Add additional layer to parse protocols & add request builder

lib/kafka_ex/new/client/request_builder.ex

@@ -0,0 +1,36 @@
+defmodule KafkaEx.New.Client.RequestBuilder do
+  @moduledoc """
+  This module is used to build request for KafkaEx.New.Client.
+  It's main decision point which protocol to use for building request and what
+  is required version.
+  """
+  @protocol Application.get_env(
+              :kafka_ex,
+              :protocol,
+              KafkaEx.New.Protocols.KayrockProtocol
+            )
+
+  @default_api_version %{
+    describe_groups: 1
+  }
+
+  alias KafkaEx.New.Client.State
+
+  @doc """
+  Builds request for Describe Groups API
+  """
+  @spec describe_groups_request([binary], State.t()) :: term
+  def describe_groups_request(group_names, state) do
+    api_version = get_api_version(state, :describe_groups)
+
+    @protocol.build_request(:describe_groups, api_version,
+      group_names: group_names
+    )
+  end
+
+  # -----------------------------------------------------------------------------
+  defp get_api_version(state, request_type) do
+    default = Map.fetch!(@default_api_version, request_type)
+    State.max_supported_api_version(state, request_type, default)
+  end
+end

lib/kafka_ex/new/protocols/describe_groups.ex → lib/kafka_ex/new/protocols/kayrock/describe_groups.ex

@@ -1,6 +1,8 @@
-defprotocol KafkaEx.New.Protocols.DescribeGroups do
+defprotocol KafkaEx.New.Protocols.Kayrock.DescribeGroups do
   @moduledoc """
-  This module handles Describe Groups request & response handling & parsing
+  This module handles Describe Groups request & response parsing.
+  Request is built using Kayrock protocol, response is parsed to
+  native KafkaEx structs.
   """
 
   defprotocol Request do

lib/kafka_ex/new/protocols/kayrock/describe_groups/default_request_impl.ex

@@ -1,4 +1,4 @@
-defimpl KafkaEx.New.Protocols.DescribeGroups.Request,
+defimpl KafkaEx.New.Protocols.Kayrock.DescribeGroups.Request,
   for: [Kayrock.DescribeGroups.V0.Request, Kayrock.DescribeGroups.V1.Request] do
   def build_request(request_template, consumer_group_names) do
     Map.put(request_template, :group_ids, consumer_group_names)

lib/kafka_ex/new/protocols/kayrock/describe_groups/default_response_impl.ex

@@ -1,4 +1,4 @@
-defimpl KafkaEx.New.Protocols.DescribeGroups.Response,
+defimpl KafkaEx.New.Protocols.Kayrock.DescribeGroups.Response,
   for: [Kayrock.DescribeGroups.V0.Response, Kayrock.DescribeGroups.V1.Response] do
   def parse_response(%{groups: groups}) do
     case Enum.filter(groups, &(&1.error_code != 0)) do

lib/kafka_ex/new/protocols/kayrock_protocol.ex

@@ -0,0 +1,20 @@
+defmodule KafkaEx.New.Protocols.KayrockProtocol do
+  @moduledoc """
+  This module handles Kayrock request & response handling & parsing.
+  Once Kafka Ex v1.0 is released, this module will be renamed to KayrockProtocol
+  and will become a separated package.
+  """
+
+  alias KafkaEx.New.Protocols.Kayrock, as: KayrockProtocol
+
+  @doc """
+  Builds request for Describe Groups API
+  """
+  def build_request(:describe_groups, api_version, opts) do
+    group_names = Keyword.fetch!(opts, :group_names)
+
+    api_version
+    |> Kayrock.DescribeGroups.get_request_struct()
+    |> KayrockProtocol.DescribeGroups.Request.build_request(group_names)
+  end
+end

test/kafka_ex/new/client/request_builder_test.exs

@@ -0,0 +1,17 @@
+defmodule KafkaEx.New.Client.RequestBuilderTest do
+  use ExUnit.Case, async: true
+  alias KafkaEx.New.Client.RequestBuilder
+
+  describe "describe_groups_request/2" do
+    test "returns request for DescribeGroups API" do
+      state = %KafkaEx.New.Client.State{api_versions: %{describe_groups: 1}}
+      group_names = ["group1", "group2"]
+
+      assert RequestBuilder.describe_groups_request(group_names, state) ==
+               {:ok,
+                %KafkaEx.New.Protocols.DescribeGroups.Request{
+                  group_names: group_names
+                }}
+    end
+  end
+end

test/kafka_ex/new/protocols/kayrock/describe_groups_test.exs

@@ -0,0 +1,81 @@
+defmodule KafkaEx.New.Protocols.Kayrock.DescribeGroupsTest do
+  use ExUnit.Case, async: true
+
+  alias KafkaEx.New.Protocols.Kayrock.DescribeGroups, as: KayrockDescribeGroups
+
+  alias Kayrock.DescribeGroups.V0
+
+  describe "build_request/2" do
+    test "builds request for Describe Groups API" do
+      api_version = 0
+      consumer_group_names = ["test-group"]
+      expected_request = %V0.Request{group_ids: groups}
+
+      assert KayrockDescribeGroups.build_request(
+               api_version,
+               consumer_group_names
+             ) == expected_request
+    end
+  end
+
+  describe "build_response/1" do
+    test "for api version 0 - returns response if all groups succeeded" do
+      response = %V0.Response{
+        groups: [
+          %{
+            group_id: "succeeded",
+            error_code: 0,
+            state: "stable",
+            protocol_type: "protocol_type",
+            protocol: "protocol",
+            members: [
+              %{
+                member_id: "member_id",
+                client_id: "client_id",
+                client_host: "client_host",
+                member_metadata: "member_metadata",
+                member_assignment: %{
+                  version: 0,
+                  user_data: "user_data",
+                  partition_assignments: [
+                    %{topic: "test-topic", partitions: [1, 2, 3]}
+                  ]
+                }
+              }
+            ]
+          }
+        ]
+      }
+
+      assert {:ok,
+              [
+                %KafkaEx.New.ConsumerGroup{
+                  group_id: "succeeded",
+                  state: "stable",
+                  protocol_type: "protocol_type",
+                  protocol: "protocol",
+                  members: [
+                    %KafkaEx.New.ConsumerGroup.Member{
+                      member_id: "member_id",
+                      client_id: "client_id",
+                      client_host: "client_host",
+                      member_metadata: "member_metadata",
+                      member_assignment:
+                        %KafkaEx.New.ConsumerGroup.Member.MemberAssignment{
+                          version: 0,
+                          user_data: "user_data",
+                          partition_assignments: [
+                            %KafkaEx.New.ConsumerGroup.Member.MemberAssignment.PartitionAssignment{
+                              topic: "test-topic",
+                              partitions: [1, 2, 3]
+                            }
+                          ]
+                        }
+                    }
+                  ]
+                }
+              ]} ==
+               DescribeGroups.Response.parse_response(response)
+    end
+  end
+end