"""Verwaltung der selbst definierten Felder je Kategorie."""

import json

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 Category, FieldDefinition, FieldType, ProductFieldValue, User
from ..schemas import FieldDefinitionCreate, FieldDefinitionOut, FieldDefinitionUpdate
from ..services.fields import options_list, slugify

router = APIRouter(prefix="/field-definitions", tags=["field-definitions"])


def to_out(fd: FieldDefinition, inherited: bool = False) -> FieldDefinitionOut:
    return FieldDefinitionOut(
        id=fd.id,
        category_id=fd.category_id,
        label=fd.label,
        key=fd.key,
        field_type=FieldType(fd.field_type),
        unit=fd.unit,
        options=options_list(fd),
        required=fd.required,
        position=fd.position,
        is_builtin=fd.is_builtin,
        inherited=inherited,
    )


def _unique_key(db: Session, category_id: int, label: str, exclude_id: int | None = None) -> str:
    """Eindeutigen Schlüssel je Kategorie erzeugen (kapazitaet, kapazitaet_2, …)."""
    basis = slugify(label)
    kandidat = basis
    n = 1
    while True:
        query = db.query(FieldDefinition).filter(
            FieldDefinition.category_id == category_id, FieldDefinition.key == kandidat
        )
        if exclude_id is not None:
            query = query.filter(FieldDefinition.id != exclude_id)
        if query.first() is None:
            return kandidat
        n += 1
        kandidat = f"{basis}_{n}"


def _options_json(field_type: FieldType, options: list[str] | None) -> str | None:
    if field_type != FieldType.select:
        return None
    return json.dumps([o.strip() for o in (options or []) if o.strip()])


@router.get("", response_model=list[FieldDefinitionOut])
def list_field_definitions(
    category_id: int | None = None,
    db: Session = Depends(get_db),
    _: User = Depends(get_current_user),
) -> list[FieldDefinitionOut]:
    """Felder auflisten – ohne category_id alle, sonst nur die dieser Kategorie."""
    query = db.query(FieldDefinition)
    if category_id is not None:
        query = query.filter(FieldDefinition.category_id == category_id)
    rows = query.order_by(
        FieldDefinition.category_id, FieldDefinition.position, FieldDefinition.id
    ).all()
    return [to_out(fd) for fd in rows]


@router.post("", response_model=FieldDefinitionOut, status_code=status.HTTP_201_CREATED)
def create_field_definition(
    payload: FieldDefinitionCreate,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> FieldDefinitionOut:
    if db.get(Category, payload.category_id) is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Kategorie nicht gefunden")
    fd = FieldDefinition(
        category_id=payload.category_id,
        label=payload.label.strip(),
        key=_unique_key(db, payload.category_id, payload.label),
        field_type=payload.field_type.value,
        unit=(payload.unit or None),
        options=_options_json(payload.field_type, payload.options),
        required=bool(payload.required),
        position=payload.position,
    )
    db.add(fd)
    db.commit()
    db.refresh(fd)
    return to_out(fd)


@router.patch("/{field_id}", response_model=FieldDefinitionOut)
def update_field_definition(
    field_id: int,
    payload: FieldDefinitionUpdate,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> FieldDefinitionOut:
    fd = db.get(FieldDefinition, field_id)
    if fd is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Feld nicht gefunden")

    data = payload.model_dump(exclude_unset=True)
    if "label" in data and data["label"]:
        fd.label = data["label"].strip()
        fd.key = _unique_key(db, fd.category_id, fd.label, exclude_id=fd.id)
    if "field_type" in data and data["field_type"] is not None:
        fd.field_type = data["field_type"].value
    if "unit" in data:
        fd.unit = data["unit"] or None
    if "required" in data and data["required"] is not None:
        fd.required = bool(data["required"])
    if "position" in data and data["position"] is not None:
        fd.position = data["position"]
    # Optionen immer passend zum (ggf. neuen) Typ ablegen.
    if "options" in data or "field_type" in data:
        neuer_typ = FieldType(fd.field_type)
        optionen = data["options"] if "options" in data else options_list(fd)
        fd.options = _options_json(neuer_typ, optionen)
    db.commit()
    db.refresh(fd)
    return to_out(fd)


@router.delete("/{field_id}", status_code=status.HTTP_204_NO_CONTENT)
def delete_field_definition(
    field_id: int,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
) -> None:
    """Löscht das Feld samt aller dazu erfassten Werte (ON DELETE CASCADE)."""
    fd = db.get(FieldDefinition, field_id)
    if fd is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Feld nicht gefunden")
    db.query(ProductFieldValue).filter(
        ProductFieldValue.field_definition_id == field_id
    ).delete()
    db.delete(fd)
    db.commit()