# combo - content management system
# Copyright (C) 2014-2020  Entr'ouvert
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU Affero 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

from django.conf import settings
from django.contrib.contenttypes.models import ContentType
from django.contrib.postgres.search import SearchQuery, SearchRank, SearchVector
from django.db import connection
from django.db.models import Q, Prefetch
from django.db.transaction import atomic

from combo.data.models import Page, CellBase, ValidityInfo
from .models import IndexedCell


def set_cell_groups(indexed_cell, cell):
    restricted_groups = []
    excluded_groups = []
    if not indexed_cell.public_access:
        restricted_groups = cell.prefetched_groups
        if cell.restricted_to_unlogged:
            excluded_groups = cell.page.prefetched_groups
        else:
            for group in cell.page.prefetched_groups:
                restricted_groups.append(group)
    if restricted_groups:
        indexed_cell.restricted_groups.add(*restricted_groups)
    if excluded_groups:
        indexed_cell.excluded_groups.add(*excluded_groups)


@atomic
def index_site():
    cell_classes = list(CellBase.get_cell_classes())
    # populate ContentType cache
    ContentType.objects.get_for_models(*cell_classes)
    IndexedCell.objects.all().delete()
    external_urls = {}
    validity_info_list = list(ValidityInfo.objects.select_related('content_type'))
    pages_by_pk = {
        p.pk: p for p in (Page.objects.prefetch_related(Prefetch('groups', to_attr='prefetched_groups')))
    }
    for klass in cell_classes:
        if getattr(klass, 'exclude_from_search', False) is True:
            # do not load cells marked as excluded from search (example: MenuCell, SearchCell, ...)
            continue
        queryset = (
            klass.objects.filter(page__snapshot__isnull=True, page__sub_slug='')
            .exclude(placeholder__startswith='_')
            .prefetch_related(Prefetch('groups', to_attr='prefetched_groups'))
        )
        for cell in queryset:
            cell.page = pages_by_pk.get(cell.page_id)
            # exclude cells with an inactive placeholder
            if not cell.is_placeholder_active():
                continue
            cell.prefetched_validity_info = [
                v
                for v in validity_info_list
                if v.object_id == cell.pk and v.content_type.model_class() == cell.__class__
            ]
            cell_type = ContentType.objects.get_for_model(cell)
            indexed_cell = IndexedCell(cell_type=cell_type, cell_pk=cell.id)
            try:
                indexed_cell.indexed_text = cell.render_for_search()
            except Exception:  # ignore rendering error
                continue
            if indexed_cell.indexed_text:
                indexed_cell.public_access = bool(cell.page.public and cell.public)
                indexed_cell.page_id = cell.page_id
                indexed_cell.url = cell.page.get_online_url()
                indexed_cell.title = cell.page.title
                indexed_cell.save()
                set_cell_groups(indexed_cell, cell)

            for link_data in cell.get_external_links_data():
                # index external links
                indexed_cell = external_urls.get(link_data.get('url'))
                if indexed_cell is None:
                    # create an entry for that link.
                    indexed_cell = IndexedCell(
                        cell_type=cell_type,
                        cell_pk=cell.id,
                        public_access=bool(cell.page.public and cell.public),
                        url=link_data['url'],
                        title=link_data['title'],
                        indexed_text=link_data.get('text') or '',
                    )
                    indexed_cell.save()
                    set_cell_groups(indexed_cell, cell)
                    external_urls[indexed_cell.url] = indexed_cell
                else:
                    # if that link already exists, add detailed texts
                    indexed_cell.indexed_text += ' ' + link_data['title']
                    indexed_cell.indexed_text += ' ' + (link_data.get('text') or '')
                    indexed_cell.save()


def search_site(request, query, pages=None, with_description=None):
    pages = pages or []

    if connection.vendor == 'postgresql':
        config = settings.POSTGRESQL_FTS_SEARCH_CONFIG
        vector = SearchVector('title', config=config, weight='A') + SearchVector(
            'indexed_text', config=config, weight='B'
        )
        query = SearchQuery(query, config=config)
        qs = (
            IndexedCell.objects.annotate(rank=SearchRank(vector, query))
            .filter(rank__gte=0.2)
            .order_by('-rank')
        )
    else:
        qs = IndexedCell.objects.filter(Q(indexed_text__icontains=query) | Q(title__icontains=query))
    if request.user.is_anonymous:
        qs = qs.exclude(public_access=False)
    else:
        qs = qs.filter(Q(restricted_groups=None) | Q(restricted_groups__in=request.user.groups.all()))
        qs = qs.exclude(excluded_groups__in=request.user.groups.all())

    if pages:
        qs = qs.filter(page__in=pages)

    hits = []
    seen = {}
    for hit in qs:
        if hit.url in seen:
            continue
        hits.append(
            {
                'text': hit.title,
                'rank': getattr(hit, 'rank', None),
                'url': hit.url,
                'description': hit.page.description if (hit.page and with_description is True) else '',
            }
        )
        seen[hit.url] = True
        if len(hits) == 10:
            break

    return hits