package engine

import (
	"context"
	"errors"

	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard"
	tracingPkg "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/tracing"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util"
	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client"
	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/trace"
	"go.uber.org/zap"
)

// PutPrm groups the parameters of Put operation.
type PutPrm struct {
	obj *objectSDK.Object
}

var errPutShard = errors.New("could not put object to any shard")

type putToShardStatus byte

const (
	putToShardUnknown putToShardStatus = iota
	putToShardSuccess
	putToShardExists
	putToShardRemoved
)

type putToShardRes struct {
	status putToShardStatus
	err    error
}

// WithObject is a Put option to set object to save.
//
// Option is required.
func (p *PutPrm) WithObject(obj *objectSDK.Object) {
	p.obj = obj
}

// Put saves the object to local storage.
//
// Returns any error encountered that
// did not allow to completely save the object.
//
// Returns an error if executions are blocked (see BlockExecution).
//
// Returns an error of type apistatus.ObjectAlreadyRemoved if the object has been marked as removed.
func (e *StorageEngine) Put(ctx context.Context, prm PutPrm) (err error) {
	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.Put",
		trace.WithAttributes(
			attribute.String("address", object.AddressOf(prm.obj).EncodeToString()),
		))
	defer span.End()

	err = e.execIfNotBlocked(func() error {
		err = e.put(ctx, prm)
		return err
	})

	return
}

func (e *StorageEngine) put(ctx context.Context, prm PutPrm) error {
	if e.metrics != nil {
		defer elapsed("Put", e.metrics.AddMethodDuration)()
	}

	addr := object.AddressOf(prm.obj)

	// In #1146 this check was parallelized, however, it became
	// much slower on fast machines for 4 shards.
	_, err := e.exists(ctx, addr)
	if err != nil {
		return err
	}

	var shRes putToShardRes
	e.iterateOverSortedShards(addr, func(_ int, sh hashedShard) (stop bool) {
		e.mtx.RLock()
		pool, ok := e.shardPools[sh.ID().String()]
		e.mtx.RUnlock()
		if !ok {
			// Shard was concurrently removed, skip.
			return false
		}
		shRes = e.putToShard(ctx, sh, pool, addr, prm.obj)
		return shRes.status != putToShardUnknown
	})
	switch shRes.status {
	case putToShardUnknown:
		return errPutShard
	case putToShardRemoved:
		return shRes.err
	case putToShardExists, putToShardSuccess:
		return nil
	default:
		return errPutShard
	}
}

// putToShard puts object to sh.
// Return putToShardStatus and error if it is necessary to propagate an error upper.
func (e *StorageEngine) putToShard(ctx context.Context, sh hashedShard, pool util.WorkerPool,
	addr oid.Address, obj *objectSDK.Object,
) (res putToShardRes) {
	exitCh := make(chan struct{})

	if err := pool.Submit(func() {
		defer close(exitCh)

		var existPrm shard.ExistsPrm
		existPrm.SetAddress(addr)

		exists, err := sh.Exists(ctx, existPrm)
		if err != nil {
			if shard.IsErrObjectExpired(err) {
				// object is already found but
				// expired => do nothing with it
				res.status = putToShardExists
			}

			return // this is not ErrAlreadyRemoved error so we can go to the next shard
		}

		if exists.Exists() {
			res.status = putToShardExists
			return
		}

		var putPrm shard.PutPrm
		putPrm.SetObject(obj)

		_, err = sh.Put(ctx, putPrm)
		if err != nil {
			if errors.Is(err, shard.ErrReadOnlyMode) || errors.Is(err, blobstor.ErrNoPlaceFound) ||
				errors.Is(err, common.ErrReadOnly) || errors.Is(err, common.ErrNoSpace) {
				e.log.Warn(logs.EngineCouldNotPutObjectToShard,
					zap.Stringer("shard_id", sh.ID()),
					zap.String("error", err.Error()),
					zap.String("trace_id", tracingPkg.GetTraceID(ctx)))
				return
			}
			if client.IsErrObjectAlreadyRemoved(err) {
				e.log.Warn(logs.EngineCouldNotPutObjectToShard,
					zap.Stringer("shard_id", sh.ID()),
					zap.String("error", err.Error()),
					zap.String("trace_id", tracingPkg.GetTraceID(ctx)))
				res.status = putToShardRemoved
				res.err = err
				return
			}

			e.reportShardError(sh, "could not put object to shard", err)
			return
		}

		res.status = putToShardSuccess
	}); err != nil {
		e.log.Warn(logs.EngineCouldNotPutObjectToShard, zap.Error(err))
		close(exitCh)
	}

	<-exitCh

	return
}

// Put writes provided object to local storage.
func Put(ctx context.Context, storage *StorageEngine, obj *objectSDK.Object) error {
	var putPrm PutPrm
	putPrm.WithObject(obj)

	return storage.Put(ctx, putPrm)
}