Add lib/plugin that was removed in the last commit, whoops

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

lib/plugin/base.ex

@@ -0,0 +1,129 @@
+defmodule Omnibot.Plugin.Base do
+  defmodule Hooks do
+    defmacro __before_compile__(_env) do
+      quote generated: true do
+        @impl true
+        def on_channel_msg(_irc, _channel, _nick, _line), do: nil
+
+        @impl true
+        def on_channel_msg(_irc, _channel, _nick, _cmd, _params), do: nil
+
+        @impl true
+        def on_join(_irc, _channel, _nick), do: nil
+
+        @impl true
+        def on_part(_irc, _channel, _nick), do: nil
+
+        @impl true
+        def on_kick(_irc, _channel, _nick, _target), do: nil
+
+        @impl true
+        def on_init(_cfg), do: nil
+
+        @impl true
+        def default_config(), do: @default_config
+
+        def commands(), do: MapSet.to_list(@commands)
+      end
+    end
+  end
+
+  defmacro __using__([]) do
+    quote do
+      alias Omnibot.{Irc, Plugin}
+      import Omnibot.Plugin.Base
+
+      @behaviour Plugin.Base
+
+      @impl Plugin.Base
+      def on_msg(irc, 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(irc, msg)
+      end
+
+      defp route_msg(irc, msg) do
+        nick = msg.prefix.nick
+        case String.upcase(msg.command) do
+          "PRIVMSG" ->
+            [channel | params] = msg.params
+            line = Enum.join(params, " ")
+
+            case String.split(line, " ") do
+              [cmd | params] -> if Enum.member?(commands(), cmd),
+                  do: on_channel_msg(irc, channel, nick, cmd, params),
+                  else: on_channel_msg(irc, channel, nick, line)
+              _ -> on_channel_msg(irc, channel, nick, line)
+            end
+
+          "JOIN" ->
+            [channel | _] = msg.params
+            on_join(irc, channel, nick)
+
+          "PART" ->
+            [channel | _] = msg.params
+            on_part(irc, channel, nick)
+
+          "KICK" ->
+            [channel, target | _] = msg.params
+            on_kick(irc, channel, nick, target)
+
+          _ ->
+            nil
+        end
+      end
+
+      defoverridable Plugin.Base
+
+      @commands MapSet.new()
+      @default_config []
+      @before_compile Omnibot.Plugin.Base.Hooks
+    end
+  end
+
+  @callback on_msg(irc :: pid(), msg :: %Omnibot.Irc.Msg{}) :: any
+  @callback on_channel_msg(irc :: pid(), channel :: String.t(), nick :: String.t(), line :: String.t()) :: any
+  @callback on_channel_msg(
+              irc :: pid(),
+              channel :: String.t(),
+              nick :: String.t(),
+              cmd :: String.t(),
+              params :: [String.t()]
+            ) :: any
+  @callback on_join(irc :: pid(), channel :: String.t(), nick :: String.t()) :: any
+  @callback on_part(irc :: pid(), channel :: String.t(), nick :: String.t()) :: any
+  @callback on_kick(irc :: pid(), channel :: String.t(), nick :: String.t(), target :: String.t()) :: any
+  @callback on_init(cfg :: any) :: any
+  @callback default_config() :: any
+
+  defmacro command(cmd, opts) do
+    quote generated: true do
+      @commands MapSet.put(@commands, unquote(cmd))
+      @impl Omnibot.Plugin.Base
+      def on_channel_msg(var!(irc), var!(channel), var!(nick), unquote(cmd), var!(params)) do
+        unquote(opts[:do])
+      end
+    end
+  end
+
+  defmacro command(cmd, params, opts) do
+    params =
+      Enum.map(
+        params,
+        fn param ->
+          case param do
+            {_, _, _} -> quote(do: var!(unquote(param)))
+            lit -> Macro.escape(lit)
+          end
+        end
+      )
+
+    quote generated: true do
+      @commands MapSet.put(@commands, unquote(cmd))
+      @impl Omnibot.Plugin.Base
+      def on_channel_msg(var!(irc), var!(channel), var!(nick), unquote(cmd), unquote(params)) do
+        unquote(opts[:do])
+      end
+    end
+  end
+end