from datetime import datetime

from fastapi import APIRouter, Depends, HTTPException, Path
from sqlmodel import Session, col, select

from app.auth import get_current_user
from app.db import get_session
from app.models.models import (
    SavingsAccrual,
    SavingsAccrualCreate,
    SavingsAccrualRead,
    SavingsAccrualUpdate,
)

router = APIRouter(prefix="/savings-accrual", tags=["savings-accrual"])


@router.get("/", response_model=list[SavingsAccrualRead])
def list_accruals(
    session: Session = Depends(get_session),
    _user: str = Depends(get_current_user),
):
    query = select(SavingsAccrual).order_by(
        col(SavingsAccrual.year).desc(), col(SavingsAccrual.month).desc()
    )
    return session.exec(query).all()


@router.post("/", response_model=SavingsAccrualRead, status_code=201)
def create_accrual(
    data: SavingsAccrualCreate,
    session: Session = Depends(get_session),
    _user: str = Depends(get_current_user),
):
    existing = session.exec(
        select(SavingsAccrual).where(
            SavingsAccrual.year == data.year,
            SavingsAccrual.month == data.month,
        )
    ).first()
    if existing:
        raise HTTPException(
            status_code=409,
            detail=f"Accrual for {data.year}-{data.month:02d} already exists (id={existing.id})",
        )
    accrual = SavingsAccrual.model_validate(data)
    accrual.applied_at = datetime.utcnow()
    session.add(accrual)
    session.commit()
    session.refresh(accrual)
    return accrual


@router.patch("/{accrual_id}", response_model=SavingsAccrualRead)
def update_accrual(
    accrual_id: int,
    data: SavingsAccrualUpdate,
    session: Session = Depends(get_session),
    _user: str = Depends(get_current_user),
):
    accrual = session.get(SavingsAccrual, accrual_id)
    if not accrual:
        raise HTTPException(status_code=404, detail="Accrual not found")
    update_data = data.model_dump(exclude_unset=True)
    for key, value in update_data.items():
        setattr(accrual, key, value)
    session.add(accrual)
    session.commit()
    session.refresh(accrual)
    return accrual


@router.delete("/{accrual_id}", status_code=204)
def delete_accrual(
    accrual_id: int = Path(...),
    session: Session = Depends(get_session),
    _user: str = Depends(get_current_user),
):
    accrual = session.get(SavingsAccrual, accrual_id)
    if not accrual:
        raise HTTPException(status_code=404, detail="Accrual not found")
    session.delete(accrual)
    session.commit()