package shard

import (
	"context"

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
	meta "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase"
	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/trace"
)

// ExistsPrm groups the parameters of Exists operation.
type ExistsPrm struct {
	// Exists option to set object checked for existence.
	Address oid.Address
	// Exists option to set parent object checked for existence.
	ParentAddress oid.Address
}

// ExistsRes groups the resulting values of Exists operation.
type ExistsRes struct {
	ex bool
	lc bool
}

// Exists returns the fact that the object is in the shard.
func (p ExistsRes) Exists() bool {
	return p.ex
}

// Locked returns the fact that the object is locked.
func (p ExistsRes) Locked() bool {
	return p.lc
}

// Exists checks if object is presented in shard.
//
// Returns any error encountered that does not allow to
// unambiguously determine the presence of an object.
//
// Returns an error of type apistatus.ObjectAlreadyRemoved if object has been marked as removed.
// Returns the object.ErrObjectIsExpired if the object is presented but already expired.
// Returns the ErrShardDisabled if the shard is disabled.
func (s *Shard) Exists(ctx context.Context, prm ExistsPrm) (ExistsRes, error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "Shard.Exists",
		trace.WithAttributes(
			attribute.String("shard_id", s.ID().String()),
			attribute.String("address", prm.Address.EncodeToString()),
		))
	defer span.End()

	var exists bool
	var locked bool
	var err error

	s.m.RLock()
	defer s.m.RUnlock()

	if s.info.Mode.Disabled() {
		return ExistsRes{}, ErrShardDisabled
	} else if s.info.Mode.NoMetabase() {
		var p common.ExistsPrm
		p.Address = prm.Address

		var res common.ExistsRes
		res, err = s.blobStor.Exists(ctx, p)
		exists = res.Exists
	} else {
		var existsPrm meta.ExistsPrm
		existsPrm.SetAddress(prm.Address)
		existsPrm.SetParent(prm.ParentAddress)

		var res meta.ExistsRes
		res, err = s.metaBase.Exists(ctx, existsPrm)
		exists = res.Exists()
		locked = res.Locked()
	}

	return ExistsRes{
		ex: exists,
		lc: locked,
	}, err
}