"""Database connection and session management (SQLite + SQLAlchemy)."""
from sqlalchemy import create_engine, event
from sqlalchemy.orm import sessionmaker, declarative_base

from .config import DATABASE_URL

# SQLite engine (check_same_thread=False for FastAPI async)
engine = create_engine(
    DATABASE_URL,
    connect_args={"check_same_thread": False},
    echo=False,
)

# F2 fix: enable foreign key constraints for SQLite (OFF by default)
@event.listens_for(engine, "connect")
def _set_sqlite_pragma(dbapi_connection, connection_record):
    cursor = dbapi_connection.cursor()
    cursor.execute("PRAGMA foreign_keys=ON")
    cursor.close()

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


def get_db():
    """Dependency for FastAPI route database sessions."""
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


def init_db():
    """Create all database tables."""
    from . import models  # noqa: F401 - ensure models are imported
    Base.metadata.create_all(bind=engine)