from fastapi import APIRouter, Depends, File, HTTPException, UploadFile, status
from fastapi.responses import Response
from sqlalchemy.orm import Session, joinedload, selectinload

from ..crud import product_to_out, product_tracking, products_to_out_bulk
from ..database import get_db
from ..deps import get_current_user, require_admin
from ..models import (
    Barcode,
    BaseUnit,
    Category,
    Group,
    Location,
    Movement,
    MovementType,
    Product,
    ProductImage,
    ProductLocationMinStock,
    RemovalReason,
    Shop,
    User,
)
from ..off import lookup_barcode
from ..schemas import (
    BarcodeCreate,
    LocationMinStockIn,
    LookupResult,
    ProductCreate,
    ProductOut,
    ProductUpdate,
    RemovalHistoryItem,
    RemovalStat,
    RemovalSummary,
)
from ..services import images
from ..services.categories import suggest_category
from .categories import descendant_ids
from ..services.conversion import ConversionError, resolve_product_unit
from ..services.fields import FieldError, apply_field_values
from ..services.group_codes import detach as detach_group_code, sync as sync_group_code
from ..services.stock import removal_stats

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


@router.get("", response_model=list[ProductOut])
def list_products(
    q: str | None = None,
    category_id: int | None = None,
    db: Session = Depends(get_db),
    _: User = Depends(get_current_user),
) -> list[ProductOut]:
    """Artikel auflisten, optional nach Name und Kategorie eingegrenzt.

    ``category_id=0`` liefert die Artikel ohne Kategorie. Bei einer echten
    Kategorie zählen die Unterkategorien mit: Wer auf "Süßwaren" filtert, will
    auch "Schokolade" sehen.
    """
    query = db.query(Product).options(
        # Relationen vorab laden, damit products_to_out_bulk kein N+1 auslöst.
        joinedload(Product.category),
        joinedload(Product.shop),
        joinedload(Product.display_unit),
        joinedload(Product.min_stock_unit),
        selectinload(Product.field_values),
        selectinload(Product.location_min_stocks).joinedload(ProductLocationMinStock.location),
    )
    if q:
        like = f"%{q}%"
        query = query.filter(Product.name.ilike(like))
    if category_id == 0:
        query = query.filter(Product.category_id.is_(None))
    elif category_id is not None:
        query = query.filter(Product.category_id.in_(descendant_ids(db, category_id)))
    products = query.order_by(Product.name).all()
    return products_to_out_bulk(db, products)


@router.get("/lookup", response_model=LookupResult)
def lookup(
    barcode: str,
    db: Session = Depends(get_db),
    _: User = Depends(get_current_user),
) -> LookupResult:
    """Barcode auflösen: Produkt (Haupt- oder Alias-Code), Gruppen-Code, sonst OFF."""
    code = barcode.strip()

    existing = db.query(Product).filter(Product.barcode == code).first()
    if existing is None:
        alias = db.query(Barcode).filter(Barcode.code == code).first()
        if alias is not None and alias.product_id:
            existing = db.get(Product, alias.product_id)
    if existing:
        return LookupResult(found=True, existing_product=product_to_out(db, existing))

    # Code kann einer Gruppe zugeordnet sein (z.B. alle Mehl-Marken in "Mehl").
    group_id = group_name = None
    alias = db.query(Barcode).filter(Barcode.code == code).first()
    if alias is not None and alias.group_id:
        group = db.get(Group, alias.group_id)
        if group is not None:
            group_id, group_name = group.id, group.name

    suggestion = lookup_barcode(code)
    # Die OFF-Einordnung steuert die KATEGORIE (Ueberblick), nicht die Gruppe.
    category = suggest_category(db, suggestion)
    category_id = category.id if category else None
    category_name = category.name if category else None
    if suggestion:
        return LookupResult(
            found=True, suggestion=suggestion, group_id=group_id, group_name=group_name,
            category_id=category_id, category_name=category_name,
        )
    return LookupResult(found=False, group_id=group_id, group_name=group_name)


@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.put("/{product_id}/location-min-stock", response_model=ProductOut)
def set_product_location_min_stock(
    product_id: int,
    payload: list[LocationMinStockIn],
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> ProductOut:
    """Mindestbestände je Lagerort komplett ersetzen (Menge 0 = Eintrag entfällt)."""
    product = db.get(Product, product_id)
    if product is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Produkt nicht gefunden")

    db.query(ProductLocationMinStock).filter(
        ProductLocationMinStock.product_id == product_id
    ).delete()
    gesehen: set[int] = set()
    for eintrag in payload:
        if eintrag.min_stock <= 0 or eintrag.location_id in gesehen:
            continue
        if db.get(Location, eintrag.location_id) is None:
            raise HTTPException(status.HTTP_404_NOT_FOUND, "Lagerort nicht gefunden")
        gesehen.add(eintrag.location_id)
        db.add(ProductLocationMinStock(
            product_id=product_id,
            location_id=eintrag.location_id,
            min_stock=eintrag.min_stock,
        ))
    db.commit()
    db.refresh(product)
    return product_to_out(db, product)


@router.get("/{product_id}/removals", response_model=RemovalSummary)
def product_removals(
    product_id: int,
    db: Session = Depends(get_db),
    _: User = Depends(get_current_user),
) -> RemovalSummary:
    """Entnahmen mit Grund: Summe je Grund plus die jüngsten Einträge."""
    product = db.get(Product, product_id)
    if product is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Produkt nicht gefunden")

    stats = [
        RemovalStat(reason=RemovalReason(grund), quantity=v["quantity"], count=v["count"])
        for grund, v in removal_stats(db, product_id).items()
    ]
    stats.sort(key=lambda s: s.quantity, reverse=True)

    rows = (
        db.query(Movement)
        .filter(
            Movement.product_id == product_id,
            Movement.type == MovementType.out,
            Movement.reason.isnot(None),
        )
        .order_by(Movement.created_at.desc())
        .limit(50)
        .all()
    )
    loc_names = {loc.id: loc.name for loc in db.query(Location).all()}
    user_ids = {m.user_id for m in rows if m.user_id}
    users = (
        {u.id: u.username for u in db.query(User).filter(User.id.in_(user_ids)).all()}
        if user_ids
        else {}
    )
    history = [
        RemovalHistoryItem(
            reason=RemovalReason(m.reason),
            quantity=m.quantity,
            location_id=m.location_id,
            location_name=loc_names.get(m.location_id),
            note=m.note,
            username=users.get(m.user_id),
            created_at=m.created_at,
        )
        for m in rows
    ]
    return RemovalSummary(stats=stats, history=history)


@router.get("/{product_id}/off", response_model=LookupResult)
def off_vergleich(
    product_id: int,
    db: Session = Depends(get_db),
    _: User = Depends(get_current_user),
) -> LookupResult:
    """Open Food Facts erneut befragen – auch für einen bereits angelegten Artikel.

    ``/lookup`` kann das nicht: Kennt es den Barcode schon, meldet es den eigenen
    Artikel und fragt OFF gar nicht erst. Zum Vergleichen braucht es aber genau
    die fremden Daten.

    Neben dem Haupt-Barcode werden die zusätzlichen EAN-Codes durchprobiert –
    oft ist nur einer davon bei OFF hinterlegt.
    """
    product = db.get(Product, product_id)
    if product is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Produkt nicht gefunden")

    codes = [product.barcode] if product.barcode else []
    codes += [
        b.code
        for b in db.query(Barcode).filter(Barcode.product_id == product_id).all()
        if b.code not in codes
    ]
    if not codes:
        raise HTTPException(
            status.HTTP_400_BAD_REQUEST,
            "Dieser Artikel hat keinen Barcode – ohne den kann Open Food Facts nichts finden.",
        )

    # Gegenstände zuerst in der allgemeinen Produkt-DB nachschlagen, Lebensmittel in OFF.
    prefer = "object" if product_tracking(db, product) == "object" else None
    for code in codes:
        suggestion = lookup_barcode(code, prefer=prefer)
        if suggestion:
            category = suggest_category(db, suggestion)
            return LookupResult(
                found=True,
                suggestion=suggestion,
                category_id=category.id if category else None,
                category_name=category.name if category else None,
            )
    return LookupResult(found=False)


@router.get("/{product_id}/image")
def get_product_image(
    product_id: int,
    db: Session = Depends(get_db),
    _: User = Depends(get_current_user),
) -> Response:
    """Artikelbild aus der eigenen Datenbank – nie von Open Food Facts.

    Anders als das Logo verlangt diese Route eine Anmeldung: Aus den Bildern
    liesse sich sonst ohne Konto ablesen, was im Vorrat liegt.
    """
    product = db.get(Product, product_id)
    if product is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Produkt nicht gefunden")

    bild = images.ensure(db, product)
    if bild is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Kein Bild vorhanden")
    return Response(
        content=bild.data,
        media_type=bild.content_type,
        headers={
            "Cache-Control": "private, max-age=300",
            "ETag": f'"bild-{product_id}-{int(bild.updated_at.timestamp())}"',
        },
    )


@router.put("/{product_id}/image", response_model=ProductOut)
async def upload_product_image(
    product_id: int,
    file: UploadFile = File(...),
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> ProductOut:
    """Eigenes Foto hochladen (Kamera oder Galerie) und beim Artikel ablegen.

    ``source_url = None`` markiert das Bild als selbst hochgeladen – so ersetzt
    es der Bildabgleich beim Speichern nicht durch ein Bild aus einer Adresse
    (solange keine Bildadresse gesetzt ist).
    """
    product = db.get(Product, product_id)
    if product is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Produkt nicht gefunden")
    if file.content_type not in images.ALLOWED_TYPES:
        erlaubt = ", ".join(sorted(t.split("/")[-1] for t in images.ALLOWED_TYPES))
        raise HTTPException(
            status.HTTP_400_BAD_REQUEST,
            f"Dieses Bildformat wird nicht unterstützt. Erlaubt sind: {erlaubt}.",
        )
    data = await file.read()
    if not data:
        raise HTTPException(status.HTTP_400_BAD_REQUEST, "Die Datei ist leer.")
    if len(data) > images.MAX_BYTES:
        raise HTTPException(
            status.HTTP_400_BAD_REQUEST,
            f"Das Bild ist zu groß ({len(data) // 1024} KB). "
            f"Erlaubt sind höchstens {images.MAX_BYTES // 1024} KB.",
        )
    bild = db.get(ProductImage, product.id)
    if bild is None:
        bild = ProductImage(
            product_id=product.id, content_type=file.content_type, data=data, source_url=None
        )
        db.add(bild)
    else:
        bild.content_type, bild.data, bild.source_url = file.content_type, data, None
    db.commit()
    db.refresh(product)
    return product_to_out(db, product)


@router.delete("/{product_id}/image", status_code=status.HTTP_204_NO_CONTENT)
def delete_product_image(
    product_id: int,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> None:
    """Foto entfernen. Eine gesetzte Bildadresse bleibt bestehen."""
    bild = db.get(ProductImage, product_id)
    if bild is not None:
        db.delete(bild)
        db.commit()


@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
    if payload.shop_id is not None and db.get(Shop, payload.shop_id) is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Shop nicht gefunden")
    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,
        date_precision=payload.date_precision.value,
        group_id=payload.group_id,
        category_id=payload.category_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),
        shop_id=payload.shop_id,
        product_url=payload.product_url or None,
        individual=bool(payload.individual),
        bulk=bool(payload.bulk),
        source="manual",
    )
    db.add(product)
    db.flush()                      # product.id fuer den Gruppen-Code
    sync_group_code(db, product)
    try:
        apply_field_values(db, product, payload.field_values)
    except FieldError as exc:
        raise HTTPException(status.HTTP_400_BAD_REQUEST, str(exc)) from exc
    if product.image_url:
        # Gleich beim Anlegen holen. Schlaegt es fehl, entsteht kein Fehler:
        # Ein fehlendes Bild darf das Anlegen eines Artikels nicht verhindern.
        images.store(db, product, product.image_url)
    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)
    # Feldwerte sind keine Spalte, sondern eigene Zeilen – getrennt behandeln.
    field_values = data.pop("field_values", None)
    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"
            )
    if data.get("shop_id") is not None and db.get(Shop, data["shop_id"]) is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Shop nicht gefunden")
    # 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
    if data.get("date_precision") is None:
        data.pop("date_precision", None)         # Spalte ist NOT NULL
    else:
        data["date_precision"] = data["date_precision"].value
    for field, value in data.items():
        setattr(product, field, value)
    if field_values is not None:
        try:
            apply_field_values(db, product, field_values)
        except FieldError as exc:
            raise HTTPException(status.HTTP_400_BAD_REQUEST, str(exc)) from exc
    # Gruppe oder Barcode koennen sich geaendert haben - Code nachziehen.
    sync_group_code(db, product)
    if "image_url" in data:
        # Massgeblich ist, woher die vorhandene Kopie stammt - nicht, ob sich
        # die Adresse am Artikel geaendert hat. Sonst passierte genau dann
        # nichts, wenn die Adresse schon stimmte, der Abruf damals aber
        # fehlschlug: Der Artikel bliebe dauerhaft ohne Bild.
        alt = db.get(ProductImage, product.id)
        if alt is not None and alt.source_url != product.image_url:
            db.delete(alt)
            db.flush()
            alt = None
        if alt is None and product.image_url:
            images.store(db, product, product.image_url)
    db.commit()
    db.refresh(product)
    return product_to_out(db, product)


@router.post("/{product_id}/barcodes", response_model=ProductOut, status_code=status.HTTP_201_CREATED)
def add_product_barcode(
    product_id: int,
    payload: BarcodeCreate,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> ProductOut:
    """Weiteren EAN-Code zu einem Produkt hinzufügen."""
    product = db.get(Product, product_id)
    if product is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Produkt 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), product_id=product.id))
    db.commit()
    db.refresh(product)
    return product_to_out(db, product)


@router.delete("/{product_id}/barcodes/{code}", status_code=status.HTTP_204_NO_CONTENT)
def delete_product_barcode(
    product_id: int,
    code: str,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> None:
    entry = (
        db.query(Barcode)
        .filter(Barcode.product_id == product_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("/{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")
    detach_group_code(db, product)
    db.delete(product)
    db.commit()