Provide a default implementation for Sender.client/1

Author: adriankumpf

lib/telegram_logger_backend.ex

@@ -7,13 +7,14 @@ defmodule LoggerTelegramBackend do
   @behaviour :gen_event
 
   defmodule State do
+    @moduledoc false
     defstruct [:name, :level, :metadata, :metadata_filter, :send_message]
   end
 
-  alias LoggerTelegramBackend.{Formatter, Telegram}
+  alias LoggerTelegramBackend.{Formatter, Sender}
 
   @default_name :telegram
-  @default_sender {Telegram, [:token, :chat_id, :proxy]}
+  @default_sender {Sender.Telegram, [:token, :chat_id, :proxy]}
   @default_metadata [:line, :function, :module, :application, :file]
 
   @impl :gen_event

lib/telegram_logger_backend/sender.ex

@@ -1,5 +1,45 @@
 defmodule LoggerTelegramBackend.Sender do
-  @callback client(Keyword.t()) :: Tesla.Client.t()
+  @moduledoc """
+  Specifies the API for using a custom Sender.
+  """
 
-  @callback send_message(Tesla.Client.t(), String.t(), Keyword.t()) :: :ok | {:error, any}
+  @doc """
+  Creates a custom Tesla.Client
+  """
+  @callback client(opts :: Keyword.t()) :: Tesla.Client.t()
+
+  @doc """
+  Sends a message
+  """
+  @callback send_message(
+              tesla_client :: Tesla.Client.t(),
+              message :: String.t(),
+              opts :: Keyword.t()
+            ) :: :ok | {:error, any}
+
+  defmacro __using__(opts) do
+    quote do
+      @behaviour LoggerTelegramBackend.Sender
+
+      @base_url unquote(Keyword.fetch!(opts, :base_url))
+      @adapter unquote(Keyword.fetch!(opts, :adapter))
+
+      @impl true
+      def client(opts \\ []) do
+        {adapter, opts} = Keyword.pop(opts, :adapter, @adapter)
+        {base_url, opts} = Keyword.pop(opts, :base_url, @base_url)
+
+        middlewares = [
+          {Tesla.Middleware.BaseUrl, base_url},
+          {Tesla.Middleware.Headers, [{"user-agent", ""}]},
+          Tesla.Middleware.FormUrlencoded,
+          {Tesla.Middleware.Opts, opts}
+        ]
+
+        Tesla.client(middlewares, adapter)
+      end
+
+      defoverridable client: 1
+    end
+  end
 end

lib/telegram_logger_backend/telegram.ex …legram_logger_backend/sender/telegram.exlib/telegram_logger_backend/telegram.ex renamed to lib/telegram_logger_backend/sender/telegram.ex lib/telegram_logger_backend/telegram.ex renamed to lib/telegram_logger_backend/sender/telegram.ex

@@ -1,25 +1,9 @@
-defmodule LoggerTelegramBackend.Telegram do
-  @behaviour LoggerTelegramBackend.Sender
-
+defmodule LoggerTelegramBackend.Sender.Telegram do
   @moduledoc false
 
-  @base_url "https://api.telegram.org"
-  @adapter {Tesla.Adapter.Hackney, pool: :logger_telegram_backend}
-
-  @impl true
-  def client(opts \\ []) do
-    {adapter, opts} = Keyword.pop(opts, :adapter, @adapter)
-    {base_url, opts} = Keyword.pop(opts, :base_url, @base_url)
-
-    middlewares = [
-      {Tesla.Middleware.BaseUrl, base_url},
-      {Tesla.Middleware.Headers, [{"user-agent", ""}]},
-      Tesla.Middleware.FormUrlencoded,
-      {Tesla.Middleware.Opts, opts}
-    ]
-
-    Tesla.client(middlewares, adapter)
-  end
+  use LoggerTelegramBackend.Sender,
+    base_url: "https://api.telegram.org",
+    adapter: {Tesla.Adapter.Hackney, pool: :logger_telegram_backend}
 
   @impl true
   def send_message(client, text, opts) when is_binary(text) do

test/logger_telegram_backend/sender_telegram_test.exs

@@ -2,7 +2,7 @@ defmodule SenderTelegramTest do
   use ExUnit.Case
   use ExVCR.Mock, adapter: ExVCR.Adapter.Hackney
 
-  alias LoggerTelegramBackend.Telegram
+  alias LoggerTelegramBackend.Sender.Telegram
 
   setup do
     ExVCR.Config.cassette_library_dir("test/fixture/vcr_cassettes")