<?php
/**
 * Permalink bootstrap + rewrite rule flush owner.
 *
 * WordPress snapshots `permalink_structure` into `$wp_rewrite` before the theme loads
 * (wp-settings.php, ahead of functions.php). On a fresh install that option is empty, so
 * no post/page permalink rules exist and every single post resolves to 404 until someone
 * re-saves Settings → Permalinks.
 *
 * `ensure_permalink_structure()` mirrors what wp-admin/options-permalink.php does:
 * `WP_Rewrite::set_permalink_structure()` persists the option *and* refreshes the in-memory
 * snapshot for the current request. Hooking it on `after_setup_theme` (still inside
 * wp-settings.php, before the main query is parsed) fixes the very first request instead of
 * only the next one.
 *
 * @package Jio
 */

namespace Jio\Core;

defined('ABSPATH') || exit;

class RewriteBootstrap {

    private static $instance = null;

    /**
     * Structure installed on a site that never chose one. `/%postname%/` is the CMS-friendly
     * default and is what the theme's own routing has always assumed.
     */
    public const DEFAULT_STRUCTURE = '/%postname%/';

    private function __construct() {}

    public static function get_instance(): self {
        if (null === self::$instance) {
            self::$instance = new self();
        }
        return self::$instance;
    }

    public function init(): void {
        // Runs inside wp-settings.php, after the theme's rules are registered but before
        // wp-blog-header.php parses the query — the last point this can still affect the
        // current request.
        add_action('after_setup_theme', [$this, 'ensure_permalink_structure'], 1);
        add_action('after_switch_theme', [$this, 'flush_on_activate']);
        // Version bumps land here rather than on `init`: `init` runs before every
        // add_rewrite_rule() callback, and core defers pre-wp_loaded flushes anyway.
        add_action('wp_loaded', [$this, 'flush_when_version_changes'], 20);
    }

    /**
     * Guarantee a usable permalink structure so pretty rules actually apply.
     *
     * A structure the administrator chose is never overridden — only an empty one is filled.
     */
    public function ensure_permalink_structure(): void {
        $structure = (string) get_option('permalink_structure');
        if ($structure !== '') {
            return;
        }

        global $wp_rewrite;
        if ($wp_rewrite instanceof \WP_Rewrite) {
            $wp_rewrite->set_permalink_structure(self::DEFAULT_STRUCTURE);
            return;
        }

        // No rewrite object (CLI/tests): persist the option so the next request boots sane.
        update_option('permalink_structure', self::DEFAULT_STRUCTURE);
    }

    /**
     * Theme activation: persist the theme's own rewrite rules immediately.
     */
    public function flush_on_activate(): void {
        flush_rewrite_rules();
    }

    /**
     * Self-heal after a theme version bump without the repeated flush the old
     * `init`-hook version stamp caused on every first request of a new version.
     */
    public function flush_when_version_changes(): void {
        $flushed = (string) get_option('jio_rewrite_flushed_version', '');
        if ($flushed === JIO_VERSION) {
            return;
        }

        flush_rewrite_rules();
        update_option('jio_rewrite_flushed_version', JIO_VERSION);
    }
}