'use strict';

var nativeImpl = require('crypto');

var checkParameters = require('./lib/precondition');
var defaultEncoding = require('./lib/default-encoding');
var toBuffer = require('./lib/to-buffer');

function nativePBKDF2(password, salt, iterations, keylen, digest, callback) {
	checkParameters(iterations, keylen);
	password = toBuffer(password, defaultEncoding, 'Password');
	salt = toBuffer(salt, defaultEncoding, 'Salt');

	if (typeof digest === 'function') {
		callback = digest;
		digest = 'sha1';
	}
	if (typeof callback !== 'function') {
		throw new Error('No callback provided to pbkdf2');
	}

	return nativeImpl.pbkdf2(password, salt, iterations, keylen, digest, callback);
}

function nativePBKDF2Sync(password, salt, iterations, keylen, digest) {
	checkParameters(iterations, keylen);
	password = toBuffer(password, defaultEncoding, 'Password');
	salt = toBuffer(salt, defaultEncoding, 'Salt');
	digest = digest || 'sha1';
	return nativeImpl.pbkdf2Sync(password, salt, iterations, keylen, digest);
}

/* istanbul ignore next */
if (!nativeImpl.pbkdf2Sync || nativeImpl.pbkdf2Sync.toString().indexOf('keylen, digest') === -1) {
	/* eslint global-require: 0 */
	exports.pbkdf2Sync = require('./lib/sync');
	exports.pbkdf2 = require('./lib/async');

// native
} else {
	exports.pbkdf2Sync = nativePBKDF2Sync;
	exports.pbkdf2 = nativePBKDF2;
}