rn-sms-reader/lib/module/index.js

This package reads Android text messages.

import { NativeModules, NativeEventEmitter, Platform, PermissionsAndroid } from 'react-native';

/**
 * Error message displayed when the package 'rn-sms-reader' is not linked.
 * Instructions for linking are provided based on the platform.
 */
const ERROR_MESSAGE = `The package 'rn-sms-reader' doesn't seem to be linked. Make sure: \n\n` + Platform.select({
  ios: "- You have run 'pod install'\n",
  default: ''
}) + '- You rebuilt the app after installing the package\n' + '- You are not using Expo Go';

/**
 * Access the RnSmsReader module or throw an error if not linked.
 */
const RnSmsReader = NativeModules.RnSmsReader ? NativeModules.RnSmsReader : new Proxy({}, {
  get() {
    throw new Error(ERROR_MESSAGE);
  }
});

/**
 * Define SMS permissions for checking and requesting.
 */
const receiveSmsPermission = PermissionsAndroid.PERMISSIONS.RECEIVE_SMS;
const readSmsPermission = PermissionsAndroid.PERMISSIONS.READ_SMS;

/**
 * Extracts OTP from SMS text using a regular expression.
 * @param text - SMS text from which OTP is to be extracted.
 * @param otpLength - Length of the OTP to be extracted.
 * @returns Extracted OTP or null if not found.
 */
const extractOtpFromText = (text, otpLength) => {
  const regex = new RegExp(`\\b\\d{${otpLength}}\\b`);
  const match = text.match(regex);
  return match ? match[0] : null;
};

/**
 * RnSmsService provides functions to check, request SMS permissions,
 * and fetch SMS messages to extract OTP.
 */
const RnSmsService = {
  /**
   * Checks if SMS permissions are already granted.
   * @returns A Promise that resolves to true if both permissions are granted, false otherwise.
   */
  checkingSmsPermission: async () => {
    const receiveSmsGranted = await PermissionsAndroid.check(receiveSmsPermission);
    const readSmsGranted = await PermissionsAndroid.check(readSmsPermission);
    return receiveSmsGranted && readSmsGranted;
  },
  /**
   * Requests SMS permissions and returns a Promise indicating success.
   * @returns A Promise that resolves to true if permissions are granted, false otherwise.
   */
  requestSmsPermission: async () => {
    try {
      const checkPermission = await RnSmsService.checkingSmsPermission();
      if (checkPermission) {
        return true;
      } else {
        const granted = await PermissionsAndroid.requestMultiple([receiveSmsPermission, readSmsPermission]);
        if (granted[receiveSmsPermission] === PermissionsAndroid.RESULTS.GRANTED && granted[readSmsPermission] === PermissionsAndroid.RESULTS.GRANTED) {
          console.log('Read SMS permission granted::: ', granted);
          return true;
        } else {
          console.log('Read SMS permission denied::: ', granted);
          return false;
        }
      }
    } catch (error) {
      console.error('Error requesting SMS permissions::: ', error);
      return false;
    }
  },
  /**
   * Fetches SMS messages and extracts OTP.
   * @param length - Length of the OTP to be extracted from the SMS.
   * @returns A Promise that resolves to an object containing the extracted OTP or undefined.
   */
  fetchSms: async length => {
    return new Promise(async resolve => {
      let otp = undefined;
      const status = await RnSmsService.requestSmsPermission();
      if (status) {
        try {
          RnSmsReader.initiateSmsReading(() => {
            const subscription = new NativeEventEmitter(RnSmsReader).addListener('on_sms_received', sms => {
              otp = extractOtpFromText(sms, length);
              subscription.remove();
              console.log('OTP::: ', otp);
              resolve({
                otp
              });
            });
          }, error => {
            console.log('Error while reading SMS::: ', error);
            resolve({
              otp
            });
          });
        } catch (error) {
          console.log('Error while reading SMS::: ', error);
          resolve({
            otp
          });
        }
      } else {
        resolve({
          otp
        });
      }
    });
  }
};
export default RnSmsService;
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