[WIP] Google sign in web

packages/google_sign_in/google_sign_in_web/lib/google_sign_in_web.dart

@@ -3,19 +3,29 @@ import 'dart:html' as html;
 
 import 'package:flutter/services.dart';
 import 'package:flutter_web_plugins/flutter_web_plugins.dart';
+import 'package:js/js.dart';
+
+import 'src/gapi.dart';
+
+const String _kClientIdMetaSelector = 'meta[name=google-signin-client_id]';
+const String _kClientIdAttributeName = 'content';
+const List<String> _kJsLibraries = <String>[
+  'https://apis.google.com/js/platform.js'
+];
 
 /// Implementation of the google_sign_in plugin for Web
 class GoogleSignInPlugin {
   GoogleSignInPlugin() {
-    _jsLibrariesLoading = _injectJSLibraries(<String>[
-      'https://apis.google.com/js/platform.js',
-    ])..then(_initGapi);    
+    _autoDetectedClientId = html
+        .querySelector(_kClientIdMetaSelector)
+        ?.getAttribute(_kClientIdAttributeName);
+
+    _isGapiInitialized = _injectJSLibraries(_kJsLibraries).then((_) => _initGapi());
   }
 
-  Future<List<void>> _jsLibrariesLoading;
+  Future<void> _isGapiInitialized;
+  String _autoDetectedClientId;
 
-  Future<void> get isJsLoaded => _jsLibrariesLoading;
-
   static void registerWith(Registrar registrar) {
     final MethodChannel channel = MethodChannel(
         'plugins.flutter.io/google_sign_in',
@@ -28,14 +38,50 @@ class GoogleSignInPlugin {
 
   Future<dynamic> handleMethodCall(MethodCall call) async {
     // Await for initialization promises to complete, then do your thing...
-    await isJsLoaded;
+    await _isGapiInitialized;
 
-    html.window.console.log('Doing things! $call');
+    final GoogleAuth authInstance = gapi.auth2.getAuthInstance();
+    final GoogleUser currentUser = authInstance?.currentUser?.get();
 
     switch (call.method) {
       case 'init':
-        // Initialize the gapi
-        return _init(call.arguments);
+        _init(call.arguments);
+        return true;
+        break;
+      case 'signInSilently':
+        // TODO: convert call.arguments to an Auth2SignInOptions object (when needed)
+        await _signIn(Auth2SignInOptions(
+          prompt: 'none',
+        ));
+        return _currentUserToPluginMap(currentUser);
+        break;
+      case 'signIn':
+        // TODO: convert call.arguments to an Auth2SignInOptions object (when needed)
+        await _signIn(null);
+        return _currentUserToPluginMap(currentUser);
+        break;
+      case 'getTokens':
+        final Auth2AuthResponse response = currentUser.getAuthResponse();
+        return <String, String>{
+          'idToken': response.id_token,
+          'accessToken': response.access_token,
+        };
+        break;
+      case 'signOut':
+        await _signOut();
+        return null;
+        break;
+      case 'disconnect':
+        currentUser.disconnect();
+        return null;
+        break;
+      case 'isSignedIn':
+        return currentUser.isSignedIn();
+        break;
+      case 'clearAuthCache':
+        // We really don't keep any cache here, but let's try to be drastic:
+        authInstance.disconnect();
+        return null;
         break;
       default:
         throw PlatformException(
@@ -45,31 +91,61 @@ class GoogleSignInPlugin {
     }
   }
 
+  Map<String, dynamic> _currentUserToPluginMap(GoogleUser currentUser) {
+    assert(currentUser != null);
+    final Auth2BasicProfile profile = currentUser.getBasicProfile();
+    return <String, dynamic>{
+      'displayName': profile?.getName(),
+      'email': profile?.getEmail(),
+      'id': profile?.getId(),
+      'photoUrl': profile?.getImageUrl(),
+      'idToken': currentUser?.getAuthResponse()?.id_token,
+    };
+  }
+
   // Load the auth2 library
-  Future<void> _init(Map<String, dynamic> arguments) {
-    // 
+  GoogleAuth _init(dynamic arguments) => gapi.auth2.init(Auth2ClientConfig(
+        hosted_domain: arguments['hostedDomain'],
+        // The js lib wants a space-separated list of values
+        scope: arguments['scopes'].join(' '),
+        client_id: arguments['clientId'] ?? _autoDetectedClientId,
+      ));
+
+  Future<dynamic> _signIn(Auth2SignInOptions signInOptions) async {
+    return html.promiseToFuture<dynamic>(
+        gapi.auth2.getAuthInstance().signIn(signInOptions));
+  }
+
+  Future<void> _signOut() async {
+    return html.promiseToFuture<void>(gapi.auth2.getAuthInstance().signOut());
   }
 
-  Future<void> _initGapi(List<void> _) {
-    // JS-interop with the global gapi method and call gapi.load('auth2'), and wait for the 
-    // promise to resolve...
-
+  Future<void> _initGapi() {
+    // JS-interop with the global gapi method and call gapi.load('auth2'),
+    // then wait for the promise to resolve...
+    final Completer<void> gapiLoadCompleter = Completer<void>();
+    gapi.load('auth2', allowInterop(() {
+      gapiLoadCompleter.complete();
+    }));
+
+    // After this is resolved, we can use gapi.auth2!
+    return gapiLoadCompleter.future;
   }
 
-  /// Injects a bunch of libraries in the <head> and returns a 
+  /// Injects a bunch of libraries in the <head> and returns a
   /// Future that resolves when all load.
-  Future<List<void>> _injectJSLibraries(List<String> libraries, { Duration timeout }) {
-    final List<Future<void>> loading = <Future<void>>[
-      Future<bool>.delayed(const Duration(seconds: 10), () => true) // TODO: Remove this delay before submitting :)
-    ];
+  Future<void> _injectJSLibraries(List<String> libraries,
+      {Duration timeout}) {
+    final List<Future<void>> loading = <Future<void>>[];
     final List<html.HtmlElement> tags = <html.HtmlElement>[];
 
     libraries.forEach((String library) {
       final html.ScriptElement script = html.ScriptElement()
         ..async = true
         ..defer = true
         ..src = library;
-      loading.add(script.onLoad.first); // TODO add a timeout race to fail this future
+      // TODO add a timeout race to fail this future
+      loading.add(script.onLoad.first);
       tags.add(script);
     });
     html.querySelector('head').children.addAll(tags);

packages/google_sign_in/google_sign_in_web/lib/src/gapi.dart

@@ -0,0 +1,168 @@
+/// This library describes the global gapi object, and the 'auth2' module
+/// as described here: https://developers.google.com/identity/sign-in/web/reference
+@JS()
+library gapi;
+
+import 'dart:async';
+import 'dart:html' as html;
+
+import 'package:js/js.dart';
+
+// Global window.gapi, we need to call `load('auth2', cb)` on it...
+@JS('gapi')
+external Gapi get gapi;
+
+@JS()
+abstract class Gapi {
+  external void load(String module, Function callback);
+  external Auth2 get auth2;
+}
+
+@JS()
+abstract class Auth2 {
+  // https://developers.google.com/identity/sign-in/web/reference#gapiauth2initparams
+  external GoogleAuth init(Auth2ClientConfig params);
+  external GoogleAuth getAuthInstance();
+  external void authorize(
+      Auth2AuthorizeConfig params, Auth2AuthorizeCallback callback);
+}
+
+typedef Auth2AuthorizeCallback = void Function(Auth2AuthorizeResponse response);
+
+@JS()
+abstract class Auth2CurrentUser {
+  external GoogleUser get();
+  external void listen(Auth2CurrentUserListener listener);
+}
+
+typedef Auth2CurrentUserListener = void Function(bool);
+
+@JS()
+abstract class GoogleAuth {
+  external Future<void> then(Function onInit, Function onError);
+  // Authentication: https://developers.google.com/identity/sign-in/web/reference#authentication
+  external Future<GoogleUser> signIn([Auth2SignInOptions options]);
+  external Future<void> signOut();
+  external void disconnect();
+  // Offline access not implemented
+  external void attachClickHandler(html.HtmlElement container,
+      Auth2SignInOptions options, Function onSuccess, Function onFailure);
+  external Auth2CurrentUser get currentUser;
+}
+
+// https://developers.google.com/identity/sign-in/web/reference#googleusergetbasicprofile
+@JS()
+abstract class Auth2BasicProfile {
+  external String getId();
+  external String getName();
+  external String getGivenName();
+  external String getFamilyName();
+  external String getImageUrl();
+  external String getEmail();
+}
+
+// https://developers.google.com/identity/sign-in/web/reference#gapiauth2authresponse
+@JS()
+abstract class Auth2AuthResponse {
+  external String get access_token;
+  external String get id_token;
+  external String get scope;
+  external num get expires_in;
+  external num get first_issued_at;
+  external num get expires_at;
+}
+
+// https://developers.google.com/identity/sign-in/web/reference#gapiauth2authorizeresponse
+@JS()
+abstract class Auth2AuthorizeResponse {
+  external String get access_token;
+  external String get id_token;
+  external String get code;
+  external String get scope;
+  external int get expires_in;
+  external int get first_issued_at;
+  external int get expires_at;
+  external String get error;
+  external String get error_subtype;
+}
+
+// https://developers.google.com/identity/sign-in/web/reference#users
+@JS()
+abstract class GoogleUser {
+  external String getId();
+  external bool isSignedIn();
+  external String getHostedDomain();
+  external String getGrantedScopes();
+  external Auth2BasicProfile getBasicProfile();
+  external Auth2AuthResponse getAuthResponse([bool includeAuthorizationData]);
+  external Future<Auth2AuthResponse> reloadAuthResponse();
+  external bool hasGrantedScopes(String scopes);
+  external void grant(Auth2SignInOptions options);
+  // Offline access not implemented
+  external void disconnect();
+}
+
+// https://developers.google.com/identity/sign-in/web/reference#gapiauth2signinoptions
+@JS()
+@anonymous
+abstract class Auth2SignInOptions {
+  external factory Auth2SignInOptions(
+      {String prompt, String scope, String ux_mode, String redirect_uri});
+
+  external String get prompt;
+  external String get scope;
+  external String get ux_mode;
+  external String get redirect_uri;
+}
+
+// https://developers.google.com/identity/sign-in/web/reference#gapiauth2clientconfig
+@JS()
+@anonymous
+abstract class Auth2ClientConfig {
+  external factory Auth2ClientConfig({
+    String client_id,
+    String cookie_policy,
+    String scope,
+    bool fetch_basic_profile,
+    String hosted_domain,
+    String open_id_realm,
+    String ux_mode,
+    String redirect_uri,
+  });
+
+  external String get client_id;
+  external String get cookie_policy;
+  external String get scope;
+  external bool get fetch_basic_profile;
+  external String get hosted_domain;
+  external String get open_id_realm;
+  external String get ux_mode;
+  external String get redirect_uri;
+}
+
+// https://developers.google.com/identity/sign-in/web/reference#gapiauth2authorizeconfig
+@JS()
+@anonymous
+abstract class Auth2AuthorizeConfig {
+  external factory Auth2AuthorizeConfig({
+    String client_id,
+    String scope,
+    String response_type,
+    String prompt,
+    String cookie_policy,
+    String hosted_domain,
+    String login_hint,
+    String open_id_realm,
+    bool include_granted_scopes,
+  });
+
+  external String get client_id;
+  external String get scope;
+  external String get response_type;
+  external String get prompt;
+  external String get cookie_policy;
+  external String get hosted_domain;
+  external String get login_hint;
+  external String get open_id_realm;
+  external bool get include_granted_scopes;
+}

packages/google_sign_in/google_sign_in_web/pubspec.yaml

@@ -18,6 +18,7 @@ dependencies:
   flutter_web_plugins:
     sdk: flutter
   meta: ^1.1.7
+  js: ^0.6.1
 
 dev_dependencies:
   flutter_test: