"""
app/database.py
───────────────
SQLAlchemy synchronous engine, session factory, and declarative base.
"""
from __future__ import annotations

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

from app.config import settings

engine = create_engine(
    settings.DATABASE_URL,
    pool_pre_ping=True,   # recycle stale connections automatically
    pool_size=10,
    max_overflow=20,
)

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


class Base(DeclarativeBase):
    """Shared declarative base – all ORM models inherit from this."""
    pass


def get_db():
    """FastAPI dependency: yields a scoped DB session and guarantees closure."""
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()