Begin defining cron to words in a helper

Author: sorentwo

lib/oban/web/helpers/cron_helper.ex

@@ -0,0 +1,82 @@
+defmodule Oban.Web.Helpers.CronHelper do
+  @moduledoc false
+
+
+  @doc """
+
+  """
+  @spec to_words(String.t()) :: String.t()
+  def to_words("@reboot"), do: "After rebooting"
+  def to_words("@annually"), do: to_words("0 0 1 1 *")
+  def to_words("@yearly"), do: to_words("0 0 1 1 *")
+  def to_words("@monthly"), do: to_words("0 0 1 * *")
+  def to_words("@weekly"), do: to_words("0 0 * * 0")
+  def to_words("@midnight"), do: to_words("0 0 * * *")
+  def to_words("@daily"), do: to_words("0 0 * * *")
+  def to_words("@hourly"), do: to_words("0 * * * *")
+
+  def to_words(expr) when is_binary(expr) do
+    expr
+    |> String.split(~r/\s+/, trim: true, parts: 5)
+    |> Enum.zip(~w(minute hour day month weekday))
+    |> Enum.map(&part_to_words/1)
+    |> Enum.reject(& &1 == "")
+    |> Enum.join(", ")
+  end
+
+  defp part_to_words({field, unit}) do
+    field
+    |> String.split(~r/\s*,\s*/)
+    |> Enum.map_join(" and ", &parse_part(&1, unit))
+  end
+
+  defp parse_part(part, unit) do
+    cond do
+      part == "*" and unit == "minute" ->
+        "Every minute"
+
+      part == "*" ->
+        nil
+
+      part =~ ~r/^\d+$/ ->
+        part
+
+      part =~ ~r/^\*\/[1-9]\d?$/ ->
+        "*/" <> step = part
+
+        "Every #{step} #{unit}s"
+
+#       part =~ ~r/^\d+(\-\d+)?\/[1-9]\d?$/ ->
+#         parse_range_step(part, range)
+
+#       part =~ ~r/^\d+\-\d+$/ ->
+#         parse_range(part, range)
+    end
+  end
+
+  # defp parse_range_step(part, max_range) do
+  #   [range, step] = String.split(part, "/")
+
+  #   parse_step(step, parse_range(range, max_range))
+  # end
+
+  # defp parse_range(part, max_range) do
+  #   case String.split(part, "-") do
+  #     [rall] ->
+  #       String.to_integer(rall)..Enum.max(max_range)
+
+  #     [rmin, rmax] ->
+  #       rmin = String.to_integer(rmin)
+  #       rmax = String.to_integer(rmax)
+
+  #       if rmin <= rmax do
+  #         rmin..rmax
+  #       else
+  #         throw(
+  #           {:error,
+  #            "left side (#{rmin}) of a range must be less than or equal to the right side (#{rmax})"}
+  #         )
+  #       end
+  #   end
+  # end
+end