feat: add otherLangUrl() for simple language switchers

RockFrontend.module.php

@@ -195,6 +195,7 @@ public function init()
     $this->addHookBefore("Inputfield::render", $this, "addFooterlinksNote");
     $this->addHookAfter("Page::changed", $this, "resetCustomLess");
     $this->addHookBefore("Page::render", $this, "createCustomLess");
+    $this->addHookMethod("Page::otherLangUrl", $this, "otherLangUrl");
 
     // health checks
     $this->checkHealth();
@@ -1462,6 +1463,18 @@ public function minifyFile($file, $minFile = null): string
     return $minFile->path;
   }
 
+  /**
+   * Get other's language url of current page
+   * For super-simple language switchers, see here:
+   * https://processwire.com/talk/topic/12243-language-switcher-on-front-end/?do=findComment&comment=178873
+   */
+  public function otherLangUrl(HookEvent $event): void
+  {
+    $page = $event->object;
+    $lang = $this->wire->languages->findOther()->first();
+    $event->return = $page->localUrl($lang);
+  }
+
   /**
    * Apply postCSS rules to given string
    */