<?php

declare(strict_types=1);

namespace AdsDestroyer\Admin;

use AdsDestroyer\Security\CapabilitiesService;
use AdsDestroyer\Settings\OptionsRepository;

/**
 * Gives admin submenu items a stable class to build selectors on.
 *
 * WordPress prints submenu items without an id and offers no filter for that
 * markup, so a rule created on a menu item can only fall back to its position in
 * the tree — and a position stops being meaningful as soon as the menu changes.
 * The class field of the `$submenu` array is the only extension point core
 * offers, and it is enough: a class based selector does not depend on the
 * screen, so the same rule applies everywhere in the admin.
 *
 * Top level menu items and admin bar nodes already carry unique ids and are left
 * untouched.
 *
 * @since 1.0.32
 */
final class MenuAnchorService {

    /**
     * Marks a class the plugin added purely as a selector anchor.
     */
    public const CLASS_PREFIX = 'adsd-anchor-';

    /**
     * Longest readable class before falling back to a hash.
     */
    private const MAX_CLASS_LENGTH = 60;

    private OptionsRepository $options_repository;

    private CapabilitiesService $capabilities_service;

    /**
     * Constructor.
     *
     * @since 1.0.32
     * @param OptionsRepository $options_repository Options repository instance.
     * @param CapabilitiesService $capabilities_service Capabilities service instance.
     */
    public function __construct(
        OptionsRepository $options_repository,
        CapabilitiesService $capabilities_service
    ) {
        $this->options_repository = $options_repository;
        $this->capabilities_service = $capabilities_service;
    }

    /**
     * Append an anchor class to every submenu item.
     *
     * Hooked to `add_menu_classes`, the last step of `wp-admin/includes/menu.php`:
     * `admin_menu` is not enough because plugins register items at any priority
     * (Elementor uses PHP_INT_MAX), while this filter runs after all of them and
     * still before `menu-header.php` renders the sidebar. The menu itself is
     * passed through untouched; only `$submenu` is edited.
     *
     * @since 1.0.32
     * @param mixed $menu Top level menu items, as handed over by the filter.
     * @return mixed The same menu items.
     */
    public function add_anchor_classes($menu = null) {
        if (!$this->should_add_anchors()) {
            return $menu;
        }

        global $submenu;

        if (!is_array($submenu)) {
            return $menu;
        }

        foreach ($submenu as $parent => $items) {
            if (!is_array($items)) {
                continue;
            }

            foreach ($items as $key => $item) {
                if (!is_array($item) || !isset($item[2]) || !is_scalar($item[2])) {
                    continue;
                }

                $anchor = $this->build_anchor_class((string) $parent, (string) $item[2]);
                if ($anchor === '') {
                    continue;
                }

                $existing = isset($item[4]) && is_scalar($item[4]) ? (string) $item[4] : '';
                if (in_array($anchor, preg_split('/\s+/', $existing) ?: [], true)) {
                    continue;
                }

                // phpcs:ignore WordPress.WP.GlobalVariablesOverride.Prohibited -- Editing $submenu on admin_menu is the documented way to alter the admin menu.
                $submenu[$parent][$key][4] = trim($existing . ' ' . $anchor);
            }
        }

        return $menu;
    }

    /**
     * Decide whether anchor classes are needed on this request.
     *
     * @since 1.0.32
     * @return bool True when submenu items should be marked.
     */
    private function should_add_anchors(): bool {
        /**
         * Filters whether admin submenu items receive selector anchor classes.
         *
         * @since 1.0.32
         * @param bool $enabled Whether anchor classes are added.
         */
        if (!apply_filters('adsd_enable_menu_anchors', true)) {
            return false;
        }

        if (!$this->capabilities_service->can_use_selector()) {
            return false;
        }

        // Anchors are only useful while rules are being applied, or while the
        // user is picking blocks and new rules are about to be created.
        if ($this->is_selection_mode_active()) {
            return true;
        }

        return !empty($this->options_repository->get_active_rules());
    }

    /**
     * Check whether the block picker is currently active.
     *
     * @since 1.0.32
     * @return bool True when selection mode is on.
     */
    private function is_selection_mode_active(): bool {
        // phpcs:ignore WordPress.Security.NonceVerification.Recommended -- URL parameter check, not form submission
        if (!isset($_GET['adsd_selection_mode_active'])) {
            return false;
        }

        // phpcs:ignore WordPress.Security.NonceVerification.Recommended -- URL parameter check, not form submission
        return sanitize_text_field(wp_unslash($_GET['adsd_selection_mode_active'])) === '1';
    }

    /**
     * Build the anchor class for a submenu item.
     *
     * The readable form doubles as documentation in the rules table; overly long
     * slug combinations fall back to a hash so the class stays usable.
     *
     * @since 1.0.32
     * @param string $parent_slug Parent menu slug.
     * @param string $item_slug Submenu item slug.
     * @return string Class name, or an empty string when none can be built.
     */
    private function build_anchor_class(string $parent_slug, string $item_slug): string {
        $item = $this->normalize_slug($item_slug);
        if ($item === '') {
            return '';
        }

        $parent = $this->normalize_slug($parent_slug);
        $readable = self::CLASS_PREFIX . ($parent === '' ? $item : $parent . '-' . $item);

        if (strlen($readable) <= self::MAX_CLASS_LENGTH) {
            return $readable;
        }

        return self::CLASS_PREFIX . substr(md5($parent_slug . '|' . $item_slug), 0, 10);
    }

    /**
     * Reduce a menu slug to characters usable in a class name.
     *
     * Menu slugs are either file names (`update-core.php`) or query strings
     * (`admin.php?page=elementor-one-upgrade`); for the latter the `page`
     * parameter alone identifies the screen.
     *
     * @since 1.0.32
     * @param string $slug Menu slug.
     * @return string Normalized slug.
     */
    private function normalize_slug(string $slug): string {
        if (preg_match('/[?&]page=([^&]+)/', $slug, $matches) === 1) {
            $slug = $matches[1];
        }

        $slug = (string) preg_replace('/\.php$/i', '', $slug);
        $slug = (string) preg_replace('/[^A-Za-z0-9_-]+/', '-', $slug);

        return trim(strtolower($slug), '-');
    }
}