package engine

// Status is the engine's lifecycle state.
type Status string

const (
	StatusIdle     Status = "idle"
	StatusStarting Status = "starting"
	StatusActive   Status = "active"
	StatusFailed   Status = "failed"
	// Reconnecting added in P2.3.
)

// isValidTransition guards the state machine. Used by Engine.transition
// to assert in dev/test; production code logs a warning rather than
// panicking on invalid transitions.
func isValidTransition(from, to Status) bool {
	switch from {
	case StatusIdle:
		return to == StatusStarting
	case StatusStarting:
		return to == StatusActive || to == StatusFailed
	case StatusActive:
		return to == StatusIdle || to == StatusFailed
	case StatusFailed:
		return to == StatusStarting || to == StatusIdle
	}
	return false
}