from sqlalchemy import distinct, func, select

from orm.author import Author
from orm.shout import ShoutTopic
from orm.topic import Topic
from resolvers.stat import get_with_stat
from services.auth import login_required
from services.db import local_session
from services.memorycache import cache_region
from services.schema import mutation, query


@query.field("get_topics_all")
def get_topics_all(_, _info):
    cache_key = "get_topics_all"

    @cache_region.cache_on_arguments(cache_key)
    def _get_topics_all():
        topics_query = select(Topic)
        return get_with_stat(topics_query)

    return _get_topics_all()


@query.field("get_topics_by_community")
def get_topics_by_community(_, _info, community_id: int):
    cache_key = f"get_topics_by_community_{community_id}"

    @cache_region.cache_on_arguments(cache_key)
    def _get_topics_by_community():
        topics_by_community_query = select(Topic).where(Topic.community == community_id)
        return get_with_stat(topics_by_community_query)

    return _get_topics_by_community()


@query.field("get_topics_by_author")
async def get_topics_by_author(_, _info, author_id=0, slug="", user=""):
    topics_by_author_query = select(Topic)
    if author_id:
        topics_by_author_query = topics_by_author_query.join(Author).where(
            Author.id == author_id
        )
    elif slug:
        topics_by_author_query = topics_by_author_query.join(Author).where(
            Author.slug == slug
        )
    elif user:
        topics_by_author_query = topics_by_author_query.join(Author).where(
            Author.user == user
        )

    return get_with_stat(topics_by_author_query)


@query.field("get_topic")
def get_topic(_, _info, slug: str):
    topic_query = select(Topic).filter(Topic.slug == slug)
    result = get_with_stat(topic_query)
    for topic in result:
        return topic


@mutation.field("create_topic")
@login_required
async def create_topic(_, _info, inp):
    with local_session() as session:
        # TODO: check user permissions to create topic for exact community
        # and actor is permitted to craete it
        new_topic = Topic(**inp)
        session.add(new_topic)
        session.commit()

        return {"topic": new_topic}


@mutation.field("update_topic")
@login_required
async def update_topic(_, _info, inp):
    slug = inp["slug"]
    with local_session() as session:
        topic = session.query(Topic).filter(Topic.slug == slug).first()
        if not topic:
            return {"error": "topic not found"}
        else:
            Topic.update(topic, inp)
            session.add(topic)
            session.commit()

            return {"topic": topic}


@mutation.field("delete_topic")
@login_required
async def delete_topic(_, info, slug: str):
    user_id = info.context["user_id"]
    with local_session() as session:
        t: Topic = session.query(Topic).filter(Topic.slug == slug).first()
        if not t:
            return {"error": "invalid topic slug"}
        author = session.query(Author).filter(Author.user == user_id).first()
        if author:
            if t.created_by != author.id:
                return {"error": "access denied"}

            session.delete(t)
            session.commit()

            return {}
    return {"error": "access denied"}


@query.field("get_topics_random")
def get_topics_random(_, _info, amount=12):
    q = select(Topic)
    q = q.join(ShoutTopic)
    q = q.group_by(Topic.id)
    q = q.having(func.count(distinct(ShoutTopic.shout)) > 2)
    q = q.order_by(func.random()).limit(amount)

    topics = []
    with local_session() as session:
        for [topic] in session.execute(q):
            topics.append(topic)

    return topics