<?php
declare(strict_types=1);

namespace WPMultiCity;

final class Helpers
{
    private static ?string $current_town_memo = null;
    private static bool $current_town_resolved = false;
    private static array $term_cache = [];

    public static function reset_cache(): void
    {
        self::$current_town_memo = null;
        self::$current_town_resolved = false;
        self::$term_cache = [];
    }

    public static function get_term_by_slug(string $slug, string $taxonomy = 'town'): ?\WP_Term
    {
        $key = $taxonomy . '|' . $slug;
        if (array_key_exists($key, self::$term_cache)) {
            return self::$term_cache[$key];
        }
        $term = \get_term_by('slug', $slug, $taxonomy);
        return self::$term_cache[$key] = ($term instanceof \WP_Term) ? $term : null;
    }

    public static function current_town(): ?string
    {
        if (self::$current_town_resolved) {
            return self::$current_town_memo;
        }

        $uri = $_SERVER['REQUEST_URI'] ?? '/';
        $first_segment = self::first_path_segment($uri);

        $resolved = null;
        if ($first_segment !== null) {
            $terms = \get_terms('town', [
                'hide_empty' => false,
                'fields'     => 'id=>slug',
            ]);
            if (is_array($terms) && in_array($first_segment, $terms, true)) {
                $resolved = $first_segment;
            }
        }

        if ($resolved === null) {
            $resolved = \apply_filters('wpmc_main_town_slug', null);
            if (!is_string($resolved) || $resolved === '') {
                $resolved = null;
            }
        }

        $resolved = \apply_filters('wpmc_current_town_slug', $resolved);
        if (!is_string($resolved) || $resolved === '') {
            $resolved = null;
        }

        self::$current_town_memo = $resolved;
        self::$current_town_resolved = true;
        return $resolved;
    }

    private static function first_path_segment(string $uri): ?string
    {
        $path = strtok($uri, '?');
        if ($path === false) {
            return null;
        }
        $parts = array_values(array_filter(explode('/', $path), static fn(string $p) => $p !== ''));
        return $parts[0] ?? null;
    }
}