ISTWCMS-3682: move button-adding into JS (since it requires JS to work) and make minor improvements

js/user-login-min.js

-!function(l,i){i.behaviors.uwFdsuThemeRespUserLogin={attach:function(i,n){l("#user-login-form").css("display","none"),l("#local-login-link").click(function(){l("#user-login-form").css("display","block"),l("#local-login-link").css("display","none"),l("#adfs-login-link").css("display","none"),l("#edit-submit").val("Log In Locally")}),l("#adfs-login-link").click(function(){l("#edit-simplesamlphp-auth-login-link")[0].click()})}}}(jQuery,Drupal);
+!function(l,i){i.behaviors.uwFdsuThemeRespUserLogin={attach:function(i,n){l("#edit-simplesamlphp-auth-login-link").length&&(l("#user-login-form").css("display","none"),l("#user-login-form").after('<button id="adfs-login-link" class="button--primary">Log in via ADFS</button> &nbsp; <button id="local-login-link" class="button--medium">Log in locally</button>'),l("#edit-submit").val("Log in locally"),l("#local-login-link").click(function(){l("#user-login-form").css("display","block"),l("#local-login-link").css("display","none"),l("#adfs-login-link").css("display","none"),l("#edit-name").focus()}),l("#adfs-login-link").click(function(){l("#edit-simplesamlphp-auth-login-link")[0].click()}))}}}(jQuery,Drupal);

js/user-login.js

 (function ($, Drupal) {
   Drupal.behaviors.uwFdsuThemeRespUserLogin = {
     attach: function (context, settings) {
-      $('#user-login-form').css('display', 'none');
-      $('#local-login-link').click(function () {
-        $('#user-login-form').css('display', 'block');
-        $('#local-login-link').css('display', 'none');
-        $('#adfs-login-link').css('display', 'none');
-        $('#edit-submit').val('Log In Locally');
-      });
-      $('#adfs-login-link').click(function () {
-        $('#edit-simplesamlphp-auth-login-link')[0].click();
-      });
+      // Don't do anything if SimpleSAML isn't enabled.
+      if ($('#edit-simplesamlphp-auth-login-link').length)
+      {
+        // Hide the normal login form.
+        $('#user-login-form').css('display', 'none');
+        // Add buttons (using JS because they don't work without JS)
+        $('#user-login-form').after('<button id="adfs-login-link" class="button--primary">Log in via ADFS</button> &nbsp; <button id="local-login-link" class="button--medium">Log in locally</button>');
+        // Update the existing login form's link text.
+        $('#edit-submit').val('Log in locally');
+        // If the local login link is clicked, show the normal login form and hide the buttons.
+        // Be nice to the user, and put focus on the name field so they can just start typing.
+        $('#local-login-link').click(function () {
+          $('#user-login-form').css('display', 'block');
+          $('#local-login-link').css('display', 'none');
+          $('#adfs-login-link').css('display', 'none');
+          $('#edit-name').focus();
+        });
+        // If the ADFS login link is clicked, click on the original log in with ADFS link.
+        $('#adfs-login-link').click(function () {
+          $('#edit-simplesamlphp-auth-login-link')[0].click();
+        });
+      }
     }
   };
 })(jQuery, Drupal);

templates/form/form--user-login-form.html.twig

-{#
-/**
- * @file
- * Theme override for a 'form' element.
- *
- * Available variables
- * - attributes: A list of HTML attributes for the wrapper element.
- * - children: The child elements of the form.
- *
- * @see template_preprocess_form()
- */
-#}
-<form{{ attributes }}>
-  {{ children }}
-</form>
-<button id="adfs-login-link" class="button--primary">Log In Via ADFS</button>
-<button id="local-login-link">Log In Locally</button>

uw_fdsu_theme_resp.theme

@@ -24,32 +24,6 @@ require_once dirname(__FILE__) . '/includes/navigation.inc';
 require_once dirname(__FILE__) . '/includes/taxonomy.inc';
 require_once dirname(__FILE__) . '/includes/views.inc';
 
-/**
- * Implements hook_theme_suggestions_form_alter().
- *
- * Add suggestion for forms.
- */
-function uw_fdsu_theme_resp_theme_suggestions_form_alter(array &$suggestions, array $variables) {
-
-  // form--user-login-form.html.twig.
-  $suggestions[] = 'form__' . str_replace('-', '_', $variables['element']['#id']);
-}
-
-/**
- * Implements hook_theme().
- *
- * Custom twig for forms.
- */
-function uw_fdsu_theme_resp_theme($existing, $type, $theme, $path) {
-
-  return [
-    'form__user-login-form' => [
-      '#theme' => 'form--user-login-form',
-      'render element' => 'form',
-    ],
-  ];
-}
-
 /**
  * Implements hook_preprocess_HOOK().
  *