services.py

from django.contrib.auth import get_user_model
from django.contrib.contenttypes.models import ContentType
from django.core.cache import cache
from django.db.models import Count

from core.constants import VIEWS_CACHING_TIMEOUT
from core.models import Like, View, Link

User = get_user_model()


def add_like(obj, user):
    obj_type = ContentType.objects.get_for_model(obj)
    like, is_created = Like.objects.get_or_create(
        content_type=obj_type, object_id=obj.id, user=user
    )
    return like


def remove_like(obj, user):
    obj_type = ContentType.objects.get_for_model(obj)
    Like.objects.filter(content_type=obj_type, object_id=obj.id, user=user).delete()


def is_fan(obj, user) -> bool:
    if not user.is_authenticated:
        return False
    obj_type = ContentType.objects.get_for_model(obj)
    likes = Like.objects.filter(content_type=obj_type, object_id=obj.id, user=user)
    return likes.exists()


def get_fans(obj):
    obj_type = ContentType.objects.get_for_model(obj)
    return User.objects.filter(likes__content_type=obj_type, likes__object_id=obj.id)


def get_likes_count(obj):
    obj_type = ContentType.objects.get_for_model(obj)
    # todo: temp comment
    # likes_count = cache.get(f"likes_count_{obj_type}_{obj.id}")
    # if likes_count is None:
    #     likes_count = User.objects.filter(
    #         likes__content_type=obj_type, likes__object_id=obj.id
    #     ).count()
    #     # cache for LIKES_CACHING_TIMEOUT seconds
    #     cache.set(f"likes_count_{obj_type}_{obj.id}", likes_count, LIKES_CACHING_TIMEOUT)
    return User.objects.filter(
        likes__content_type=obj_type, likes__object_id=obj.id
    ).count()
    # return likes_count


def set_like(obj, user, is_liked):
    if is_liked:
        add_like(obj, user)
    else:
        remove_like(obj, user)


def add_view(obj, user):
    # TODO: add docstring
    # TODO: add caching
    obj_type = ContentType.objects.get_for_model(obj)
    view, is_created = View.objects.get_or_create(
        content_type=obj_type, object_id=obj.id, user=user
    )
    views_count = cache.get(f"views_count_{obj_type}_{obj.id}", None)
    if views_count is not None:
        cache.set(
            f"views_count_{obj_type}_{obj.id}", views_count + 1, VIEWS_CACHING_TIMEOUT
        )

    return view


def remove_view(obj, user):
    obj_type = ContentType.objects.get_for_model(obj)
    View.objects.filter(content_type=obj_type, object_id=obj.id, user=user).delete()
    views_count = cache.get(f"views_count_{obj_type}_{obj.id}", None)
    if views_count is not None:
        cache.set(
            f"views_count_{obj_type}_{obj.id}", views_count - 1, VIEWS_CACHING_TIMEOUT
        )


def is_viewer(obj, user) -> bool:
    if not user.is_authenticated:
        return False
    obj_type = ContentType.objects.get_for_model(obj)
    views = View.objects.filter(content_type=obj_type, object_id=obj.id, user=user)
    return views.exists()


def get_viewers(obj):
    obj_type = ContentType.objects.get_for_model(obj)
    return User.objects.filter(views__content_type=obj_type, views__object_id=obj.id)


def cache_views_for_many_objects(objs):
    """
    Set cached views count for many objects in 1 SQL query

    Args:
        objs:
            List of objects that need their views retrieved

    Returns: QuerySet[dict[object_id, count]]
    """
    obj_type = ContentType.objects.get_for_model(objs[0])
    ids = [obj.id for obj in objs]
    data = (
        View.objects.filter(content_type=obj_type, object_id__in=ids)
        .values("object_id")
        .annotate(count=Count("object_id"))
    )
    for i in data:
        cache.set(f"views_count_{obj_type}_{i.object_id}", i.count, VIEWS_CACHING_TIMEOUT)
    return data


def get_views_count_cached(obj):
    obj_type = ContentType.objects.get_for_model(obj)
    return cache.get(f"views_count_{obj_type}_{obj.id}", None)


def get_views_count(obj):
    obj_type = ContentType.objects.get_for_model(obj)
    # cache this
    views_count = cache.get(f"views_count_{obj_type}_{obj.id}", None)
    if views_count is None:
        views_count = User.objects.filter(
            views__content_type=obj_type, views__object_id=obj.id
        ).count()
        # cache for VIEWS_CACHING_TIMEOUT seconds
        cache.set(f"views_count_{obj_type}_{obj.id}", views_count, VIEWS_CACHING_TIMEOUT)

    return views_count


def set_viewed(obj, user, is_viewed):
    if is_viewed:
        add_view(obj, user)
    else:
        remove_view(obj, user)


def add_link(obj, link: str):
    obj_type = ContentType.objects.get_for_model(obj)
    like, is_created = Link.objects.get_or_create(
        content_type=obj_type, object_id=obj.id, link=link
    )
    return like


def remove_link(obj, link):
    obj_type = ContentType.objects.get_for_model(obj)
    Like.objects.filter(content_type=obj_type, object_id=obj.id, link=link).delete()


def get_links(obj):
    obj_type = ContentType.objects.get_for_model(obj)
    return Link.objects.filter(content_type=obj_type, object_id=obj.id)