package settings

import (
	"github.com/anytypeio/any-sync/commonspace/object/tree/objecttree"
	"github.com/anytypeio/any-sync/commonspace/spacesyncproto"
	"github.com/gogo/protobuf/proto"
)

type DeletedIdsProvider interface {
	ProvideIds(tr objecttree.ObjectTree, startId string) (ids []string, lastId string, err error)
}

type provider struct{}

func (p *provider) processChange(change *objecttree.Change, rootId, startId string, ids []string) []string {
	// ignoring root change which has empty model or startId change
	if change.Model == nil || (change.Id == startId && startId != "") {
		return ids
	}

	deleteChange := change.Model.(*spacesyncproto.SettingsData)
	// getting data from snapshot if we start from it
	if change.Id == rootId {
		ids = deleteChange.Snapshot.DeletedIds
		return ids
	}

	// otherwise getting data from content
	for _, cnt := range deleteChange.Content {
		if cnt.GetObjectDelete() != nil {
			ids = append(ids, cnt.GetObjectDelete().GetId())
		}
	}
	return ids
}

func (p *provider) ProvideIds(tr objecttree.ObjectTree, startId string) (ids []string, lastId string, err error) {
	rootId := tr.Root().Id
	process := func(change *objecttree.Change) bool {
		lastId = change.Id
		ids = p.processChange(change, rootId, startId, ids)
		return true
	}
	convert := func(decrypted []byte) (res any, err error) {
		deleteChange := &spacesyncproto.SettingsData{}
		err = proto.Unmarshal(decrypted, deleteChange)
		if err != nil {
			return nil, err
		}
		return deleteChange, nil
	}

	if startId == "" {
		startId = rootId
	}
	err = tr.IterateFrom(startId, convert, process)
	return
}