<?php

namespace State;

use Machine\CNC6600;
use RuntimeException;

class Persister
{
	private const WORKING_DIR = __DIR__ . '/../../var';


	public function persist(string $identifier, CNC6600 $CNC6600): void
	{
		$filename = $this->getFilename($identifier);
		$state = serialize($CNC6600);
		$state = gzcompress($state, 6);
		@file_put_contents($filename, $state);
	}


	public function load(string $identifier): CNC6600
	{
		$filename = $this->getFilename($identifier);
		$this->guardStateFileDoesNotExist($filename);
		$state = file_get_contents($filename);
		$state = gzuncompress($state);

		return unserialize($state);
	}


	public function getFilename(string $identifier): string
	{
		$identifier = md5("machine_state_$identifier");

		return self::WORKING_DIR . "/$identifier";
	}


	private function guardStateFileDoesNotExist(string $filename): void
	{
		if (!file_exists($filename)) {
			throw new RuntimeException('State not found');
		}
	}
}