''' openlibrary data connector '''
from datetime import datetime
from django.core.exceptions import ObjectDoesNotExist
from django.core.files.base import ContentFile
import re
import requests

from fedireads import models
from .abstract_connector import AbstractConnector, SearchResult, \
    update_from_mappings


class Connector(AbstractConnector):
    ''' instantiate a connector for OL '''
    def __init__(self, identifier):
        super().__init__(identifier)


    def search(self, query):
        ''' query openlibrary search '''
        resp = requests.get(
            '%s%s' % (self.search_url, query),
            headers={
                'Accept': 'application/json; charset=utf-8',
            },
        )
        if not resp.ok:
            resp.raise_for_status()
        data = resp.json()
        results = []

        for doc in data['docs'][:5]:
            key = doc['key']
            key = key.split('/')[-1]
            author = doc.get('author_name') or ['Unknown']
            results.append(SearchResult(
                doc.get('title'),
                key,
                author[0],
                doc.get('first_publish_year'),
                doc
            ))
        return results


    def get_or_create_book(self, olkey):
        ''' pull up a book record by whatever means possible '''
        if re.match(r'^OL\d+W$', olkey):
            model = models.Work
        elif re.match(r'^OL\d+M$', olkey):
            model = models.Edition
        else:
            raise ValueError('Invalid OpenLibrary ID')

        try:
            book = model.objects.get(openlibrary_key=olkey)
            return book
        except ObjectDoesNotExist:
            # no book was found, so we start creating a new one
            book = model(openlibrary_key=olkey)
        self.update_book(book)


    def update_book(self, book):
        ''' query openlibrary for data on a book '''
        olkey = book.openlibrary_key
        # load the book json from openlibrary.org
        response = requests.get('%s/works/%s.json' % (self.url, olkey))
        if not response.ok:
            response.raise_for_status()

        data = response.json()

        # great, we can update our book.
        mappings = {
            'publish_date': ('published_date', get_date),
            'first_publish_date': ('first_published_date', get_date),
            'description': ('description', get_description),
            'isbn_13': ('isbn', None),
            'oclc_numbers': ('oclc_number', lambda a: a[0]),
            'lccn': ('lccn', lambda a: a[0]),
        }
        book = update_from_mappings(book, data, mappings)

        if 'identifiers' in data:
            if 'goodreads' in data['identifiers']:
                book.goodreads_key = data['identifiers']['goodreads']

        if not book.source_url:
            book.source_url = response.url
        if not book.connector:
            book.connector = self.connector
        book.save()

        # this book sure as heck better be an edition
        if data.get('works'):
            key = data.get('works')[0]['key']
            key = key.split('/')[-1]
            work = self.get_or_create_book(key)

            book.parent_work = work

        # we also need to know the author get the cover
        for author_blob in data.get('authors', []):
            # this id is "/authors/OL1234567A" and we want just "OL1234567A"
            author_blob = author_blob.get('author', author_blob)
            author_id = author_blob['key']
            author_id = author_id.split('/')[-1]
            book.authors.add(self.get_or_create_author(author_id))

        if book.sync_cover and data.get('covers') and len(data['covers']):
            book.cover.save(*self.get_cover(data['covers'][0]), save=True)

        return book


    def get_or_create_author(self, olkey):
        ''' load that author '''
        if not re.match(r'^OL\d+A$', olkey):
            raise ValueError('Invalid OpenLibrary author ID')
        try:
            return models.Author.objects.get(openlibrary_key=olkey)
        except ObjectDoesNotExist:
            pass

        response = requests.get('%s/authors/%s.json' % (self.url, olkey))
        if not response.ok:
            response.raise_for_status()

        data = response.json()
        author = models.Author(openlibrary_key=olkey)
        mappings = {
            'birth_date': ('born', get_date),
            'death_date': ('died', get_date),
            'bio': ('bio', get_description),
        }
        author = update_from_mappings(author, data, mappings)
        # TODO this is making some BOLD assumption
        name = data['name']
        author.last_name = name.split(' ')[-1]
        author.first_name = ' '.join(name.split(' ')[:-1])
        author.save()

        return author


    def get_cover(self, cover_id):
        ''' ask openlibrary for the cover '''
        # TODO: get medium and small versions
        image_name = '%s-M.jpg' % cover_id
        url = '%s/b/id/%s' % (self.covers_url, image_name)
        response = requests.get(url)
        if not response.ok:
            response.raise_for_status()
        image_content = ContentFile(response.content)
        return [image_name, image_content]


def get_date(date_string):
    ''' helper function to try to interpret dates '''
    formats = [
        '%B %Y',
        '%Y',
    ]
    for date_format in formats:
        try:
            return datetime.strptime(date_string, date_format)
        except ValueError:
            pass
    return None


def get_description(description_blob):
    ''' descriptions can be a string or a dict '''
    if isinstance(description_blob, dict):
        return description_blob.get('value')
    return  description_blob