<?php
/**
 * Built-in Cache System
 *
 * Ultra-fast page caching system built into the theme
 * No plugins needed - WP Rocket alternative
 *
 * @package MyTheme
 */

// Exit if accessed directly
if (!defined('ABSPATH')) {
    exit;
}

class MyTheme_Cache_System {

    private $cache_dir;
    private $cache_enabled;
    private $cache_duration;

    /**
     * Constructor
     */
    public function __construct() {
        // Cache settings
        $this->cache_enabled = function_exists('mytheme_get_option') ? mytheme_get_option('cache_enabled', true) : true;
        $this->cache_duration = function_exists('mytheme_get_option') ? mytheme_get_option('cache_duration', 3600) : 3600;

        // Cache directory
        $upload_dir = wp_upload_dir();
        $this->cache_dir = $upload_dir['basedir'] . '/mytheme-cache';

        // Initialize
        $this->init();
    }

    /**
     * Initialize cache system
     */
    private function init() {
        if (!$this->cache_enabled) {
            return;
        }

        // Create cache directory
        $this->create_cache_dir();

        // Start output buffering for page caching
        add_action('template_redirect', array($this, 'start_page_cache'), 1);

        // Clear cache actions
        add_action('save_post', array($this, 'clear_post_cache'));
        add_action('comment_post', array($this, 'clear_post_cache'));
        add_action('switch_theme', array($this, 'clear_all_cache'));
        add_action('mytheme_clear_cache', array($this, 'clear_all_cache'));

        // Admin bar cache clear button
        add_action('admin_bar_menu', array($this, 'add_cache_clear_button'), 999);
        add_action('admin_post_mytheme_clear_cache', array($this, 'handle_cache_clear'));

        // AJAX cache clear
        add_action('wp_ajax_mytheme_clear_cache', array($this, 'ajax_clear_cache'));
    }

    /**
     * Create cache directory
     */
    private function create_cache_dir() {
        if (!file_exists($this->cache_dir)) {
            wp_mkdir_p($this->cache_dir);

            // Add .htaccess for security
            $htaccess = $this->cache_dir . '/.htaccess';
            if (!file_exists($htaccess)) {
                file_put_contents($htaccess, 'deny from all');
            }
        }
    }

    /**
     * Get cache file path
     */
    private function get_cache_file_path($url = null) {
        if ($url === null) {
            $url = $_SERVER['REQUEST_URI'];
        }

        // Generate unique cache key
        $cache_key = md5($url . (is_user_logged_in() ? 'logged_in' : 'guest'));

        return $this->cache_dir . '/' . $cache_key . '.html';
    }

    /**
     * Start page caching
     */
    public function start_page_cache() {
        // Don't cache for logged-in users or admin
        if (is_user_logged_in() || is_admin()) {
            return;
        }

        // Don't cache POST requests
        if ($_SERVER['REQUEST_METHOD'] === 'POST') {
            return;
        }

        // Don't cache search, 404, feeds
        if (is_search() || is_404() || is_feed() || is_trackback()) {
            return;
        }

        // Check if cached version exists
        $cache_file = $this->get_cache_file_path();

        if (file_exists($cache_file)) {
            $cache_age = time() - filemtime($cache_file);

            // Serve cached version if not expired
            if ($cache_age < $this->cache_duration) {
                header('X-MyTheme-Cache: HIT');
                header('Cache-Control: max-age=' . $this->cache_duration);
                readfile($cache_file);
                exit;
            } else {
                // Delete expired cache
                unlink($cache_file);
            }
        }

        // Start output buffering to create cache
        header('X-MyTheme-Cache: MISS');
        ob_start(array($this, 'save_page_cache'));
    }

    /**
     * Save page to cache
     */
    public function save_page_cache($html) {
        // Don't cache if HTML is empty or too small
        if (strlen($html) < 255) {
            return $html;
        }

        // Save to cache file
        $cache_file = $this->get_cache_file_path();
        file_put_contents($cache_file, $html);

        return $html;
    }

    /**
     * Clear post cache
     */
    public function clear_post_cache($post_id) {
        $post_url = get_permalink($post_id);
        $cache_file = $this->get_cache_file_path($post_url);

        if (file_exists($cache_file)) {
            unlink($cache_file);
        }

        // Also clear homepage and category archives
        $this->clear_homepage_cache();
    }

    /**
     * Clear homepage cache
     */
    private function clear_homepage_cache() {
        $home_cache = $this->get_cache_file_path('/');
        if (file_exists($home_cache)) {
            unlink($home_cache);
        }
    }

    /**
     * Clear all cache
     */
    public function clear_all_cache() {
        if (!file_exists($this->cache_dir)) {
            return;
        }

        // Delete all cache files
        $files = glob($this->cache_dir . '/*.html');
        foreach ($files as $file) {
            if (is_file($file)) {
                unlink($file);
            }
        }
    }

    /**
     * Add cache clear button to admin bar
     */
    public function add_cache_clear_button($wp_admin_bar) {
        if (!current_user_can('manage_options')) {
            return;
        }

        $wp_admin_bar->add_node(array(
            'id' => 'mytheme-clear-cache',
            'title' => 'Clear Cache',
            'href' => wp_nonce_url(admin_url('admin-post.php?action=mytheme_clear_cache'), 'clear_cache'),
            'meta' => array(
                'title' => 'Clear MyTheme Cache',
            ),
        ));
    }

    /**
     * Handle cache clear from admin bar
     */
    public function handle_cache_clear() {
        check_admin_referer('clear_cache');

        if (!current_user_can('manage_options')) {
            wp_die('Unauthorized');
        }

        $this->clear_all_cache();

        wp_redirect(wp_get_referer());
        exit;
    }

    /**
     * AJAX clear cache
     */
    public function ajax_clear_cache() {
        check_ajax_referer('mytheme-nonce', 'nonce');

        if (!current_user_can('manage_options')) {
            wp_send_json_error('Unauthorized');
        }

        $this->clear_all_cache();

        wp_send_json_success('Cache cleared successfully');
    }

    /**
     * Get cache statistics
     */
    public function get_cache_stats() {
        if (!file_exists($this->cache_dir)) {
            return array(
                'files' => 0,
                'size' => 0,
            );
        }

        $files = glob($this->cache_dir . '/*.html');
        $total_size = 0;

        foreach ($files as $file) {
            $total_size += filesize($file);
        }

        return array(
            'files' => count($files),
            'size' => size_format($total_size),
            'size_bytes' => $total_size,
        );
    }
}

// Initialize cache system
new MyTheme_Cache_System();

/**
 * Helper function to clear cache
 */
function mytheme_clear_cache() {
    do_action('mytheme_clear_cache');
}