from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.orm import Session

from ..crud import product_to_out
from ..database import get_db
from ..deps import get_current_user, require_admin
from ..models import BaseUnit, Product, User
from ..off import lookup_barcode
from ..schemas import LookupResult, ProductCreate, ProductOut, ProductUpdate
from ..services.conversion import ConversionError, resolve_product_unit

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


@router.get("", response_model=list[ProductOut])
def list_products(
    q: str | None = None,
    db: Session = Depends(get_db),
    _: User = Depends(get_current_user),
) -> list[ProductOut]:
    query = db.query(Product)
    if q:
        like = f"%{q}%"
        query = query.filter(Product.name.ilike(like))
    products = query.order_by(Product.name).all()
    return [product_to_out(db, p) for p in products]


@router.get("/lookup", response_model=LookupResult)
def lookup(
    barcode: str,
    db: Session = Depends(get_db),
    _: User = Depends(get_current_user),
) -> LookupResult:
    """Barcode: erst lokal, dann Open Food Facts. Nur Vorschlag, legt nichts an."""
    existing = db.query(Product).filter(Product.barcode == barcode).first()
    if existing:
        return LookupResult(found=True, existing_product=product_to_out(db, existing))

    suggestion = lookup_barcode(barcode)
    if suggestion:
        return LookupResult(found=True, suggestion=suggestion)
    return LookupResult(found=False)


@router.get("/{product_id}", response_model=ProductOut)
def get_product(
    product_id: int,
    db: Session = Depends(get_db),
    _: User = Depends(get_current_user),
) -> ProductOut:
    product = db.get(Product, product_id)
    if product is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Produkt nicht gefunden")
    return product_to_out(db, product)


@router.post("", response_model=ProductOut, status_code=status.HTTP_201_CREATED)
def create_product(
    payload: ProductCreate,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> ProductOut:
    if payload.barcode:
        exists = db.query(Product).filter(Product.barcode == payload.barcode).first()
        if exists:
            raise HTTPException(
                status.HTTP_409_CONFLICT, "Ein Produkt mit diesem Barcode existiert bereits"
            )
    base_unit = payload.base_unit
    display_unit_id = None
    if payload.unit_id is not None:
        try:
            base_unit, display_unit_id = resolve_product_unit(db, payload.unit_id)
        except ConversionError as exc:
            raise HTTPException(status.HTTP_400_BAD_REQUEST, str(exc)) from exc
    product = Product(
        barcode=payload.barcode or None,
        name=payload.name,
        brand=payload.brand,
        image_url=payload.image_url,
        base_unit=base_unit,
        display_unit_id=display_unit_id,
        package_size=payload.package_size,
        package_label=payload.package_label or None,
        group_id=payload.group_id,
        min_stock=payload.min_stock,
        min_stock_unit_id=payload.min_stock_unit_id,
        min_stock_in_packages=bool(payload.min_stock_in_packages),
        source="manual",
    )
    db.add(product)
    db.commit()
    db.refresh(product)
    return product_to_out(db, product)


@router.patch("/{product_id}", response_model=ProductOut)
def update_product(
    product_id: int,
    payload: ProductUpdate,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> ProductOut:
    product = db.get(Product, product_id)
    if product is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Produkt nicht gefunden")

    data = payload.model_dump(exclude_unset=True)
    if "barcode" in data and data["barcode"]:
        clash = (
            db.query(Product)
            .filter(Product.barcode == data["barcode"], Product.id != product_id)
            .first()
        )
        if clash:
            raise HTTPException(
                status.HTTP_409_CONFLICT, "Ein anderes Produkt hat diesen Barcode bereits"
            )
    # Einheit: unit_id (falls gesetzt) bestimmt base_unit + Anzeigeeinheit.
    if "unit_id" in data:
        unit_id = data.pop("unit_id")
        data.pop("base_unit", None)  # unit_id hat Vorrang
        if unit_id is None:
            product.display_unit_id = None
        else:
            try:
                product.base_unit, product.display_unit_id = resolve_product_unit(db, unit_id)
            except ConversionError as exc:
                raise HTTPException(status.HTTP_400_BAD_REQUEST, str(exc)) from exc
    if data.get("min_stock_in_packages") is None:
        data.pop("min_stock_in_packages", None)  # Spalte ist NOT NULL
    for field, value in data.items():
        setattr(product, field, value)
    db.commit()
    db.refresh(product)
    return product_to_out(db, product)


@router.delete("/{product_id}", status_code=status.HTTP_204_NO_CONTENT)
def delete_product(
    product_id: int,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> None:
    product = db.get(Product, product_id)
    if product is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Produkt nicht gefunden")
    db.delete(product)
    db.commit()