package hostbox

import (
	"reflect"

	"github.com/carlosframework/platform/internal/registry"
)

// GenerationHandover is retained transfer evidence, read from root's journal.
// It cannot authorize a new handover or discard a launch reservation.
type GenerationHandover coldJournal

func DecodeGenerationHandover(raw []byte) (GenerationHandover, error) {
	var j coldJournal
	if decodeStrict(raw, &j) != nil || j.V != 1 || j.Phase != "complete" || j.IntendedAbsent || j.ServingInstallation == nil {
		return GenerationHandover{}, ErrTypedJournal
	}
	p, n, in := j.Prior, j.Successor, j.Inventory
	if p.Host == "" || p.Incarnation == "" || n.Host != p.Host || n.Incarnation != p.Incarnation || n.Box != p.Box || n.Enrollment != p.Enrollment || n.Stamp <= p.Stamp || n.Session != n.Stamp || n.Session <= p.Session || n.Generation == "" || n.ETag == "" || n.Op != "" || n.Phase != "" || p.Op != "" || p.Phase != "" || p.ObligationID != "" || j.ID != "serving-handover-"+ownershipFor(n.Host, n.Incarnation, n.Stamp, n.Box) || !in.Complete || in.Host != p.Host || in.Incarnation != p.Incarnation || in.InstallationStamp != p.Stamp || in.Box != p.Box || in.Enrollment != p.Enrollment || in.DirectoryRevision != p.DirectoryRevision {
		return GenerationHandover{}, ErrTypedJournal
	}
	barrier := p
	barrier.FenceID, barrier.Stamp, barrier.Session, barrier.ClaimETag, barrier.DirectoryRevision = j.ID, n.Stamp, n.Session, n.ETag, n.DirectoryRevision
	if j.Barrier != barrier {
		return GenerationHandover{}, ErrTypedJournal
	}
	after := j.Before
	after.Timers = append([]registry.Timer(nil), j.Before.Timers...)
	owner := ownershipFor(n.Host, n.Incarnation, n.Stamp, n.Box)
	after.Route.ClaimOwnership = registry.ClaimOwnership{ClaimIncarnation: n.Incarnation, ClaimStamp: n.Stamp, ClaimOwner: owner, ClaimRowID: rowIDFor(owner, "route", n.Host)}
	for i := range after.Timers {
		after.Timers[i].ClaimOwnership = after.Route.ClaimOwnership
		after.Timers[i].ClaimRowID = rowIDFor(owner, "timer", after.Timers[i].Name)
	}
	if !reflect.DeepEqual(after, j.After) {
		return GenerationHandover{}, ErrTypedJournal
	}
	return GenerationHandover(j), nil
}