<?php
function create_signed_code(
	$key,
	$message,
	$ttl = 31536000,
	$appended_data = ""
) {
	$expires = time() + $ttl;
	$body = $message . $expires . $appended_data;
	$signature = hash_hmac("sha256", $body, $key);
	return dechex($expires) .
		":" .
		$signature .
		":" .
		base64_url_encode($appended_data);
}

function verify_signed_code($key, $message, $code) {
	$code_parts = explode(":", $code, 3);
	if (count($code_parts) !== 3) {
		return false;
	}
	$expires = hexdec($code_parts[0]);
	if (time() > $expires) {
		return false;
	}
	$body = $message . $expires . base64_url_decode($code_parts[2]);
	$signature = hash_hmac("sha256", $body, $key);
	return hash_equals($signature, $code_parts[1]);
}

function filter_input_regexp($type, $variable, $regexp, $flags = null) {
	$options = [
		"options" => ["regexp" => $regexp],
	];
	if ($flags !== null) {
		$options["flags"] = $flags;
	}
	return filter_input($type, $variable, FILTER_VALIDATE_REGEXP, $options);
}

function get_q_value($mime, $accept) {
	$fulltype = preg_replace('@^([^/]+\/).+$@', '$1*', $mime);
	$regex = implode("", [
		"/(?<=^|,)\s*(\*\/\*|",
		preg_quote($fulltype, "/"),
		"|",
		preg_quote($mime, "/"),
		')\s*(?:[^,]*?;\s*q\s*=\s*([0-9.]+))?\s*(?:,|$)/',
	]);
	$out = preg_match_all($regex, $accept, $matches);
	$types = array_combine($matches[1], $matches[2]);
	if (array_key_exists($mime, $types)) {
		$q = $types[$mime];
	} elseif (array_key_exists($fulltype, $types)) {
		$q = $types[$fulltype];
	} elseif (array_key_exists("*/*", $types)) {
		$q = $types["*/*"];
	} else {
		return 0;
	}
	return $q === "" ? 1 : floatval($q);
}

function base64_url_encode($string) {
	$string = base64_encode($string);
	$string = rtrim($string, "=");
	$string = strtr($string, "+/", "-_");
	return $string;
}

function base64_url_decode($string) {
	$string = strtr($string, "-_", "+/");
	$padding = strlen($string) % 4;
	if ($padding !== 0) {
		$string .= str_repeat("=", 4 - $padding);
	}
	$string = base64_decode($string);
	return $string;
}