WIP: Supervisor-based plugin base

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

lib/core/core.ex

@@ -0,0 +1,74 @@
+defmodule Omnibot.Core do
+  use Omnibot.Plugin
+  alias Omnibot.State
+
+  @default_config [channels: :all]
+
+  @impl true
+  def on_join(irc, channel, nick) do
+    cfg = State.cfg()
+    if nick == cfg.nick do
+      add_channel(channel)
+      # Sync if we join a channel we shouldn't be in
+      if !Enum.member?(State.all_channels(), channel),
+        do: sync_channels(irc)
+    end
+  end
+
+  @impl true
+  def on_part(irc, channel, nick) do
+    cfg = State.cfg()
+    if nick == cfg.nick do
+      remove_channel(channel)
+      # Sync if we join a channel we forcibly part a channel we shouldn't leave
+      if Enum.member?(State.all_channels(), channel),
+        do: sync_channels(irc)
+    end
+  end
+
+  @impl true
+  def on_kick(irc, channel, _nick, target) do
+    cfg = State.cfg()
+    if target == cfg.nick do
+      remove_channel(channel)
+      # Generally, being kicked is not intentionally leaving a channel, so always sync here
+      sync_channels(irc)
+    end
+  end
+
+  @impl true
+  def on_msg(irc, msg) do
+    case String.upcase(msg.command) do
+      "001" -> sync_channels(irc)
+      "PING" -> Irc.send_msg(irc, "PONG", msg.params)
+      _ -> route_msg(irc, msg)
+    end
+  end
+
+  @impl true
+  def on_init(_cfg) do
+    MapSet.new()
+  end
+
+  defp sync_channels(irc) do
+    desired = MapSet.new(State.all_channels())
+    present = state()
+
+    to_join = MapSet.difference(desired, present)
+      |> MapSet.to_list()
+    to_part = MapSet.difference(present, desired)
+      |> MapSet.to_list()
+
+    Enum.each(to_join, fn channel -> Irc.join(irc, channel) end)
+    Enum.each(to_part, fn channel -> Irc.part(irc, channel) end)
+  end
+
+  defp add_channel(channel) do
+    update_state(fn state -> MapSet.put(state, channel) end)
+  end
+  
+  defp remove_channel(channel) do
+    update_state(fn state -> MapSet.delete(state, channel) end)
+  end
+end
+