xiaoxia-saas/packages/middleware/points_gate.py

"""AI 功能入口的积分扣费装饰器 (#1895)

支持 sync 和 async 函数。业务失败时自动退还积分。
"""

from __future__ import annotations

import asyncio
import functools
import inspect
import logging
from collections.abc import Callable
from typing import Any

from fastapi import HTTPException

logger = logging.getLogger(__name__)


def _points_gate_enabled() -> bool:
    """读取配置开关：总开关关闭时装饰器完全放行（零开销/零副作用）。

    放在模块顶层便于测试时 monkeypatch。
    """
    try:
        from app.config import settings as _settings

        return bool(_settings.points_enabled)
    except Exception:  # pragma: no cover - 配置加载失败默认关闭
        return False


def points_gate(
    scene_key: str,
    per_unit: int | None = None,
    unit_field: str | None = None,
    quantity_field: str | None = None,
) -> Callable:
    """AI 功能入口积分扣费装饰器。

    当 POINTS_ENABLED=false（默认）时，装饰器完全透传原函数，零副作用。
    开启后才会执行扣费逻辑：业务异常自动退费，积分不足返回 402。

    Args:
        scene_key: 消耗场景标识（对应 points_rules.POINTS_SCENES 的 key）
        per_unit: 固定消耗积分（直接指定，不走规则计算）
        unit_field: 从 request body 取时长字段名（按时长计费场景）
        quantity_field: 从 request body 取数量字段名（按次计费场景）

    使用示例::

        @router.post("/ai/voice")
        @points_gate("ai_voice", unit_field="duration_minutes")
        async def create_ai_voice(body: VoiceRequest, current_user=Depends(get_current_user), db=Depends(get_db_session)):
            ...
    """

    def decorator(func: Callable) -> Callable:
        is_async = asyncio.iscoroutinefunction(func)

        @functools.wraps(func)
        async def async_wrapper(*args: Any, **kwargs: Any) -> Any:
            if not _points_gate_enabled():
                return await func(*args, **kwargs)
            return await _execute_with_gate(
                func, args, kwargs, scene_key, per_unit, unit_field, quantity_field, is_async=True
            )

        @functools.wraps(func)
        def sync_wrapper(*args: Any, **kwargs: Any) -> Any:
            if not _points_gate_enabled():
                return func(*args, **kwargs)
            return _execute_with_gate(
                func, args, kwargs, scene_key, per_unit, unit_field, quantity_field, is_async=False
            )

        if is_async:
            return async_wrapper
        return sync_wrapper

    return decorator


def _extract_kwargs(func: Callable, args: tuple, kwargs: dict) -> dict:
    """将位置参数映射到函数签名中的参数名，便于统一按 kwargs 提取。"""
    sig = inspect.signature(func)
    bound = sig.bind_partial(*args, **kwargs)
    merged = dict(bound.arguments)
    merged.update(kwargs)
    return merged


def _execute_with_gate(
    func: Callable,
    args: tuple,
    kwargs: dict,
    scene_key: str,
    per_unit: int | None,
    unit_field: str | None,
    quantity_field: str | None,
    is_async: bool,
) -> Any:
    """积分扣费核心逻辑。"""
    merged = _extract_kwargs(func, args, kwargs)

    # 提取 current_user
    current_user = merged.get("current_user")
    if current_user is None:
        # 尝试从位置参数中找
        for arg in args:
            if hasattr(arg, "user"):
                current_user = arg
                break
    if not current_user:
        raise HTTPException(status_code=401, detail="未登录")

    # 提取 db session
    db = merged.get("db")
    if db is None:
        raise HTTPException(status_code=500, detail="缺少数据库 session")

    user = current_user.user
    is_member = getattr(user, "is_member", False)
    member_type = getattr(user, "member_type", None)

    # ── 混剪场景：先检查免费额度 ──
    if scene_key == "ai_video":
        from packages.domain.points_service import PointsService

        svc = PointsService()
        if not is_member:
            if svc.check_daily_free_clip(user.id, db):
                svc.record_daily_free_clip(user.id, db)
                kwargs["_points_deducted"] = 0
                kwargs["_is_free_quota"] = True
                if is_async:
                    return _run_async(func, args, kwargs)
                return func(*args, **kwargs)

    # ── 计算积分消耗 ──
    if per_unit is not None:
        total_points = per_unit
    else:
        from packages.domain.points_rules import calculate_points_cost

        quantity = 1
        duration = 0.0
        request_body = merged.get("body") or merged.get("request") or merged.get("payload")
        if request_body and unit_field:
            duration = float(getattr(request_body, unit_field, 0) or 0)
        if request_body and quantity_field:
            quantity = int(getattr(request_body, quantity_field, 1) or 1)

        total_points = calculate_points_cost(
            scene_key,
            is_member,
            quantity=quantity,
            duration_minutes=duration,
            member_type=member_type,
        )

    # 零消耗场景（如免费的声音克隆训练）直接放行
    if total_points == 0:
        kwargs["_points_deducted"] = 0
        if is_async:
            return _run_async(func, args, kwargs)
        return func(*args, **kwargs)

    # ── 扣减积分 ──
    from packages.domain.points_service import PointsService

    svc = PointsService()
    job_id = merged.get("job_id", "") or ""
    result = svc.deduct_points(user.id, total_points, scene_key, db, ref_id=str(job_id))

    if not result["success"]:
        raise HTTPException(
            status_code=402,
            detail={
                "code": "INSUFFICIENT_POINTS",
                "message": f"积分不足，需要 {total_points} 积分，当前余额 {result['balance']}",
                "required": total_points,
                "balance": result["balance"],
            },
        )

    kwargs["_points_deducted"] = total_points
    kwargs["_points_transaction_id"] = result["transaction_id"]

    # ── 执行业务函数，失败则退还积分 ──
    try:
        if is_async:
            return _run_async(func, args, kwargs)
        return func(*args, **kwargs)
    except Exception:
        svc.refund_points(user.id, total_points, scene_key, db, ref_id=str(job_id))
        raise


def _run_async(func: Callable, args: tuple, kwargs: dict):
    """在 async wrapper 中 await 原始 async 函数。"""
    return func(*args, **kwargs)