(use 'packer.model)
(require 'packer.util)

; Define some useful function
; to provide a constant number of items.
(defn x [n] (fn [_] n))

; Define a store - the single source
; of truth of all items from which
; we are going to choose what we want to pack.
; The items are grouped by categories.
(def store {
  :cloths [
    (->Item :t-shirt #(/ % 4))
  ]

  :electronics [
    (->Item :smartphone (x 1))
    (->Item :tablet (x 1))
    (->Item :laptop (x 1))
  ]
})

; Define the display names for each
; item, category and question.
(def i18n {
  :nights? "How many nights?"
  :tablet? "Do you need your tablet there?"
  :laptop? "Do you need your laptop there?"
  :electronics "Electronics"
  :cloths "Cloths"
  :t-shirt "T-shirt"
  :smartphone "Smartphone"
  :tablet "Tablet"
  :laptop "Laptop"
})

; Define some utility function
; to generate preset basing on some question
(defn preset [question items seq] 
  (if (packer.util/ask-bool (get i18n question))
    (concat seq items)
    seq))

; Define profile - a function which takes
; a number of provided nights and produces
; the sequence of all items which should
; be in the target list. If the sequence is empty
; no item will be produced on the target list.
(defn profile [nights] 
  (->> [:smartphone :t-shirt]
      (preset :tablet? [:tablet])
      (preset :laptop? [:laptop])))

; Wrap it up together. It should be
; the last expression in the file.
(->Template store i18n profile)