"""P0-3 · 公开注册：建租户 + 建用户 + owner membership + free 订阅 + JWT。

POST /api/v1/auth/register/（AllowAny，已进 TenantMiddleware 白名单）：
入参 username / password / company_name /（可选）phone。
租户 code 由公司名 slug 化，冲突加数字后缀；非法 slug → 400。
密码最低 8 位；用户名已存在 → 400。
事务内：Tenant → User → TenantMembership(owner) → billing.subscribe(free)。
返回 JWT（access + refresh），免二次登录。
防滥用：同 IP 限速 10 次/小时（复用 core.ratelimit 的 cache 计数器）。
"""

import re

from adrf.decorators import api_view
from django.db import transaction
from django.utils.text import slugify
from rest_framework import status
from rest_framework.decorators import authentication_classes, permission_classes
from rest_framework.exceptions import ValidationError
from rest_framework.permissions import AllowAny
from rest_framework.response import Response
from rest_framework_simplejwt.tokens import RefreshToken

REGISTER_IP_LIMIT = 10
REGISTER_IP_WINDOW = 3600


def _tenant_code_for(company_name: str) -> str:
    base = slugify(company_name, allow_unicode=False) or ""
    base = re.sub(r"[^a-z0-9-]", "", base.lower())[:50].strip("-")
    if not base:
        raise ValidationError({"company_name": "公司名称无法生成有效的租户编码，请换一个名称"})
    from apps.core.models import Tenant

    code, i = base, 0
    while Tenant.objects.filter(code=code).exists():
        i += 1
        code = f"{base}-{i}"[:64]
    return code


@api_view(["POST"])
@authentication_classes([])
@permission_classes([AllowAny])
def register(request):
    from django.core.cache import cache

    from apps.core import ratelimit as rl

    ip = rl.client_ip(request)
    ip_key = f"dealerhub:register-ip:{ip}"
    if int(cache.get(ip_key) or 0) >= REGISTER_IP_LIMIT:
        return Response(
            {"code": "register_throttled", "detail": "同一 IP 注册过于频繁，请 1 小时后再试"},
            status=status.HTTP_429_TOO_MANY_REQUESTS,
        )

    payload = request.data or {}
    username = (payload.get("username") or "").strip()
    password = payload.get("password") or ""
    company_name = (payload.get("company_name") or "").strip()
    phone = (payload.get("phone") or "").strip()

    if not username or not password or not company_name:
        raise ValidationError({"detail": "username / password / company_name 均为必填"})
    if len(password) < 8:
        raise ValidationError({"password": "密码长度至少 8 位"})
    if len(username) > 150:
        raise ValidationError({"username": "用户名过长（最多 150 字符）"})

    from django.contrib.auth import get_user_model

    User = get_user_model()
    if User.objects.filter(username=username).exists():
        raise ValidationError({"username": "该用户名已被注册"})

    code = _tenant_code_for(company_name)

    from apps.core.models import Tenant, TenantMembership

    with transaction.atomic():
        tenant = Tenant.objects.create(code=code, name=company_name, phone=phone)
        user = User.objects.create_user(username=username, password=password)
        TenantMembership.objects.create(
            user=user, tenant=tenant, role="owner", is_active=True,
        )
        try:
            from apps.billing.models import subscribe

            subscribe(tenant, plan_code="free")
        except Exception:
            pass

    try:
        cache.incr(ip_key)
    except ValueError:
        cache.set(ip_key, 1, REGISTER_IP_WINDOW)

    refresh = RefreshToken.for_user(user)
    return Response({
        "access": str(refresh.access_token),
        "refresh": str(refresh),
        "tenant": tenant.code,
        "username": user.username,
    }, status=status.HTTP_201_CREATED)