"""
Database connection setup using SQLAlchemy.
The schema is managed by dbt — the backend only reads from marts.* tables.
"""

from contextlib import contextmanager

from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, declarative_base

from .config import settings

engine = create_engine(
    settings.database_url,
    pool_size=10,
    max_overflow=20,
    pool_pre_ping=True,
    echo=False,
)

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

Base = declarative_base()


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


@contextmanager
def get_db_session():
    """Context manager for non-FastAPI contexts."""
    db = SessionLocal()
    try:
        yield db
        db.commit()
    except Exception:
        db.rollback()
        raise
    finally:
        db.close()