fix: reworking some code smell issues

lib/bds/rendering/filters.ex

@@ -238,26 +238,27 @@ defmodule BDS.Rendering.Filters do
         path_part |> String.replace(~r/\.html?$/i, "")
 
       match = Regex.run(~r|^/?post/([a-z0-9-]+(?:\.html?)?)$|i, path_part) ->
-        slug = match |> Enum.at(1) |> String.replace(~r/\.html?$/i, "")
-        Map.get(canonical_post_paths, slug)
+        slug_from_match(match, canonical_post_paths)
 
       match = Regex.run(~r|^/?post/\d{4}/\d{1,2}/([a-z0-9-]+(?:\.html?)?)$|i, path_part) ->
-        slug = match |> Enum.at(1) |> String.replace(~r/\.html?$/i, "")
-        Map.get(canonical_post_paths, slug)
+        slug_from_match(match, canonical_post_paths)
 
       match = Regex.run(~r|^/?posts/([a-z0-9-]+(?:\.html?)?)$|i, path_part) ->
-        slug = match |> Enum.at(1) |> String.replace(~r/\.html?$/i, "")
-        Map.get(canonical_post_paths, slug)
+        slug_from_match(match, canonical_post_paths)
 
       match = Regex.run(~r|^/?posts/\d{4}/\d{1,2}/([a-z0-9-]+(?:\.html?)?)$|i, path_part) ->
-        slug = match |> Enum.at(1) |> String.replace(~r/\.html?$/i, "")
-        Map.get(canonical_post_paths, slug)
+        slug_from_match(match, canonical_post_paths)
 
       true ->
         nil
     end
   end
 
+  defp slug_from_match([_full, captured], canonical_post_paths) do
+    slug = String.replace(captured, ~r/\.html?$/i, "")
+    Map.get(canonical_post_paths, slug)
+  end
+
   defp normalize_media_src(raw_src, canonical_media_paths) do
     cond do
       raw_src == "" ->

lib/bds/rendering/links_and_languages.ex

@@ -120,7 +120,7 @@ defmodule BDS.Rendering.LinksAndLanguages do
 
   defp post_date_path_parts(created_at) do
     datetime = Persistence.from_unix_ms!(created_at)
-    year_month_path_parts(datetime) ++ [pad2(datetime.day)]
+    year_month_path_parts(datetime) ++ [BDS.Strings.pad2(datetime.day)]
   end
 
   defp year_month_path_parts(created_at) when is_integer(created_at) do
@@ -130,13 +130,11 @@ defmodule BDS.Rendering.LinksAndLanguages do
   end
 
   defp year_month_path_parts(%DateTime{} = datetime) do
-    [Integer.to_string(datetime.year), pad2(datetime.month)]
+    [Integer.to_string(datetime.year), BDS.Strings.pad2(datetime.month)]
   end
 
   defp normalize_language_prefix(prefix) when is_binary(prefix) and prefix != "",
     do: String.trim_trailing(prefix, "/")
 
   defp normalize_language_prefix(_prefix), do: ""
-
-  defp pad2(value), do: value |> Integer.to_string() |> String.pad_leading(2, "0")
 end