Select schedule timezone via suggestion element

Author: jrauh01

application/controllers/ScheduleController.php

@@ -100,7 +100,7 @@ public function addAction(): void
     {
         $this->setTitle($this->translate('New Schedule'));
         $form = (new ScheduleForm(Database::get()))
-            ->setShowTimezoneDropdown()
+            ->setShowTimezoneSuggestionInput()
             ->setAction($this->getRequest()->getUrl()->getAbsoluteUrl())
             ->on(Form::ON_SUCCESS, function (ScheduleForm $form) {
                 $scheduleId = $form->addSchedule();

application/controllers/SuggestController.php

@@ -0,0 +1,35 @@
+<?php
+
+/* Icinga Notifications Web | (c) 2025 Icinga GmbH | GPLv2 */
+
+namespace Icinga\Module\Notifications\Controllers;
+
+use DateTime;
+use DateTimeZone;
+use IntlTimeZone;
+use ipl\Web\Compat\CompatController;
+use ipl\Web\FormElement\SearchSuggestions;
+use Throwable;
+
+class SuggestController extends CompatController
+{
+    public function timezoneAction(): void
+    {
+        $suggestions = new SearchSuggestions((function () use (&$suggestions) {
+            foreach (IntlTimeZone::createEnumeration() as $tz) {
+                try {
+                    if (
+                        (new DateTime('now', new DateTimeZone($tz)))->getTimezone()->getLocation()
+                        && str_contains(strtolower($tz), strtolower($suggestions->getOriginalSearchValue()))
+                    ) {
+                        yield ['search' => $tz];
+                    }
+                } catch (Throwable $_) {
+                    continue;
+                }
+            }
+        })());
+
+        $this->getDocument()->addHtml($suggestions->forRequest($this->getServerRequest()));
+    }
+}

application/forms/ScheduleForm.php

@@ -11,14 +11,18 @@
 use Icinga\Module\Notifications\Model\RuleEscalationRecipient;
 use Icinga\Module\Notifications\Model\Schedule;
 use Icinga\Web\Session;
+use IntlTimeZone;
 use ipl\Html\Attributes;
 use ipl\Html\HtmlDocument;
 use ipl\Html\HtmlElement;
 use ipl\Html\Text;
 use ipl\Sql\Connection;
 use ipl\Stdlib\Filter;
+use ipl\Validator\CallbackValidator;
 use ipl\Web\Common\CsrfCounterMeasure;
 use ipl\Web\Compat\CompatForm;
+use ipl\Web\Url;
+use Throwable;
 
 class ScheduleForm extends CompatForm
 {
@@ -31,7 +35,7 @@ class ScheduleForm extends CompatForm
     protected bool $showRemoveButton = false;
 
     /** @var bool */
-    protected bool $showTimezoneDropdown = false;
+    protected bool $showTimezoneSuggestionInput = false;
 
     /** @var Connection */
     private Connection $db;
@@ -71,9 +75,9 @@ public function setShowRemoveButton(bool $state = true): self
      *
      * @return $this
      */
-    public function setShowTimezoneDropdown(bool $state = true): self
+    public function setShowTimezoneSuggestionInput(bool $state = true): self
     {
-        $this->showTimezoneDropdown = $state;
+        $this->showTimezoneSuggestionInput = $state;
 
         return $this;
     }
@@ -195,14 +199,38 @@ protected function assemble(): void
             'placeholder'   => $this->translate('e.g. working hours, on call, etc ...')
         ]);
 
-        if ($this->showTimezoneDropdown) {
-            $this->addElement('select', 'timezone', [
-                'required'     => true,
-                'label'        => $this->translate('Schedule Timezone'),
-                'description'  => $this->translate('Select the time zone in which this schedule operates.'),
-                'multiOptions' => array_combine(DateTimeZone::listIdentifiers(), DateTimeZone::listIdentifiers()),
-                'value'        => date_default_timezone_get(),
-            ]);
+        if ($this->showTimezoneSuggestionInput) {
+            $this->addElement(
+                'suggestion',
+                'timezone',
+                [
+                    'suggestionsUrl' => Url::fromPath('notifications/suggest/timezone', [
+                        'showCompact' => true, '_disableLayout' => 1
+                    ]),
+                    'label'          => $this->translate('Schedule Timezone'),
+                    'value'          => date_default_timezone_get(),
+                    'validators'     => [
+                        new CallbackValidator(function ($value, $validator) {
+                            foreach (IntlTimeZone::createEnumeration() as $tz) {
+                                try {
+                                    if (
+                                        (new DateTime('now', new DateTimeZone($tz)))->getTimezone()->getLocation()
+                                        && $value === $tz
+                                    ) {
+                                        return true;
+                                    }
+                                } catch (Throwable $_) {
+                                    continue;
+                                }
+                            }
+
+                            $validator->addMessage($this->translate('Invalid timezone'));
+
+                            return false;
+                        })
+                    ]
+                ]
+            );
         }
 
         $this->addElement('submit', 'submit', [