<?php

class CacheItem {
    public string $key;
    protected mixed $value = null;

    public function get(): mixed {
        return $this->value;
    }

    public function set($value): void {
        $this->value = $value;
    }
}

class FilesystemTagAwareAdapter {

    public function __construct() {
        $directory = sys_get_temp_dir() . \DIRECTORY_SEPARATOR . 'symfony-cache';
        $directory .= \DIRECTORY_SEPARATOR . '@';
        if (!is_dir($directory)) {
            @mkdir($directory, 0777, true);
        }
        $directory .= \DIRECTORY_SEPARATOR;

        $this->directory = $directory;
        $this->tmpSuffix = str_replace('/', '-', base64_encode(random_bytes(6)));
    }

    private string $directory;
    private string $tmpSuffix;

    private function getFile(string $id): string {
        return $this->directory . str_replace('/', '-', base64_encode(hash('xxh128', $id, true)));
    }

    public function __destruct() {
        if (is_file($this->directory . $this->tmpSuffix)) {
            unlink($this->directory . $this->tmpSuffix);
        }
    }

    public function getItem(string $key): CacheItem {
        $createCacheItem = \Closure::bind(
            static function ($key, $value) {
                $item = new CacheItem();
                $item->key = $key;
                if (\is_array($value) && \array_key_exists('value', $value)) {
                    $item->value = $value['value'];
                }
                return $item;
            },
            null,
            CacheItem::class
        );

        $file = $this->getFile($key);
        if (!is_file($file) || !$h = @fopen($file, 'r')) {
            return ($createCacheItem)($key, null);
        }
        fgets($h);
        $i = rawurldecode(rtrim(fgets($h)));
        $value = stream_get_contents($h);
        fclose($h);

        if ($i === $key) {
            return ($createCacheItem)($key, unserialize($value));
        }

        return ($createCacheItem)($key, null);
    }

    public function save(CacheItem $item) {
        foreach ([$item] as $item) {
            $tmp = $this->directory . $this->tmpSuffix;
            $h = fopen($tmp, 'x');
            fwrite($h, (0)."\n".rawurlencode($item->key)."\n".serialize(['value' => $item->get()]));
            fclose($h);
            rename($tmp, $this->getFile($item->key));
        }
    }

}

$cache = new FilesystemTagAwareAdapter();
$item = $cache->getItem('key');
$item->set('5');
$cache->save($item);

$item = $cache->getItem('key');
$item->get();

$cache = new FilesystemTagAwareAdapter();
$item = $cache->getItem('key');
$item->set(5);
$cache->save($item);

$item = $cache->getItem('key');
$item->get();