import logging
from typing import Protocol

import requests
from django.conf import settings
from django.utils.module_loading import import_string

logger = logging.getLogger(__name__)


class SMSError(Exception):
    pass


class SMSBackend(Protocol):
    def send_otp(self, phone_number: str, code: str) -> None: ...


class ConsoleSMSBackend:
    """Dev backend — logs the OTP instead of sending. Never use in production."""

    def send_otp(self, phone_number: str, code: str) -> None:
        logger.warning("[SMS-CONSOLE] OTP for %s: %s", phone_number, code)


class SMSIRBackend:
    """sms.ir template-based OTP via /v1/send/verify."""

    def __init__(self):
        self.api_key = settings.SMSIR_API_KEY
        self.template_id = settings.SMSIR_TEMPLATE_ID
        self.param_name = settings.SMSIR_TEMPLATE_PARAM_NAME
        self.base_url = settings.SMSIR_BASE_URL.rstrip("/")
        self.timeout = 15
        if not self.api_key:
            raise SMSError("SMSIR_API_KEY is not configured")
        if not self.template_id:
            raise SMSError("SMSIR_TEMPLATE_ID is not configured")

    def send_otp(self, phone_number: str, code: str) -> None:
        url = f"{self.base_url}/v1/send/verify"
        headers = {"x-api-key": self.api_key, "Content-Type": "application/json"}
        payload = {
            "mobile": phone_number,
            "templateId": int(self.template_id),
            "parameters": [{"name": self.param_name, "value": str(code)}],
        }
        try:
            resp = requests.post(url, json=payload, headers=headers, timeout=self.timeout)
        except requests.RequestException as e:
            raise SMSError(f"SMS network error: {e}") from e

        try:
            data = resp.json()
        except ValueError as e:
            raise SMSError(f"SMS non-JSON response (HTTP {resp.status_code})") from e

        if not (200 <= resp.status_code < 300) or data.get("status") != 1:
            msg = data.get("message") or f"HTTP {resp.status_code}"
            raise SMSError(f"sms.ir error: {msg}")

        logger.info("OTP delivered to %s via sms.ir template %s", phone_number, self.template_id)


_DEFAULT_BACKEND = "apps.accounts.services.sms.ConsoleSMSBackend"


def get_sms_backend() -> SMSBackend:
    backend_path = getattr(settings, "SMS_BACKEND", _DEFAULT_BACKEND)
    return import_string(backend_path)()