feat: format locales (#24)

* fix flakey test

* feat: format locales properly

* fmt

lib/idiom/cache.ex

@@ -6,6 +6,8 @@ defmodule Idiom.Cache do
   and retrieving values. table
   """
 
+  alias Idiom.Locales
+
   @cache_table_name :idiom_cache
 
   @doc false
@@ -85,7 +87,7 @@ defmodule Idiom.Cache do
   end
 
   defp map_to_cache_data(value, keys) when is_binary(value) do
-    locale = Enum.at(keys, 0)
+    locale = Enum.at(keys, 0) |> Locales.format_locale()
     namespace = Enum.at(keys, 1)
     key = Enum.slice(keys, 2..-1) |> Enum.join(".")
 

lib/idiom/local.ex

@@ -69,8 +69,8 @@ defmodule Idiom.Local do
   defp parse_file(path) do
     with {:ok, contents} <- File.read(path),
          {:ok, map} <- Jason.decode(contents),
-         {lang, domain} <- extract_lang_and_domain(path) do
-      [{lang, Map.new([{domain, map}])}]
+         {locale, domain} <- extract_locale_and_domain(path) do
+      [{locale, Map.new([{domain, map}])}]
       |> Map.new()
     else
       {:error, _error} ->
@@ -79,7 +79,7 @@ defmodule Idiom.Local do
     end
   end
 
-  defp extract_lang_and_domain(path) do
+  defp extract_locale_and_domain(path) do
     path
     |> String.split("/")
     |> Enum.reverse()

lib/idiom/locales.ex

@@ -2,9 +2,10 @@ defmodule Idiom.Locales do
   @moduledoc """
   Utility functions for handling locales.
 
-  Locale identifiers consist of a language code, an optional script code, and an optional region code, separated by a hyphen (-).
+  Locale identifiers consist of a language code, an optional script code, and an optional region code, separated by a hyphen (-) or underscore (_).
   """
 
+  @scripts ~w(arab cans cyrl hans hant latn mong)
   @rtl_languages ~w(ar dv fa ha he ks ps sd ur yi)
 
   @doc """
@@ -29,7 +30,7 @@ defmodule Idiom.Locales do
     fallback = Keyword.get(opts, :fallback)
 
     [
-      locale,
+      format_locale(locale),
       get_language_and_script(locale),
       get_language(locale),
       fallback
@@ -55,6 +56,7 @@ defmodule Idiom.Locales do
   @spec get_language(String.t()) :: String.t()
   def get_language(locale) when is_binary(locale) do
     locale
+    |> format_locale()
     |> String.split("-")
     |> hd()
   end
@@ -76,7 +78,10 @@ defmodule Idiom.Locales do
   """
   @spec get_language_and_script(String.t()) :: String.t() | nil
   def get_language_and_script(locale) when is_binary(locale) do
-    case String.split(locale, "-") do
+    locale
+    |> format_locale()
+    |> String.split("-")
+    |> case do
       parts when length(parts) <= 2 -> nil
       parts -> Enum.take(parts, 2) |> Enum.join("-")
     end
@@ -98,6 +103,48 @@ defmodule Idiom.Locales do
   @spec direction(String.t()) :: :ltr | :rtl
   def direction(locale) do
     language = get_language(locale)
+
     if Enum.member?(@rtl_languages, language), do: :rtl, else: :ltr
   end
+
+  @doc """
+  Formats a locale string.
+
+  Idiom internally supports separating different parts of the locale code by either hyphen or underscore, which is then normalised by this function. Different
+  locales also have different capitalisation rules, which are handled here.
+
+  ## Examples
+
+  ```elixir
+  iex> Idiom.Locales.format_locale("de_de")
+  "de-DE"
+
+  iex> Idiom.Locales.format_locale("zh-hant-hk")
+  "zh-Hant-HK"
+  ```
+  """
+  @spec format_locale(String.t()) :: String.t()
+  def format_locale(locale) do
+    locale
+    |> String.downcase()
+    |> String.replace("_", "-")
+    |> String.split("-")
+    |> case do
+      [locale] ->
+        [locale]
+
+      [language, script] when script in @scripts ->
+        [language, String.capitalize(script)]
+
+      [language, region] ->
+        [language, String.upcase(region)]
+
+      [language, script, region] when script in @scripts ->
+        [language, String.capitalize(script), String.upcase(region)]
+
+      [language, region, rest] ->
+        [language, String.upcase(region), rest]
+    end
+    |> Enum.join("-")
+  end
 end

test/idiom/cache/init_test.exs

@@ -1,5 +1,5 @@
 defmodule Idiom.Cache.InitTest do
-  use ExUnit.Case, async: true
+  use ExUnit.Case, async: false
   alias Idiom.Cache
 
   setup do