"""数据库引擎、会话工厂、初始化。"""

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

from app.config import settings


class Base(DeclarativeBase):
    pass


def _make_engine():
    """创建 SQLite 引擎，启用 foreign_keys。"""
    engine = create_engine(
        settings.DATABASE_URL,
        echo=settings.APP_DEBUG,
        connect_args={"check_same_thread": False},
    )

    @event.listens_for(engine, "connect")
    def _set_sqlite_pragma(dbapi_connection, _connection_record):
        cursor = dbapi_connection.cursor()
        cursor.execute("PRAGMA foreign_keys=ON")
        cursor.execute("PRAGMA journal_mode=WAL")
        cursor.close()

    return engine


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


def get_db():
    """FastAPI 依赖注入：获取数据库会话。"""
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()