Markov chains appear to be training correctly

* Markov chains record words correctly from a single line to the end of
  their line with a couple of exceptions.
* Start working on using ETS for storing markov chains, and saving it as
  a DETS periodically

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

lib/contrib/markov/markov.ex

@@ -3,20 +3,44 @@ defmodule Omnibot.Contrib.Markov do
 
   alias Omnibot.Contrib.Markov.Chain
 
-  @default_config path: :"wordbot.ets", order: 2
+  @default_config path: "markov", order: 2
 
   @impl true
   def on_init(cfg) do
     # Create the markov database
-    path = if is_atom(cfg[:path]),
-      do: cfg[:path],
-      else: String.to_atom(cfg[:path])
-    {:ok, db} = :dets.open_file(path)
-    db
+    path = String.to_atom(cfg[:path])
+    :ets.new(path, [:public])
   end
 
   @impl true
-  def on_channel_msg(_irc, _channel, _nick, msg) do
-    _words = String.split(msg, ~r/\s+/)
+  def on_channel_msg(_irc, channel, nick, msg) do
+    train(channel, nick, msg)
+  end
+
+  def train(channel, user, msg) do
+    chain = (user_chain(channel, user) || create_user_chain(channel, user))
+            |> Chain.train(msg)
+    true = update_user_chain(channel, user, chain)
+  end
+
+  def user_chain(channel, user) do
+    db = state()
+    case :ets.lookup(db, {channel, user}) do
+      [] -> nil
+      [{{^channel, ^user}, chains}] -> chains
+    end
+  end
+
+  def update_user_chain(channel, user, chain) do
+    db = state()
+    case user_chain(channel, user) do
+      nil -> :ets.insert_new(db, {{channel, user}, chain})
+      chain -> :ets.insert(db, {{channel, user}, chain})
+    end
+  end
+
+  defp create_user_chain(channel, user) do
+    true = update_user_chain(channel, user, %Chain{order: cfg()[:order]})
+    user_chain(channel, user)
   end
 end