;; Hi and welcome to team Gilded Rose. As you know, we are a small inn
;; with a prime location in a prominent city ran by a friendly
;; innkeeper named Allison. We also buy and sell only the finest goods.
;; Unfortunately, our goods are constantly degrading in quality as they
;; approach their sell by date. We have a system in place that updates
;; our inventory for us. It was developed by a no-nonsense type named
;; Leeroy, who has moved on to new adventures. Your task is to add the
;; new feature to our system so that we can begin selling a new
;; category of items.

;; First an introduction to our system:
;; All items have a SellIn value which denotes the number of days we have to sell the item
;; All items have a Quality value which denotes how valuable the item is
;; At the end of each day our system lowers both values for every item
;; Pretty simple, right? Well this is where it gets interesting:
;; Once the sell by date has passed, Quality degrades twice as fast
;; The Quality of an item is never negative
;; "Aged Cheese" actually increases in Quality the older it gets
;; The Quality of an item is never more than 50
;; "Fine Italian Silk", being a luxury item, never has to be sold or decreases in Quality
;; "Backstage passes", like Aged Cheese, increases in Quality as it's
;;   SellIn value approaches; Quality increases by 2 when there are 10
;;   days or less and by 3 when there are 5 days or less but Quality
;;   drops to 0 after the concert

;; We have recently signed a supplier of Baked items. This requires an update to our system:
;; "Baked" items degrade in Quality twice as fast as normal items
;; Feel free to make any changes to the UpdateQuality method and add
;; any new code as long as everything still works correctly. However,
;; do not alter the Item class or Items property as those belong to the
;; goblin in the corner who will insta-rage and one-shot you as he
;; doesn't believe in shared code ownership (you can make the
;; UpdateQuality method and Items property static if you like, we'll
;; cover for you).
;; Just for clarification, an item can never have its Quality increase
;; above 50, however "Fine Italian Silk" is a luxury item and as such its
;; Quality is 80 and it never alters.

;; https://github.com/emilybache/GildedRose-Refactoring-Kata

;; Common Lisp version: Rainer Joswig, joswig@lisp.de, 2016
;; Minor modifications (independent of CL impl.): Manfred Bergmann, 2022

;;; ================================================================
;;; Code

(defpackage :gilded-rose
  (:use :cl))

(in-package :gilded-rose)


;;; Class ITEM

(defclass item ()
  ((name    :initarg :name    :type string)
   (sell-in :initarg :sell-in :type integer)
   (quality :initarg :quality :type integer)))

(defmethod to-string ((i item))
  (with-slots (name quality sell-in) i
    (format nil "~a, ~a, ~a" name sell-in quality)))

;;; Class gilded-rose

(defclass gilded-rose ()
  ((items :initarg :items)))

(defmethod update-quality ((gr gilded-rose))
  (with-slots (items) gr
    (dotimes (i (length items))
      (with-slots (name quality sell-in)
          (elt items i)
        (if (and (not (equalp name "Aged Cheese"))
                 (not (equalp name "Backstage passes to a concert")))
            (if (> quality 0)
                (if (not (equalp name "Fine Italian Silk"))
                    (setf quality (- quality 1))))
          (when (< quality 50)
            (setf quality (+ quality 1))
            (when (equalp name "Backstage passes to a concert")
              (if (< sell-in 11)
                  (if (< quality 50)
                      (setf quality (+ quality 1))))
              (if (< sell-in 6)
                  (if (< quality 50)
                      (setf quality (+ quality 1)))))))

        (if (not (equalp name "Fine Italian Silk"))
            (setf sell-in (- sell-in 1)))

        (if (< sell-in 0)
            (if (not (equalp name "Aged Cheese"))
                (if (not (equalp name "Backstage passes to a concert"))
                    (if (> quality 0)
                        (if (not (equalp name "Fine Italian Silk"))
                            (setf quality (- quality 1))))
                  (setf quality (- quality quality)))
              (if (< quality 50)
                  (setf quality (+ quality 1)))))))))

;;; Example

(defun run-gilded-rose (days)
  (write-line "OMGHAI!")
  (let* ((descriptions '(("Sports Memorabilia"                         10 20)
                         ("Aged Cheese"                                  2  0)
                         ("Coffee Table Book"                     5  7)
                         ("Fine Italian Silk"                 0 80)
                         ("Fine Italian Silk"                -1 80)
                         ("Backstage passes to a concert" 15 20)
                         ("Backstage passes to a concert" 10 49)
                         ("Backstage passes to a concert"  5 49)
                         ;; this Baked item does not work properly yet
                         ("Baked Chocolate Cake"                         3  6)))
         (items (loop :for (name sell-in quality) :in descriptions
                      :collect (make-instance 'item
                                              :name name
                                              :sell-in sell-in
                                              :quality quality)))
         (app (make-instance 'gilded-rose :items items)))
    (dotimes (i days)
      (format t "-------- day ~a --------~%" i)
      (format t "name, sell-in, quality~%")
      (dolist (item items)
        (write-line (to-string item)))
      (terpri)
      (update-quality app))))

;;; ================================================================
;;; EOF