commit 0e2d1cd54abfcf359025e498f0bf26e474c665f1
Author: Lewin Probst <info@emirror.de>
Date:   Wed Mar 18 12:29:36 2020 +0100

    Initial version, untested.

diff --git a/etc/config.php b/etc/config.php
new file mode 100644
index 0000000..b248749
--- /dev/null
+++ b/etc/config.php
@@ -0,0 +1,5 @@
+<?php
+
+return [
+    "element_type_module" => "form",
+];
diff --git a/module.php b/module.php
new file mode 100644
index 0000000..8dd6263
--- /dev/null
+++ b/module.php
@@ -0,0 +1,148 @@
+<?php
+
+use Lewp\Resolve;
+use Lewp\VarFolder;
+
+return new class extends Lewp\Module
+{
+    const OPTIONS_ELEMENTS = 'elements';
+    const OPTIONS_ELEMENT = 'element';
+
+    // element specific
+    const OPTIONS_SHOW_PLACEHOLDER = 'show_placeholder';
+    const OPTIONS_TYPE = 'type';
+    const OPTIONS_CONTENT = 'content';
+
+    // form generics
+    const OPTIONS_METHOD = 'method';
+    const OPTIONS_ACTION = 'action';
+
+    private $non_attribute_options = [
+        self::OPTIONS_ELEMENTS => false,
+        self::OPTIONS_ELEMENT => false,
+        self::OPTIONS_CONTENT => false,
+    ];
+
+    private $element_id = 0;
+
+    private function canContainData(array $element)
+    {
+        $non_data_elements = [
+            [
+                self::OPTIONS_ELEMENT => "button"
+            ],
+            [
+                self::OPTIONS_ELEMENT => "input",
+                self::OPTIONS_TYPE => "submit",
+            ],
+        ];
+        foreach ($non_data_elements as $non) {
+            if (count(array_intersect($non, $element)) == count($non)) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    private function createFormElement(array $element)
+    {
+        $element += [self::OPTIONS_CONTENT => ''];
+        if ($this->canContainData($element)) {
+            $element["name"] = implode('-', [
+                $this->getModuleName(),
+                $this->getExecutionCount(),
+                $this->element_id++,
+            ]);
+        } else {
+            unset($element["name"]);
+        }
+
+        $form_element = $this->createAndSetupElement(
+            $element[self::OPTIONS_ELEMENT],
+            $element[self::OPTIONS_CONTENT],
+            array_diff_key($element, $this->non_attribute_options)
+        );
+        foreach ($element[self::OPTIONS_ELEMENTS] as $element) {
+            $form_element->appendChild($this->createFormElement($element));
+        }
+        return $form_element;
+    }
+
+    private function setupForm(array $elements)
+    {
+        foreach ($elements as $element) {
+            $this->appendChild($this->createFormElement($element));
+        }
+    }
+
+    private function collectFormKeys() {
+        return preg_grep(
+            '/'.
+            $this->getModuleName()
+            .'-'
+            .$this->getExecutionCount()
+            .'-\d+'
+            .'/',
+            array_keys($_POST)
+        );
+    }
+
+    /**
+     * \brief IMPORTANT: Needs to be called AFTER setupForm to work correctly!
+     */
+    private function isSubmitted()
+    {
+        return count($this->collectFormKeys()) > 0;
+    }
+
+    public function getData()
+    {
+        if (!$this->isSubmitted()) {
+            return null;
+        }
+        $data = [];
+        $keys = $this->collectFormKeys();
+        sort($keys, SORT_NUMERIC);
+        foreach ($keys as $key) {
+            $data []= $_POST[$key];
+        }
+        return $data;
+    }
+
+    private function processAction($action)
+    {
+        if ($action === '/') {
+            return '/'.$this->getLanguage();
+        }
+        if (strpos($action, '/') === 0) {
+            return '/'.$this->getLanguage().$action;
+        }
+        return implode('/', [
+            '',
+            $this->getLanguage(),
+            ($action ?? Resolve::idToUri($this->getPageId())),
+        ]);
+    }
+
+    public function run(array $options = []) : bool
+    {
+        // SETUP FORM ATTRIBUTES
+        $this->setAttribute('method', $options[self::OPTIONS_METHOD] ?? 'POST');
+        $this->setAttribute(
+            'action',
+            $this->processAction($options[self::OPTIONS_ACTION]) ?? '/'
+        );
+
+
+        $this->setupForm($options[self::OPTIONS_ELEMENTS]);
+        if ($this->isSubmitted()) {
+            return false;
+        }
+        return true;
+    }
+
+    public function onWebsocketRequest(
+        \Lewp\Websocket\Message $message
+    ) : \Lewp\Websocket\Message {
+    }
+};