"""Shared CRUD skeleton for id-keyed entity repositories."""

from typing import Generic, Optional, TypeVar

from sqlmodel import Session, select

from agenteval.storage.db import get_session

M = TypeVar("M")  # domain model
DB = TypeVar("DB")  # persisted table row


class BaseRepository(Generic[M, DB]):
    """Shared CRUD skeleton for id-keyed entity repositories.

    Subclasses declare the table (``_table``) and the ``list_all`` ordering
    column name (``_order_by``, newest-first), and implement the ``_to_db`` /
    ``_from_db`` converter pair. The converters are instance methods so a
    subclass whose ``_from_db`` needs cross-table reads (e.g. Scenario's model
    bindings) can reach ``self.session``. Entities with bespoke create/update
    (binding validation, versioning) override just those methods.
    """

    _table: type
    _order_by: str

    def __init__(self, session: Optional[Session] = None):
        self.session = session or get_session()

    def _to_db(self, obj: M) -> DB:
        raise NotImplementedError

    def _from_db(self, db: DB) -> M:
        raise NotImplementedError

    def list_all(self) -> list[M]:
        column = getattr(self._table, self._order_by)
        statement = select(self._table).order_by(column.desc())
        return [self._from_db(r) for r in self.session.exec(statement).all()]

    def get(self, entity_id: str) -> Optional[M]:
        db = self.session.get(self._table, entity_id)
        return self._from_db(db) if db else None

    def create(self, obj: M) -> M:
        db = self._to_db(obj)
        self.session.add(db)
        self.session.commit()
        self.session.refresh(db)
        return self._from_db(db)

    def delete(self, entity_id: str) -> bool:
        db = self.session.get(self._table, entity_id)
        if not db:
            return False
        self.session.delete(db)
        self.session.commit()
        return True