MDL-80037 theme: Indicate when $CFG->theme is defined in config.php

* And prevent selection of theme if $CFG->theme is defined in config.php

admin/amd/src/themeselector/preview_modal.js

@@ -29,6 +29,7 @@ import Templates from 'core/templates';
 import {getString} from 'core/str';
 
 const SELECTORS = {
+    THEMES_CONTAINER: 'themelist',
     PREVIEW: '[data-action="preview"]',
 };
 
@@ -66,6 +67,8 @@ const buildModal = async(element) => {
     // This string can be long. We will fetch it with JS as opposed to passing it as an attribute.
     let description = await getString('choosereadme', 'theme_' + element.getAttribute('data-choose'));
 
+    const themesContainer = document.getElementById(SELECTORS.THEMES_CONTAINER);
+    const definedInConfig = parseInt(themesContainer.dataset.definedinconfig);
     // Prepare data for modal.
     const data = {
         name: element.getAttribute('data-name'),
@@ -75,11 +78,12 @@ const buildModal = async(element) => {
         actionurl: element.getAttribute('data-actionurl'),
         choose: element.getAttribute('data-choose'),
         sesskey: element.getAttribute('data-sesskey'),
+        definedinconfig: definedInConfig,
     };
 
     // Determine which modal template we should use.
     let modalTemplate = ModalSaveCancel;
-    if (data.current) {
+    if (data.current || data.definedinconfig) {
         modalTemplate = ModalCancel;
     }
 

admin/classes/output/theme_selector.php

@@ -34,13 +34,18 @@ class theme_selector implements renderable, templatable {
     /** @var array $themedata Theme data to pass to the template. */
     private $themedata = null;
 
+    /** @var bool Whether $CFG->theme is defined in config.php. */
+    private $definedinconfig;
+
     /**
      * Constructor.
      *
      * @param array $themedata Theme data used for template.
+     * @param bool $definedinconfig Whether $CFG->theme is defined in config.php.
      */
-    public function __construct(array $themedata) {
+    public function __construct(array $themedata, bool $definedinconfig = false) {
         $this->themedata = $themedata;
+        $this->definedinconfig = $definedinconfig;
     }
 
     /**
@@ -59,6 +64,7 @@ public function export_for_template(renderer_base $output): stdClass {
         $resetbutton = new \single_button($reseturl, get_string('themeresetcaches', 'admin'), 'post',
             \single_button::BUTTON_SECONDARY);
         $data->resetbutton = $resetbutton->export_for_template($output);
+        $data->definedinconfig = $this->definedinconfig;
 
         return $data;
     }

admin/templates/themeselector/theme_card.mustache

@@ -58,6 +58,9 @@
     <div class="d-flex align-items-end flex-column p-3">
         {{#current}}
             <strong><span class="text-success" id="current-theme-{{choose}}">{{#str}}currenttheme, moodle{{/str}}</span></strong>
+            {{#definedinconfig}}
+                <div class="alert alert-info p-1">{{#str}}configoverride, admin{{/str}}</div>
+            {{/definedinconfig}}
         {{/current}}
         {{^current}}
             {{#actionurl}}

admin/templates/themeselector/theme_preview_modal.mustache

@@ -39,9 +39,12 @@
         <div class="flex-grow-1">
             <p><strong>{{#str}}themepreviewdescription, moodle, {{name}}{{/str}}</strong></p>
         </div>
-        <div>
+        <div class="d-flex align-items-end flex-column">
         {{#current}}
             <strong><span class="text-success">{{#str}}currenttheme, moodle{{/str}}</span></strong>
+            {{#definedinconfig}}
+                <div class="alert alert-info p-1">{{#str}}configoverride, admin{{/str}}</div>
+            {{/definedinconfig}}
         {{/current}}
         </div>
     </div>

admin/templates/themeselector/theme_selector.mustache

@@ -62,7 +62,7 @@
         {{>core/single_button}}
     </div>
 {{/resetbutton}}
-<div class="card-deck dashboard-card-deck" id="themelist" data-region="card-deck" role="list">
+<div class="card-deck dashboard-card-deck" id="themelist" data-region="card-deck" role="list" data-definedinconfig="{{definedinconfig}}">
     {{#themes}}
         {{>core_admin/themeselector/theme_card}}
     {{/themes}}

admin/themeselector.php

@@ -42,8 +42,15 @@
     theme_reset_all_caches();
 }
 
+$definedinconfig = array_key_exists('theme', $CFG->config_php_settings);
+if ($definedinconfig) {
+    $forcedthemename = get_string('pluginname', 'theme_'.$CFG->theme);
+    // Show a notification that the theme is defined in config.php.
+    \core\notification::info(get_string('themedefinedinconfigphp', 'admin', $forcedthemename));
+}
+
 // Change theme.
-if (!empty($choose) && confirm_sesskey()) {
+if (!$definedinconfig && !empty($choose) && confirm_sesskey()) {
 
     // Load the theme to make sure it is valid.
     $theme = theme_config::load($choose);
@@ -105,7 +112,7 @@
     if ($themename === $CFG->theme) {
         $themedata['current'] = true;
         $currentthemeindex = $index;
-    } else {
+    } else if (!$definedinconfig) {
         // Form params.
         $actionurl = new moodle_url('/admin/themeselector.php');
         $themedata['actionurl'] = $actionurl;
@@ -124,7 +131,7 @@
 }
 
 // Show theme selector.
-$renderable = new \core_admin\output\theme_selector($data);
+$renderable = new \core_admin\output\theme_selector($data, $definedinconfig);
 $renderer = $PAGE->get_renderer('core', 'admin');
 echo $renderer->theme_selector_list($renderable);
 

lang/en/admin.php

@@ -1452,6 +1452,7 @@
 $string['testoutgoingmailconf_subject'] = '{$a->site}: test message. {$a->additional} Sent: {$a->time}';
 $string['testoutgoingmailconf_subjectadditional'] = 'Additional subject';
 $string['testoutgoingmailconf_toemail'] = 'To email address';
+$string['themedefinedinconfigphp'] = 'The theme cannot be changed because it is set to {$a} in config.php.';
 $string['themedesignermode'] = 'Theme designer mode';
 $string['themedesignermodewarning'] = 'Theme designer mode is enabled. This should not be enabled on production sites as it can significantly reduce performance.';
 $string['themelist'] = 'Theme list';