from datetime import date, datetime

from fastapi import APIRouter, Depends, Query
from sqlalchemy import func, select
from sqlalchemy.orm import Session, selectinload

from ..database import get_db
from ..models import PriceSnapshot, Product
from ..schemas import CheapestProduct, Product as ProductSchema

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


@router.get("/cheapest", response_model=list[CheapestProduct])
def get_cheapest(
    date_filter: date = Query(default=None, alias="date"),
    limit: int = Query(default=20, le=100),
    db: Session = Depends(get_db),
):
    target = date_filter or date.today()
    day_start = datetime(target.year, target.month, target.day, 0, 0, 0)
    day_end = datetime(target.year, target.month, target.day, 23, 59, 59)

    min_per_product = (
        select(
            PriceSnapshot.product_id,
            func.min(PriceSnapshot.price).label("min_price"),
        )
        .where(PriceSnapshot.timestamp.between(day_start, day_end))
        .group_by(PriceSnapshot.product_id)
        .subquery()
    )

    rows = db.execute(
        select(PriceSnapshot, Product)
        .join(
            min_per_product,
            (PriceSnapshot.product_id == min_per_product.c.product_id)
            & (PriceSnapshot.price == min_per_product.c.min_price),
        )
        .join(Product, PriceSnapshot.product_id == Product.id)
        .options(selectinload(Product.store))
        .order_by(PriceSnapshot.price.asc())
        .limit(limit)
    ).all()

    return [
        CheapestProduct(
            product=ProductSchema.model_validate(product),
            price=snapshot.price,
            unit_price=snapshot.unit_price,
            unit_description=snapshot.unit_description,
            is_on_sale=snapshot.is_on_sale,
            timestamp=snapshot.timestamp,
        )
        for snapshot, product in rows
    ]