Initial commit with IRC and bot example.

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

lib/irc/msg.ex

@@ -0,0 +1,109 @@
+alias Omnibot.Irc
+alias Omnibot.Util
+
+defmodule Omnibot.Irc.Msg do
+  defmodule Prefix do
+    defstruct [:nick, :user, :host]
+
+    @prefix_regex ~r/(?<nick>[^!]+)(!(?<user>[^@]+)(@(?<host>.+))?)?/
+    def parse(prefix) do
+      cap = Regex.named_captures(@prefix_regex, prefix)
+
+      if cap do
+        %{
+          "nick" => nick,
+          "user" => user,
+          "host" => host
+        } = cap
+
+        %Irc.Msg.Prefix{
+          nick: nick,
+          user: if(user == "", do: nil, else: user),
+          host: if(host == "", do: nil, else: host)
+        }
+      else
+        nil
+      end
+    end
+  end
+
+  @enforce_keys [:command]
+  defstruct prefix: nil, command: nil, params: []
+
+  @msg_regex ~r/
+    ^(:(?P<prefix>[^ ]+)\ )?
+    (?<command>[a-zA-Z]+|[0-9]{3})
+    (?<params>(\ [^: \r\n]+)*)
+    (?<trailing>\ :[^\r\n]+)?
+  /x
+
+  def parse(msg) do
+    %{
+      "prefix" => prefix,
+      "command" => command,
+      "params" => params,
+      "trailing" => trailing
+    } = Regex.named_captures(@msg_regex, msg)
+
+    prefix = Irc.Msg.Prefix.parse(prefix)
+
+    params =
+      String.slice(params, 1..-1)
+      |> String.split(" ")
+      |> Enum.filter(fn s -> String.length(s) > 0 end)
+
+    trailing =
+      trailing
+      |> String.slice(2..-1)
+      |> Util.string_or_nil()
+
+    params = if trailing, do: params ++ [trailing], else: params
+
+    %Irc.Msg{
+      prefix: prefix,
+      command: command,
+      params: params,
+    }
+  end
+end
+
+defimpl String.Chars, for: Irc.Msg.Prefix do
+  def to_string(prefix) do
+    nick = prefix.nick || ""
+    user = if prefix.user, do: "!#{prefix.user}", else: ""
+    host = if prefix.host, do: "@#{prefix.host}", else: ""
+    "#{nick}#{user}#{host}"
+  end
+end
+
+defimpl String.Chars, for: Irc.Msg do
+  def to_string(msg) do
+    prefix =
+      case String.Chars.to_string(msg.prefix) do
+        "" -> ""
+        p -> ":#{p}"
+      end
+
+    # Figure out where "trailing" parameters begin, e.g.
+    # ["privmsg", "param", "some message", "with another param"]
+    #
+    #   becomes
+    #
+    # {["privmsg", "param"], ["some message", "with another param"]}
+    #
+    {params, trailing} = Enum.split_while(msg.params, fn param -> !String.contains?(param, " ") end)
+
+    # If trailing parameters exist, then join them with a space character and prefix with a colon,
+    # appending it as another list item to the non-trailing parameter list
+    #
+    # If trailing parameters don't exist, don't append anything
+    params = params ++
+      if length(trailing) > 0,
+        do: [":" <> Enum.join(trailing, " ")],
+        else: []
+
+    ([prefix, msg.command] ++ params)
+    |> Enum.filter(fn n -> String.length(n) > 0 end)
+    |> Enum.join(" ")
+  end
+end