package engine

import (
	"errors"

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

// GetPrm groups the parameters of Get operation.
type GetPrm struct {
	addr *objectSDK.Address
}

// GetRes groups resulting values of Get operation.
type GetRes struct {
	obj *object.Object
}

// WithAddress is a Get option to set the address of the requested object.
//
// Option is required.
func (p *GetPrm) WithAddress(addr *objectSDK.Address) *GetPrm {
	if p != nil {
		p.addr = addr
	}

	return p
}

// Object returns the requested object.
func (r *GetRes) Object() *object.Object {
	return r.obj
}

// Get reads an object from local storage.
//
// Returns any error encountered that
// did not allow to completely read the object part.
//
// Returns ErrNotFound if requested object is missing in local storage.
func (e *StorageEngine) Get(prm *GetPrm) (*GetRes, error) {
	var (
		obj *object.Object

		alreadyRemoved = false
	)

	shPrm := new(shard.GetPrm).
		WithAddress(prm.addr)

	e.iterateOverSortedShards(prm.addr, func(_ int, sh *shard.Shard) (stop bool) {
		res, err := sh.Get(shPrm)
		if err != nil {
			switch {
			case errors.Is(err, object.ErrNotFound):
				return false // ignore, go to next shard
			case errors.Is(err, object.ErrAlreadyRemoved):
				alreadyRemoved = true

				return true // stop, return it back
			default:
				// TODO: smth wrong with shard, need to be processed, but
				// still go to next shard
				e.log.Warn("could not get object from shard",
					zap.Stringer("shard", sh.ID()),
					zap.String("error", err.Error()),
				)

				return false
			}
		}

		obj = res.Object()

		return true
	})

	if obj == nil {
		if alreadyRemoved {
			return nil, object.ErrAlreadyRemoved
		}

		return nil, object.ErrNotFound
	}

	return &GetRes{
		obj: obj,
	}, nil
}

// Get reads object from local storage by provided address.
func Get(storage *StorageEngine, addr *objectSDK.Address) (*object.Object, error) {
	res, err := storage.Get(new(GetPrm).
		WithAddress(addr),
	)
	if err != nil {
		return nil, err
	}

	return res.Object(), nil
}