"""Database engine and session setup.

The connection string comes from the DATABASE_URL environment variable, e.g.
    postgresql+psycopg://wpsuite:secret@db-host:5432/wpsuite

If unset, it falls back to a local SQLite file so the API can be run and tested
on any machine without Postgres. The schema is identical either way (SQLAlchemy
handles the dialect differences).
"""
import os
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, DeclarativeBase

# Load a local .env if present (dev convenience). In production the DATABASE_URL
# normally comes from the systemd unit's Environment / EnvironmentFile instead.
try:
    from dotenv import load_dotenv
    load_dotenv()
except Exception:
    pass

DATABASE_URL = os.getenv("DATABASE_URL", "sqlite:///./wpsuite.db")

# SQLite needs this flag to be used from FastAPI's threadpool; Postgres ignores it.
connect_args = {"check_same_thread": False} if DATABASE_URL.startswith("sqlite") else {}

engine = create_engine(DATABASE_URL, connect_args=connect_args, pool_pre_ping=True, future=True)
SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False, future=True)


class Base(DeclarativeBase):
    pass


def get_db():
    """FastAPI dependency that yields a session and always closes it."""
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()