package deletesvc

import (
	"context"
	"errors"
	"fmt"
	"strconv"

	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/util"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger"
	objectV2 "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/api/object"
	apiclient "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client"
	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
	"go.uber.org/zap"
)

var errDeleteECChunk = errors.New("invalid operation: delete EC object chunk")

type execCtx struct {
	svc *Service

	prm Prm

	log *logger.Logger

	tombstone *objectSDK.Tombstone

	splitInfo *objectSDK.SplitInfo

	tombstoneObj *objectSDK.Object
}

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

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

func (exec *execCtx) containerID() cid.ID {
	return exec.prm.addr.Container()
}

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

func (exec *execCtx) newAddress(id oid.ID) oid.Address {
	var a oid.Address
	a.SetObject(id)
	a.SetContainer(exec.containerID())

	return a
}

func (exec *execCtx) formExtendedInfo(ctx context.Context) error {
	obj, err := exec.svc.header.head(ctx, exec)

	var errSplitInfo *objectSDK.SplitInfoError
	var errECInfo *objectSDK.ECInfoError

	switch {
	case err == nil:
		if ech := obj.ECHeader(); ech != nil {
			return errDeleteECChunk
		}
		return nil
	case errors.As(err, &errSplitInfo):
		exec.splitInfo = errSplitInfo.SplitInfo()
		exec.tombstone.SetSplitID(exec.splitInfo.SplitID())

		exec.log.Debug(ctx, logs.DeleteSplitInfoSuccessfullyFormedCollectingMembers)

		if err := exec.collectMembers(ctx); err != nil {
			return err
		}

		exec.log.Debug(ctx, logs.DeleteMembersSuccessfullyCollected)
		return nil
	case errors.As(err, &errECInfo):
		exec.log.Debug(ctx, logs.DeleteECObjectReceived)
		return nil
	}

	if !apiclient.IsErrObjectAlreadyRemoved(err) {
		// IsErrObjectAlreadyRemoved check is required because splitInfo
		// implicitly performs Head request that may return ObjectAlreadyRemoved
		// status that is not specified for Delete.
		return err
	}

	return nil
}

func (exec *execCtx) collectMembers(ctx context.Context) error {
	if exec.splitInfo == nil {
		exec.log.Debug(ctx, logs.DeleteNoSplitInfoObjectIsPHY)
		return nil
	}

	var err error
	if _, withLink := exec.splitInfo.Link(); withLink {
		err = exec.collectChildren(ctx)
	}

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

	return exec.supplementBySplitID(ctx)
}

func (exec *execCtx) collectChain(ctx context.Context) error {
	var chain []oid.ID

	exec.log.Debug(ctx, logs.DeleteAssemblingChain)

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

		p, err := exec.svc.header.previous(ctx, exec, prev)
		if err != nil {
			return fmt.Errorf("get previous split element for %s: %w", prev, err)
		}

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

	exec.addMembers(chain)
	return nil
}

func (exec *execCtx) collectChildren(ctx context.Context) error {
	exec.log.Debug(ctx, logs.DeleteCollectingChildren)

	children, err := exec.svc.header.children(ctx, exec)
	if err != nil {
		return fmt.Errorf("collect children: %w", err)
	}

	link, _ := exec.splitInfo.Link()
	exec.addMembers(append(children, link))
	return nil
}

func (exec *execCtx) supplementBySplitID(ctx context.Context) error {
	exec.log.Debug(ctx, logs.DeleteSupplementBySplitID)

	chain, err := exec.svc.searcher.splitMembers(ctx, exec)
	if err != nil {
		return fmt.Errorf("search split chain members: %w", err)
	}

	exec.addMembers(chain)
	return nil
}

func (exec *execCtx) addMembers(incoming []oid.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() error {
	payload, err := exec.tombstone.Marshal()
	if err != nil {
		return fmt.Errorf("marshal tombstone: %w", err)
	}

	exec.tombstoneObj = objectSDK.New()
	exec.tombstoneObj.SetContainerID(exec.containerID())
	exec.tombstoneObj.SetType(objectSDK.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
		localUser := exec.svc.netInfo.LocalNodeID()
		exec.tombstoneObj.SetOwnerID(localUser)
	}

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

	exec.tombstoneObj.SetAttributes(a)

	return nil
}

func (exec *execCtx) saveTombstone(ctx context.Context) error {
	id, err := exec.svc.placer.put(ctx, exec)
	if err != nil {
		return fmt.Errorf("save tombstone: %w", err)
	}

	exec.prm.tombAddrWriter.SetAddress(exec.newAddress(*id))
	return nil
}