PHP Filesize Parser

parse-filesize.php

<?php

/**
 * Parse a filesize to its number of bytes
 *
 * @param string|int|float $input
 * @param int $base
 * @return int
 *
 * @see https://github.com/patrickkettner/filesize-parser, the original JavaScript implementation of this function
 */
function parse_filesize($input, int $base = 2): int
{
	$validAmount = function ($n) {
		$n = preg_replace('/[^0-9]+$/', '', $n);
		return is_numeric($n) && is_finite((float) $n);
	};
	$parsableUnit = function ($u) {
		return strcspn($u, '0123456789') === strlen($u);
	};

	static $incrementBases = [
		2 => [
			[['b', 'bit', 'bits'], 1 / 8],
			[['B', 'Byte', 'Bytes', 'bytes'], 1],
			[['Kb'], 128],
			[['k', 'K', 'kb', 'KB', 'KiB', 'Ki', 'ki'], 1024],
			[['Mb'], 131072],
			[['m', 'M', 'mb', 'MB', 'MiB', 'Mi', 'mi'], 1024 ** 2],
			[['Gb'], 1.342e8],
			[['g', 'G', 'gb', 'GB', 'GiB', 'Gi', 'gi'], 1024 ** 3],
			[['Tb'], 1.374e11],
			[['t', 'T', 'tb', 'TB', 'TiB', 'Ti', 'ti'], 1024 ** 4],
			[['Pb'], 1.407e14],
			[['p', 'P', 'pb', 'PB', 'PiB', 'Pi', 'pi'], 1024 ** 5],
			[['Eb'], 1.441e17],
			[['e', 'E', 'eb', 'EB', 'EiB', 'Ei', 'ei'], 1024 ** 6],
		],
		10 => [
			[['b', 'bit', 'bits'], 1 / 8],
			[['B', 'Byte', 'Bytes', 'bytes'], 1],
			[['Kb'], 125],
			[['k', 'K', 'kb', 'KB', 'KiB', 'Ki', 'ki'], 1000],
			[['Mb'], 125000],
			[['m', 'M', 'mb', 'MB', 'MiB', 'Mi', 'mi'], 1.0e6],
			[['Gb'], 1.25e8],
			[['g', 'G', 'gb', 'GB', 'GiB', 'Gi', 'gi'], 1.0e9],
			[['Tb'], 1.25e11],
			[['t', 'T', 'tb', 'TB', 'TiB', 'Ti', 'ti'], 1.0e12],
			[['Pb'], 1.25e14],
			[['p', 'P', 'pb', 'PB', 'PiB', 'Pi', 'pi'], 1.0e15],
			[['Eb'], 1.25e17],
			[['e', 'E', 'eb', 'EB', 'EiB', 'Ei', 'ei'], 1.0e18],
		],
	];

	if (!isset($incrementBases[$base])) {
		throw new InvalidArgumentException(
			sprintf(
				'Invalid base: %s. Expected one of: %s.',
				json_encode($base),
				join(', ', array_keys($incrementBases)),
			),
		);
	}

	preg_match('/^([0-9\\.,]*)(?:\\s*)?(.*)$/', (string) $input, $parsed);
	$amount = str_replace(',', '.', $parsed[1]);
	$unit = $parsed[2];

	if (!$validAmount($amount) || !$parsableUnit($unit)) {
		throw new InvalidArgumentException("Cannot interpret \"$input\".");
	}

	$amount = (float) $amount;

	if ($unit === '') {
		return round($amount);
	}

	$validUnit = fn($source_unit) => $source_unit === $unit;

	$increments = $incrementBases[$base];
	foreach ($increments as [$units, $factor]) {
		foreach ($units as $unit) {
			if ($validUnit($unit)) {
				return round($amount * $factor);
			}
		}
	}

	throw new InvalidArgumentException("Invalid unit: \"$unit\".");
}