package control

import (
	"bytes"
	"context"
	"crypto/sha256"
	"encoding/hex"
	"errors"
	"fmt"

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/engine"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/pilorama"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/control"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object_manager/placement"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/replicator"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/tree"
	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/netmap"
	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
)

var errFailedToBuildListOfContainerNodes = errors.New("can't build a list of container nodes")

func (s *Server) EvacuateShard(ctx context.Context, req *control.EvacuateShardRequest) (*control.EvacuateShardResponse, error) {
	err := s.isValidRequest(req)
	if err != nil {
		return nil, status.Error(codes.PermissionDenied, err.Error())
	}

	prm := engine.EvacuateShardPrm{
		ShardID:        s.getShardIDList(req.GetBody().GetShard_ID()),
		IgnoreErrors:   req.GetBody().GetIgnoreErrors(),
		ObjectsHandler: s.replicateObject,
		Scope:          engine.EvacuateScopeObjects,
	}

	res, err := s.s.Evacuate(ctx, prm)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}

	resp := &control.EvacuateShardResponse{
		Body: &control.EvacuateShardResponse_Body{
			Count: uint32(res.ObjectsEvacuated()),
		},
	}

	err = SignMessage(s.key, resp)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}
	return resp, nil
}

func (s *Server) replicateObject(ctx context.Context, addr oid.Address, obj *objectSDK.Object) error {
	cid, ok := obj.ContainerID()
	if !ok {
		// Return nil to prevent situations where a shard can't be evacuated
		// because of a single bad/corrupted object.
		return nil
	}

	nodes, err := s.getContainerNodes(cid)
	if err != nil {
		return err
	}

	var res replicatorResult
	task := replicator.Task{
		NumCopies: 1,
		Addr:      addr,
		Obj:       obj,
		Nodes:     nodes,
	}
	s.replicator.HandleTask(ctx, task, &res)

	if res.count == 0 {
		return errors.New("object was not replicated")
	}
	return nil
}

func (s *Server) replicateTree(ctx context.Context, contID cid.ID, treeID string, forest pilorama.Forest) (string, error) {
	nodes, err := s.getContainerNodes(contID)
	if err != nil {
		return "", err
	}
	if len(nodes) == 0 {
		return "", fmt.Errorf("no remote nodes available to replicate tree '%s' of container %s", treeID, contID)
	}

	for _, node := range nodes {
		err = s.replicateTreeToNode(ctx, forest, contID, treeID, node)
		if err == nil {
			return hex.EncodeToString(node.PublicKey()), nil
		}
	}
	return "", err
}

func (s *Server) replicateTreeToNode(ctx context.Context, forest pilorama.Forest, contID cid.ID, treeID string, node netmap.NodeInfo) error {
	rawCID := make([]byte, sha256.Size)
	contID.Encode(rawCID)

	var height uint64
	for {
		op, err := forest.TreeGetOpLog(ctx, contID, treeID, height)
		if err != nil {
			return err
		}

		if op.Time == 0 {
			return nil
		}

		req := &tree.ApplyRequest{
			Body: &tree.ApplyRequest_Body{
				ContainerId: rawCID,
				TreeId:      treeID,
				Operation: &tree.LogMove{
					ParentId: op.Parent,
					Meta:     op.Meta.Bytes(),
					ChildId:  op.Child,
				},
			},
		}

		err = tree.SignMessage(req, s.key)
		if err != nil {
			return fmt.Errorf("can't sign apply request: %w", err)
		}

		err = s.treeService.ReplicateTreeOp(ctx, node, req)
		if err != nil {
			return err
		}

		height = op.Time + 1
	}
}

func (s *Server) getContainerNodes(contID cid.ID) ([]netmap.NodeInfo, error) {
	nm, err := s.netMapSrc.GetNetMap(0)
	if err != nil {
		return nil, err
	}

	c, err := s.cnrSrc.Get(contID)
	if err != nil {
		return nil, err
	}

	binCnr := make([]byte, sha256.Size)
	contID.Encode(binCnr)

	ns, err := nm.ContainerNodes(c.Value.PlacementPolicy(), binCnr)
	if err != nil {
		return nil, errFailedToBuildListOfContainerNodes
	}

	nodes := placement.FlattenNodes(ns)
	bs := (*keys.PublicKey)(&s.key.PublicKey).Bytes()
	for i := 0; i < len(nodes); i++ {
		if bytes.Equal(nodes[i].PublicKey(), bs) {
			copy(nodes[i:], nodes[i+1:])
			nodes = nodes[:len(nodes)-1]
		}
	}
	return nodes, nil
}

type replicatorResult struct {
	count int
}

// SubmitSuccessfulReplication implements the replicator.TaskResult interface.
func (r *replicatorResult) SubmitSuccessfulReplication(_ netmap.NodeInfo) {
	r.count++
}