Github GitHub - e-oj/visa: Easy third party authentication (OAuth 2.0) for Flutt...

// Possible imports:
import 'package:visa/fb.dart';
import 'package:visa/google.dart';
import 'package:visa/github.dart';
import 'package:visa/discord.dart';
import 'package:visa/twitch.dart';
import 'package:visa/auth-data.dart';
import 'package:visa/engine/oauth.dart';
import 'package:visa/engine/simple-auth.dart';
import 'package:visa/engine/visa.dart';

  FacebookAuth()
  TwitchAuth()
  DiscordAuth()
  GithubAuth()
  GoogleAuth({ String personFields })

FacebookAuth fbAuth = FacebookAuth();
SimpleAuth visa = fbAuth.visa;

WebView authenticate({
  bool newSession=false // If true, user has to reenter username and password even if they've logged in before
  String clientSecret, // Some providers (GitHub for instance) require the OAuth client secret (from developer portal).
  @required String clientID, // OAuth client ID (from developer portal)
  @required String redirectUri, // OAuth redirect url (from developer portal) 
  @required String state, // OAuth state string can be whatever you want.
  @required String scope, // OAuth scope (Check provider's API docs for allowed scopes)
  @required Function onDone, // Callback function which expects an AuthData object.
});

import 'package:visa/auth-data.dart';
import 'package:visa/fb.dart';

class AuthPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      /// Simply Provide all the necessary credentials
      body: FaceBookAuth().visa.authenticate(
          clientID: '139732240983759',
          redirectUri: 'https://www.e-oj.com/oauth',
          scope: 'public_profile,email',
          state: 'fbAuth',
          onDone: done
      )
    );
  }
}

done(AuthData authData){
  print(authData);

  /// You can pass the [AuthData] object to a 
  /// post-authentication screen. It contaions 
  /// all the user and OAuth data collected during
  /// the authentication process. In this example,
  /// our post-authentication screen is "complete-profile".
  Navigator.pushReplacementNamed(
      context, '/complete-profile', arguments: authData
  );
}

class AuthData {
  final String userID; // User's profile id
  final String firstName; // User's first name
  final String lastName; // User's last name
  final String email; // User's email
  final String profileImgUrl; // User's profile image url
  final Map<String, dynamic> userJson; // Full returned user json
  final Map<String, String> response; // Full returned auth response.
  final String clientID; // OAuth client id
  final String accessToken; // OAuth access token
}

/// Visa interface
abstract class Visa{
  /// a [SimpleAuth] instance
  SimpleAuth visa;

  /// This function combines information
  /// from the user [json] and auth response [data]
  /// to build an [AuthData] object.
  AuthData authData(
      Map<String, dynamic> json,
      Map<String, String> data
  );
}

class SimpleAuth{

  /// Creates a new instance based on the given OAuth
  /// baseUrl and getAuthData function.
  const SimpleAuth ({
    @required this.baseUrl, @required this.getAuthData
  });
  
  
  final String baseUrl; // OAuth base url
  
  /// This function makes the necessary api calls to
  /// get a user's profile data. It accepts a single
  /// argument: a Map<String, String> containing the 
  /// full auth response including an api access token.
  /// An [AuthData] object is created from a combination 
  /// of the passed in auth response and the user 
  /// response returned from the api.
  ///
  /// @return [AuthData]
  final Function getAuthData; 
}

/// Enables Discord [OAuth] authentication
class DiscordAuth implements Visa{
  // User profile API endpoint.
  final baseUrl = 'https://discord.com/api/oauth2/authorize';
  SimpleAuth visa;

  DiscordAuth(){
    visa = SimpleAuth(
        baseUrl: baseUrl,
        /// Sends a request to the user profile api
        /// endpoint. Returns an AuthData object.
        getAuthData: (Map <String, String> data) async {
          var token = data[OAuth.TOKEN_KEY];
          var baseProfileUrl = 'https://discord.com/api/users/@me';
          var profileResponse = await http.get(baseProfileUrl, headers: {
            'Authorization': 'Bearer $token',
          });
          var profileJson = json.decode(profileResponse.body);

          return authData(profileJson, data);
        }
    );
  }
}

/// This function combines information
/// from the user [json] and auth response [data]
/// to build an [AuthData] object.
@override
AuthData authData(
    Map<String, dynamic> json,
    Map<String, String> data
){
  final String accessToken = data[OAuth.TOKEN_KEY];
  final String userId = json['id'] as String;
  final String avatar = json['avatar'] as String;
  final String profileImgUrl = 'https://cdn.discordapp.com/'
      'avatars/$userId/$avatar.png';

  return AuthData(
      clientID: data['clientID'],
      accessToken: accessToken,
      userID: userId,
      email: json['email'] as String,
      profileImgUrl: profileImgUrl,
      response: data,
      userJson: json
  );
}

getAuthData(Map <String, String> data) async {
    // This function retrieves the access token and
    // adds it to the data HashMap.
    await _getToken(data);
    
    // We can now access the token
    var token = data[OAuth.TOKEN_KEY];
    
    // ... Make api requests/retrieve user data  with the token
}

  /// Github's [OAuth] endpoint returns a code
  /// which can be exchanged for a token. This
  /// function performs the exchange and adds the
  /// returned data to the response [data] map.
  _getToken(Map<String, String> data) async {
    var tokenEndpoint = 'https://github.com/login/oauth/access_token';
    var tokenResponse = await http.post(tokenEndpoint,
        headers: {'Accept': 'application/json',},
        body: {
          'client_id': data[OAuth.CLIENT_ID_KEY],
          'client_secret': data[OAuth.CLIENT_SECRET_KEY],
          'code': data[OAuth.CODE_KEY],
          'redirect_uri': data[OAuth.REDIRECT_URI_KEY],
          'state': data[OAuth.STATE_KEY]
        });

    var responseJson = json.decode(tokenResponse.body);
    var tokenTypeKey = 'token_type';

    data[OAuth.TOKEN_KEY] = responseJson[OAuth.TOKEN_KEY] as String;
    data[OAuth.SCOPE_KEY] = responseJson[OAuth.SCOPE_KEY] as String;
    data[tokenTypeKey] = responseJson[tokenTypeKey] as String;
  }
}