"""
Database configuration and session management.
Provides SQLAlchemy engine and session factory.
"""
from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

from app.config import settings

# Create SQLAlchemy engine
engine = create_engine(
    settings.database_url,
    pool_pre_ping=True,  # Enable connection health checks
    pool_size=10,
    max_overflow=20
)

# Create session factory
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

# Base class for SQLAlchemy models
Base = declarative_base()


def get_db():
    """
    Dependency function that provides a database session.
    Automatically closes the session after the request is completed.

    Yields:
        Session: SQLAlchemy database session
    """
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()