defmodule PlantIdDiscordBot.Utils.Duration do
  @moduledoc """
  Duration conversion functions.
  """
  @minute 60
  @hour @minute * 60
  @day @hour * 24
  @week @day * 7
  @divisor [@week, @day, @hour, @minute, 1]

  @doc """
  Convert seconds to a time string.
  # https://rosettacode.org/wiki/Convert_seconds_to_compound_duration

  ## Examples
      iex> PlantIdDiscordBot.Utils.Duration.sec_to_str(65)
      iex> "1m 5s"
  """
  def sec_to_str(sec) do
    {_, [s, m, h, d, w]} =
      Enum.reduce(@divisor, {sec, []}, fn divisor, {n, acc} ->
        {rem(n, divisor), [div(n, divisor) | acc]}
      end)

    ["#{w}w", "#{d}d", "#{h}h", "#{m}m", "#{s}s"]
    |> Enum.reject(fn str -> String.starts_with?(str, "0") end)
    |> Enum.join(" ")
  end
end