<?php
declare(strict_types=1);

namespace WPMultiCity;

final class Redirect
{
    public static function register(): void
    {
        \add_action('template_redirect', [self::class, 'handle'], 1);
    }

    public static function handle(): void
    {
        if (\is_admin() || (\defined('DOING_AJAX') && \DOING_AJAX)) {
            return;
        }
        if (!\is_404()) {
            return;
        }

        $main = Helpers::main_town_slug();
        if ($main === null) {
            return;
        }

        $slug = self::extract_last_segment($_SERVER['REQUEST_URI'] ?? '/');
        if ($slug === null) {
            return;
        }

        $candidates = \get_posts([
            'name'           => $slug,
            'post_type'      => 'page',
            'post_status'    => ['private', 'publish'],
            'posts_per_page' => 1,
            'no_found_rows'  => true,
        ]);
        if (empty($candidates)) {
            return;
        }

        $candidate_id = (int) $candidates[0]->ID;

        if (!Helpers::acf_ready() || !\function_exists('get_field')) {
            return;
        }
        $rows = \get_field('page_unic', 'option');
        if (!is_array($rows)) {
            return;
        }

        foreach ($rows as $row) {
            if (!is_array($row)) {
                continue;
            }
            if ((int) ($row['page_new'] ?? 0) !== $candidate_id) {
                continue;
            }
            $town_term_id = (int) ($row['town'] ?? 0);
            $orig_id      = (int) ($row['page_old'] ?? 0);
            if (!$town_term_id || !$orig_id) {
                continue;
            }
            $term = \get_term_by('id', $town_term_id, 'town');
            if (!($term instanceof \WP_Term) || $term->slug === '' || $term->slug === $main) {
                continue;
            }
            $orig_permalink = Helpers::without_url_filters(
                static fn () => \get_permalink($orig_id)
            );
            if (!is_string($orig_permalink) || $orig_permalink === '') {
                continue;
            }
            $path_only = Helpers::remove_domain_link($orig_permalink);
            $redirect_to = '/' . $term->slug . $path_only;
            \wp_safe_redirect($redirect_to, 301);
            exit;
        }
    }

    private static function extract_last_segment(string $uri): ?string
    {
        $path = strtok($uri, '?');
        if ($path === false) {
            return null;
        }
        $parts = array_values(array_filter(
            explode('/', $path),
            static fn (string $p) => $p !== ''
        ));
        $last = end($parts);
        return $last !== false && $last !== '' ? $last : null;
    }
}