client: Distinguish login failure from server error

The 403 or 500 HTTP errors have nothing to do with selfoss credentials so we should show a different error.
While at it, move the error detection to the request function and remove redundant redirect.

assets/js/errors.js

@@ -18,3 +18,10 @@ export class HttpError extends Error {
         this.name = 'HttpError';
     }
 }
+
+export class LoginError extends Error {
+    constructor(message) {
+        super(message);
+        this.name = 'LoginError';
+    }
+}

assets/js/requests/common.js

@@ -1,3 +1,4 @@
+import { LoginError } from '../errors';
 import * as ajax from '../helpers/ajax';
 
 /**
@@ -16,7 +17,15 @@ export function getInstanceInfo() {
 export function login(credentials) {
     return ajax.post('login', {
         body: new URLSearchParams(credentials)
-    }).promise.then(response => response.json());
+    }).promise.then(
+        response => response.json()
+    ).then((data) => {
+        if (data.success) {
+            return Promise.resolve();
+        } else {
+            return Promise.reject(new LoginError(data.error));
+        }
+    });
 }
 
 /**

assets/js/selfoss-base.js

@@ -199,19 +199,13 @@ var selfoss = {
             username,
             password
         };
-        return login(credentials).then((data) => {
-            if (data.success) {
-                selfoss.setSession();
-                selfoss.history.push('/');
-                // init offline if supported and not inited yet
+        return login(credentials).then(() => {
+            selfoss.setSession();
+            // init offline if supported and not inited yet
+            selfoss.dbOffline.init();
+            if ((!selfoss.db.storage || selfoss.db.broken) && selfoss.db.enableOffline.value) {
+                // Initialize database in offline mode when it has not been initialized yet or it got broken.
                 selfoss.dbOffline.init();
-                if ((!selfoss.db.storage || selfoss.db.broken) && selfoss.db.enableOffline.value) {
-                    // Initialize database in offline mode when it has not been initialized yet or it got broken.
-                    selfoss.dbOffline.init();
-                }
-                return Promise.resolve();
-            } else {
-                return Promise.reject(new Error(data.error));
             }
         });
     },

assets/js/templates/LoginForm.jsx

@@ -3,6 +3,7 @@ import PropTypes from 'prop-types';
 import classNames from 'classnames';
 import { SpinnerBig } from './Spinner';
 import { useHistory, useLocation } from 'react-router-dom';
+import { HttpError, LoginError } from '../errors';
 import { ConfigurationContext } from '../helpers/configuration';
 import { LocalizationContext } from '../helpers/i18n';
 
@@ -20,9 +21,18 @@ function handleLogIn({
 
     selfoss.login({ username, password, offlineEnabled }).then(() => {
         history.push('/');
-    }).catch(() => {
+    }).catch((err) => {
+        const message =
+            err instanceof LoginError
+                ? selfoss.app._('login_invalid_credentials')
+                : selfoss.app._('login_error_generic', {
+                    errorMessage:
+                        err instanceof HttpError
+                            ? `HTTP ${err.response.status} ${err.message}`
+                            : err.message,
+                });
         history.replace('/sign/in', {
-            error: selfoss.app._('login_invalid_credentials')
+            error: message,
         });
     }).finally(() => {
         setLoading(false);

assets/locale/cs.json

@@ -65,6 +65,7 @@
   "lang_login_username": "Jméno",
   "lang_login_password": "Heslo",
   "lang_login_invalid_credentials": "Špatné jméno nebo heslo",
+  "lang_login_error_generic": "Pokus o přihlášení selhal: {errorMessage}",
   "lang_no_title": "Bez titulku",
   "lang_error": "Nastala chyba",
   "lang_error_unauthorized": "Pro pokračování se prosím {link_begin}přihlaste{link_end}.",

assets/locale/en.json

@@ -77,6 +77,7 @@
   "lang_login_username": "Username",
   "lang_login_password": "Password",
   "lang_login_invalid_credentials": "Wrong username/password",
+  "lang_login_error_generic": "Could not log in: {errorMessage}",
   "lang_login_offline": "Offline storage",
   "lang_no_title": "No title",
   "lang_experimental": "Experimental",