import random
import string
import logging
from abc import ABC, abstractmethod

from django.conf import settings

logger = logging.getLogger(__name__)


def generate_sms_code(length=6) -> str:
    return ''.join(random.choices(string.digits, k=length))


# ── 策略接口 ──────────────────────────────────────────────────────────────────

class SmsService(ABC):
    @abstractmethod
    def send_code(self, phone: str, scene: str, code: str) -> None:
        """发送验证码短信。失败时抛出 SmsError。"""


class SmsError(Exception):
    pass


def get_sms_service() -> SmsService:
    provider = getattr(settings, 'SMS_PROVIDER', 'mock')
    if provider == 'aliyun':
        from apps.user.utils.sms_aliyun import AliyunSmsService
        return AliyunSmsService()
    from apps.user.utils.sms_mock import MockSmsService
    return MockSmsService()