import {Chacha20, encrypt as _encrypt, decrypt as _decrypt} from "./chacha.js";

const VERSION = 1;

const MAX_ITERS = 24;

function encrypt(s, password) {

	let bs = util.str2utf8(s);

	let pass = util.str2utf8(password);

	let salt = util.createRandomNonce(12);

	let [iters, key] = stretchKey(pass, salt);

	let [_, ciphertext] = _encrypt(bs, key, salt);

	let signature = blake2s([VERSION, iters].concat(salt, ciphertext), 16, key);

	let arr = [VERSION, iters].concat(signature, salt, ciphertext);

function decrypt(s, password) {

	let pass = util.str2utf8(password);

	let arr = util.base642bytes(s);

	let version = arr[0];

	let iters = arr[1];

	let signature = arr.slice(2, 18);

	let salt = arr.slice(18, 30);

	let ciphertext = arr.slice(30);

	if (ciphertext.length == 0) {return 4;}

	if (version > VERSION) {return 2;}

	if (iters > MAX_ITERS) {return 3;}

	let key = pbkdf2(pass, salt, 1 << iters, 32);

	let check = blake2s([version, iters].concat(salt, ciphertext), 16, key);

	if (!signature.every((b, i) => b === check[i])) {return 1;}

	let plainbytes = _decrypt(ciphertext, key, salt);

function stretchKey(password, salt) {

	let start = Date.now(); // ms

	let i, key;

	for (i = 0; i <= MAX_ITERS; i++) {

		key = pbkdf2(password, salt, 1<<i, 32);

		if (Date.now()-start >= 500) {break;}

	return [i, key];

export default {util, blake2s, pbkdf2, Chacha20, encrypt, decrypt};

if (typeof module !== 'undefined' && module.hasOwnProperty('exports')) {

	module.exports.util = util;

	module.exports.blake2s = blake2s;

	module.exports.pbkdf2 = pbkdf2;

	module.exports.Chacha20 = Chacha20;

	module.exports.encrypt = _encrypt;

	module.exports.decrypt = _decrypt;