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/chain.ex

@@ -4,6 +4,10 @@ defmodule Omnibot.Contrib.Markov.Chain do
   @enforce_keys [:order]
   defstruct order: 2, chain: []
 
+  def train(chain, line) when is_binary(line) do
+    train(chain, line |> String.split(~r/\s+/))
+  end
+
   def train(chain, words) when is_list(words) do
     order = chain.order
 
@@ -12,22 +16,12 @@ defmodule Omnibot.Contrib.Markov.Chain do
     |> Enum.reduce(chain, &case Enum.split(&1, order) do
       {words, []} -> if length(words) == order,
           # Null case for the chain; this is an "end" state
-          do: add_weight(&2, words, nil)
-          # else: TODO ? train [a, nil] -> b ?
-      {words, [next]} ->
-        add_weight(&2, words, next)
-    end
-    )
+          do: add_weight(&2, words, nil),
+          else: &2 # TODO ? train [a, nil] -> b ?
+      {words, [next]} -> add_weight(&2, words, next)
+    end)
   end
 
-  #def lookup(%Chain {chain: chain, order: order}, key) do
-  #  if length(key) != order, do: raise(ArgumentError, message: "invalid key (length #{length(key)} vs. order #{order})")
-  #  case Util.binary_search(chain, key) do
-  #    {_index, value} -> value[word]
-  #    nil -> nil
-  #  end
-  #end
-
   def add_weight(%Chain {chain: chain, order: order}, key, word, increment \\ 1) do
     if length(key) != order, do: raise(ArgumentError, message: "invalid key (length #{length(key)} vs. order #{order})")
     chain = case Enum.find_index(chain, fn {listkey, _} -> listkey == key end) do

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