v3 refactor (#1868)

* Move to v3

Co-authored-by: Ben Toogood <bentoogood@gmail.com>

util/mux/mux.go

@@ -5,10 +5,11 @@ import (
 	"context"
 	"sync"
 
-	"github.com/micro/go-micro/v2/client"
-	"github.com/micro/go-micro/v2/debug/service/handler"
-	"github.com/micro/go-micro/v2/proxy"
-	"github.com/micro/go-micro/v2/server"
+	"github.com/micro/go-micro/v3/client/grpc"
+	"github.com/micro/go-micro/v3/debug/service/handler"
+	"github.com/micro/go-micro/v3/proxy"
+	"github.com/micro/go-micro/v3/server"
+	"github.com/micro/go-micro/v3/server/mucp"
 )
 
 // Server is a proxy muxer that incudes the use of the DefaultHandler
@@ -17,6 +18,14 @@ type Server struct {
 	Name string
 	// Proxy handler
 	Proxy proxy.Proxy
+	// The default handler
+	Handler Handler
+}
+
+type Handler interface {
+	proxy.Proxy
+	NewHandler(interface{}, ...server.HandlerOption) server.Handler
+	Handle(server.Handler) error
 }
 
 var (
@@ -25,32 +34,35 @@ var (
 
 func (s *Server) ProcessMessage(ctx context.Context, msg server.Message) error {
 	if msg.Topic() == s.Name {
-		return server.DefaultRouter.ProcessMessage(ctx, msg)
+		return s.Handler.ProcessMessage(ctx, msg)
 	}
 	return s.Proxy.ProcessMessage(ctx, msg)
 }
 
 func (s *Server) ServeRequest(ctx context.Context, req server.Request, rsp server.Response) error {
 	if req.Service() == s.Name {
-		return server.DefaultRouter.ServeRequest(ctx, req, rsp)
+		return s.Handler.ServeRequest(ctx, req, rsp)
 	}
 	return s.Proxy.ServeRequest(ctx, req, rsp)
 }
 
 func New(name string, p proxy.Proxy) *Server {
+	r := mucp.DefaultRouter
+
 	// only register this once
 	once.Do(func() {
-		server.DefaultRouter.Handle(
+		r.Handle(
 			// inject the debug handler
-			server.DefaultRouter.NewHandler(
-				handler.NewHandler(client.DefaultClient),
+			r.NewHandler(
+				handler.NewHandler(grpc.NewClient()),
 				server.InternalHandler(true),
 			),
 		)
 	})
 
 	return &Server{
-		Name:  name,
-		Proxy: p,
+		Name:    name,
+		Proxy:   p,
+		Handler: r,
 	}
 }