package host

import "errors"

// generationCensusRefusal is a refusal of root's kernel generation census
// (productionGenerationKernelCensus). Recovery with no journal open defers
// a settlement this refused (settleWithoutJournal), and only this: an image
// that does not verify, malformed state and a failed durable write keep
// their own errors and still fail.
type generationCensusRefusal struct{ err error }

func (r *generationCensusRefusal) Error() string { return "generation census: " + r.err.Error() }

func (r *generationCensusRefusal) Unwrap() error { return r.err }

// onlyCensusRefusal reports whether every error err carries is a
// generationCensusRefusal: a wrapped refusal is, a join with any other
// error (a durable write that failed beside it) is not.
func onlyCensusRefusal(err error) bool {
	switch e := err.(type) {
	case nil:
		return false
	case *generationCensusRefusal:
		return true
	case interface{ Unwrap() []error }:
		found := false
		for _, inner := range e.Unwrap() {
			if inner == nil {
				continue
			}
			if !onlyCensusRefusal(inner) {
				return false
			}
			found = true
		}
		return found
	}
	if inner := errors.Unwrap(err); inner != nil {
		return onlyCensusRefusal(inner)
	}
	return false
}