<?php declare(strict_types=1);

define('CACHE_FILE','/home/seb/.cache/test_php_{file}.txt');

print 'get(yep) -> '.get('yep').PHP_EOL;
print 'cache file for yep : '.cache_file_path('yep');

function get(string $x): ?string {
	return cached($x) ?? fetch($x); // @todo fetch is not supposed to cache, no implicite.
}

function cached(string $x): ?string {
	$content = fread(cache_file_stream($x),filesize(cache_file_path($x)));
	return $content === false ? null : $content;
}

function fetch(string $x): ?string {
	$content = (string)time(); // fake content
	throw new \LogicException('re implement this');
	return cache($x, $content);
}

function cache(string $x, string $content): string {
	if(false === fwrite(cache_file_stream($x), $content)) {
		throw new FailToWriteToFile(cache_file_path($x));
	};
	return $content;
}

/** @return resource */
function cache_file_stream(string $x)/*: resource*/ {
	if(false === ($resource = fopen(cache_file_path($x), 'c+'))) {
		throw new FailToOpenFile(cache_file_path($x));
	}
	return $resource;
}

function cache_file_path(string $x): string {
	return strtr(CACHE_FILE,['{file}' => crc32($x)]);
}