package tagging

import (
	"context"

	"google.golang.org/grpc"
	"google.golang.org/grpc/metadata"
)

const (
	ioTagHeader = "x-frostfs-io-tag"
)

// NewUnaryClientInteceptor creates new gRPC unary interceptor to set an IO tag to gRPC metadata.
func NewUnaryClientInteceptor() grpc.UnaryClientInterceptor {
	return func(ctx context.Context, method string, req, reply any, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
		return invoker(setIOTagToGRPCMetadata(ctx), method, req, reply, cc, opts...)
	}
}

// NewStreamClientInterceptor creates new gRPC stream interceptor to set an IO tag to gRPC metadata.
func NewStreamClientInterceptor() grpc.StreamClientInterceptor {
	return func(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
		return streamer(setIOTagToGRPCMetadata(ctx), desc, cc, method, opts...)
	}
}

// NewUnaryServerInterceptor creates new gRPC unary interceptor to extract an IO tag to gRPC metadata.
func NewUnaryServerInterceptor() grpc.UnaryServerInterceptor {
	return func(ctx context.Context, req any, _ *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (resp interface{}, err error) {
		return handler(extractIOTagFromGRPCMetadata(ctx), req)
	}
}

// NewStreamServerInterceptor creates new gRPC stream interceptor to extract an IO tag to gRPC metadata.
func NewStreamServerInterceptor() grpc.StreamServerInterceptor {
	return func(srv any, ss grpc.ServerStream, _ *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
		return handler(srv, &serverStream{origin: ss})
	}
}

func setIOTagToGRPCMetadata(ctx context.Context) context.Context {
	ioTag, ok := IOTagFromContext(ctx)
	if !ok {
		return ctx
	}
	md, ok := metadata.FromOutgoingContext(ctx)
	if !ok {
		md = metadata.MD{}
	}
	md.Set(ioTagHeader, ioTag)
	return metadata.NewOutgoingContext(ctx, md)
}

func extractIOTagFromGRPCMetadata(ctx context.Context) context.Context {
	md, ok := metadata.FromIncomingContext(ctx)
	if !ok {
		return ctx
	}

	values := md.Get(ioTagHeader)
	if len(values) > 0 {
		return ContextWithIOTag(ctx, values[0])
	}
	return ctx
}

var _ grpc.ServerStream = &serverStream{}

type serverStream struct {
	origin grpc.ServerStream
}

func (s *serverStream) Context() context.Context {
	return extractIOTagFromGRPCMetadata(s.origin.Context())
}

func (s *serverStream) RecvMsg(m any) error {
	return s.origin.RecvMsg(m)
}

func (s *serverStream) SendHeader(md metadata.MD) error {
	return s.origin.SendHeader(md)
}

func (s *serverStream) SendMsg(m any) error {
	return s.origin.SendMsg(m)
}

func (s *serverStream) SetHeader(md metadata.MD) error {
	return s.origin.SetHeader(md)
}

func (s *serverStream) SetTrailer(md metadata.MD) {
	s.origin.SetTrailer(md)
}