Commons and EDRPOU basic functionality (parser (but complete only), checksum with test coverage)

lib/ukraine_taxid_ex/itin/error.ex

@@ -0,0 +1,24 @@
+defmodule UkraineTaxidEx.Itin.Error do
+  @type error() ::
+          :invalid_length
+          | :invalid_checksum
+          | :length_to_long
+          | :length_to_short
+  @type errors() :: [error()]
+  @errors [
+    :invalid_length,
+    :invalid_checksum,
+    :length_to_long,
+    :length_to_short
+  ]
+  @messages [
+    invalid_length: "EDRPOU violates the required length",
+    invalid_checksum: "EDRPOU checksum is invalid",
+    length_to_long: "EDRPOU longer then required length",
+    length_to_short: "EDRPOU shorter then required length"
+  ]
+
+  @spec message(error()) :: String.t()
+  def message(error) when error in @errors, do: @messages[error]
+  def message(_error), do: "Undefined error"
+end