Move shared boilerplate in servers to Amethyst.Server

lib/servers/generic.ex

@@ -37,3 +37,30 @@ defmodule Amethyst.Server.Generic do
     end
   end
 end
+
+defmodule Amethyst.Server do
+  @moduledoc """
+  This module includes shared boilerplate code for all stages of the server.
+  """
+
+  defmacro __using__(_opts) do
+    quote do
+      @spec serve(:gen_tcp.socket()) :: no_return()
+      def serve(client) do
+        {id, data} = Amethyst.Server.Generic.get_packet(client)
+        packet = deserialize(id, data)
+        Logger.debug("Got packet #{inspect(packet)}")
+        handle(packet, client)
+        serve(client)
+      end
+
+
+      def transmit(packet, client) do
+        Logger.debug("Transmitting #{inspect(packet)}")
+        data = serialize(packet)
+        length = byte_size(data) |> Amethyst.Minecraft.Write.varint()
+        :gen_tcp.send(client, length <> data)
+      end
+    end
+  end
+end

lib/servers/stage1.ex

@@ -19,16 +19,9 @@ defmodule Amethyst.Server.Stage1 do
   This module contains the stage 1 (Handshaking) server logic.
   """
   require Logger
-  alias Amethyst.Minecraft.Read
+  use Amethyst.Server
 
-  @spec serve(:gen_tcp.socket()) :: no_return()
-  def serve(client) do
-    {id, data} = Amethyst.Server.Generic.get_packet(client)
-    packet = deserialize(id, data)
-    Logger.debug("Got packet #{inspect(packet)}")
-    handle(packet, client)
-    serve(client)
-  end
+  alias Amethyst.Minecraft.Read
 
   ## DESERIALIZATION
   # Handshake https://wiki.vg/Protocol#Handshake
@@ -48,6 +41,11 @@ defmodule Amethyst.Server.Stage1 do
     raise RuntimeError, "Got unknown packet type #{type}!"
   end
 
+  ## SERIALIZATION
+  def serialize(_) do
+    raise RuntimeError, "No packets can be transmitted while still in the handshake stage!"
+  end
+
   ## HANDLING
   # Handshake https://wiki.vg/Protocol#Handshake
   @spec handle(any(), any()) :: no_return()

lib/servers/status.ex

@@ -20,25 +20,11 @@ defmodule Amethyst.Server.Status do
   is only asking a bit of information.
   """
   require Logger
+  use Amethyst.Server
+
   alias Amethyst.Minecraft.Read
   alias Amethyst.Minecraft.Write
 
-  @spec serve(:gen_tcp.socket()) :: no_return()
-  def serve(client) do
-    {id, data} = Amethyst.Server.Generic.get_packet(client)
-    packet = deserialize(id, data)
-    Logger.debug("Got packet #{inspect(packet)}")
-    handle(packet, client)
-    serve(client)
-  end
-
-  def transmit(packet, client) do
-    Logger.debug("Transmitting #{inspect(packet)}")
-    data = serialize(packet)
-    length = byte_size(data) |> Write.varint()
-    :gen_tcp.send(client, length <> data)
-  end
-
   ## DESERIALIZATION
   # Status Request https://wiki.vg/Protocol#Status_Request
   def deserialize(0x00, _) do