1 files changed, 143 insertions, 0 deletions
diff --git a/lib/irc/parser/line.ex b/lib/irc/parser/line.ex
new file mode 100644
index 0000000..3ba2016
--- /dev/null
+++ b/lib/irc/parser/line.ex
@@ -0,0 +1,143 @@
+defmodule Irc.Parser.Line do
+  @moduledoc """
+  IRC line parser
+  """
+
+  defstruct tags: %{}, source: nil, command: nil, args: []
+
+  @doc "Parse a server-to-client line."
+  def parse(line) do
+    {tags, rest} = parse_tags(line)
+    {source, rest} = parse_source(rest)
+    {command, rest} = parse_cmd(rest)
+    args = parse_args(rest)
+    %__MODULE__{tags: tags, source: source, command: command, args: args}
+  end
+
+  # ARGS
+
+  def parse_args(input), do: parse_args(input, [])
+
+  def parse_args(input, acc) do
+    case parse_arg(input, []) do
+      {:continue, new, rest} -> parse_args(rest, [new | acc])
+      {:finished, new} ->
+        list = new ++ acc
+        format_args(list)
+    end
+  end
+
+  # Final argument is the only argument.
+  def parse_arg([?: | rest], acc) when length(acc) == 0 do
+    final = parse_final_arg(rest, [])
+    {:finished, [final]}
+  end
+
+  def parse_arg([0x20, ?: | rest], acc) do
+    final = parse_final_arg(rest, [])
+    {:finished, [final, acc]}
+  end
+
+  def parse_arg([0x20 | rest], acc) do
+    {:continue, acc, rest}
+  end
+
+  def parse_arg([char | rest], acc) do
+    parse_arg(rest, [char | acc])
+  end
+
+  def parse_arg([], acc) do
+    {:finished, [acc]}
+  end
+
+  def parse_final_arg([char | rest], acc) do
+    parse_final_arg(rest, [char | acc])
+  end
+
+  def parse_final_arg([], acc) do
+    acc
+  end
+
+  def format_args(list) when is_list(list) do
+    list
+    |> Enum.map(fn(arg) -> String.trim(acc_to_str(arg)) end)
+    |> Enum.reverse()
+  end
+
+  # COMMAND
+
+  def parse_cmd(input), do: parse_cmd(input, [])
+
+  def parse_cmd([0x20 | rest], acc) do
+    {acc_to_str(acc), rest}
+  end
+
+  def parse_cmd([char | rest], acc) do
+    parse_cmd(rest, [char | acc])
+  end
+
+  # SOURCE
+
+  def parse_source([?: | input]), do: parse_source(input, [])
+  def parse_source(input), do: {nil, input}
+
+  def parse_source([0x20 | rest], acc) do
+    {acc_to_str(acc), rest}
+  end
+  def parse_source([char | rest], acc), do: parse_source(rest, [char | acc])
+
+  # TAGS
+
+  def parse_tags([?@ | input]), do: parse_tags(input, [])
+  def parse_tags(input), do: {%{}, input}
+
+  def parse_tags(input, acc) do
+    case parse_tag(input) do
+      {:continue, new, rest} -> parse_tags([new | acc], rest)
+      {:finished, new, rest} -> {format_tags([new | acc]), rest}
+    end
+  end
+
+  def parse_tag(input) do
+    parse_tag({[], nil}, input)
+  end
+
+  def parse_tag({acc, nil}, [?= | rest]) do
+    parse_tag({acc, []}, rest)
+  end
+  def parse_tag({acc, nil}, [?; | rest]) do
+    {:continue, {acc, true}, rest}
+  end
+  def parse_tag({acc, nil}, [char | rest]) do
+    parse_tag({[char | acc], nil}, rest)
+  end
+
+  def parse_tag({key, acc}, [?; | rest]) do
+    {:continue, {key, acc}, rest}
+  end
+
+  def parse_tag({key, acc}, [0x20 | rest]) do
+    {:finished, {key, acc}, rest}
+  end
+  def parse_tag({key, acc}, [char | rest]) do
+    parse_tag({key, [char | acc]}, rest)
+  end
+
+  def format_tags(list) do
+    list
+    |> Enum.map(fn({k,v}) ->
+      {acc_to_str(k), acc_to_str(v)}
+    end)
+    |> Enum.into(Map.new)
+  end
+
+  def acc_to_str([]), do: nil
+  def acc_to_str(list) when is_list(list) do
+    list
+    |> Enum.reverse()
+    |> to_string()
+  end
+  def acc_to_str(other), do: other
+
+end
+