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).




open System
 
let convert seconds =
    let span = TimeSpan.FromSeconds(seconds |> float)
    let (wk, day) = Math.DivRem(span.Days, 7)
    let parts =
        [(wk, "wk"); (day, "day"); (span.Hours, "hr"); (span.Minutes, "min"); (span.Seconds, "sec")]
    let result =
        List.foldBack (fun (n, u) acc -> 
                    (if n > 0 then n.ToString() + " " + u else "")
                    + (if n > 0 && acc.Length > 0 then ", " else "")
                    + acc
                  ) parts ""
    if result.Length > 0 then result else "0 sec"
 
[<EntryPoint>]
let main argv = 
    argv
    |> Seq.map (fun str -> let sec = UInt32.Parse str in (sec, convert sec))
    |> Seq.iter (fun (s, v) -> printfn "%10i = %s" s v)
    0