otp

type Algorithm interface {
	// Generate generates an otp value
	Generate(reference int64) string

	// Validate validates the given otp value for the given reference
	// opts can optionally be used to provide algorithm specific validation options
	Validate(value string, reference int64, opts ...ValidationOption) (int64, error)

	// Export exports the configuration of the algorithm
	Export(exporter Exporter)
}

type Digits int

type Exporter interface {
	SetAlgorithm(algorithm string)
	SetHashAlgorithm(algorithm HashAlgorithm)
	SetKey(key []byte)
	SetDigits(digits Digits)
	SetT0(t0 int64)
	SetPeriod(period time.Duration)
}

type HashAlgorithm string

type SkewIterator interface {
	HasNext() bool
	Value() int64
}

type ValidationOption func(current int64) SkewIterator