auth.dart

import 'dart:async';

import 'package:firebase_auth/firebase_auth.dart';
import 'package:logging/logging.dart';
import 'package:pmw_test/data/user.dart';

abstract class Auth {
  Future<User> currentUser();

  Future<String> verifyPhoneNumber(String phoneNumber);

  Future<User> signIn(String phoneNumber, String verificationCode);
}

class FBAuth implements Auth {
  final FirebaseAuth _fbAuth = FirebaseAuth.instance;
  final mapFBUserToUser = (FirebaseUser fbUser) => null != fbUser ? User(uid: fbUser.uid) : null;

  @override
  Future<User> currentUser() {
    return _fbAuth.currentUser().then(mapFBUserToUser);
  }

  @override
  Future<User> signIn(String verificationCode, String smsCode) {
    return _fbAuth
        .signInWithPhoneNumber(
            verificationId: verificationCode, smsCode: smsCode)
        .then(mapFBUserToUser);
  }

  @override
  Future<String> verifyPhoneNumber(String phoneNumber) async {
    String verificationCode;

    final PhoneVerificationCompleted verificationCompleted =
        (FirebaseUser user) =>
            _log.info("verification for user ${user.uid} completed");

    final PhoneVerificationFailed verificationFailed =
        (AuthException authException) => _log.info(
            'Phone numbber verification failed. Code: ${authException.code}. Message: ${authException.message}');

    final PhoneCodeSent codeSent =
        (String verificationId, [int forceResendingToken]) async {
      verificationCode = verificationId;
    };

    final PhoneCodeAutoRetrievalTimeout codeAutoRetrievalTimeout =
        (String verificationId) {
      verificationCode = verificationId;
    };

    await _fbAuth.verifyPhoneNumber(
        phoneNumber: phoneNumber,
        timeout: Duration(seconds: 5),
        verificationCompleted: verificationCompleted,
        verificationFailed: verificationFailed,
        codeSent: codeSent,
        codeAutoRetrievalTimeout: codeAutoRetrievalTimeout);

    return Future.value(verificationCode);
  }
}