"""
数据库连接管理

SQLite 数据库，支持异步操作。
"""

from __future__ import annotations

from pathlib import Path
from typing import AsyncGenerator

from sqlalchemy import text
from sqlalchemy.ext.asyncio import (
    AsyncSession,
    async_sessionmaker,
    create_async_engine,
)

from app.config import settings

# ──────────────────────────── 数据库引擎 ────────────────────────────

DB_URL = settings.DATABASE_URL

# 解析 SQLite 文件路径
sqlite_path = DB_URL.replace("sqlite+aiosqlite:///", "")
if not sqlite_path.startswith("/"):
    sqlite_path = str(Path(__file__).parent.parent / sqlite_path)

# 确保数据目录存在
Path(sqlite_path).parent.mkdir(parents=True, exist_ok=True)

engine = create_async_engine(
    f"sqlite+aiosqlite:///{sqlite_path}",
    echo=False,
    pool_size=1,
    max_overflow=0,
)

# ──────────────────────────── 会话工厂 ────────────────────────────

async_session_factory = async_sessionmaker(
    bind=engine,
    class_=AsyncSession,
    expire_on_commit=False,
    autoflush=False,
)


# ──────────────────────────── 依赖注入 ────────────────────────────

async def get_db() -> AsyncGenerator[AsyncSession, None]:
    """
    FastAPI 依赖项：获取异步数据库会话。
    请求正常结束后自动 commit，异常时自动 rollback。
    """
    async with async_session_factory() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise


async def close_db() -> None:
    """关闭数据库连接池"""
    await engine.dispose()


async def init_db() -> None:
    """初始化数据库：建表"""
    from app.models.base import Base

    async with engine.begin() as conn:
        # SQLite 启用 WAL 模式和外键约束
        await conn.execute(text("PRAGMA journal_mode=WAL"))
        await conn.execute(text("PRAGMA foreign_keys=ON"))
        # 创建所有表
        await conn.run_sync(Base.metadata.create_all)