from sqlalchemy import create_engine, event
from sqlalchemy.orm import DeclarativeBase, sessionmaker

from app.config import settings

engine = create_engine(settings.database_url, connect_args={"check_same_thread": False})


# SQLite: WAL-Modus, damit Reader (z.B. Backup-Export) nicht von gleichzeitigen
# Writern (Scheduler/Log) blockiert werden. busy_timeout sorgt dafür, dass kurze
# Lock-Konflikte automatisch retryen statt sofort zu failen.
if settings.database_url.startswith("sqlite"):
    @event.listens_for(engine, "connect")
    def _set_sqlite_pragmas(dbapi_connection, _):
        cursor = dbapi_connection.cursor()
        cursor.execute("PRAGMA journal_mode=WAL")
        cursor.execute("PRAGMA busy_timeout=10000")
        cursor.execute("PRAGMA synchronous=NORMAL")
        cursor.close()


SessionLocal = sessionmaker(bind=engine)


class Base(DeclarativeBase):
    pass


def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()