from fastapi import APIRouter, Depends
from sqlalchemy.orm import Session
from datetime import datetime
from app.models.customer import Customer_Customer
from app.models.delivery import Delivery
from database import get_db
from sqlalchemy import func

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

def get_customers_without_delivery_since(db: Session, date_threshold: datetime):
    """
    Queries all customers who haven't received a delivery since the specified date.

    Args:
        db: The database session.
        date_threshold: The date threshold. Customers whose last delivery is
                        before this date (or have no deliveries) will be returned.

    Returns:
        A tuple containing the count and a list of Customer_Customer objects.
    """
    # Subquery to find the last delivery date for each customer
    last_delivery_subquery = (
        db.query(
            Delivery.customer_id,
            func.max(Delivery.when_delivered).label("last_delivery_date")
        )
        .group_by(Delivery.customer_id)
        .subquery()
    )

    # Main query to join customers with their last delivery date
    # and filter based on the date threshold
    customers = (
        db.query(Customer_Customer)
        .outerjoin(
            last_delivery_subquery,
            Customer_Customer.id == last_delivery_subquery.c.customer_id
        )
        .filter(
            (last_delivery_subquery.c.last_delivery_date < date_threshold) |
            (last_delivery_subquery.c.last_delivery_date == None)
        )
        .all()
    )
    return len(customers), customers

@router.get("/customers/no_delivery_since/{year}/{month}/{day}")
async def customers_no_delivery_since(
    year: int, 
    month: int, 
    day: int, 
    db: Session = Depends(get_db)
):
    """
    Get customers who have not had a delivery since the specified date.
    """
    try:
        threshold_date = datetime(year, month, day).date()
        count, customers = get_customers_without_delivery_since(db, threshold_date)
        return {"customer_count": count, "customers": customers}
    except ValueError as e:
        return {"error": str(e)}