Flutter で Yahoo Japan へのログインをする Dialog

yahoo_login_dialog.dart

/*
pubspec.yaml

dependencies:
  flutter_inappwebview: 5.5.0
  http: ^0.13.5
*/

// https://developer.yahoo.co.jp/yconnect/v2/authorization_code/

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';
import 'package:http/http.dart' as http;

class YahooAccessToken {
  final String accessToken;
  final String tokenType;
  final String idToken;
  final int expiresIn;
  final String refreshToken;

  YahooAccessToken({
    required this.accessToken,
    required this.tokenType,
    required this.idToken,
    required this.expiresIn,
    required this.refreshToken,
  });

  factory YahooAccessToken.fromJsonString(String jsonString) {
    final json = jsonDecode(jsonString);
    return YahooAccessToken(
      accessToken: json["access_token"],
      tokenType: json["token_type"],
      idToken: json["id_token"],
      expiresIn: json["expires_in"],
      refreshToken: json["refresh_token"],
    );
  }
}

mixin YahooLoginDialogMixin {
  void showYahooLoginDialog({
    required BuildContext context,
    required Function(YahooAccessToken?) onLogin,
  }) {
    showDialog(
      context: context,
      builder: (_) {
        return AlertDialog(
          content: _YahooLoginDialogContent(
            onLogin: onLogin,
          ),
        );
      },
    );
  }
}

class _YahooLoginDialogContent extends StatefulWidget {
  final Function(YahooAccessToken? token) onLogin;

  const _YahooLoginDialogContent({
    required this.onLogin,
  });

  @override
  State<StatefulWidget> createState() => _YahooLoginDialogContentState();
}

class _YahooLoginDialogContentState extends State<_YahooLoginDialogContent> {
  final String _clientId = "";
  final String _secret = "";
  final String _redirectUri = "";
  final String _authUri =
      "https://auth.login.yahoo.co.jp/yconnect/v2/authorization";
  final String _tokenUri = "https://auth.login.yahoo.co.jp/yconnect/v2/token";

  String get _authRequestUri {
    final params = {
      "client_id": _clientId,
      "redirect_uri": Uri.encodeFull(_redirectUri),
      "response_type": "code",
      "scope": "openid email profile",
      "bail": 1,
    }.entries.map((e) => "${e.key}=${e.value}").join("&");
    return "$_authUri?$params";
  }

  Future<void> _getAccessToken(String code) async {
    final response = await http.post(
      Uri.parse(_tokenUri),
      headers: {
        "Authorization":
            "Basic ${base64Encode(utf8.encode("$_clientId:$_secret"))}",
      },
      body: {
        "grant_type": "authorization_code",
        "code": code,
        "redirect_uri": _redirectUri,
      },
    );
    if (response.statusCode == 200) {
      final token = YahooAccessToken.fromJsonString(response.body);
      widget.onLogin(token);
    } else {
      widget.onLogin(null);
    }
  }

  /// yahoo login
  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: double.maxFinite,
      child: InAppWebView(
        initialUrlRequest: URLRequest(url: Uri.parse(_authRequestUri)),
        onLoadStop: (controller, url) async {
          if (url.toString().startsWith(_redirectUri)) {
            final code = Uri.parse(url.toString()).queryParameters["code"];
            if (code != null) {
              await _getAccessToken(code);
            } else {
              widget.onLogin(null);
            }
            if (!mounted) return;
            Navigator.of(context).pop();
          }
        },
      ),
    );
  }
}