Adds basic gender detector.

Changes:
1. Adds more tests
2. Fixes credo issues

lib/petrovich/detector.ex

@@ -3,11 +3,49 @@ defmodule Petrovich.Detector do
   Guesses the gender by person's name.
   """
 
+  alias Petrovich.GenderStore
+
   @doc """
   Returns gender from person's name
   """
-  def detect_gender(values, type) do
+  def detect_gender(value, type) do
+    GenderStore.start_link()
+
+    %{"exceptions" => exceptions,
+      "suffixes" => suffixes} = GenderStore.get("gender", to_string(type))
+
+    value
+    |> String.downcase
+    |> maybe_exception(exceptions)
+    |> maybe_rule(suffixes)
+  end
+
+  defp maybe_exception(name, exceptions) do
+    exceptions
+    |> Enum.find(fn({_, names}) -> name in names end)
+    |> case do
+      {gender, _} -> {:ok, gender}
+      nil -> {:error, name}
+    end
+  end
+
+  defp maybe_rule({:ok, gender}, _), do: {:ok, gender}
+  defp maybe_rule({:error, name}, suffixes) do
+    suffixes
+    |> Enum.find(fn({_, rule}) -> fits?(name, rule) end)
+    |> case do
+      {gender, _} -> {:ok, gender}
+      nil -> {:error, name}
+    end
+  end
+
+  defp fits?(name, rule) do
+    name_len = String.length(name)
 
+    Enum.any?(rule, fn(test) ->
+      test_len = String.length(test)
+      test == String.slice(name, name_len - test_len, test_len)
+    end)
   end
 
 end

lib/petrovich/stores/base.ex

@@ -38,15 +38,13 @@ defmodule Petrovich.Store do
       end
 
       defp load_values do
-        try do
-          :petrovich_elixir
-          |> Config.get_env(@setting)
-          |> File.read!
-          |> Poison.decode!
-        rescue
-          e in File.Error ->
-            raise RulesFileException, message: Exception.message(e)
-        end
+        :petrovich_elixir
+        |> Config.get_env(@setting)
+        |> File.read!
+        |> Poison.decode!
+      rescue
+        e in File.Error ->
+          raise RulesFileException, message: Exception.message(e)
       end
     end
   end

test/petrovich_test/detector_test.exs

@@ -0,0 +1,16 @@
+defmodule PetrovichTest.DetectorTest do
+  use ExUnit.Case
+
+  alias Petrovich.Detector
+
+  test "detects exception genders" do
+    assert Detector.detect_gender("Никита", :firstname) == {:ok, "male"}
+    assert Detector.detect_gender("Женя", :firstname) == {:ok, "androgynous"}
+    assert Detector.detect_gender("Наташа", :firstname) == {:ok, "female"}
+  end
+
+  test "detects correct gender" do
+    assert Detector.detect_gender("Айгуль", :firstname) == {:ok, "female"}
+    assert Detector.detect_gender("Ибрагим", :firstname) == {:ok, "male"}
+  end
+end