<?php
/**
 * @package         Regular Labs Library
 * @version         23.12.10783
 * 
 * @author          Peter van Westen <[email protected]>
 * @link            https://regularlabs.com
 * @copyright       Copyright © 2023 Regular Labs All Rights Reserved
 * @license         GNU General Public License version 2 or later
 */

namespace RegularLabs\Library;

defined('_JEXEC') or die;

use Joomla\CMS\Application\CMSApplication as JCMSApplication;
use Joomla\CMS\Application\CMSApplicationInterface as JCMSApplicationInterface;
use Joomla\CMS\Document\Document as JDocument;
use Joomla\CMS\Factory as JFactory;
use Joomla\CMS\Filesystem\File as JFile;
use Joomla\CMS\Version as JVersion;

class Php
{
    static $rl_variables;

    public static function execute(
        string  $rl_string,
        object|false|null $rl_article = null,
        object|false|null $rl_module = null,
        bool    $has_own_return = false
    ): mixed
    {
        self::prepareString($rl_string);

        $function_name = self::getFunctionName($rl_string);

        if ( ! $function_name)
        {
            // Something went wrong!
            return true;
        }

        if ( ! $rl_article && str_contains($rl_string, '$article'))
        {
            if (Input::get('option', '') == 'com_content' && Input::get('view', '') == 'article')
            {
                $rl_article = Article::get(Input::getInt('id'));
            }
        }

        $rl_pre_variables = array_keys(get_defined_vars());

        ob_start();
        $rl_post_variables = $function_name(self::$rl_variables, $rl_article, $rl_module);
        $rl_output         = ob_get_contents();
        ob_end_clean();

        if ($has_own_return)
        {
            return $rl_post_variables;
        }

        if ( ! is_array($rl_post_variables))
        {
            return $rl_output;
        }

        $rl_diff_variables = array_diff(array_keys($rl_post_variables), $rl_pre_variables);

        foreach ($rl_diff_variables as $rl_diff_key)
        {
            if (
                in_array($rl_diff_key, ['Itemid', 'mainframe', 'app', 'document', 'doc', 'database', 'db', 'user'], true)
                || (substr($rl_diff_key, 0, 4) == 'rl_')
            )
            {
                continue;
            }

            self::$rl_variables[$rl_diff_key] = $rl_post_variables[$rl_diff_key];
        }

        return $rl_output;
    }

    public static function getApplication(): JCMSApplicationInterface
    {
        if (Input::get('option', '') != 'com_finder')
        {
            return JFactory::getApplication();
        }

        return JCMSApplication::getInstance('site');
    }

    public static function getDocument(): JDocument
    {
        if (Input::get('option', '') != 'com_finder')
        {
            return Document::get();
        }

        $lang    = JFactory::getLanguage();
        $version = new JVersion;

        $attributes = [
            'charset'      => 'utf-8',
            'lineend'      => 'unix',
            'tab'          => "\t",
            'language'     => $lang->getTag(),
            'direction'    => $lang->isRtl() ? 'rtl' : 'ltr',
            'mediaversion' => $version->getMediaVersion(),
        ];

        return JDocument::getInstance('html', $attributes);
    }

    private static function createFunctionInMemory(string $string): void
    {
        $file_name = getmypid() . '_' . md5($string);

        $tmp_path  = JFactory::getApplication()->get('tmp_path', JPATH_ROOT . '/tmp');
        $temp_file = $tmp_path . '/regularlabs/custom_php/' . $file_name;

        // Write file
        if ( ! file_exists($temp_file) || is_writable($temp_file))
        {
            JFile::write($temp_file, $string);
        }

        // Include file
        include_once $temp_file;

        // Delete file
        if ( ! JFactory::getApplication()->get('debug'))
        {
            @chmod($temp_file, 0777);
            @unlink($temp_file);
        }
    }

    private static function extractUseStatements(string &$string): string
    {
        $use_statements = [];

        $string = trim($string);

        RegEx::matchAll('^use\s+[^\s;]+\s*;', $string, $matches, 'm');

        foreach ($matches as $match)
        {
            $use_statements[] = $match[0];
            $string           = str_replace($match[0], '', $string);
        }

        $string = trim($string);

        return implode("\n", $use_statements);
    }

    private static function generateFileContents(
        string $function_name = 'rl_function',
        string $string = ''
    ): string
    {
        $use_statements = self::extractUseStatements($string);

        $init_variables = self::getVarInits();

        $init_variables[] =
            'if (is_array($rl_variables)) {'
            . 'foreach ($rl_variables as $rl_key => $rl_value) {'
            . '${$rl_key} = $rl_value;'
            . '}'
            . '}';

        $contents = [
            '<?php',
            'defined(\'_JEXEC\') or die;',
            $use_statements,
            'function ' . $function_name . '($rl_variables, $article, $module){',
            implode("\n", $init_variables),
            $string . ';',
            'return get_defined_vars();',
            ';}',
        ];

        $contents = implode("\n", $contents);

        // Remove Zero Width spaces / (non-)joiners
        $contents = str_replace(
            [
                "\xE2\x80\x8B",
                "\xE2\x80\x8C",
                "\xE2\x80\x8D",
            ],
            '',
            $contents
        );

        return $contents;
    }

    private static function getFunctionName(string $string): string|false
    {
        $function_name = 'regularlabs_php_' . md5($string);

        if (function_exists($function_name))
        {
            return $function_name;
        }

        $contents = self::generateFileContents($function_name, $string);
        self::createFunctionInMemory($contents);

        if ( ! function_exists($function_name))
        {
            // Something went wrong!
            return false;
        }

        return $function_name;
    }

    private static function getVarInits(): array
    {
        return [
            '$app = $mainframe = RegularLabs\Library\Php::getApplication();',
            '$document = $doc = RegularLabs\Library\Php::getDocument();',
            '$database = $db = JFactory::getDbo();',
            '$user = $app->getIdentity() ?: JFactory::getUser();',
            '$Itemid = $app->getInput()->getInt(\'Itemid\');',
        ];
    }

    private static function prepareString(string &$string): void
    {
        $string = trim($string);
        $string = str_replace('?><?php', '', $string . '<?php ;');

        if ( ! str_starts_with($string, '<?php'))
        {
            $string = '?>' . $string;

            return;
        }

        $string = substr($string, 5);

        $string = trim($string);
    }
}