package deletesvc

import (
	"context"
	"strconv"

	objectV2 "github.com/nspcc-dev/neofs-api-go/v2/object"
	"github.com/nspcc-dev/neofs-node/pkg/services/object/util"
	"github.com/nspcc-dev/neofs-node/pkg/util/logger"
	cid "github.com/nspcc-dev/neofs-sdk-go/container/id"
	"github.com/nspcc-dev/neofs-sdk-go/object"
	addressSDK "github.com/nspcc-dev/neofs-sdk-go/object/address"
	oidSDK "github.com/nspcc-dev/neofs-sdk-go/object/id"
	"go.uber.org/zap"
)

type statusError struct {
	status int
	err    error
}

type execCtx struct {
	svc *Service

	ctx context.Context

	prm Prm

	statusError

	log *logger.Logger

	tombstone *object.Tombstone

	splitInfo *object.SplitInfo

	tombstoneObj *object.Object
}

const (
	statusUndefined int = iota
	statusOK
)

func (exec *execCtx) setLogger(l *logger.Logger) {
	exec.log = l.With(
		zap.String("request", "DELETE"),
		zap.Stringer("address", exec.address()),
		zap.Bool("local", exec.isLocal()),
		zap.Bool("with session", exec.prm.common.SessionToken() != nil),
		zap.Bool("with bearer", exec.prm.common.BearerToken() != nil),
	)
}

func (exec execCtx) context() context.Context {
	return exec.ctx
}

func (exec execCtx) isLocal() bool {
	return exec.prm.common.LocalOnly()
}

func (exec *execCtx) address() *addressSDK.Address {
	return exec.prm.addr
}

func (exec *execCtx) containerID() *cid.ID {
	id, ok := exec.prm.addr.ContainerID()
	if ok {
		return &id
	}

	return nil
}

func (exec *execCtx) commonParameters() *util.CommonPrm {
	return exec.prm.common
}

func (exec *execCtx) newAddress(id *oidSDK.ID) *addressSDK.Address {
	a := addressSDK.NewAddress()
	a.SetObjectID(*id)
	a.SetContainerID(*exec.containerID())

	return a
}

func (exec *execCtx) formSplitInfo() bool {
	var err error

	exec.splitInfo, err = exec.svc.header.splitInfo(exec)

	switch {
	default:
		exec.status = statusUndefined
		exec.err = err

		exec.log.Debug("could not compose split info",
			zap.String("error", err.Error()),
		)
	case err == nil:
		exec.status = statusOK
		exec.err = nil
	}

	return err == nil
}

func (exec *execCtx) collectMembers() (ok bool) {
	if exec.splitInfo == nil {
		exec.log.Debug("no split info, object is PHY")
		return true
	}

	if _, withLink := exec.splitInfo.Link(); withLink {
		ok = exec.collectChildren()
	}

	if !ok {
		if _, withLast := exec.splitInfo.LastPart(); withLast {
			ok = exec.collectChain()
			if !ok {
				return
			}
		}
	} // may be fail if neither right nor linking ID is set?

	return exec.supplementBySplitID()
}

func (exec *execCtx) collectChain() bool {
	var chain []oidSDK.ID

	exec.log.Debug("assembling chain...")

	for prev, withPrev := exec.splitInfo.LastPart(); withPrev; {
		chain = append(chain, prev)

		p, err := exec.svc.header.previous(exec, &prev)

		switch {
		default:
			exec.status = statusUndefined
			exec.err = err

			exec.log.Debug("could not get previous split element",
				zap.Stringer("id", prev),
				zap.String("error", err.Error()),
			)

			return false
		case err == nil:
			exec.status = statusOK
			exec.err = nil

			withPrev = p != nil
			if withPrev {
				prev = *p
			}
		}
	}

	exec.addMembers(chain)

	return true
}

func (exec *execCtx) collectChildren() bool {
	exec.log.Debug("collecting children...")

	children, err := exec.svc.header.children(exec)

	switch {
	default:
		exec.status = statusUndefined
		exec.err = err

		exec.log.Debug("could not collect object children",
			zap.String("error", err.Error()),
		)

		return false
	case err == nil:
		exec.status = statusOK
		exec.err = nil

		link, _ := exec.splitInfo.Link()

		exec.addMembers(append(children, link))

		return true
	}
}

func (exec *execCtx) supplementBySplitID() bool {
	exec.log.Debug("supplement by split ID")

	chain, err := exec.svc.searcher.splitMembers(exec)

	switch {
	default:
		exec.status = statusUndefined
		exec.err = err

		exec.log.Debug("could not search for split chain members",
			zap.String("error", err.Error()),
		)

		return false
	case err == nil:
		exec.status = statusOK
		exec.err = nil

		exec.addMembers(chain)

		return true
	}
}

func (exec *execCtx) addMembers(incoming []oidSDK.ID) {
	members := exec.tombstone.Members()

	for i := range members {
		for j := 0; j < len(incoming); j++ { // don't use range, slice mutates in body
			if members[i].Equals(incoming[j]) {
				incoming = append(incoming[:j], incoming[j+1:]...)
				j--
			}
		}
	}

	exec.tombstone.SetMembers(append(members, incoming...))
}

func (exec *execCtx) initTombstoneObject() bool {
	payload, err := exec.tombstone.Marshal()
	if err != nil {
		exec.status = statusUndefined
		exec.err = err

		exec.log.Debug("could not marshal tombstone structure",
			zap.String("error", err.Error()),
		)

		return false
	}

	exec.tombstoneObj = object.New()
	exec.tombstoneObj.SetContainerID(*exec.containerID())
	exec.tombstoneObj.SetType(object.TypeTombstone)
	exec.tombstoneObj.SetPayload(payload)

	tokenSession := exec.commonParameters().SessionToken()
	if tokenSession != nil {
		issuer := tokenSession.Issuer()
		exec.tombstoneObj.SetOwnerID(&issuer)
	} else {
		// make local node a tombstone object owner
		exec.tombstoneObj.SetOwnerID(exec.svc.netInfo.LocalNodeID())
	}

	var a object.Attribute
	a.SetKey(objectV2.SysAttributeExpEpoch)
	a.SetValue(strconv.FormatUint(exec.tombstone.ExpirationEpoch(), 10))

	exec.tombstoneObj.SetAttributes(a)

	return true
}

func (exec *execCtx) saveTombstone() bool {
	id, err := exec.svc.placer.put(exec)

	switch {
	default:
		exec.status = statusUndefined
		exec.err = err

		exec.log.Debug("could not save the tombstone",
			zap.String("error", err.Error()),
		)

		return false
	case err == nil:
		exec.status = statusOK
		exec.err = nil

		exec.prm.tombAddrWriter.
			SetAddress(exec.newAddress(id))
	}

	return true
}