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

from ..database import get_db
from ..deps import get_current_user, require_admin
from ..models import Barcode, Group, Product, User
from ..schemas import BarcodeCreate, BarcodeOut, GroupCreate, GroupOut, GroupUpdate
from ..services.conversion import BASE_OF_KIND
from ..services.stock import current_stock

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


def _group_to_out(db: Session, group: Group) -> GroupOut:
    out = GroupOut.model_validate(group)
    products = db.query(Product).filter(Product.group_id == group.id).all()
    out.product_count = len(products)
    out.barcodes = [
        BarcodeOut.model_validate(b)
        for b in db.query(Barcode).filter(Barcode.group_id == group.id).order_by(Barcode.id).all()
    ]
    unit = group.min_stock_unit
    if unit is not None:
        # Bestand nur über Produkte gleicher Art, in der Gruppen-Einheit ausgedrückt.
        base = BASE_OF_KIND[unit.kind]
        matching = [p for p in products if p.base_unit == base]
        stock_base = float(sum(current_stock(db, p.id) for p in matching))
        out.stock = stock_base / unit.factor
        out.min_stock_unit_name = unit.name
        out.kind = unit.kind.value
    else:
        out.stock = float(sum(current_stock(db, p.id) for p in products))
    return out


@router.get("", response_model=list[GroupOut])
def list_groups(
    db: Session = Depends(get_db), _: User = Depends(get_current_user)
) -> list[GroupOut]:
    groups = db.query(Group).order_by(Group.name).all()
    return [_group_to_out(db, g) for g in groups]


@router.post("", response_model=GroupOut, status_code=status.HTTP_201_CREATED)
def create_group(
    payload: GroupCreate,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> GroupOut:
    if db.query(Group).filter(Group.name == payload.name).first():
        raise HTTPException(status.HTTP_409_CONFLICT, "Gruppe existiert bereits")
    group = Group(
        name=payload.name,
        min_stock=payload.min_stock,
        min_stock_unit_id=payload.min_stock_unit_id,
    )
    db.add(group)
    db.commit()
    db.refresh(group)
    return _group_to_out(db, group)


@router.patch("/{group_id}", response_model=GroupOut)
def update_group(
    group_id: int,
    payload: GroupUpdate,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> GroupOut:
    group = db.get(Group, group_id)
    if group is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Gruppe nicht gefunden")
    data = payload.model_dump(exclude_unset=True)
    if "name" in data and data["name"]:
        clash = (
            db.query(Group)
            .filter(Group.name == data["name"], Group.id != group_id)
            .first()
        )
        if clash:
            raise HTTPException(status.HTTP_409_CONFLICT, "Name bereits vergeben")
    for field, value in data.items():
        setattr(group, field, value)
    db.commit()
    db.refresh(group)
    return _group_to_out(db, group)


@router.post("/{group_id}/barcodes", response_model=GroupOut, status_code=status.HTTP_201_CREATED)
def add_group_barcode(
    group_id: int,
    payload: BarcodeCreate,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> GroupOut:
    """EAN einer Gruppe zuordnen (z.B. alle Mehl-Marken zur Gruppe "Mehl")."""
    group = db.get(Group, group_id)
    if group is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Gruppe nicht gefunden")
    code = payload.code.strip()
    if db.query(Barcode).filter(Barcode.code == code).first() or (
        db.query(Product).filter(Product.barcode == code).first()
    ):
        raise HTTPException(status.HTTP_409_CONFLICT, "Dieser Code ist bereits vergeben")
    db.add(Barcode(code=code, note=(payload.note or None), group_id=group.id))
    db.commit()
    db.refresh(group)
    return _group_to_out(db, group)


@router.delete("/{group_id}/barcodes/{code}", status_code=status.HTTP_204_NO_CONTENT)
def delete_group_barcode(
    group_id: int,
    code: str,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> None:
    entry = (
        db.query(Barcode).filter(Barcode.group_id == group_id, Barcode.code == code).first()
    )
    if entry is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Code nicht gefunden")
    db.delete(entry)
    db.commit()


@router.delete("/{group_id}", status_code=status.HTTP_204_NO_CONTENT)
def delete_group(
    group_id: int,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> None:
    group = db.get(Group, group_id)
    if group is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Gruppe nicht gefunden")
    db.delete(group)
    db.commit()