Update modules to be more egonomic, add command macro

Modules are now defined using on_{msg,channel_msg,join,part,kick}.
Additionally, commands can be defined using a convenient macro.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

lib/contrib/fortune.ex

@@ -17,20 +17,15 @@ defmodule Omnibot.Contrib.Fortune do
     "Godly Luck",
   ]
 
-  ## Client API
-
-  def privmsg(module, channel, nick, line) do
-    GenServer.cast(module, {:privmsg, {channel, nick, line}})
+  command "!fortune", [to] do
+    fortune = Enum.random(@fortunes)
+    reply = "#{to}: #{fortune}"
+    Irc.send_to(channel, reply)
   end
 
-  ## Server callbacks
-
-  @impl true
-  def on_channel_msg(channel, nick, line) do
-    if line == "!fortune" do
-      fortune = Enum.random(@fortunes)
-      reply = "#{nick}: #{fortune}"
-      Irc.send_to(channel, reply)
-    end
+  command "!fortune" do
+    fortune = Enum.random(@fortunes)
+    reply = "#{nick}: #{fortune}"
+    Irc.send_to(channel, reply)
   end
 end

lib/module.ex

@@ -1,72 +1,123 @@
 defmodule Omnibot.Module do
+  defmodule Hooks do
+    defmacro __before_compile__(_env) do
+      quote do
+        @impl true
+        def on_channel_msg(_channel, _nick, _line), do: nil
+
+        @impl true
+        def on_channel_msg(_channel, _nick, _cmd, _params), do: nil
+
+        @impl true
+        def on_join(_channel, _nick), do: nil
+
+        @impl true
+        def on_part(_channel, _nick), do: nil
+
+        @impl true
+        def on_kick(_channel, _nick), do: nil
+      end
+    end
+  end
+
   defmacro __using__([]) do
     quote do
-      use GenServer
+      use Agent
       alias Omnibot.{Irc, Module}
+      import Omnibot.Module
       require Logger
 
       @behaviour Module
 
-      ## Client API
-
       def start_link(opts) do
-        GenServer.start_link(__MODULE__, opts[:cfg], opts ++ [name: __MODULE__])
+        Agent.start_link(fn -> opts[:cfg] end, opts ++ [name: __MODULE__])
       end
 
-      def msg(msg), do: GenServer.cast(__MODULE__, msg)
-      def msg(module, msg), do: GenServer.cast(module, {:msg, msg})
-
-      ## Server callbacks
-
-      @impl GenServer
-      def init(cfg), do: {:ok, cfg}
+      def cfg do
+        Agent.get(__MODULE__, & &1)
+      end
 
       @impl Module
       def on_msg(msg) do
+        # TODO - instead of using a router for modules, consider using a PubSub with a Registry:
+        # https://hexdocs.pm/elixir/master/Registry.html#module-using-as-a-pubsub
         route_msg(msg)
       end
 
-      def route_msg(msg) do
+      defp route_msg(msg) do
         nick = msg.prefix.nick
+
         case String.upcase(msg.command) do
-          "PRIVMSG" -> [channel | text] = msg.params
-            on_channel_msg(channel, nick, Enum.join(text, " "))
-          "JOIN" -> [channel | _] = msg.params
+          "PRIVMSG" ->
+            [channel | params] = msg.params
+            line = Enum.join(params, " ")
+
+            case String.split(line, " ") do
+              [cmd | params] -> on_channel_msg(channel, nick, cmd, params)
+              _ -> on_channel_msg(channel, nick, line)
+            end
+
+          "JOIN" ->
+            [channel | _] = msg.params
             on_join(channel, nick)
-          "PART" -> [channel | _] = msg.params
+
+          "PART" ->
+            [channel | _] = msg.params
             on_part(channel, nick)
-          "KICK" -> [channel | _] = msg.params
+
+          "KICK" ->
+            [channel | _] = msg.params
             on_kick(channel, nick)
-          _ -> nil
+
+          _ ->
+            nil
         end
       end
 
-      @impl Module
-      def on_channel_msg(_channel, _nick, _line), do: nil
-
-      @impl Module
-      def on_join(_channel, _nick), do: nil
-
-      @impl Module
-      def on_part(_channel, _nick), do: nil
-
-      @impl Module
-      def on_kick(_channel, _nick), do: nil
-
-      @impl GenServer
-      def handle_cast({:msg, msg}, cfg) do
-        on_msg(msg)
-        {:noreply, cfg}
-      end
-
       defoverridable Module
-      defoverridable GenServer
+
+      @before_compile Omnibot.Module.Hooks
     end
   end
 
   @callback on_msg(msg :: %Omnibot.Irc.Msg{}) :: any
-  @callback on_channel_msg(channel :: String.t, nick :: String.t, line :: String.t) :: any
-  @callback on_join(channel :: String.t, nick :: String.t) :: any
-  @callback on_part(channel :: String.t, nick :: String.t) :: any
-  @callback on_kick(channel :: String.t, nick :: String.t) :: any
+  @callback on_channel_msg(channel :: String.t(), nick :: String.t(), line :: String.t()) :: any
+  @callback on_channel_msg(
+              channel :: String.t(),
+              nick :: String.t(),
+              cmd :: String.t(),
+              params :: [String.t()]
+            ) :: any
+  @callback on_join(channel :: String.t(), nick :: String.t()) :: any
+  @callback on_part(channel :: String.t(), nick :: String.t()) :: any
+  @callback on_kick(channel :: String.t(), nick :: String.t()) :: any
+
+  defmacro command(cmd, opts) do
+    quote generated: true do
+      @impl Omnibot.Module
+      def on_channel_msg(var!(channel), var!(nick), unquote(cmd), var!(params)) do
+        unquote(opts[:do])
+      end
+    end
+  end
+
+  defmacro command(cmd, params, opts) do
+    params =
+      Enum.map(
+        IO.inspect(params),
+        fn param ->
+          case param do
+            {_, _, _} -> quote(do: var!(unquote(param)))
+            lit -> Macro.escape(lit)
+          end
+        end
+      )
+
+    quote generated: true do
+      @impl Omnibot.Module
+      def on_channel_msg(var!(channel), var!(nick), unquote(cmd), unquote(params)) do
+        unquote(opts[:do])
+      end
+    end
+  end
 end

lib/router.ex

@@ -33,7 +33,7 @@ defmodule Omnibot.Router do
     # Find modules that want this message
     State.cfg()
       |> Config.channel_modules(channel)
-      |> Enum.each(fn {module, _} -> module.msg(module, msg) end)
+      |> Enum.each(fn {module, _} -> module.on_msg(msg) end)
   end
 
   def handle(_irc, :join, %Msg {prefix: %Msg.Prefix{nick: nick}, params: [channel | _]}) do