"""
資料庫連線與 Session 管理
"""
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, Session, DeclarativeBase
from sqlalchemy.pool import QueuePool
from typing import Generator

from app.core.config import settings


# 建立引擎
# 建立引擎
connect_args = {}
if settings.database_url.startswith("sqlite"):
    connect_args["check_same_thread"] = False

engine = create_engine(
    settings.database_url,
    poolclass=QueuePool,
    pool_size=10,
    max_overflow=20,
    pool_pre_ping=True,
    echo=settings.debug,
    connect_args=connect_args
)

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


class Base(DeclarativeBase):
    """SQLAlchemy 基礎類別"""
    pass


def get_db() -> Generator[Session, None, None]:
    """取得資料庫 Session（依賴注入用）"""
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


def init_db() -> None:
    """初始化資料庫（建立所有表）"""
    from app.models import user, news, group, report, interaction, system
    Base.metadata.create_all(bind=engine)