index.php

<?php
require_once('redirects.php');

$path = $_GET['q'] ?? '/';
foreach ($redirects as $r) {
  if (preg_match($r['pattern'], $path) === 1) {
    $location = preg_replace($r['pattern'], $r['redirect'], $path);
    header('Location: '.$location);
    exit;
  }
}

http_response_code(404);