package engine

import (
	"errors"

	"github.com/nspcc-dev/neofs-node/pkg/core/object"
	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard"
	"go.uber.org/zap"
)

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

// PutRes groups resulting values of Put operation.
type PutRes struct{}

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

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

	return p
}

// Put saves the object to local storage.
//
// Returns any error encountered that
// did not allow to completely save the object.
func (e *StorageEngine) Put(prm *PutPrm) (*PutRes, error) {
	if e.metrics != nil {
		defer elapsed(e.metrics.AddPutDuration)()
	}

	_, err := e.exists(prm.obj.Address()) // todo: make this check parallel
	if err != nil {
		return nil, err
	}

	existPrm := new(shard.ExistsPrm)
	existPrm.WithAddress(prm.obj.Address())

	finished := false

	e.iterateOverSortedShards(prm.obj.Address(), func(ind int, s *shard.Shard) (stop bool) {
		e.mtx.RLock()
		pool := e.shardPools[s.ID().String()]
		e.mtx.RUnlock()

		exitCh := make(chan struct{})

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

			exists, err := s.Exists(existPrm)
			if err != nil {
				return // this is not ErrAlreadyRemoved error so we can go to the next shard
			}

			if exists.Exists() {
				if ind != 0 {
					toMoveItPrm := new(shard.ToMoveItPrm)
					toMoveItPrm.WithAddress(prm.obj.Address())

					_, err = s.ToMoveIt(toMoveItPrm)
					if err != nil {
						e.log.Warn("could not mark object for shard relocation",
							zap.Stringer("shard", s.ID()),
							zap.String("error", err.Error()),
						)
					}
				}

				finished = true

				return
			}

			putPrm := new(shard.PutPrm)
			putPrm.WithObject(prm.obj)

			_, err = s.Put(putPrm)
			if err != nil {
				e.log.Warn("could not put object in shard",
					zap.Stringer("shard", s.ID()),
					zap.String("error", err.Error()),
				)

				return
			}

			finished = true
		}); err != nil {
			// TODO: log errors except ErrOverload when errors of util.WorkerPool will be documented
			close(exitCh)
		}

		<-exitCh

		return finished
	})

	if !finished {
		err = errPutShard
	}

	return nil, err
}

// Put writes provided object to local storage.
func Put(storage *StorageEngine, obj *object.Object) error {
	_, err := storage.Put(new(PutPrm).
		WithObject(obj),
	)

	return err
}