from datetime import datetime, timedelta, timezone

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

from auth.authenticate import login_required
from auth.credentials import AuthCredentials
from base.exceptions import ObjectNotExist, OperationNotAllowed
from base.orm import local_session
from base.resolvers import query
from orm import 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.kind == ReactionKind.COMMENT, 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'),
        func.max(case(
            (aliased_reaction.kind != ReactionKind.COMMENT, None),
            else_=aliased_reaction.createdAt
        )).label('last_comment'))

    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('excludeLayout'):
        q = q.filter(Shout.layout != filters.get("excludeLayout"))
    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=None, shout_id=None):
    with local_session() as session:
        q = select(Shout).options(
            joinedload(Shout.authors),
            joinedload(Shout.topics),
        )
        q = add_stat_columns(q)

        if slug is not None:
            q = q.filter(
                Shout.slug == slug
            )

        if shout_id is not None:
            q = q.filter(
                Shout.id == shout_id
            )

        q = q.filter(
            Shout.deletedAt.is_(None)
        ).group_by(Shout.id)

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

            shout.stat = {
                "viewed": shout.views,
                "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: 'music',
            excludeLayout: 'article',
            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(
        and_(
            Shout.deletedAt.is_(None),
            Shout.layout.is_not(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.publishedAt)

    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(nulls_last(query_order_by)).limit(limit).offset(offset)

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

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

    return shouts


@query.field("loadDrafts")
@login_required
async def get_drafts(_, info):
    auth: AuthCredentials = info.context["request"].auth
    user_id = auth.user_id

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

    q = q.group_by(Shout.id)

    shouts = []
    with local_session() as session:
        for [shout] in session.execute(q).unique():
            shouts.append(shout)

    return shouts


@query.field("myFeed")
@login_required
async def get_my_feed(_, info, options):
    auth: AuthCredentials = info.context["request"].auth
    user_id = auth.user_id

    subquery = select(Shout.id).join(
        ShoutAuthor
    ).join(
        AuthorFollower, AuthorFollower.follower == user_id
    ).join(
        ShoutTopic
    ).join(
        TopicFollower, TopicFollower.follower == user_id
    )

    q = select(Shout).options(
        joinedload(Shout.authors),
        joinedload(Shout.topics),
    ).where(
        and_(
            Shout.publishedAt.is_not(None),
            Shout.deletedAt.is_(None),
            Shout.id.in_(subquery)
        )
    )

    q = add_stat_columns(q)
    q = apply_filters(q, options.get("filters", {}), user_id)

    order_by = options.get("order_by", Shout.publishedAt)

    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(nulls_last(query_order_by)).limit(limit).offset(offset)

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

    return shouts