Add checkbox to set configurable theme colours to default (bug #814354)

Change-Id: I899308f41457696d3c4578e5f3105d7d32685d23
Signed-off-by: Richard Mansfield <richard.mansfield@catalyst.net.nz>

htdocs/admin/users/institutions.php

@@ -351,6 +351,12 @@ if ($institution || $add) {
                 'defaultvalue' => isset($customtheme[$name]) ? $customtheme[$name] : $styledata['value'],
             );
         }
+        $elements['customthemefs']['elements']['resetcustom'] = array(
+            'type'         => 'checkbox',
+            'class'        => 'nojs-hidden-inline',
+            'title'        => get_string('resetcolours', 'admin'),
+            'description'  => get_string('resetcoloursdesc', 'admin'),
+        );
         $elements['showonlineusers'] = array(
             'type'                  => 'select',
             'title'                 => get_string('showonlineusers', 'admin'),
@@ -591,6 +597,10 @@ function institution_submit(Pieform $form, $values) {
         $newinstitution->style = null;
     }
 
+    if (!empty($values['resetcustom']) && !empty($oldinstitution->style)) {
+        $newinstitution->style = null;
+    }
+
     if ($USER->get('admin') || get_config_plugin('artefact', 'file', 'institutionaloverride')) {
         $newinstitution->defaultquota = empty($values['defaultquota']) ? get_config_plugin('artefact', 'file', 'defaultquota') : $values['defaultquota'];
     }
@@ -668,6 +678,11 @@ function institution_submit(Pieform $form, $values) {
         update_record('institution', $newinstitution, $where);
     }
 
+    if (is_null($newinstitution->style) && !empty($oldinstitution->style)) {
+        delete_records('style_property', 'style', $oldinstitution->style);
+        delete_records('style', 'id', $oldinstitution->style);
+    }
+
     // Set the logo after updating the institution, because the institution
     // needs to exist before it can own the logo artefact.
     if ($values['logo']) {

htdocs/lang/en.utf8/admin.php

@@ -688,6 +688,8 @@ $string['customtheme.sidebarfg'] = 'Side block content background';
 $string['customtheme.sidebarlink'] = 'Side block link';
 $string['customtheme.rowbg'] = 'Row background';
 $string['customstylesforinstitution'] = 'Custom styles for %s';
+$string['resetcolours'] = 'Reset colours';
+$string['resetcoloursdesc'] = 'Restore default colours';
 
 $string['authenticatedby'] = 'Authentication Method';
 $string['authenticatedbydescription'] = 'How this user authenticates to Mahara';