From c62cd5c5a9519f03b7ad4084bc6737a091eb2710 Mon Sep 17 00:00:00 2001
From: Leonard Lyubich <leonard@nspcc.ru>
Date: Thu, 20 Aug 2020 13:01:55 +0300
Subject: [PATCH] v2/session: Add universal client

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
---
 v2/session/client.go | 156 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 156 insertions(+)
 create mode 100644 v2/session/client.go

diff --git a/v2/session/client.go b/v2/session/client.go
new file mode 100644
index 0000000..7232f9f
--- /dev/null
+++ b/v2/session/client.go
@@ -0,0 +1,156 @@
+package session
+
+import (
+	"context"
+
+	"github.com/nspcc-dev/neofs-api-go/v2/client"
+	session "github.com/nspcc-dev/neofs-api-go/v2/session/grpc"
+	"github.com/pkg/errors"
+	"google.golang.org/grpc"
+)
+
+// Client represents universal session
+// transport client.
+type Client struct {
+	client *createClient
+}
+
+// Option represents Client option.
+type Option func(*cfg)
+
+type cfg struct {
+	proto client.Protocol
+
+	globalOpts []client.Option
+
+	gRPC cfgGRPC
+}
+
+type cfgGRPC struct {
+	serviceClient session.SessionServiceClient
+
+	grpcCallOpts []grpc.CallOption
+
+	callOpts []session.Option
+
+	client *session.Client
+}
+
+type createClient struct {
+	requestConverter func(*CreateRequest) interface{}
+
+	caller func(context.Context, interface{}) (interface{}, error)
+
+	responseConverter func(interface{}) *CreateResponse
+}
+
+// Create sends CreateRequest over the network and returns CreateResponse.
+//
+// It returns any error encountered during the call.
+func (c *Client) Create(ctx context.Context, req *CreateRequest) (*CreateResponse, error) {
+	resp, err := c.client.caller(ctx, c.client.requestConverter(req))
+	if err != nil {
+		return nil, errors.Wrap(err, "could not send session init request")
+	}
+
+	return c.client.responseConverter(resp), nil
+}
+
+func defaultCfg() *cfg {
+	return &cfg{
+		proto: client.ProtoGRPC,
+	}
+}
+
+func New(opts ...Option) (*Client, error) {
+	cfg := defaultCfg()
+
+	for i := range opts {
+		opts[i](cfg)
+	}
+
+	var err error
+
+	switch cfg.proto {
+	case client.ProtoGRPC:
+		var c *session.Client
+		if c, err = newGRPCClient(cfg); err != nil {
+			break
+		}
+
+		return &Client{
+			client: &createClient{
+				requestConverter: func(req *CreateRequest) interface{} {
+					return CreateRequestToGRPCMessage(req)
+				},
+				caller: func(ctx context.Context, req interface{}) (interface{}, error) {
+					return c.Create(ctx, req.(*session.CreateRequest))
+				},
+				responseConverter: func(resp interface{}) *CreateResponse {
+					return CreateResponseFromGRPCMessage(resp.(*session.CreateResponse))
+				},
+			},
+		}, nil
+	default:
+		err = client.ErrProtoUnsupported
+	}
+
+	return nil, errors.Wrapf(err, "could not create %s Session client", cfg.proto)
+}
+
+func newGRPCClient(cfg *cfg) (*session.Client, error) {
+	var err error
+
+	if cfg.gRPC.client == nil {
+		if cfg.gRPC.serviceClient == nil {
+			conn, err := client.NewGRPCClientConn(cfg.globalOpts...)
+			if err != nil {
+				return nil, errors.Wrap(err, "could not open gRPC client connection")
+			}
+
+			cfg.gRPC.serviceClient = session.NewSessionServiceClient(conn)
+		}
+
+		cfg.gRPC.client, err = session.NewClient(
+			cfg.gRPC.serviceClient,
+			append(
+				cfg.gRPC.callOpts,
+				session.WithCallOptions(cfg.gRPC.grpcCallOpts),
+			)...,
+		)
+	}
+
+	return cfg.gRPC.client, err
+}
+
+func WithGlobalOpts(v ...client.Option) Option {
+	return func(c *cfg) {
+		if len(v) > 0 {
+			c.globalOpts = v
+		}
+	}
+}
+
+func WithGRPCServiceClient(v session.SessionServiceClient) Option {
+	return func(c *cfg) {
+		c.gRPC.serviceClient = v
+	}
+}
+
+func WithGRPCCallOpts(v []grpc.CallOption) Option {
+	return func(c *cfg) {
+		c.gRPC.grpcCallOpts = v
+	}
+}
+
+func WithGRPCClientOpts(v []session.Option) Option {
+	return func(c *cfg) {
+		c.gRPC.callOpts = v
+	}
+}
+
+func WithGRPCClient(v *session.Client) Option {
+	return func(c *cfg) {
+		c.gRPC.client = v
+	}
+}