login: Display message when account already logged in

This provides some user feedback since the previous behavior looked as
if nothing happened.

Fixes: #108

Author: chrisirhc

assets/l10n/app_en.arb

@@ -63,6 +63,18 @@
   "@actionSheetOptionUnstarMessage":  {
     "description": "Label for unstar button on action sheet."
   },
+  "errorAccountLoggedInTitle": "Account already logged in",
+  "@errorAccountLoggedInTitle": {
+    "description": "Error title on attempting to log into an account that's already logged in."
+  },
+  "errorAccountLoggedIn": "The account {email} at {server} is already in your list of accounts.",
+  "@errorAccountLoggedIn": {
+    "description": "Error message on attempting to log into an account that's already logged in.",
+    "placeholders": {
+      "email": {"type": "String", "example": "[email protected]"},
+      "server": {"type": "String", "example": "https://example.com"}
+    }
+  },
   "errorCouldNotFetchMessageSource": "Could not fetch message source",
   "@errorCouldNotFetchMessageSource": {
     "description": "Error message when the source of a message could not be fetched."

lib/widgets/login.dart

@@ -258,16 +258,31 @@ class _PasswordLoginPageState extends State<PasswordLoginPage> {
     required int userId,
   }) async {
     final globalStore = GlobalStoreWidget.of(context);
-    // TODO(#108): give feedback to user on SQL exception, like dupe realm+user
-    final accountId = await globalStore.insertAccount(AccountsCompanion.insert(
-      realmUrl: widget.serverSettings.realmUrl,
-      email: email,
-      apiKey: apiKey,
-      userId: userId,
-      zulipFeatureLevel: widget.serverSettings.zulipFeatureLevel,
-      zulipVersion: widget.serverSettings.zulipVersion,
-      zulipMergeBase: Value(widget.serverSettings.zulipMergeBase),
-    ));
+    final realmUrl = widget.serverSettings.realmUrl;
+    final int accountId;
+    try {
+      accountId = await globalStore.insertAccount(AccountsCompanion.insert(
+        realmUrl: realmUrl,
+        email: email,
+        apiKey: apiKey,
+        userId: userId,
+        zulipFeatureLevel: widget.serverSettings.zulipFeatureLevel,
+        zulipVersion: widget.serverSettings.zulipVersion,
+        zulipMergeBase: Value(widget.serverSettings.zulipMergeBase),
+      ));
+      // TODO give feedback to user on other SQL exceptions
+    } on AccountAlreadyExistsException {
+      if (!mounted) {
+        return;
+      }
+      final zulipLocalizations = ZulipLocalizations.of(context);
+      showErrorDialog(
+        context: context,
+        title: zulipLocalizations.errorAccountLoggedInTitle,
+        message: zulipLocalizations.errorAccountLoggedIn(
+          email, realmUrl.toString()));
+      return;
+    }
 
     if (!mounted) {
       return;

test/widgets/login_test.dart

@@ -5,6 +5,7 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:http/http.dart' as http;
 import 'package:zulip/api/route/account.dart';
 import 'package:zulip/api/route/realm.dart';
+import 'package:zulip/model/localizations.dart';
 import 'package:zulip/widgets/login.dart';
 import 'package:zulip/widgets/store.dart';
 
@@ -113,6 +114,28 @@ void main() {
           id: testBinding.globalStore.accounts.single.id));
     });
 
+    testWidgets('account already exists', (tester) async {
+      final serverSettings = eg.serverSettings();
+      await prepare(tester, serverSettings);
+      check(testBinding.globalStore.accounts).isEmpty();
+      testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot());
+
+      await tester.enterText(findUsernameInput, eg.selfAccount.email);
+      await tester.enterText(findPasswordInput, 'p455w0rd');
+      connection.prepare(json: FetchApiKeyResult(
+        apiKey: eg.selfAccount.apiKey,
+        email: eg.selfAccount.email,
+        userId: eg.selfAccount.userId,
+      ).toJson());
+      await tester.tap(findSubmitButton);
+      await tester.pumpAndSettle();
+
+      final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
+      final findAlertDialogWithExistsMessage = find.widgetWithText(
+        AlertDialog, zulipLocalizations.errorAccountLoggedInTitle);
+      check(findAlertDialogWithExistsMessage.evaluate()).isNotEmpty();
+    });
+
     // TODO test validators on the TextFormField widgets
     // TODO test navigation, i.e. the call to pushAndRemoveUntil
     // TODO test _getUserId case