<?php

/**
 * @package     Joomla.Plugin
 * @subpackage  System.cache
 *
 * @copyright   (C) 2022 Open Source Matters, Inc. <https://www.joomla.org>
 * @license     GNU General Public License version 2 or later; see LICENSE.txt
 */

namespace Joomla\Plugin\System\Cache\Extension;

use Joomla\CMS\Cache\CacheController;
use Joomla\CMS\Cache\CacheControllerFactoryInterface;
use Joomla\CMS\Document\FactoryInterface as DocumentFactoryInterface;
use Joomla\CMS\Plugin\CMSPlugin;
use Joomla\CMS\Plugin\PluginHelper;
use Joomla\CMS\Profiler\Profiler;
use Joomla\CMS\Router\SiteRouter;
use Joomla\CMS\Uri\Uri;
use Joomla\Event\DispatcherInterface;
use Joomla\Event\Event;
use Joomla\Event\Priority;
use Joomla\Event\SubscriberInterface;

// phpcs:disable PSR1.Files.SideEffects
\defined('_JEXEC') or die;
// phpcs:enable PSR1.Files.SideEffects

/**
 * Joomla! Page Cache Plugin.
 *
 * @since  1.5
 */
final class Cache extends CMSPlugin implements SubscriberInterface
{
    /**
     * Cache instance.
     *
     * @var    CacheController
     * @since  1.5
     */
    private $cache;

    /**
     * The application's document factory interface
     *
     * @var   DocumentFactoryInterface
     * @since 4.2.0
     */
    private $documentFactory;

    /**
     * Cache controller factory interface
     *
     * @var    CacheControllerFactoryInterface
     * @since  4.2.0
     */
    private $cacheControllerFactory;

    /**
     * The application profiler, used when Debug Site is set to Yes in Global Configuration.
     *
     * @var    Profiler|null
     * @since  4.2.0
     */
    private $profiler;

    /**
     * The frontend router, injected by the service provider.
     *
     * @var   SiteRouter|null
     * @since 4.2.0
     */
    private $router;

    /**
     * Constructor
     *
     * @param   DispatcherInterface              $subject                 The object to observe
     * @param   array                            $config                  An optional associative
     *                                                                    array of configuration
     *                                                                    settings. Recognized key
     *                                                                    values include 'name',
     *                                                                    'group', 'params',
     *                                                                    'language'
     *                                                                    (this list is not meant
     *                                                                    to be comprehensive).
     * @param   DocumentFactoryInterface         $documentFactory         The application's
     *                                                                    document factory
     * @param   CacheControllerFactoryInterface  $cacheControllerFactory  Cache controller factory
     * @param   Profiler|null                    $profiler                The application profiler
     * @param   SiteRouter|null                  $router                  The frontend router
     *
     * @since   4.2.0
     */
    public function __construct(
        &$subject,
        $config,
        DocumentFactoryInterface $documentFactory,
        CacheControllerFactoryInterface $cacheControllerFactory,
        ?Profiler $profiler,
        ?SiteRouter $router
    ) {
        parent::__construct($subject, $config);

        $this->documentFactory        = $documentFactory;
        $this->cacheControllerFactory = $cacheControllerFactory;
        $this->profiler               = $profiler;
        $this->router                 = $router;
    }

    /**
     * Returns an array of CMS events this plugin will listen to and the respective handlers.
     *
     * @return  array
     *
     * @since   4.2.0
     */
    public static function getSubscribedEvents(): array
    {
        /**
         * Note that onAfterRender and onAfterRespond must be the last handlers to run for this
         * plugin to operate as expected. These handlers put pages into cache. We must make sure
         * that a. the page SHOULD be cached and b. we are caching the complete page, as it's
         * output to the browser.
         */
        return [
            'onAfterRoute'   => 'onAfterRoute',
            'onAfterRender'  => ['onAfterRender', Priority::LOW],
            'onAfterRespond' => ['onAfterRespond', Priority::LOW],
        ];
    }

    /**
     * Returns a cached page if the current URL exists in the cache.
     *
     * @param   Event  $event  The Joomla event being handled
     *
     * @return  void
     *
     * @since   4.0.0
     */
    public function onAfterRoute(Event $event)
    {
        if (!$this->appStateSupportsCaching()) {
            return;
        }

        // If any `pagecache` plugins return false for onPageCacheSetCaching, do not use the cache.
        PluginHelper::importPlugin('pagecache');

        $results = $this->getApplication()->triggerEvent('onPageCacheSetCaching');

        $this->getCacheController()->setCaching(!in_array(false, $results, true));

        $data = $this->getCacheController()->get($this->getCacheKey());

        if ($data === false) {
            // No cached data.
            return;
        }

        // Set the page content from the cache and output it to the browser.
        $this->getApplication()->setBody($data);

        echo $this->getApplication()->toString((bool) $this->getApplication()->get('gzip'));

        // Mark afterCache in debug and run debug onAfterRespond events, e.g. show Joomla Debug Console if debug is active.
        if (JDEBUG) {
            // Create a document instance and load it into the application.
            $document = $this->documentFactory
                ->createDocument($this->getApplication()->getInput()->get('format', 'html'));
            $this->getApplication()->loadDocument($document);

            if ($this->profiler) {
                $this->profiler->mark('afterCache');
            }

            $this->getApplication()->triggerEvent('onAfterRespond');
        }

        // Closes the application.
        $this->getApplication()->close();
    }

    /**
     * Does the current application state allow for caching?
     *
     * The following conditions must be met:
     * * This is the frontend application. This plugin does not apply to other applications.
     * * This is a GET request. This plugin does not apply to POST, PUT etc.
     * * There is no currently logged in user (pages might have user–specific content).
     * * The message queue is empty.
     *
     * The first two tests are cached to make early returns possible; these conditions cannot change
     * throughout the lifetime of the request.
     *
     * The other two tests MUST NOT be cached because auto–login plugins may fire anytime within
     * the application lifetime logging in a user and messages can be generated anytime within the
     * application's lifetime.
     *
     * @return  boolean
     * @since   4.2.0
     */
    private function appStateSupportsCaching(): bool
    {
        static $isSite = null;
        static $isGET  = null;

        if ($isSite === null) {
            $isSite = $this->getApplication()->isClient('site');
            $isGET  = $this->getApplication()->getInput()->getMethod() === 'GET';
        }

        // Boolean short–circuit evaluation means this returns fast false when $isSite is false.
        return $isSite
            && $isGET
            && $this->getApplication()->getIdentity()->guest
            && empty($this->getApplication()->getMessageQueue());
    }

    /**
     * Get the cache controller
     *
     * @return  CacheController
     * @since   4.2.0
     */
    private function getCacheController(): CacheController
    {
        if (!empty($this->cache)) {
            return $this->cache;
        }

        // Set the cache options.
        $options = [
            'defaultgroup' => 'page',
            'browsercache' => $this->params->get('browsercache', 0),
            'caching'      => false,
        ];

        // Instantiate cache with previous options.
        $this->cache = $this->cacheControllerFactory->createCacheController('page', $options);

        return $this->cache;
    }

    /**
     * Get a cache key for the current page based on the url and possible other factors.
     *
     * @return  string
     *
     * @since   3.7
     */
    private function getCacheKey(): string
    {
        static $key;

        if (!$key) {
            PluginHelper::importPlugin('pagecache');

            $parts   = $this->getApplication()->triggerEvent('onPageCacheGetKey');
            $parts[] = Uri::getInstance()->toString();

            $key = md5(serialize($parts));
        }

        return $key;
    }

    /**
     * After Render Event. Check whether the current page is excluded from cache.
     *
     * @param   Event  $event  The CMS event we are handling.
     *
     * @return  void
     *
     * @since   3.9.12
     */
    public function onAfterRender(Event $event)
    {
        if (!$this->appStateSupportsCaching() || $this->getCacheController()->getCaching() === false) {
            return;
        }

        if ($this->isExcluded() === true) {
            $this->getCacheController()->setCaching(false);

            return;
        }

        // Disable compression before caching the page.
        $this->getApplication()->set('gzip', false);
    }

    /**
     * Check if the page is excluded from the cache or not.
     *
     * @return   boolean  True if the page is excluded else false
     *
     * @since    3.5
     */
    private function isExcluded(): bool
    {
        // Check if menu items have been excluded.
        $excludedMenuItems = $this->params->get('exclude_menu_items', []);

        if ($excludedMenuItems) {
            // Get the current menu item.
            $active = $this->getApplication()->getMenu()->getActive();

            if ($active && $active->id && in_array((int) $active->id, (array) $excludedMenuItems)) {
                return true;
            }
        }

        // Check if regular expressions are being used.
        $exclusions = $this->params->get('exclude', '');

        if ($exclusions) {
            // Convert the exclusions into a normalised array
            $exclusions       = str_replace(["\r\n", "\r"], "\n", $exclusions);
            $exclusions       = explode("\n", $exclusions);
            $filterExpression = function ($x) {
                return $x !== '';
            };
            $exclusions       = array_filter($exclusions, $filterExpression);

            // Gets the internal (non-SEF) and the external (possibly SEF) URIs.
            $internalUrl = '/index.php?'
                . Uri::getInstance()->buildQuery($this->router->getVars());
            $externalUrl = Uri::getInstance()->toString();

            $reduceCallback
                = function (bool $carry, string $exclusion) use ($internalUrl, $externalUrl) {
                    // Test both external and internal URIs
                    return $carry && preg_match(
                        '#' . $exclusion . '#i',
                        $externalUrl . ' ' . $internalUrl,
                        $match
                    );
                };
            $excluded       = array_reduce($exclusions, $reduceCallback, false);

            if ($excluded) {
                return true;
            }
        }

        // If any pagecache plugins return true for onPageCacheIsExcluded, exclude.
        PluginHelper::importPlugin('pagecache');

        $results = $this->getApplication()->triggerEvent('onPageCacheIsExcluded');

        return in_array(true, $results, true);
    }

    /**
     * After Respond Event. Stores page in cache.
     *
     * @param   Event  $event  The application event we are handling.
     *
     * @return  void
     *
     * @since   1.5
     */
    public function onAfterRespond(Event $event)
    {
        if (!$this->appStateSupportsCaching() || $this->getCacheController()->getCaching() === false) {
            return;
        }

        // Saves current page in cache.
        $this->getCacheController()->store($this->getApplication()->getBody(), $this->getCacheKey());
    }
}
