<?php

namespace App\Example;

use Doctrine\Common\Cache\Cache;
use GuzzleHttp\Client;
use Symfony\Component\Filesystem\Filesystem;

interface Fetcher
{
    public function fetch(string $url): string;
}

class HttpFetcher implements Fetcher
{
    /**
     * @var Client
     */
    private $httpClient;


    public function fetch(string $url): string
    {
        return $this->httpClient->get($url);
    }
}

abstract class DecoratorFetcher implements Fetcher
{
    /**
     * @var Fetcher
     */
    protected $next;

    public function __construct(Fetcher $next)
    {
        $this->next = $next;
    }
}

class CachingFetcher extends DecoratorFetcher
{
    private const CACHE_ID = 'cycki';

    /**
     * @var Cache
     */
    private $cache;

    public function __construct(Fetcher $next, Cache $cache)
    {
        parent::__construct($next);

        $this->cache = $cache;
    }

    public function fetch(string $url): string
    {
        if ($this->cache->contains(self::CACHE_ID)) {
            return $this->cache->fetch(self::CACHE_ID);
        }

        $content = $this->fetch($url);

        $this->cache->save(self::CACHE_ID, $content);

        return $content;
    }
}

class CreatingBackupFetcher extends DecoratorFetcher
{
    private const FILE = 'some/path.txt';

    /**
     * @var Filesystem
     */
    private $filesystem;

    public function __construct(Fetcher $next, Filesystem $filesystem)
    {
        parent::__construct($next);

        $this->filesystem = $filesystem;
    }

    public function fetch(string $url): string
    {
        $content = $this->next->fetch($url);

        $this->filesystem->remove(self::FILE);

        $this->filesystem->touch(self::FILE);

        $this->filesystem->appendToFile(self::FILE, $content);

        return $content;
    }
}