package blobovnicza

import (
	"context"
	"errors"
	"syscall"

	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
	tracingPkg "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/tracing"
	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
	apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
	"go.etcd.io/bbolt"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/trace"
	"go.uber.org/zap"
)

// DeletePrm groups the parameters of Delete operation.
type DeletePrm struct {
	addr oid.Address
}

// DeleteRes groups the resulting values of Delete operation.
type DeleteRes struct{}

// SetAddress sets the address of the requested object.
func (p *DeletePrm) SetAddress(addr oid.Address) {
	p.addr = addr
}

// Delete removes an object from Blobovnicza by address.
//
// Returns any error encountered that
// did not allow to completely delete the object.
//
// Returns an error of type apistatus.ObjectNotFound if the object to be deleted is not in blobovnicza.
//
// Should not be called in read-only configuration.
func (b *Blobovnicza) Delete(ctx context.Context, prm DeletePrm) (DeleteRes, error) {
	_, span := tracing.StartSpanFromContext(ctx, "Blobovnicza.Delete",
		trace.WithAttributes(
			attribute.String("path", b.path),
			attribute.String("address", prm.addr.EncodeToString()),
		))
	defer span.End()

	b.controlMtx.RLock()
	defer b.controlMtx.RUnlock()

	addrKey := addressKey(prm.addr)

	found := false
	var sizeUpperBound uint64
	var sizeLowerBound uint64
	var dataSize uint64
	var recordSize uint64

	err := b.boltDB.Update(func(tx *bbolt.Tx) error {
		err := b.iterateAllDataBuckets(tx, func(lower, upper uint64, buck *bbolt.Bucket) (bool, error) {
			objData := buck.Get(addrKey)
			if objData == nil {
				// object is not in bucket => continue iterating
				return false, nil
			}
			dataSize = uint64(len(objData))
			sizeLowerBound = lower
			sizeUpperBound = upper
			recordSize = dataSize + uint64(len(addrKey))
			found = true
			return true, buck.Delete(addrKey)
		})
		if err != nil {
			return err
		}
		if found {
			return updateMeta(tx, func(count, size uint64) (uint64, uint64) {
				if count > 0 {
					count--
				}
				if size >= recordSize {
					size -= recordSize
				} else {
					size = 0
				}
				return count, size
			})
		}
		return nil
	})

	if err == nil && !found {
		return DeleteRes{}, new(apistatus.ObjectNotFound)
	}

	if err == nil && found {
		b.log.Debug(logs.BlobovniczaObjectWasRemovedFromBucket,
			zap.String("binary size", stringifyByteSize(dataSize)),
			zap.String("range", stringifyBounds(sizeLowerBound, sizeUpperBound)),
			zap.String("trace_id", tracingPkg.GetTraceID(ctx)),
		)
		b.itemDeleted(recordSize)
	}

	if errors.Is(err, syscall.ENOSPC) {
		err = ErrNoSpace
	}

	return DeleteRes{}, err
}