from datetime import datetime, timedelta, timezone

from sqlalchemy.orm import joinedload, aliased
from sqlalchemy.sql.expression import desc, asc, select, func, case

from auth.authenticate import login_required
from auth.credentials import AuthCredentials
from base.exceptions import ObjectNotExist
from base.orm import local_session
from base.resolvers import query
from orm import ViewedEntry, TopicFollower
from orm.reaction import Reaction, ReactionKind
from orm.shout import Shout, ShoutAuthor, ShoutTopic
from orm.user import AuthorFollower


def add_stat_columns(q):
    aliased_reaction = aliased(Reaction)

    q = q.outerjoin(aliased_reaction).add_columns(
        func.sum(
            aliased_reaction.id
        ).label('reacted_stat'),
        func.sum(
            case(
                (aliased_reaction.body.is_not(None), 1),
                else_=0
            )
        ).label('commented_stat'),
        func.sum(case(
            # do not count comments' reactions
            (aliased_reaction.replyTo.is_not(None), 0),
            (aliased_reaction.kind == ReactionKind.AGREE, 1),
            (aliased_reaction.kind == ReactionKind.DISAGREE, -1),
            (aliased_reaction.kind == ReactionKind.PROOF, 1),
            (aliased_reaction.kind == ReactionKind.DISPROOF, -1),
            (aliased_reaction.kind == ReactionKind.ACCEPT, 1),
            (aliased_reaction.kind == ReactionKind.REJECT, -1),
            (aliased_reaction.kind == ReactionKind.LIKE, 1),
            (aliased_reaction.kind == ReactionKind.DISLIKE, -1),
            else_=0)
        ).label('rating_stat'))

    return q


def apply_filters(q, filters, user_id=None):
    if filters.get("reacted") and user_id:
        q.join(Reaction, Reaction.createdBy == user_id)

    v = filters.get("visibility")
    if v == "public":
        q = q.filter(Shout.visibility == filters.get("visibility"))
    if v == "community":
        q = q.filter(Shout.visibility.in_(["public", "community"]))

    if filters.get("layout"):
        q = q.filter(Shout.layout == filters.get("layout"))
    if filters.get("author"):
        q = q.filter(Shout.authors.any(slug=filters.get("author")))
    if filters.get("topic"):
        q = q.filter(Shout.topics.any(slug=filters.get("topic")))
    if filters.get("title"):
        q = q.filter(Shout.title.ilike(f'%{filters.get("title")}%'))
    if filters.get("body"):
        q = q.filter(Shout.body.ilike(f'%{filters.get("body")}%s'))
    if filters.get("days"):
        before = datetime.now(tz=timezone.utc) - timedelta(days=int(filters.get("days")) or 30)
        q = q.filter(Shout.createdAt > before)

    return q


@query.field("loadShout")
async def load_shout(_, info, slug):
    with local_session() as session:
        q = select(Shout).options(
            joinedload(Shout.authors),
            joinedload(Shout.topics),
        )
        q = add_stat_columns(q)
        q = q.filter(
            Shout.slug == slug
        ).filter(
            Shout.deletedAt.is_(None)
        ).group_by(Shout.id)

        try:
            [shout, reacted_stat, commented_stat, rating_stat] = session.execute(q).first()

            viewed_stat_query = select().select_from(
                Shout
            ).where(
                Shout.id == shout.id
            ).join(
                ViewedEntry
            ).group_by(
                Shout.id
            ).add_columns(
                func.sum(ViewedEntry.amount).label('viewed_stat')
            )

            # Debug tip:
            # print(viewed_stat_query.compile(compile_kwargs={"literal_binds": True}))
            viewed_stat = session.execute(viewed_stat_query).scalar()

            shout.stat = {
                "viewed": viewed_stat,
                "reacted": reacted_stat,
                "commented": commented_stat,
                "rating": rating_stat
            }

            for author_caption in session.query(ShoutAuthor).join(Shout).where(Shout.slug == slug):
                for author in shout.authors:
                    if author.id == author_caption.user:
                        author.caption = author_caption.caption
            return shout
        except Exception:
            raise ObjectNotExist("Slug was not found: %s" % slug)


@query.field("loadShouts")
async def load_shouts_by(_, info, options):
    """
    :param options: {
        filters: {
            layout: 'audio',
            visibility: "public",
            author: 'discours',
            topic: 'culture',
            title: 'something',
            body: 'something else',
            days: 30
        }
        offset: 0
        limit: 50
        order_by: 'createdAt' | 'commented' | 'reacted' | 'rating'
        order_by_desc: true

    }
    :return: Shout[]
    """

    q = select(Shout).options(
        joinedload(Shout.authors),
        joinedload(Shout.topics),
    ).where(
        Shout.deletedAt.is_(None)
    )

    q = add_stat_columns(q)

    auth: AuthCredentials = info.context["request"].auth
    q = apply_filters(q, options.get("filters", {}), auth.user_id)

    order_by = options.get("order_by", Shout.createdAt)
    if order_by == 'reacted':
        aliased_reaction = aliased(Reaction)
        q.outerjoin(aliased_reaction).add_columns(func.max(aliased_reaction.createdAt).label('reacted'))

    query_order_by = desc(order_by) if options.get('order_by_desc', True) else asc(order_by)
    offset = options.get("offset", 0)
    limit = options.get("limit", 10)

    q = q.group_by(Shout.id).order_by(query_order_by).limit(limit).offset(offset)

    with local_session() as session:
        shouts = []
        shouts_map = {}

        for [shout, reacted_stat, commented_stat, rating_stat] in session.execute(q).unique():
            shouts.append(shout)
            shout.stat = {
                "viewed": 0,
                "reacted": reacted_stat,
                "commented": commented_stat,
                "rating": rating_stat
            }
            shouts_map[shout.id] = shout

        viewed_stat_query = select(
            Shout.id
        ).where(
            Shout.id.in_(shouts_map.keys())
        ).join(
            ViewedEntry
        ).group_by(
            Shout.id
        ).add_columns(
            func.sum(ViewedEntry.amount).label('viewed_stat')
        )

        for [shout_id, viewed_stat] in session.execute(viewed_stat_query).unique():
            shouts_map[shout_id].stat['viewed'] = viewed_stat

    return shouts


@query.field("myFeed")
@login_required
async def get_my_feed(_, info):
    auth: AuthCredentials = info.context["request"].auth
    user_id = auth.user_id
    with local_session() as session:
        q = select(Shout).options(
            joinedload(Shout.authors),
            joinedload(Shout.topics),
        ).where(
            Shout.deletedAt.is_(None)
        )

        q = q.join(
            ShoutAuthor
        ).join(
            AuthorFollower
        ).where(
            AuthorFollower.follower == user_id
        ).join(
            ShoutTopic
        ).join(
            TopicFollower
        ).where(TopicFollower.follower == user_id)

        q = add_stat_columns(q)

        shouts = []
        for [shout, reacted_stat, commented_stat, rating_stat] in session.execute(q).unique():
            shouts.append(shout)
            shout.stat = {
                "viewed": 0,
                "reacted": reacted_stat,
                "commented": commented_stat,
                "rating": rating_stat
            }

        return shouts