''' using a bookwyrm instance as a source of book data '''
from django.contrib.postgres.search import SearchRank, SearchVector
from django.db.models import Count, F

from bookwyrm import models
from .abstract_connector import AbstractConnector, SearchResult


class Connector(AbstractConnector):
    ''' instantiate a connector  '''
    def search(self, query, min_confidence=0.1):
        ''' search your local database '''
        vector = SearchVector('title', weight='A') +\
            SearchVector('subtitle', weight='B') +\
            SearchVector('authors__name', weight='C')

        results = models.Edition.objects.annotate(
            search=vector
        ).annotate(
            rank=SearchRank(vector, query)
        ).filter(
            rank__gt=min_confidence
        ).order_by('-rank')

        # when there are multiple editions of the same work, pick the closest
        editions_of_work = results.values(
            'parent_work'
        ).annotate(
            Count('parent_work')
        ).values_list('parent_work')

        search_results = []
        for work_id in set(editions_of_work):
            editions = results.filter(parent_work=work_id)
            default = editions.filter(parent_work__default_edition=F('id'))
            default_rank = default.first().rank if default.exists() else 0
            # if mutliple books have the top rank, pick the default edition
            if default_rank == editions.first().rank:
                selected = default.first()
            else:
                selected = editions.first()
            search_results.append(self.format_search_result(selected))
            if len(search_results) >= 10:
                break
        return search_results


    def format_search_result(self, search_result):
        return SearchResult(
            title=search_result.title,
            key=search_result.remote_id,
            author=search_result.author_text,
            year=search_result.published_date.year if \
                    search_result.published_date else None,
            connector=self,
            confidence=search_result.rank,
        )


    def is_work_data(self, data):
        pass

    def get_edition_from_work_data(self, data):
        pass

    def get_work_from_edition_data(self, data):
        pass

    def get_authors_from_data(self, data):
        return None

    def parse_search_data(self, data):
        ''' it's already in the right format, don't even worry about it '''
        return data

    def expand_book_data(self, book):
        pass