from __future__ import annotations

from fastapi import HTTPException
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.car import Car, OdometerHistory
from app.models.expense import ExpenseEntry, FuelEntry, ServiceEntry


def validate_odometer_change(
    car: Car,
    new_odometer: int | None,
    *,
    source_record_type: str,
    confirm_lower_odometer: bool = False,
) -> None:
    if new_odometer is None:
        return
    if new_odometer < 0:
        raise HTTPException(status_code=422, detail="Odometer must be non-negative")
    current = car.current_odometer
    if current is not None and new_odometer < current and not confirm_lower_odometer:
        raise HTTPException(
            status_code=409,
            detail={
                "code": "odometer_lower_than_current",
                "message": "Новый пробег меньше текущего. Подтвердите ручную корректировку или проверьте запись.",
                "current_odometer": current,
                "new_odometer": new_odometer,
                "source": source_record_type,
            },
        )
    if current is not None and new_odometer > current + 100000 and not confirm_lower_odometer:
        raise HTTPException(
            status_code=409,
            detail={
                "code": "odometer_jump_requires_confirmation",
                "message": "Пробег сильно отличается от текущего. Проверьте число перед сохранением.",
                "current_odometer": current,
                "new_odometer": new_odometer,
                "source": source_record_type,
            },
        )


def add_odometer_history(
    session: AsyncSession,
    car: Car,
    *,
    new_odometer: int,
    source_record_type: str,
    source_record_id: int | None,
    changed_by: int | None,
    confirmation_required: bool = False,
    user_confirmed: bool = True,
) -> None:
    previous = car.current_odometer
    session.add(
        OdometerHistory(
            car_id=car.id,
            previous_odometer=previous,
            new_odometer=new_odometer,
            source_record_type=source_record_type,
            source_record_id=source_record_id,
            changed_by=changed_by,
            confirmation_required=confirmation_required,
            user_confirmed=user_confirmed,
        )
    )
    car.current_odometer = new_odometer


async def apply_odometer_from_record(
    session: AsyncSession,
    car: Car,
    *,
    new_odometer: int | None,
    source_record_type: str,
    source_record_id: int | None,
    changed_by: int | None,
    confirm_lower_odometer: bool = False,
) -> None:
    if new_odometer is None:
        return
    validate_odometer_change(
        car,
        new_odometer,
        source_record_type=source_record_type,
        confirm_lower_odometer=confirm_lower_odometer,
    )
    current = car.current_odometer
    if current is None or new_odometer > current or confirm_lower_odometer:
        add_odometer_history(
            session,
            car,
            new_odometer=new_odometer,
            source_record_type=source_record_type,
            source_record_id=source_record_id,
            changed_by=changed_by,
            confirmation_required=current is not None and new_odometer < current,
            user_confirmed=True,
        )


async def recalculate_current_odometer(
    session: AsyncSession,
    car_id: int,
    *,
    changed_by: int | None = None,
    source_record_type: str = "recalculate",
) -> None:
    car = await session.get(Car, car_id)
    if car is None:
        return
    fuel_result = await session.execute(
        select(FuelEntry.odometer)
        .where(FuelEntry.car_id == car_id)
        .order_by(FuelEntry.odometer.desc())
        .limit(1)
    )
    service_result = await session.execute(
        select(ServiceEntry.odometer)
        .where(ServiceEntry.car_id == car_id, ServiceEntry.odometer.is_not(None))
        .order_by(ServiceEntry.odometer.desc())
        .limit(1)
    )
    expense_result = await session.execute(
        select(ExpenseEntry.odometer)
        .where(ExpenseEntry.car_id == car_id, ExpenseEntry.odometer.is_not(None))
        .order_by(ExpenseEntry.odometer.desc())
        .limit(1)
    )
    values = [
        value
        for value in (
            fuel_result.scalar_one_or_none(),
            service_result.scalar_one_or_none(),
            expense_result.scalar_one_or_none(),
        )
        if value is not None
    ]
    new_value = max(values) if values else None
    if new_value != car.current_odometer:
        if new_value is None:
            car.current_odometer = None
            return
        add_odometer_history(
            session,
            car,
            new_odometer=new_value,
            source_record_type=source_record_type,
            source_record_id=None,
            changed_by=changed_by,
            confirmation_required=False,
            user_confirmed=True,
        )