from django.contrib.auth import get_user_model
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework.permissions import AllowAny, IsAdminUser
from rest_framework.throttling import ScopedRateThrottle
from rest_framework_simplejwt.views import TokenObtainPairView, TokenRefreshView


def _ok(data, message="ok"):
    return Response({"code": 200, "data": data, "message": message})


class _EnvelopeMixin:
    """错误信封统一收口（Task7 同款裁剪，无 ACAO——管理台与 API 同源，跨域由 nginx 层面不存在）。

    simplejwt 认证失败 401 / 权限 403 / 限流 429 等由 DRF 异常处理器产出的响应
    body 是 {detail}，管理台前端（Task17）按 {code,data,message} 信封对接——
    在此统一转换，视图自身的 _ok/4xx 响应不受影响（只动含 detail 的 dict）。
    """

    def finalize_response(self, request, response, *args, **kwargs):
        response = super().finalize_response(request, response, *args, **kwargs)
        if response.status_code >= 400 and isinstance(response.data, dict) and "detail" in response.data:
            response.data = {"code": response.status_code, "data": None,
                             "message": response.data["detail"]}
        return response


class LoginView(_EnvelopeMixin, TokenObtainPairView):
    """登录。JWT 取舍（M1 决策）：access 12h / refresh 24h、无黑名单轮换——
    token 泄露唯一应急是换 SECRET_KEY（全体登出），README-deploy 写明。"""
    throttle_classes = [ScopedRateThrottle]
    throttle_scope = "login"          # 10/min/IP 防爆破（settings 已配）

    def post(self, request, *args, **kwargs):
        resp = super().post(request, *args, **kwargs)   # 失败由 simplejwt 返回 401（信封由 mixin 补）
        if resp.status_code == 200:
            return _ok({"access": resp.data["access"], "refresh": resp.data["refresh"]})
        return resp


class RefreshView(_EnvelopeMixin, TokenRefreshView):
    permission_classes = [AllowAny]   # TokenRefreshView 自带 AllowAny，显式声明表意

    def post(self, request, *args, **kwargs):
        resp = super().post(request, *args, **kwargs)
        if resp.status_code == 200:   # 成功同样走信封——与 LoginView 对齐，前端只需一种解析路径
            return _ok({"access": resp.data["access"]})
        return resp


class MeView(_EnvelopeMixin, APIView):
    def get(self, request):
        return _ok({"username": request.user.username,
                    "is_admin": request.user.is_staff})


class UserCreateView(_EnvelopeMixin, APIView):
    permission_classes = [IsAdminUser]    # is_staff

    def post(self, request):
        username = (request.data.get("username") or "").strip()
        password = request.data.get("password") or ""
        # 用户名长度上限对齐 Django User.username(max_length=150)——create_user 不跑
        # full_clean，超长会直奔 MySQL DataError 500，故入口拦截
        if not username or len(username) > 150 or len(password) < 8:
            return Response({"code": 400, "data": None, "message": "invalid_input"}, status=400)
        User = get_user_model()
        if User.objects.filter(username=username).exists():
            return Response({"code": 409, "data": None, "message": "username_exists"}, status=409)
        User.objects.create_user(username=username, password=password, is_staff=False)
        return _ok({"username": username}, "created")