"use strict";

const {B, KiB, MiB, GiB, TiB, PiB, EiB} = require("../../units/bytes/iec");

let unitMap = {
	b: B,
	k: KiB,
	m: MiB,
	g: GiB,
	t: TiB,
	p: PiB,
	e: EiB
};

function mapUnit(unitString) {
	if (unitString == null) {
		return B;
	} else {
		let normalizedUnitString = unitString.toLowerCase();
	
		if (unitMap[normalizedUnitString] != null) {
			return unitMap[normalizedUnitString];
		} else {
			throw new Error(`Unknown unit: ${unit}`);
		}
	}
}

module.exports = function parseIECBytes(sizeString) {
	if (sizeString == null) {
		return sizeString;
	} else {
		let match = /^([0-9]+(?:\.[0-9]+)?)([bkmgtpe])?$/i.exec(sizeString.trim());
	
		if (match == null) {
			throw new Error(`Could not parse size string: ${sizeString}`);
		}
	
		let [_, number, unit] = match;
		let unitCreator = mapUnit(unit);
	
		return unitCreator(parseFloat(number));
	}
};