Use proper grpc requres_response interceptor for macaroon metadata

...so much to learn :)

lib/lnrpc.rb

@@ -4,6 +4,7 @@ require "lnrpc/rpc_services_pb"
 module Lnrpc
   class Error < StandardError; end
   autoload :Client, 'lnrpc/client'
+  autoload :MacaroonInterceptor, 'lnrpc/macaroon_interceptor'
 end
 
 

lib/lnrpc/client.rb

@@ -1,3 +1,5 @@
+require "grpc"
+require "lnrpc/macaroon_interceptor"
 module Lnrpc
   class Client
     attr_accessor :address, :credentials, :macaroon, :grpc_client
@@ -38,7 +40,10 @@ module Lnrpc
       end
       self.macaroon = options[:macaroon]
 
-      self.grpc_client = Lnrpc::Lightning::Stub.new(self.address, GRPC::Core::ChannelCredentials.new(self.credentials))
+      self.grpc_client = Lnrpc::Lightning::Stub.new(self.address,
+                                                    GRPC::Core::ChannelCredentials.new(self.credentials),
+                                                    interceptors: [Lnrpc::MacaroonInterceptor.new(self.macaroon)]
+                                                   )
     end
 
     def pay(payreq)
@@ -48,10 +53,9 @@ module Lnrpc
     def method_missing(m, *args, &block)
       if self.grpc_client.respond_to?(m)
         params  = args[0]
-        options = args[1] || { metadata: { macaroon: self.macaroon } }
 
-        request = params.nil? ? request_class_for(m).new : request_class_for(m).new(params)
+        args[0] = params.nil? ? request_class_for(m).new : request_class_for(m).new(params)
-        self.grpc_client.send(m, request, options)
+        self.grpc_client.send(m, *args)
       else
         super
       end

lib/lnrpc/macaroon_interceptor.rb

@@ -0,0 +1,14 @@
+require "grpc"
+
+module Lnrpc
+  class MacaroonInterceptor < GRPC::ClientInterceptor
+    def initialize(macaroon_hex)
+      @macaroon = macaroon_hex
+    end
+
+    def request_response(request:, call:, method:, metadata:)
+      metadata['macaroon'] = @macaroon
+      yield
+    end
+  end
+end