package control

import (
	"context"
	"errors"
	"fmt"

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/control"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/control/server/ape"
	apechain "git.frostfs.info/TrueCloudLab/policy-engine/pkg/chain"
	"git.frostfs.info/TrueCloudLab/policy-engine/pkg/engine"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
)

func apeTarget(chainTarget *control.ChainTarget) (engine.Target, error) {
	switch chainTarget.GetType() {
	case control.ChainTarget_CONTAINER:
		return engine.ContainerTarget(chainTarget.GetName()), nil
	case control.ChainTarget_NAMESPACE:
		return engine.NamespaceTarget(chainTarget.GetName()), nil
	default:
	}
	return engine.Target{}, status.Error(codes.InvalidArgument,
		fmt.Errorf("target type is not supported: %s", chainTarget.GetType().String()).Error())
}

func controlTarget(chainTarget *engine.Target) (control.ChainTarget, error) {
	switch chainTarget.Type {
	case engine.Container:
		return control.ChainTarget{
			Name: chainTarget.Name,
			Type: control.ChainTarget_CONTAINER,
		}, nil
	case engine.Namespace:
		// If namespace is empty, we take it for root namespace.
		nm := chainTarget.Name
		if nm == "root" {
			nm = ""
		}
		return control.ChainTarget{
			Name: nm,
			Type: control.ChainTarget_NAMESPACE,
		}, nil
	default:
	}
	return control.ChainTarget{}, status.Error(codes.InvalidArgument,
		fmt.Errorf("target type is not supported: %c", chainTarget.Type).Error())
}

func (s *Server) AddChainLocalOverride(_ context.Context, req *control.AddChainLocalOverrideRequest) (*control.AddChainLocalOverrideResponse, error) {
	if err := s.isValidRequest(req); err != nil {
		return nil, status.Error(codes.PermissionDenied, err.Error())
	}

	var chain apechain.Chain
	if err := chain.DecodeBytes(req.GetBody().GetChain()); err != nil {
		return nil, status.Error(codes.InvalidArgument, err.Error())
	}
	for _, rule := range chain.Rules {
		for _, name := range rule.Resources.Names {
			if err := ape.ValidateResourceName(name); err != nil {
				return nil, status.Error(codes.InvalidArgument, fmt.Errorf("invalid resource: %w", err).Error())
			}
		}
	}

	s.apeChainCounter.Add(1)
	// TODO (aarifullin): the such chain id is not well-designed yet.
	if len(chain.ID) == 0 {
		chain.ID = apechain.ID(fmt.Sprintf("%s:%d", apechain.Ingress, s.apeChainCounter.Load()))
	}

	target, err := apeTarget(req.GetBody().GetTarget())
	if err != nil {
		return nil, err
	}

	if _, err = s.localOverrideStorage.LocalStorage().AddOverride(apechain.Ingress, target, &chain); err != nil {
		return nil, status.Error(getCodeByLocalStorageErr(err), err.Error())
	}

	resp := &control.AddChainLocalOverrideResponse{
		Body: &control.AddChainLocalOverrideResponse_Body{
			ChainId: []byte(chain.ID),
		},
	}
	err = SignMessage(s.key, resp)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}
	return resp, nil
}

func (s *Server) GetChainLocalOverride(_ context.Context, req *control.GetChainLocalOverrideRequest) (*control.GetChainLocalOverrideResponse, error) {
	if err := s.isValidRequest(req); err != nil {
		return nil, status.Error(codes.PermissionDenied, err.Error())
	}

	target, err := apeTarget(req.GetBody().GetTarget())
	if err != nil {
		return nil, err
	}
	chain, err := s.localOverrideStorage.LocalStorage().GetOverride(apechain.Ingress, target, apechain.ID(req.GetBody().GetChainId()))
	if err != nil {
		return nil, status.Error(getCodeByLocalStorageErr(err), err.Error())
	}

	resp := &control.GetChainLocalOverrideResponse{
		Body: &control.GetChainLocalOverrideResponse_Body{
			Chain: chain.Bytes(),
		},
	}
	err = SignMessage(s.key, resp)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}
	return resp, nil
}

func (s *Server) ListChainLocalOverrides(_ context.Context, req *control.ListChainLocalOverridesRequest) (*control.ListChainLocalOverridesResponse, error) {
	if err := s.isValidRequest(req); err != nil {
		return nil, status.Error(codes.PermissionDenied, err.Error())
	}

	target, err := apeTarget(req.GetBody().GetTarget())
	if err != nil {
		return nil, err
	}

	chains, err := s.localOverrideStorage.LocalStorage().ListOverrides(apechain.Ingress, target)
	if err != nil {
		return nil, status.Error(getCodeByLocalStorageErr(err), err.Error())
	}
	serializedChains := make([][]byte, 0, len(chains))
	for _, chain := range chains {
		serializedChains = append(serializedChains, chain.Bytes())
	}

	resp := &control.ListChainLocalOverridesResponse{
		Body: &control.ListChainLocalOverridesResponse_Body{
			Chains: serializedChains,
		},
	}
	err = SignMessage(s.key, resp)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}
	return resp, nil
}

func (s *Server) RemoveChainLocalOverride(_ context.Context, req *control.RemoveChainLocalOverrideRequest) (*control.RemoveChainLocalOverrideResponse, error) {
	if err := s.isValidRequest(req); err != nil {
		return nil, status.Error(codes.PermissionDenied, err.Error())
	}

	target, err := apeTarget(req.GetBody().GetTarget())
	if err != nil {
		return nil, err
	}

	removed := true
	if err = s.localOverrideStorage.LocalStorage().RemoveOverride(apechain.Ingress, target, apechain.ID(req.GetBody().GetChainId())); err != nil {
		code := getCodeByLocalStorageErr(err)
		if code == codes.NotFound {
			removed = false
		} else {
			return nil, status.Error(code, err.Error())
		}
	}
	resp := &control.RemoveChainLocalOverrideResponse{
		Body: &control.RemoveChainLocalOverrideResponse_Body{
			Removed: removed,
		},
	}
	err = SignMessage(s.key, resp)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}
	return resp, nil
}

func (s *Server) ListTargetsLocalOverrides(_ context.Context, req *control.ListTargetsLocalOverridesRequest) (*control.ListTargetsLocalOverridesResponse, error) {
	if err := s.isValidRequest(req); err != nil {
		return nil, status.Error(codes.PermissionDenied, err.Error())
	}

	apeChainName := apechain.Name(req.GetBody().GetChainName())
	apeTargets, err := s.localOverrideStorage.LocalStorage().ListOverrideDefinedTargets(apeChainName)
	if err != nil {
		return nil, status.Error(getCodeByLocalStorageErr(err), err.Error())
	}
	targets := make([]*control.ChainTarget, 0, len(apeTargets))
	for i := range apeTargets {
		target, err := controlTarget(&apeTargets[i])
		if err != nil {
			return nil, status.Error(codes.Internal, err.Error())
		}
		targets = append(targets, &target)
	}

	resp := &control.ListTargetsLocalOverridesResponse{
		Body: &control.ListTargetsLocalOverridesResponse_Body{
			Targets: targets,
		},
	}
	err = SignMessage(s.key, resp)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}
	return resp, nil
}

func getCodeByLocalStorageErr(err error) codes.Code {
	if errors.Is(err, engine.ErrChainNotFound) || errors.Is(err, engine.ErrChainNameNotFound) {
		return codes.NotFound
	}
	return codes.Internal
}