// (c) 2019-2020, Ava Labs, Inc. All rights reserved.
// See the file LICENSE for licensing terms.

package snowball

import (
	"fmt"

	"github.com/prometheus/client_golang/prometheus"
)

// Parameters required for snowball consensus
type Parameters struct {
	Namespace                         string
	Metrics                           prometheus.Registerer
	K, Alpha, BetaVirtuous, BetaRogue int
}

// Valid returns nil if the parameters describe a valid initialization.
func (p Parameters) Valid() error {
	switch {
	case p.Alpha <= p.K/2:
		return fmt.Errorf("K = %d, Alpha = %d: Fails the condition that: K/2 < Alpha", p.K, p.Alpha)
	case p.K < p.Alpha:
		return fmt.Errorf("K = %d, Alpha = %d: Fails the condition that: Alpha <= K", p.K, p.Alpha)
	case p.BetaVirtuous <= 0:
		return fmt.Errorf("BetaVirtuous = %d: Fails the condition that: 0 < BetaVirtuous", p.BetaVirtuous)
	case p.BetaRogue < p.BetaVirtuous:
		return fmt.Errorf("BetaVirtuous = %d, BetaRogue = %d: Fails the condition that: BetaVirtuous <= BetaRogue", p.BetaVirtuous, p.BetaRogue)
	default:
		return nil
	}
}