The SMS sending functionality is refactored using the Singleton pattern to ensure the REST SDK is initialized only once. The sms.py module wraps the cloud communication SDK:

# -*- coding: utf-8 -*-

import logging
from CCPRestSDK import REST

# Credentials and configuration
ACCOUNT_SID = '8aaf07085f9eb021015fb58c56d906e8'
ACCOUNT_TOKEN = 'e21ca96da61c49ee97e0fdf1ba47de5a'
APP_ID = '8aaf07085f9eb021015fb58c574106ef'
SERVER_IP = 'app.cloopen.com'
SERVER_PORT = '8883'
SDK_VERSION = '2013-12-26'


class SMSManager:
    """Singleton wrapper for cloud communication REST SDK."""
    _instance = None

    def __new__(cls):
        if cls._instance is None:
            instance = super().__new__(cls)
            instance.sdk = REST(SERVER_IP, SERVER_PORT, SDK_VERSION)
            instance.sdk.setAccount(ACCOUNT_SID, ACCOUNT_TOKEN)
            instance.sdk.setAppId(APP_ID)
            cls._instance = instance
        return cls._instance

    def dispatch_template_message(self, phone_number, payload, template_id):
        """Send a template-based SMS and return 0 on success, -1 on failure."""
        try:
            response = self.sdk.sendTemplateSMS(phone_number, payload, template_id)
        except Exception as exc:
            logging.error(exc)
            raise

        logging.debug(response)
        return 0 if response.get('statusCode') == '000000' else -1


if __name__ == '__main__':
    sender = SMSManager()
    status = sender.dispatch_template_message('17610812003', ['1234', 5], 1)
    print('Dispatch result:', status)

A response_code.py file defines standardized response codes and messages:

# -*- coding: utf-8 -*-


class StatusCode:
    SUCCESS = '0'
    DB_ERROR = '4001'
    NO_RECORD = '4002'
    RECORD_EXISTS = '4003'
    INVALID_DATA = '4004'
    SESSION_MISSING = '4101'
    AUTH_FAIL = '4102'
    BAD_PARAM = '4103'
    USER_MISSING = '4104'
    ROLE_ISSUE = '4105'
    WRONG_PASSWORD = '4106'
    BAD_REQUEST = '4201'
    IP_BLOCKED = '4202'
    THIRD_PARTY_FAIL = '4301'
    IO_FAIL = '4302'
    INTERNAL_ERROR = '4500'
    UNKNOWN = '4501'


message_map = {
    StatusCode.SUCCESS: u'Success',
    StatusCode.DB_ERROR: u'Database query error',
    StatusCode.NO_RECORD: u'No data found',
    StatusCode.RECORD_EXISTS: u'Data already exists',
    StatusCode.INVALID_DATA: u'Invalid data',
    StatusCode.SESSION_MISSING: u'User not logged in',
    StatusCode.AUTH_FAIL: u'Login failed',
    StatusCode.BAD_PARAM: u'Parameter error',
    StatusCode.USER_MISSING: u'User does not exist or is inactive',
    StatusCode.ROLE_ISSUE: u'Incorrect user role',
    StatusCode.WRONG_PASSWORD: u'Wrong password',
    StatusCode.BAD_REQUEST: u'Illegal request or rate limit exceeded',
    StatusCode.IP_BLOCKED: u'IP restricted',
    StatusCode.THIRD_PARTY_FAIL: u'Third-party service error',
    StatusCode.IO_FAIL: u'File read/write error',
    StatusCode.INTERNAL_ERROR: u'Internal server error',
    StatusCode.UNKNOWN: u'Unknown error',
}

The API endpoint for sending a verificatoin code is implemented in api_1_0/verify_code.py:

from flask import request, jsonify
from api_1_0 import api
from models import User
from sms import SMSManager
from redis_client import redis_store
from constants import SMS_CODE_REDIS_EXPIRES
import random
import logging


@api.route('/sms_codes/<regex("1[34578]\d{9}"):mobile>')
def send_verification_code(mobile):
    input_image_code = request.args.get('image_code')
    image_uuid = request.args.get('image_code_id')

    if not all([input_image_code, image_uuid]):
        return jsonify(errno=StatusCode.BAD_PARAM, errmsg='Incomplete parameters')

    try:
        stored_code = redis_store.get('image_code_' + image_uuid)
    except Exception as exc:
        logging.error(exc)
        return jsonify(errno=StatusCode.DB_ERROR, errmsg='Failed to retrieve image code')

    if stored_code is None:
        return jsonify(errno=StatusCode.NO_RECORD, errmsg='Image code expired or invalid')

    try:
        redis_store.delete('image_code_' + image_uuid)
    except Exception as exc:
        logging.error(exc)

    if stored_code.lower() != input_image_code.lower():
        return jsonify(errno=StatusCode.INVALID_DATA, errmsg='Incorrect image code')

    try:
        existing_user = User.query.filter_by(mobile=mobile).first()
    except Exception as exc:
        logging.error(exc)
    else:
        if existing_user:
            return jsonify(errno=StatusCode.RECORD_EXISTS, errmsg='Mobile already registered')

    verification_code = '%06d' % random.randint(0, 999999)

    try:
        redis_store.setex('sms_code_' + mobile, SMS_CODE_REDIS_EXPIRES, verification_code)
    except Exception as exc:
        logging.error(exc)
        return jsonify(errno=StatusCode.DB_ERROR, errmsg='Failed to save verification code')

    try:
        sms_service = SMSManager()
        result = sms_service.dispatch_template_message(
            mobile,
            [verification_code, SMS_CODE_REDIS_EXPIRES // 60],
            1
        )
    except Exception as exc:
        logging.error(exc)
        return jsonify(errno=StatusCode.THIRD_PARTY_FAIL, errmsg='SMS dispatch failed')

    if result == 0:
        return jsonify(errno=StatusCode.SUCCESS, errmsg='SMS sent successfully')
    return jsonify(errno=StatusCode.THIRD_PARTY_FAIL, errmsg='SMS sending failed')

The frontend handles the API response and manages a countdown timer:

var requestData = {
    image_code_id: imageCodeId,
    image_code: imageCode
};

$.get('/api/v1_0/sms_codes/' + mobile, requestData, function (response) {
    if (response.errno === '4004' || response.errno === '4002') {
        $('#image-code-err span').html(response.errmsg);
        $('#image-code-err').show();
        $('.phonecode-a').attr('onclick', 'sendSMSCode();');
    } else if (response.errno === '0') {
        var button = $('.phonecode-a');
        var seconds = 60;
        var timer = setInterval(function () {
            button.html(seconds + ' seconds');
            if (seconds === 1) {
                clearInterval(timer);
                button.html('Get code');
                $('.phonecode-a').attr('onclick', 'sendSMSCode();');
            }
            seconds -= 1;
        }, 1000);
    } else {
        alert(response.errmsg);
    }
});