''' template filters '''
from django import template

from bookwyrm import models


register = template.Library()

@register.filter(name='dict_key')
def dict_key(d, k):
    '''Returns the given key from a dictionary.'''
    return d.get(k) or 0


@register.filter(name='rating')
def get_rating(book, user):
    ''' get a user's rating of a book '''
    rating = models.Review.objects.filter(
        user=user,
        book=book,
        rating__isnull=False,
    ).order_by('-published_date').first()
    if rating:
        return rating.rating
    return 0


@register.filter(name='description')
def description_format(description):
    ''' handle the various OL description formats '''
    if not description:
        return ''

    if '----------' in description:
        description = description.split('----------')[0]

    return description.strip()


@register.filter(name='author_bio')
def bio_format(bio):
    ''' clean up OL author bios '''
    if isinstance(bio, dict) and 'value' in bio:
        bio = bio['value']
    bio = bio.split('\n')
    return bio[0].strip()


@register.filter(name='username')
def get_user_identifier(user):
    ''' use localname for local users, username for remote '''
    return user.localname if user.localname else user.username


@register.filter(name='notification_count')
def get_notification_count(user):
    ''' how many UNREAD notifications are there '''
    return user.notification_set.filter(read=False).count()


@register.filter(name='replies')
def get_replies(status):
    ''' get all direct replies to a status '''
    #TODO: this limit could cause problems
    return models.Status.objects.filter(
        reply_parent=status
    ).select_subclasses().all()[:10]


@register.filter(name='reply_count')
def get_reply_count(status):
    ''' how many replies does a status have? '''
    return models.Status.objects.filter(reply_parent=status).count()


@register.filter(name='parent')
def get_parent(status):
    ''' get the reply parent for a status '''
    return models.Status.objects.filter(
        id=status.reply_parent_id
    ).select_subclasses().get()


@register.filter(name='liked')
def get_user_liked(user, status):
    ''' did the given user fav a status? '''
    try:
        models.Favorite.objects.get(user=user, status=status)
        return True
    except models.Favorite.DoesNotExist:
        return False


@register.filter(name='boosted')
def get_user_boosted(user, status):
    ''' did the given user fav a status? '''
    return user.id in status.boosters.all().values_list('user', flat=True)


@register.filter(name='follow_request_exists')
def follow_request_exists(user, requester):
    ''' see if there is a pending follow request for a user '''
    try:
        models.UserFollowRequest.objects.filter(
            user_subject=requester,
            user_object=user,
        ).get()
        return True
    except models.UserFollowRequest.DoesNotExist:
        return False


@register.filter(name='boosted_status')
def get_boosted(boost):
    ''' load a boosted status. have to do this or it wont get foregin keys '''
    return models.Status.objects.select_subclasses().filter(
        id=boost.boosted_status.id
    ).get()


@register.filter(name='edition_info')
def get_edition_info(book):
    ''' paperback, French language, 1982 '''
    if not book:
        return
    items = [
        book.physical_format if isinstance(book, models.Edition) else None,
        book.languages[0] + ' language' if book.languages and \
                book.languages[0] != 'English' else None,
        str(book.published_date.year) if book.published_date else None,
    ]
    return ', '.join(i for i in items if i)


@register.simple_tag(takes_context=True)
def shelve_button_identifier(context, book):
    ''' check what shelf a user has a book on, if any '''
    #TODO: books can be on multiple shelves, handle that better
    shelf = models.ShelfBook.objects.filter(
        shelf__user=context['request'].user,
        book=book
    ).first()
    if not shelf:
        return 'to-read'

    identifier = shelf.shelf.identifier
    if identifier == 'to-read':
        return 'reading'
    if identifier == 'reading':
        return 'read'
    return 'to-read'


@register.simple_tag(takes_context=True)
def shelve_button_text(context, book):
    ''' check what shelf a user has a book on, if any '''
    #TODO: books can be on multiple shelves
    shelf = models.ShelfBook.objects.filter(
        shelf__user=context['request'].user,
        book=book
    ).first()
    if not shelf:
        return 'Want to read'

    identifier = shelf.shelf.identifier
    if identifier == 'to-read':
        return 'Start reading'
    if identifier == 'reading':
        return 'I\'m done!'
    return 'Want to read'


@register.simple_tag(takes_context=True)
def current_shelf(context, book):
    ''' check what shelf a user has a book on, if any '''
    try:
        shelf = models.ShelfBook.objects.get(
            shelf__user=context['user'],
            book=book
        )
    except models.ShelfBook.DoesNotExist:
        return None
    return shelf.name

@register.simple_tag(takes_context=False)
def latest_read_through(book, user):
    return models.ReadThrough.objects.filter(
        user=user,
        book=book).order_by('-created_date').first()