''' select and call a connector for whatever book task needs doing '''
import importlib

from fedireads import models
from fedireads.tasks import app


def get_or_create_book(value, key='id', connector_id=None):
    ''' pull up a book record by whatever means possible '''
    try:
        book = models.Book.objects.select_subclasses().get(**{key: value})
        return book
    except models.Book.DoesNotExist:
        pass

    connector_info = models.Connector.objects.get(id=connector_id)
    connector = load_connector(connector_info)
    book = connector.get_or_create_book(value)
    load_more_data.delay(book.id)
    return book


@app.task
def load_more_data(book_id):
    ''' background the work of getting all 10,000 editions of LoTR '''
    book = models.Book.objects.select_subclasses().get(id=book_id)
    connector = load_connector(book.connector)
    connector.expand_book_data(book)


def search(query):
    ''' find books based on arbitary keywords '''
    results = []
    dedup_slug = lambda r: '%s/%s/%s' % (r.title, r.author, r.year)
    result_index = set()
    for connector in get_connectors():
        result_set = connector.search(query)

        result_set = [r for r in result_set \
                if dedup_slug(r) not in result_index]
        # `|=` concats two sets. WE ARE GETTING FANCY HERE
        result_index |= set(dedup_slug(r) for r in result_set)
        results.append({
            'connector': connector,
            'results': result_set,
        })

    return results


def first_search_result(query):
    ''' search until you find a result that fits '''
    for connector in get_connectors():
        result = connector.search(query)
        if result:
            return result[0]
    return None


def update_book(book, data=None):
    ''' re-sync with the original data source '''
    connector = load_connector(book.connector)
    connector.update_book(book, data=data)


def get_connectors():
    ''' load all connectors '''
    connectors_info = models.Connector.objects.order_by('priority').all()
    return [load_connector(c) for c in connectors_info]


def load_connector(connector_info):
    ''' instantiate the connector class '''
    connector = importlib.import_module(
        'fedireads.connectors.%s' % connector_info.connector_file
    )
    return connector.Connector(connector_info.identifier)