Finish plugin and routing overhaul, there's a new model in town:

* Plugins all derive from Omnibot.Plugin. There still is a base plugin,
  in case we want to have another plugin backend instead of a GenServer
* All plugins are monitored by a unique Plugin.Supervisor, which is in
  turn started by the PluginSupervisor (yes this is confusing, yes it
  needs to be renamed)
* Any other auxiliary child processes may be started through the
  Plugin.children/1 function.
* By default, plugins have a CfgState process which is an Agent that
  keeps track of the plugin's configuration and state
* Plugin API is now called through the GenServer backend for better
  synchronicity.
* Very few changes to the front-facing Plugin API, which is nice

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

lib/plugin/base.ex

@@ -19,6 +19,11 @@ defmodule Omnibot.Plugin.Base do
       @impl true
       def on_init(_cfg), do: nil
 
+      @impl true
+      def on_msg(irc, msg) do
+        route_msg(irc, msg)
+      end
+
       @impl true
       def default_config(), do: @default_config
 
@@ -33,11 +38,6 @@ defmodule Omnibot.Plugin.Base do
 
       @behaviour Plugin.Base
 
-      @impl Plugin.Base
-      def on_msg(irc, msg) do
-        route_msg(irc, msg)
-      end
-
       defp route_msg(irc, %Irc.Msg {prefix: nil}), do: nil
 
       defp route_msg(irc, msg) do

lib/plugin/plugin.ex

@@ -14,21 +14,24 @@ defmodule Omnibot.Plugin do
 
     def state(pid), do: Agent.get(pid, fn {_, state} -> state end)
 
-    def update_state(pid, fun, timeout \\ 5000),
-      do: Agent.update(pid, &{&1, apply(fun, [&1])}, timeout)
+    def update_state(pid, fun, timeout \\ 5000) do
+      Agent.update(pid, fn {cfg, state} -> {cfg, apply(fun, [state])} end, timeout)
+      #Agent.update(pid, &{&1, apply(fun, [&1])}, timeout)
+    end
   end
 
   defmacro __using__(opts) do
     opts = opts ++ @default_opts
 
-    quote do
-      use Supervisor
+    quote generated: true do
+      use GenServer
       use Omnibot.Plugin.Base
 
       ## Client API
 
       def start_link(opts) do
-        Supervisor.start_link(__MODULE__, {opts[:cfg], opts[:state]}, opts)
+        {cfg, opts} = Keyword.pop(opts, :cfg)
+        GenServer.start_link(__MODULE__, cfg, opts)
       end
 
       def cfg() do
@@ -48,30 +51,37 @@ defmodule Omnibot.Plugin do
         GenServer.cast(__MODULE__, {:handle_msg, irc, msg})
       end
 
-      @impl Omnibot.Plugin
-      def children(_cfg, _state), do: []
-
       ## Server callbacks
 
-      @impl Supervisor
-      def init({cfg, state}) do
-        base_children = [
-          {Omnibot.Plugin.CfgState, cfg: cfg, state: state, name: __MODULE__.CfgState},
-        ]
-        children = 
-          (if unquote(opts[:include_base]), do: base_children, else: []) ++ children(cfg, state)
-        Supervisor.init(children, unquote(opts[:opts]))
+      @impl GenServer 
+      def init(_cfg) do
+        {:ok, nil}
       end
 
+      @impl GenServer
       def handle_cast({:handle_msg, irc, msg}, state) do
         on_msg(irc, msg)
         {:noreply, state}
       end
 
+      defp base_children(cfg, state) when unquote(opts[:include_base]) do
+        [
+          {Omnibot.Plugin.CfgState, cfg: cfg, state: state, name: __MODULE__.CfgState},
+          {__MODULE__, name: __MODULE__},
+        ]
+      end
+
+      defp base_children(_cfg, _state), do: []
+
+      @impl Omnibot.Plugin
+      def children(cfg), do: []
+
+      def plugin_children(cfg, state), do: base_children(cfg, state) ++ children(cfg)
+
       @behaviour Omnibot.Plugin
       defoverridable Omnibot.Plugin
     end
   end
 
-  @callback children(cfg :: [atom: any], state :: any) :: [atom | {atom, [atom: any]} | {atom, any, [atom: any]}]
+  @callback children(cfg :: [atom: any]) :: [atom | {atom, [atom: any]} | {atom, any, [atom: any]}]
 end

lib/plugin/supervisor.ex

@@ -0,0 +1,28 @@
+defmodule Omnibot.Plugin.Supervisor do
+  use Supervisor
+
+  def start_link(opts) do
+    {plugin, opts} = Keyword.pop(opts, :plugin)
+    {cfg, opts} = Keyword.pop(opts, :cfg)
+    start_link(plugin, cfg, opts)
+  end
+
+  def start_link(plugin, cfg, opts) when is_atom(plugin) do
+    Supervisor.start_link(__MODULE__, {plugin, cfg}, opts)
+  end
+
+  def child_spec(arg) do
+    id = Module.concat(arg[:plugin], Plugin.Supervisor)
+    %{
+      id: id,
+      start: {__MODULE__, :start_link, [arg]},
+    }
+  end
+
+  @impl true
+  def init({plugin, cfg}) when is_atom(plugin) do
+    state = plugin.on_init(cfg)
+    children = IO.inspect(plugin.plugin_children(cfg, state))
+    Supervisor.init(children, strategy: :one_for_one)
+  end
+end