import re

from django.core.cache import cache
from django.conf import settings
from rest_framework.decorators import api_view, permission_classes, throttle_classes
from rest_framework.permissions import AllowAny
from rest_framework.response import Response
from rest_framework import serializers as drf_serializers
from drf_spectacular.utils import extend_schema, inline_serializer

from config.exceptions import AppError
from apps.user.models import User
from apps.user.throttling import SmsPhoneMinuteThrottle, SmsPhoneDayThrottle, SmsIpThrottle
from apps.user.utils.sms import generate_sms_code, get_sms_service, SmsError


@extend_schema(
    summary='U1 发送短信验证码',
    request=inline_serializer('SendCodeRequest', fields={
        'phone': drf_serializers.CharField(help_text='手机号'),
        'scene': drf_serializers.ChoiceField(choices=['register', 'login', 'reset'],
                                             help_text='场景：register/login/reset'),
    }),
    responses={200: inline_serializer('SendCodeResponse', fields={
        'message': drf_serializers.CharField(),
    })},
    tags=['认证'],
)
@api_view(['POST'])
@permission_classes([AllowAny])
@throttle_classes([SmsPhoneMinuteThrottle, SmsPhoneDayThrottle, SmsIpThrottle])
def send_code(request):
    """U1 发送短信验证码"""
    data = request.data
    phone = data.get('phone', '')
    scene = data.get('scene', '')

    if not re.match(r'^1[3-9]\d{9}$', str(phone)):
        raise AppError('SMS_INVALID_PHONE', '手机号格式不合法')

    if scene not in ('register', 'login', 'reset'):
        raise AppError('SMS_INVALID_SCENE', 'scene 参数无效，仅允许 register / login / reset')

    user_exists = User.objects.filter(phone=phone).exists()
    if scene == 'register' and user_exists:
        raise AppError('AUTH_PHONE_REGISTERED', '该手机号已注册')
    if scene in ('login', 'reset') and not user_exists:
        raise AppError('AUTH_PHONE_NOT_FOUND', '手机号未注册')

    code = generate_sms_code()
    cache_key = f'sms:{scene}:{phone}'
    cache.set(cache_key, code, timeout=settings.SMS_CODE_EXPIRE)

    try:
        get_sms_service().send_code(phone, scene, code)
    except SmsError as e:
        cache.delete(cache_key)
        err_code = str(e) if str(e) in ('SMS_BIZ_ERROR',) else 'SMS_PROVIDER_ERROR'
        raise AppError(err_code, '短信发送失败，请稍后重试', status_code=500)

    return Response({'message': '验证码已发送'})