"""Database engine, session, and base model."""
from sqlalchemy import create_engine, event
from sqlalchemy.orm import sessionmaker, DeclarativeBase
from app.config import settings


# Engine
if settings.DATABASE_URL.startswith("sqlite"):
    engine = create_engine(
        settings.DATABASE_URL,
        connect_args={"check_same_thread": False},
        echo=False,
    )
    # Enable foreign keys for SQLite
    @event.listens_for(engine, "connect")
    def _fk_pragma_on_connect(dbapi_con, con_record):
        cursor = dbapi_con.cursor()
        cursor.execute("PRAGMA foreign_keys=ON")
        cursor.close()
else:
    engine = create_engine(settings.DATABASE_URL, echo=False, pool_pre_ping=True)

SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)


class Base(DeclarativeBase):
    """Declarative base for all models."""
    pass


def get_db():
    """FastAPI dependency: yields a database session."""
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


def init_db():
    """Create all tables (used for dev / first run)."""
    Base.metadata.create_all(bind=engine)