(require '[clojure.string :as string])

(def seconds-in-minute 60)
(def seconds-in-hour (* 60 seconds-in-minute))
(def seconds-in-day (* 24 seconds-in-hour))
(def seconds-in-week (* 7 seconds-in-day))

(defn seconds->duration [seconds]
  (let [weeks   ((juxt quot rem) seconds seconds-in-week)
        wk      (first weeks)
        days    ((juxt quot rem) (last weeks) seconds-in-day)
        d       (first days)
        hours   ((juxt quot rem) (last days) seconds-in-hour)
        hr      (first hours)
        min     (quot (last hours) seconds-in-minute)
        sec     (rem (last hours) seconds-in-minute)]
    (string/join ", "
                 (filter #(not (string/blank? %))
                         (conj []
                               (when (> wk 0) (str wk " wk"))
                               (when (> d 0) (str d " d"))
                               (when (> hr 0) (str hr " hr"))
                               (when (> min 0) (str min " min"))
                               (when (> sec 0) (str sec " sec")))))))

(seconds->duration 7259)
(seconds->duration 86400)
(seconds->duration 6000000)