<?php

use Lewp\{Module, Resolve, VarFolder};

return new class extends Module
{
    const OPTIONS_ELEMENTS = 'elements';
    const OPTIONS_ELEMENT = 'element';
    const OPTIONS_LABEL = 'label';

    // 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,
        self::OPTIONS_LABEL => 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 generateFormElementName(bool $increase_element_id): string
    {
        return implode(
            '-',
            [
                $this->getModuleName(),
                $this->getExecutionCount(),
                ($increase_element_id) ? $this->element_id++ : $this->element_id,
            ]
        );
    }

    private function createFormElementGroup(array $element)
    {
        if (!isset($element[self::OPTIONS_LABEL])) {
            return $this->createFormElement($element);
        } else {
            $label = $this->createLabel($element);
        }

        $wrapper = $this->createAndSetupElement(
            'div',
            '',
            [
                'class' => 'element-container'
            ]
        );
        $wrapper->appendChild($label);

        $form_element = $this->createFormElement($element);

        $wrapper->appendChild($form_element);
        return $wrapper;
    }

    private function createFormElement(array $element)
    {
        $element += [self::OPTIONS_CONTENT => ''];
        if ($this->canContainData($element)) {
            // if no label given, the element id should be increased
            $element["name"] = $this->generateFormElementName(
                true//!array_key_exists($element[self::OPTIONS_LABEL])
            );
            $element["id"] = $element["name"];
        } else {
            unset($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->createFormElementGroup($element));
        }
        return $form_element;
    }

    private function createLabel(array $element)
    {

        $label = $this->createAndSetupElement(
            'label',
            $element[self::OPTIONS_LABEL],
            [
                'for' => $this->generateFormElementName(false),
            ]
        );
        return $label;
    }

    private function setupForm(array $elements)
    {
        foreach ($elements as $element) {
            $this->appendChild($this->createFormElementGroup($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 [];
        }
        $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 {
    }
};