from fastapi import APIRouter, Query
from typing import Optional
from sqlalchemy import func

from bd import make_engine
from bd.tables.response import Response
from bd.tables.poll import Poll
from bd.tables.group import Group
from bd.tables.organization import Organization

router = APIRouter(tags=["stats"], prefix="/stats")

_MONTH_NAMES = ["Янв", "Фев", "Мар", "Апр", "Май", "Июн",
                "Июл", "Авг", "Сен", "Окт", "Ноя", "Дек"]


def get_session():
    from sqlalchemy.orm import sessionmaker
    return sessionmaker(bind=make_engine(), future=True)


@router.get("/summary")
def get_summary():
    """Общая сводка: кол-во ответов, тестов, активных тестов, организаций с активностью."""
    Session = get_session()
    with Session() as session:
        total_responses = session.query(func.count(Response.id)).scalar() or 0
        total_polls = session.query(func.count(Poll.id)).scalar() or 0
        active_polls = session.query(func.count(Poll.id)).filter(Poll.is_active.is_(True)).scalar() or 0
        orgs_active = session.query(func.count(func.distinct(Response.organization_id))).scalar() or 0
    return {
        "total_responses": total_responses,
        "total_polls": total_polls,
        "active_polls": active_polls,
        "orgs_active": orgs_active,
    }


@router.get("/years")
def get_years():
    """Список лет, в которых есть хотя бы один ответ."""
    Session = get_session()
    with Session() as session:
        rows = session.query(
            func.extract("year", Response.submitted_at).label("yr")
        ).distinct().order_by("yr").all()
    return [int(r.yr) for r in rows if r.yr is not None]


@router.get("/responses")
def get_responses_grouped(
    group_by: str = Query("poll", pattern="^(poll|organization|group|month)$"),
    poll_id: Optional[str] = None,
    org_id: Optional[str] = None,
    group_id: Optional[str] = None,
    year: Optional[int] = None,
):
    """
    Возвращает агрегированные данные для графиков.

    - group_by=poll         → количество ответов по каждому тесту
    - group_by=organization → количество ответов по каждой организации
    - group_by=group        → количество ответов по каждой группе
    - group_by=month        → количество ответов по месяцам (хронологически)

    Все фильтры опциональны и комбинируются.
    """
    Session = get_session()
    with Session() as session:

        if group_by == "poll":
            q = session.query(Poll.title, func.count(Response.id).label("cnt"))
            q = q.join(Response, Poll.id == Response.poll_id)
            if org_id:
                q = q.filter(Response.organization_id == org_id)
            if group_id:
                q = q.filter(Response.group_id == group_id)
            if year:
                q = q.filter(func.extract("year", Response.submitted_at) == year)
            if poll_id:
                q = q.filter(Response.poll_id == poll_id)
            rows = q.group_by(Poll.title).order_by(func.count(Response.id).desc()).limit(20).all()
            return [{"label": r[0], "count": r[1]} for r in rows]

        if group_by == "organization":
            q = session.query(Organization.name_organization, func.count(Response.id).label("cnt"))
            q = q.outerjoin(Response, Organization.id == Response.organization_id)
            if poll_id:
                q = q.filter(Response.poll_id == poll_id)
            if group_id:
                q = q.filter(Response.group_id == group_id)
            if year:
                q = q.filter(func.extract("year", Response.submitted_at) == year)
            rows = q.group_by(Organization.name_organization).order_by(
                func.count(Response.id).desc()
            ).limit(20).all()
            return [{"label": r[0], "count": r[1] or 0} for r in rows]

        if group_by == "group":
            q = session.query(Group.name_group, func.count(Response.id).label("cnt"))
            q = q.outerjoin(Response, Group.id == Response.group_id)
            if poll_id:
                q = q.filter(Response.poll_id == poll_id)
            if org_id:
                q = q.filter(Response.organization_id == org_id)
            if year:
                q = q.filter(func.extract("year", Response.submitted_at) == year)
            rows = q.group_by(Group.name_group).order_by(
                func.count(Response.id).desc()
            ).limit(20).all()
            return [{"label": r[0], "count": r[1] or 0} for r in rows]

        if group_by == "month":
            yr_col = func.extract("year", Response.submitted_at).label("yr")
            mo_col = func.extract("month", Response.submitted_at).label("mo")
            q = session.query(yr_col, mo_col, func.count(Response.id).label("cnt"))
            if poll_id:
                q = q.filter(Response.poll_id == poll_id)
            if org_id:
                q = q.filter(Response.organization_id == org_id)
            if group_id:
                q = q.filter(Response.group_id == group_id)
            if year:
                q = q.filter(func.extract("year", Response.submitted_at) == year)
            rows = q.group_by("yr", "mo").order_by("yr", "mo").all()
            return [
                {
                    "label": f"{_MONTH_NAMES[int(r.mo) - 1]} {int(r.yr)}",
                    "count": r.cnt,
                }
                for r in rows
            ]

    return []