MDL-50472 auth: Add maintenance message to the login page.

auth/classes/output/login.php

@@ -72,6 +72,8 @@ class login implements renderable, templatable {
     public $username;
     /** @var string The csrf token to limit login to requests that come from the login form. */
     public $logintoken;
+    /** @var string Maintenance message, if Maintenance is enabled. */
+    public $maintenance;
 
     /**
      * Constructor.
@@ -109,6 +111,10 @@ class login implements renderable, templatable {
             $this->instructions = get_string('loginsteps', 'core', 'signup.php');
         }
 
+        if ($CFG->maintenance_enabled == true && !empty($CFG->maintenance_message)) {
+            $this->maintenance = $CFG->maintenance_message;
+        }
+
         // Identity providers.
         $this->identityproviders = \auth_plugin_base::get_identity_providers($authsequence);
         $this->logintoken = \core\session\manager::get_login_token();
@@ -145,6 +151,7 @@ class login implements renderable, templatable {
         $data->signupurl = $this->signupurl->out(false);
         $data->username = $this->username;
         $data->logintoken = $this->logintoken;
+        $data->maintenance = format_text($this->maintenance, FORMAT_MOODLE);
 
         return $data;
     }

lib/templates/loginform.mustache

@@ -36,7 +36,8 @@
         "signupurl": "http://localhost/stable_master/login/signup.php",
         "cookieshelpiconformatted": "",
         "username": "",
-        "logintoken": "randomstring"
+        "logintoken": "randomstring",
+        "maintenance": "For full access to this site, you need to login in as an admin."
     }
 }}
 {{#hasinstructions}}
@@ -163,6 +164,22 @@
     </div>
 </div>
 
+{{#maintenance}}
+    <div class="row justify-content-center mt-3">
+        <div class="col-xl-6 col-sm-8">
+            <div class="card">
+                <div class="card-body">
+                    <div class="card-title">
+                        <h2>{{#str}}sitemaintenance, core_admin{{/str}}</h2>
+                    </div>
+                    <div>
+                        {{{maintenance}}}
+                    </div>
+                </div>
+            </div>
+        </div>
+    </div>
+{{/maintenance}}
 {{#js}}
     {{#error}}
         require(['jquery'], function($) {