<?php

declare(strict_types=1);

namespace App\Filters;

use CodeIgniter\Filters\FilterInterface;
use CodeIgniter\HTTP\RequestInterface;
use CodeIgniter\HTTP\ResponseInterface;

/**
 * Canonical URL enforcement for SEO: any request that differs from the
 * canonical lowercase, no-trailing-slash form is 301-redirected before
 * routing. Prevents duplicate-content across case variants and slashes.
 */
final class SeoCanonical implements FilterInterface
{
    public function before(RequestInterface $request, $arguments = null)
    {
        if (! $request instanceof \CodeIgniter\HTTP\IncomingRequest) {
            return null;
        }

        // Only GET/HEAD matter for indexing.
        if (! in_array(strtolower($request->getMethod()), ['get', 'head'], true)) {
            return null;
        }

        $path = trim(uri_string());
        if ($path === '') {
            $path = trim($request->getUri()->getPath(), '/');
        }

        // Skip files that legitimately end with a slash-like pattern or assets
        if ($path === '' || str_contains($path, '.')) {
            return null;
        }

        $needsRedirect = false;

        // trailing slash
        if (str_ends_with($path, '/')) {
            $path          = rtrim($path, '/');
            $needsRedirect = true;
        }

        // uppercase / mixed case
        if ($path !== mb_strtolower($path)) {
            $path          = mb_strtolower($path);
            $needsRedirect = true;
        }

        // multiple consecutive slashes
        if (str_contains($path, '//')) {
            $path          = preg_replace('#/+#', '/', $path);
            $needsRedirect = true;
        }

        if ($needsRedirect) {
            return redirect()->to($path !== '' ? '/' . ltrim((string) $path, '/') : '/')
                ->setStatusCode(301);
        }

        return null;
    }

    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null)
    {
        return null;
    }
}