""" template filters """
from uuid import uuid4
from datetime import datetime

from dateutil.relativedelta import relativedelta
from django import template
from django.db.models import Avg
from django.utils import timezone

from bookwyrm import models, views
from bookwyrm.views.status import to_markdown


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 the overall rating of a book """
    queryset = views.helpers.privacy_filter(
        user, models.Review.objects.filter(book=book)
    )
    return queryset.aggregate(Avg("rating"))["rating__avg"]


@register.filter(name="user_rating")
def get_user_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="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,
            deleted=False,
        )
        .select_subclasses()
        .all()[:10]
    )


@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="book_description")
def get_book_description(book):
    """ use the work's text if the book doesn't have it """
    return book.description or book.parent_work.description


@register.filter(name="uuid")
def get_uuid(identifier):
    """ for avoiding clashing ids when there are many forms """
    return "%s%s" % (identifier, uuid4())


@register.filter(name="post_date")
def time_since(date):
    """ concise time ago function """
    if not isinstance(date, datetime):
        return ""
    now = timezone.now()

    if date < (now - relativedelta(weeks=1)):
        formatter = "%b %-d"
        if date.year != now.year:
            formatter += " %Y"
        return date.strftime(formatter)
    delta = relativedelta(now, date)
    if delta.days:
        return "%dd" % delta.days
    if delta.hours:
        return "%dh" % delta.hours
    if delta.minutes:
        return "%dm" % delta.minutes
    return "%ds" % delta.seconds


@register.filter(name="to_markdown")
def get_markdown(content):
    """ convert markdown to html """
    if content:
        return to_markdown(content)
    return None


@register.filter(name="mentions")
def get_mentions(status, user):
    """ people to @ in a reply: the parent and all mentions """
    mentions = set([status.user] + list(status.mention_users.all()))
    return (
        " ".join("@" + get_user_identifier(m) for m in mentions if not m == user) + " "
    )


@register.filter(name="status_preview_name")
def get_status_preview_name(obj):
    """ text snippet with book context for a status """
    name = obj.__class__.__name__.lower()
    if name == "review":
        return "%s of <em>%s</em>" % (name, obj.book.title)
    if name == "comment":
        return "%s on <em>%s</em>" % (name, obj.book.title)
    if name == "quotation":
        return "%s from <em>%s</em>" % (name, obj.book.title)
    return name


@register.filter(name="next_shelf")
def get_next_shelf(current_shelf):
    """ shelf you'd use to update reading progress """
    if current_shelf == "to-read":
        return "reading"
    if current_shelf == "reading":
        return "read"
    if current_shelf == "read":
        return "read"
    return "to-read"


@register.simple_tag(takes_context=False)
def related_status(notification):
    """ for notifications """
    if not notification.related_status:
        return None
    if hasattr(notification.related_status, "quotation"):
        return notification.related_status.quotation
    if hasattr(notification.related_status, "review"):
        return notification.related_status.review
    if hasattr(notification.related_status, "comment"):
        return notification.related_status.comment
    return notification.related_status


@register.simple_tag(takes_context=True)
def active_shelf(context, book):
    """ check what shelf a user has a book on, if any """
    shelf = models.ShelfBook.objects.filter(
        shelf__user=context["request"].user, book__in=book.parent_work.editions.all()
    ).first()
    return shelf if shelf else {"book": book}


@register.simple_tag(takes_context=False)
def latest_read_through(book, user):
    """ the most recent read activity """
    return (
        models.ReadThrough.objects.filter(user=user, book=book)
        .order_by("-start_date")
        .first()
    )


@register.simple_tag(takes_context=False)
def active_read_through(book, user):
    """ the most recent read activity """
    return (
        models.ReadThrough.objects.filter(
            user=user, book=book, finish_date__isnull=True
        )
        .order_by("-start_date")
        .first()
    )


@register.simple_tag(takes_context=False)
def comparison_bool(str1, str2):
    """ idk why I need to write a tag for this, it reutrns a bool """
    return str1 == str2