package writecache

import (
	"context"
	"errors"
	"math"
	"time"

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
	storagelog "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/log"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/metaerr"
	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
	"github.com/cockroachdb/pebble"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/trace"
)

// Delete removes object from write-cache.
//
// Returns an error of type apistatus.ObjectNotFound if object is missing in write-cache.
// Returns ErrNotInitialized if write-cache has not been initialized yet.
// Returns ErrDegraded if write-cache is in DEGRADED mode.
func (c *cache) Delete(ctx context.Context, addr oid.Address) error {
	ctx, span := tracing.StartSpanFromContext(ctx, "writecache.Delete",
		trace.WithAttributes(
			attribute.String("address", addr.EncodeToString()),
		))
	defer span.End()

	deleted := false
	storageType := StorageTypeUndefined
	startedAt := time.Now()
	defer func() {
		c.metrics.Delete(time.Since(startedAt), deleted, storageType)
	}()

	if !c.modeMtx.TryRLock() {
		return ErrNotInitialized
	}
	defer c.modeMtx.RUnlock()
	if c.readOnly() {
		return ErrReadOnly
	}
	if c.noMetabase() {
		return ErrDegraded
	}

	saddr := addr.EncodeToString()
	c.dbEditLocker.Lock(saddr)
	defer func() {
		c.dbEditLocker.Unlock(saddr)
	}()
	dbKey := []byte(saddr)
	var dataSize int
	data, closer, err := c.db.Get(dbKey)
	if err == nil {
		dataSize = len(data)
		err = closer.Close()
	}
	if err != nil && !errors.Is(err, pebble.ErrNotFound) {
		return err
	}

	if dataSize > 0 {
		storageType = StorageTypeDB

		var recordDeleted bool
		err := c.db.DeleteSized(dbKey, uint32(dataSize), pebble.Sync)
		if err != nil {
			return err
		}
		storagelog.Write(c.log,
			storagelog.AddressField(saddr),
			storagelog.StorageTypeField(wcStorageType),
			storagelog.OpField("db DELETE"),
		)
		if recordDeleted {
			c.objCounters.cDB.Add(math.MaxUint64)
			c.estimateCacheSize()
		}
		deleted = true
		return nil
	}

	storageType = StorageTypeFSTree
	_, err = c.fsTree.Delete(ctx, common.DeletePrm{Address: addr})
	if err == nil {
		storagelog.Write(c.log,
			storagelog.AddressField(saddr),
			storagelog.StorageTypeField(wcStorageType),
			storagelog.OpField("fstree DELETE"),
		)
		deleted = true
		// counter changed by fstree
		c.estimateCacheSize()
	}
	return metaerr.Wrap(err)
}