'use strict';
// limit of Crypto.getRandomValues()
// https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getRandomValues
var MAX_BYTES = 65536;
// Node supports requesting up to this number of bytes
// https://github.com/nodejs/node/blob/master/lib/internal/crypto/random.js#L48
var MAX_UINT32 = 4294967295;
var crypto = global.crypto || global.msCrypto;
if (!crypto || !crypto.getRandomValues) {
    console.warn('Secure random number generation is not supported by this browser.\nUse Chrome, Firefox or Internet Explorer 11');
}
export default function randomBytes(size, cb) {
    // phantomjs needs to throw
    if (size > MAX_UINT32)
        throw new RangeError('requested too many random bytes');
    var bytes = Buffer.allocUnsafe(size);
    if (size > 0) { // getRandomValues fails on IE if size == 0
        if (size > MAX_BYTES) { // this is the max bytes crypto.getRandomValues
            // can do at once see https://developer.mozilla.org/en-US/docs/Web/API/window.crypto.getRandomValues
            for (var generated = 0; generated < size; generated += MAX_BYTES) {
                // buffer.slice automatically checks if the end is past the end of
                // the buffer so we don't have to here
                crypto.getRandomValues(bytes.slice(generated, generated + MAX_BYTES));
            }
        }
        else {
            crypto.getRandomValues(bytes);
        }
    }
    if (typeof cb === 'function') {
        return process.nextTick(function () {
            cb(null, bytes);
        });
    }
    return bytes;
}