"""
Database connection setup using SQLAlchemy.
"""

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

from .config import settings

# Create engine
engine = create_engine(
    settings.database_url,
    pool_size=10,
    max_overflow=20,
    pool_pre_ping=True,  # Verify connections before use
    echo=False,  # Set to True for SQL debugging
)

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

# Base class for models
Base = declarative_base()


def get_db():
    """
    Dependency for FastAPI routes to get a database session.
    """
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


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


def init_db():
    """
    Initialize database - create all tables.
    """
    Base.metadata.create_all(bind=engine)


def drop_db():
    """
    Drop all tables - use with caution!
    """
    Base.metadata.drop_all(bind=engine)