From b2511369a6894d00efb9a421bdfbbff19e527b6e Mon Sep 17 00:00:00 2001
From: Maximilian Haye <m.haye@tu-berlin.de>
Date: Thu, 19 Dec 2024 18:16:58 +0100
Subject: [PATCH] feat: add generated_id_element

See: questionpy-org/questionpy-sdk#140
---
 classes/form/elements/form_element.php        |  3 +-
 .../form/elements/generated_id_element.php    | 60 +++++++++++++++++++
 2 files changed, 62 insertions(+), 1 deletion(-)
 create mode 100644 classes/form/elements/generated_id_element.php

diff --git a/classes/form/elements/form_element.php b/classes/form/elements/form_element.php
index 852b3ae..fcc3ca0 100644
--- a/classes/form/elements/form_element.php
+++ b/classes/form/elements/form_element.php
@@ -27,7 +27,7 @@
  * @copyright  2022 TU Berlin, innoCampus {@link https://www.questionpy.org}
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
-#[array_polymorphic('kind', variants: [
+#[array_polymorphic(discriminator: 'kind', variants: [
     'checkbox' => checkbox_element::class,
     'checkbox_group' => checkbox_group_element::class,
     'group' => group_element::class,
@@ -38,6 +38,7 @@
     'static_text' => static_text_element::class,
     'input' => text_input_element::class,
     'textarea' => text_area_element::class,
+    'id' => generated_id_element::class,
 ], fallbackvariant: fallback_element::class)]
 abstract class form_element implements qpy_renderable {
 }
diff --git a/classes/form/elements/generated_id_element.php b/classes/form/elements/generated_id_element.php
new file mode 100644
index 0000000..44ca247
--- /dev/null
+++ b/classes/form/elements/generated_id_element.php
@@ -0,0 +1,60 @@
+<?php
+// This file is part of the QuestionPy Moodle plugin - https://questionpy.org
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace qtype_questionpy\form\elements;
+
+use core\uuid;
+use qtype_questionpy\form\context\render_context;
+
+
+/**
+ * Generates a unique ID which won't change across form saves.
+ *
+ * @package    qtype_questionpy
+ * @author     Maximilian Haye
+ * @copyright  2024 TU Berlin, innoCampus {@link https://www.questionpy.org}
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class generated_id_element extends form_element {
+    /**
+     * Trivial constructor.
+     *
+     * @param string $name
+     */
+    public function __construct(
+        /** @var string $name */
+        public string $name
+    ) {
+    }
+
+    /**
+     * Render this item to the given context.
+     *
+     * @param render_context $context target context
+     * @package qtype_questionpy
+     */
+    public function render_to(render_context $context): void {
+        $mangledname = $context->mangle_name($this->name);
+        $value = $context->moodleform->optional_param(
+            $mangledname,
+            null,
+            PARAM_ALPHANUMEXT
+        ) ?? $context->data[$this->name] ?? uuid::generate();
+
+        $context->add_element('hidden', $mangledname, $value);
+        $context->set_type($this->name, PARAM_ALPHANUMEXT);
+    }
+}
\ No newline at end of file