package supervisor

type ReleaseState string

const (
	ReleaseCandidate  ReleaseState = "CANDIDATE"
	ReleaseHealthy    ReleaseState = "HEALTHY"
	ReleaseFailed     ReleaseState = "FAILED"
	ReleaseRolledBack ReleaseState = "ROLLED_BACK"
)

type Release struct {
	ID            string
	Version       string
	State         ReleaseState
	LastKnownGood bool
}
type Observation struct {
	ReleaseID            string
	Ready                bool
	Reason               string
	ObservedAtUnixMillis int64
}
type Lifeboat struct {
	Current       Release
	LastKnownGood Release
	Observations  []Observation
}

func (l *Lifeboat) Start(candidate Release) bool {
	if candidate.ID == "" || candidate.Version == "" {
		return false
	}
	candidate.State = ReleaseCandidate
	l.Current = candidate
	return true
}
func (l *Lifeboat) Record(o Observation) bool {
	if o.ReleaseID == "" {
		return false
	}
	l.Observations = append(l.Observations, o)
	if o.ReleaseID != l.Current.ID {
		return true
	}
	if o.Ready {
		l.Current.State = ReleaseHealthy
		l.Current.LastKnownGood = true
		l.LastKnownGood = l.Current
	} else {
		l.Current.State = ReleaseFailed
	}
	return true
}
func (l *Lifeboat) Rollback() bool {
	if l.LastKnownGood.ID == "" {
		return false
	}
	l.Current = l.LastKnownGood
	l.Current.State = ReleaseRolledBack
	return true
}