package tools

import "crypto/subtle"

// SecureCompare use constant time function to compare the two given array.
func SecureCompare(given, actual []byte) bool {
	if subtle.ConstantTimeEq(int32(len(given)), int32(len(actual))) == 1 {
		return subtle.ConstantTimeCompare(given, actual) == 1
	}
	// Securely compare actual to itself to keep constant time, but always return false
	if subtle.ConstantTimeCompare(actual, actual) == 1 {
		return false
	}
	return false
}

// SecureCompareString use constant time function to compare the two given string.
func SecureCompareString(given, actual string) bool {
	// The following code is incorrect:
	// return SecureCompare([]byte(given), []byte(actual))

	if subtle.ConstantTimeEq(int32(len(given)), int32(len(actual))) == 1 {
		return subtle.ConstantTimeCompare([]byte(given), []byte(actual)) == 1
	}
	// Securely compare actual to itself to keep constant time, but always return false
	if subtle.ConstantTimeCompare([]byte(actual), []byte(actual)) == 1 {
		return false
	}
	return false
}