# -*- coding: utf-8 -*-
# copyright 2016 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr -- mailto:contact@logilab.fr
#
# This program 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.
#
# 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 Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.

from compiler.ast import flatten

from elasticsearch_dsl import Q


def compose_search(query):
    '''
    Compose a elasticsearch-dsl query from queries :

    * simple term
    * simple terms (OR)
    * negation (add - in front of a term)
    * explicit OR
    * quoted terms (AND)
    '''
    # FIXME TODO - restructure entier code base, have a proper lexer
    must = []
    must_not = []
    should = []
    if '"' in query:
        elements = flatten([x.split() for x in query.split('"') if x])
    elif "'" in query:
        elements = flatten([x.split() for x in query.split("'") if x])
    else:
        elements = query.split()
        elements_lowercase = [e.lower() for e in elements]
        if 'or' in elements_lowercase and len(elements) >= 3:
            for element in query.split('or'):
                should.append(Q('multi_match',
                                query=element.strip(),
                                fields=()))
            elements = []
        elif '-' not in query:
            elements = [' '.join(elements)]
    for element in elements:
        if element.startswith('-'):
            must_not.append(Q('multi_match',
                              query=element[1:],
                              fields=()))
        else:
            must.append(Q('multi_match',
                          query=element,
                          fields=()))
    return Q('bool',
             must=must,
             must_not=must_not,
             should=should)