from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from app.config import settings
import logging

logger = logging.getLogger(__name__)

# Create SQLAlchemy engine with better error handling
try:
    engine = create_engine(
        settings.DATABASE_URL,
        pool_pre_ping=True,  # Verify connections before using
        pool_size=5,
        max_overflow=10,
        pool_recycle=3600,  # Recycle connections after 1 hour
        echo=settings.DEBUG,  # Log SQL queries in debug mode
        connect_args={
            "connect_timeout": 10,  # Connection timeout in seconds
        }
    )
    logger.info("Database engine created successfully")
except Exception as e:
    logger.error(f"Failed to create database engine: {e}")
    raise

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

# Base class for models
Base = declarative_base()


# Dependency for FastAPI endpoints
def get_db():
    """
    Database session dependency.
    Usage: db: Session = Depends(get_db)
    """
    db = SessionLocal()
    try:
        yield db
    except Exception as e:
        logger.error(f"Database session error: {e}")
        db.rollback()
        raise
    finally:
        db.close()