add server interface interceptors

Signed-off-by: Adphi <philippe.adrien.nousse@gmail.com>

interceptors/iface/interceptors.go

@@ -0,0 +1,41 @@
+package iface
+
+import (
+	"context"
+
+	"google.golang.org/grpc"
+
+	"go.linka.cloud/grpc/interceptors"
+)
+
+type UnaryInterceptor interface {
+	UnaryServerInterceptor() grpc.UnaryServerInterceptor
+}
+
+type StreamInterceptor interface {
+	StreamServerInterceptor() grpc.StreamServerInterceptor
+}
+
+type iface struct{}
+
+func New() interceptors.ServerInterceptors {
+	return &iface{}
+}
+
+func (s iface) UnaryServerInterceptor() grpc.UnaryServerInterceptor {
+	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (resp interface{}, err error) {
+		if i, ok := info.Server.(UnaryInterceptor); ok {
+			return i.UnaryServerInterceptor()(ctx, req, info, handler)
+		}
+		return handler(ctx, req)
+	}
+}
+
+func (s iface) StreamServerInterceptor() grpc.StreamServerInterceptor {
+	return func(srv interface{}, ss grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
+		if i, ok := srv.(StreamInterceptor); ok {
+			return i.StreamServerInterceptor()(srv, ss, info, handler)
+		}
+		return handler(srv, ss)
+	}
+}