Task

Write a function or program which:

   takes a positive integer representing a duration in seconds as input (e.g., 100), and
   returns a string which shows the same duration decomposed into:
   weeks,
   days, 
   hours, 
   minutes,   and 
   seconds.
This is detailed below (e.g., "2 hr, 59 sec").



Demonstrate that it passes the following three test-cases:

Test Cases


 input number

 output string


 7259

 2 hr, 59 sec


 86400

 1 d


 6000000

 9 wk, 6 d, 10 hr, 40 min

Details
The following five units should be used:



 unit

 suffix used in output

 conversion


 week

 wk

 1 week = 7 days


 day

 d

 1 day = 24 hours


 hour

 hr

 1 hour = 60 minutes


 minute

 min

 1 minute = 60 seconds


 second

 sec



However, only include quantities with non-zero values in the output (e.g., return "1 d" and not "0 wk, 1 d, 0 hr, 0 min, 0 sec").

Give larger units precedence over smaller ones as much as possible (e.g., return 2 min, 10 sec and not 1 min, 70 sec or 130 sec)

Mimic the formatting shown in the test-cases (quantities sorted from largest unit to smallest and separated by comma+space; value and unit of each quantity separated by space).




defmodule Convert do
  @minute 60
  @hour   @minute*60
  @day    @hour*24
  @week   @day*7
  @divisor [@week, @day, @hour, @minute, 1]
 
  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} wk", "#{d} d", "#{h} hr", "#{m} min", "#{s} sec"]
    |> Enum.reject(fn str -> String.starts_with?(str, "0") end)
    |> Enum.join(", ")
  end
end
 
Enum.each([7259, 86400, 6000000], fn sec ->
  :io.fwrite "~10w sec : ~s~n", [sec, Convert.sec_to_str(sec)]
end)