'true'
if settings.DATABASES['default']['ENGINE'].endswith(('sqlite', 'sqlite3', 'spatialite',)):
    true_value = '1'

# pycsw settings that the user shouldn't have to worry about
CONFIGURATION = {
    'server': {
        'home': '.',
        'url': settings.CATALOGUE['default']['URL'],
        'encoding': 'UTF-8',
        'language': settings.LANGUAGE_CODE,
        'maxrecords': '10',
        #  'loglevel': 'DEBUG',
        #  'logfile': '/tmp/pycsw.log',
        #  'federatedcatalogues': 'http://geo.data.gov/geoportal/csw/discovery',
        'pretty_print': 'true',
        'domainquerytype': 'range',
        'domaincounts': 'true',
        'profiles': 'apiso,ebrim',
    },
    'repository': {
        'source': 'geonode.catalogue.backends.pycsw_plugin.GeoNodeRepository',
        'filter': 'is_published = %s' % true_value,
        'mappings': os.path.join(os.path.dirname(__file__), 'pycsw_local_mappings.py')
    }
}


class CatalogueBackend(GenericCatalogueBackend):
    def __init__(self, *args, **kwargs):
        super(CatalogueBackend, self).__init__(*args, **kwargs)
        self.catalogue.formats = ['Atom', 'DIF', 'Dublin Core', 'ebRIM', 'FGDC', 'ISO']
        self.catalogue.local = True

    def remove_record(self, uuid):
        pass

    def create_record(self, item):
        pass

    def get_record(self, uuid):
        results = self._csw_local_dispatch(identifier=uuid)
        if len(results) < 1:
            return None

        result = etree.fromstring(results).find('{http://www.isotc211.org/2005/gmd}MD_Metadata')

        if result is None:
            return None

        record = MD_Metadata(result)
        record.keywords = []
        if hasattr(record, 'identification') and hasattr(record.identification, 'keywords'):
            for kw in record.identification.keywords:
                record.keywords.extend(kw['keywords'])

        record.links = {}
        record.links['metadata'] = self.catalogue.urls_for_uuid(uuid)
        record.links['download'] = self.catalogue.extract_links(record)
        return record

    def search_records(self, keywords, start, limit, bbox):
        with self.catalogue:
            lresults = self._csw_local_dispatch(keywords, keywords, start+1, limit, bbox)
            # serialize XML
            e = etree.fromstring(lresults)

            self.catalogue.records = \
                [MD_Metadata(x) for x in e.findall('//{http://www.isotc211.org/2005/gmd}MD_Metadata')]

            # build results into JSON for API
            results = [self.catalogue.metadatarecord2dict(doc) for v, doc in self.catalogue.records.iteritems()]

            result = {'rows': results,
                      'total': e.find('{http://www.opengis.net/cat/csw/2.0.2}SearchResults').attrib.get(
                          'numberOfRecordsMatched'),
                      'next_page': e.find('{http://www.opengis.net/cat/csw/2.0.2}SearchResults').attrib.get(
                          'nextRecord')
                      }

            return result

    def _csw_local_dispatch(self, keywords=None, start=0, limit=10, bbox=None, identifier=None):
        """
        HTTP-less CSW
        """

        # serialize pycsw settings into SafeConfigParser
        # object for interaction with pycsw
        mdict = dict(settings.PYCSW['CONFIGURATION'], **CONFIGURATION)
        if 'server' in settings.PYCSW['CONFIGURATION']:
            # override server system defaults with user specified directives
            mdict['server'].update(settings.PYCSW['CONFIGURATION']['server'])
        config = SafeConfigParser()

        for section, options in mdict.iteritems():
            config.add_section(section)
            for option, value in options.iteritems():
                config.set(section, option, value)

        # fake HTTP environment variable
        os.environ['QUERY_STRING'] = ''

        # init pycsw
        csw = server.Csw(config, version='2.0.2')

        # fake HTTP method
        csw.requesttype = 'GET'

        # fake HTTP request parameters
        if identifier is None:  # it's a GetRecords request
            formats = []
            for f in self.catalogue.formats:
                formats.append(METADATA_FORMATS[f][0])

            csw.kvp = {
                'service': 'CSW',
                'version': '2.0.2',
                'elementsetname': 'full',
                'typenames': formats,
                'resulttype': 'results',
                'constraintlanguage': 'CQL_TEXT',
                'outputschema': 'http://www.isotc211.org/2005/gmd',
                'constraint': None,
                'startposition': start,
                'maxrecords': limit
            }
            response = csw.getrecords()
        else:  # it's a GetRecordById request
            csw.kvp = {
                'service': 'CSW',
                'version': '2.0.2',
                'request': 'GetRecordById',
                'id': identifier,
                'outputschema': 'http://www.isotc211.org/2005/gmd',
            }
            # FIXME(Ariel): Remove this try/except block when pycsw deals with
            # empty geometry fields better.
            # https://gist.github.com/ingenieroariel/717bb720a201030e9b3a
            try:
                response = csw.dispatch()
            except ReadingError:
                return []

        if isinstance(response, list):  # pycsw 2.0+
            response = response[1]

        return response
