"""Раздел «Анализ надёжности» (инженеры и руководители; включается в настройках сервера)."""
from datetime import datetime, timedelta
from typing import Literal, Optional

from fastapi import APIRouter, Depends, HTTPException, Query
from fastapi.responses import Response
from sqlalchemy import select
from sqlalchemy.orm import Session

from .. import config, reliability as R, schemas as S, scope, settings_store as ss
from ..db import get_db
from ..models import Equipment, User
from ..security import require_engineer

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


def enabled(db: Session) -> bool:
    return ss.get(db, "reliability") != "0"


def guard(db: Session = Depends(get_db), u: User = Depends(require_engineer)) -> User:
    if not enabled(db):
        raise HTTPException(404, "Анализ надёжности выключен в настройках сервера")
    return u


def period(date_from: Optional[datetime], date_to: Optional[datetime]) -> tuple[datetime, datetime]:
    end = S._dt_in(date_to) if date_to else config.now()
    start = S._dt_in(date_from) if date_from else end - timedelta(days=365)
    if start >= end:
        raise HTTPException(422, "Начало периода должно быть раньше конца")
    return start, end


def machines(db: Session, u: User, department_id: Optional[int], cranes: Optional[bool], equipment_id: Optional[int]) -> set[int]:
    """Машины, которые видит пользователь (отделы), с фильтрами отчёта."""
    stmt = select(Equipment.id)
    cond = scope.equipment_filter(db, u)
    if cond is not None:
        stmt = stmt.where(cond)
    if department_id:
        stmt = stmt.where(Equipment.department_id.in_(scope.dept_tree(db, department_id)))
    if cranes is not None:
        stmt = stmt.where(Equipment.is_crane.is_(cranes))
    if equipment_id:
        stmt = stmt.where(Equipment.id == equipment_id)
    return set(db.scalars(stmt))


@router.get("/dictionaries")
def dictionaries(_: User = Depends(guard)):
    """Справочники формы закрытия отказа: причины, характер, что сделано, признаки заранее."""
    return {"cause": R.CAUSE_RU, "nature": R.NATURE_RU, "action": R.ACTION_RU, "precursor": R.PRECURSOR_RU}


@router.get("")
def summary(date_from: Optional[datetime] = Query(None, alias="from"), date_to: Optional[datetime] = Query(None, alias="to"),
            department_id: Optional[int] = None, cranes: Optional[bool] = None, equipment_id: Optional[int] = None,
            confidence: float = Query(0.9, ge=0.5, le=0.99), horizon_days: int = Query(30, ge=1, le=365),
            db: Session = Depends(get_db), u: User = Depends(guard)):
    """Показатели надёжности по машинам и парку за период: λ, θ, оценки по малоотказному опыту, Tв, Kг, прогноз, причины."""
    start, end = period(date_from, date_to)
    return R.analyze(db, start, end, machines(db, u, department_id, cranes, equipment_id), confidence, horizon_days)


@router.get("/drift")
def drift(days: int = Query(180, ge=14, le=1095), horizon: int = Query(90, ge=7, le=730), department_id: Optional[int] = None,
          cranes: Optional[bool] = None, equipment_id: Optional[int] = None, db: Session = Depends(get_db), u: User = Depends(guard)):
    """«Параметр — граница работоспособности»: дрейф числовых пунктов чек-листов к границе нормы и выходы за неё."""
    return R.drift(db, machines(db, u, department_id, cranes, equipment_id), days, horizon)


@router.get("/export")
def export(kind: Literal["failures", "service"] = "failures",
           date_from: Optional[datetime] = Query(None, alias="from"), date_to: Optional[datetime] = Query(None, alias="to"),
           department_id: Optional[int] = None, cranes: Optional[bool] = None, equipment_id: Optional[int] = None,
           db: Session = Depends(get_db), u: User = Depends(guard)):
    """CSV для расчётов: failures — отказы и неисправности (строка на запись); service — история обслуживания узлов."""
    start, end = period(date_from, date_to)
    ids = machines(db, u, department_id, cranes, equipment_id)
    text = (R.export_failures if kind == "failures" else R.export_service_events)(db, start, end, ids)
    name = f"{'failures' if kind == 'failures' else 'service_events'}_{start:%Y%m%d}_{end:%Y%m%d}.csv"
    return Response(text, media_type="text/csv; charset=utf-8", headers={"Content-Disposition": f'attachment; filename="{name}"'})