From 478bfae5749874633bfa7ce871782e6132299ae1 Mon Sep 17 00:00:00 2001
From: mgd <mgd@posteo.net>
Date: Sat, 5 Oct 2024 18:15:48 +0100
Subject: [PATCH] Inital commit for elisp version of kata

---
 elisp/gilded-rose-test.el | 68 +++++++++++++++++++++++++++++++++++++++
 elisp/gilded-rose.el      | 42 ++++++++++++++++++++++++
 2 files changed, 110 insertions(+)
 create mode 100644 elisp/gilded-rose-test.el
 create mode 100644 elisp/gilded-rose.el

diff --git a/elisp/gilded-rose-test.el b/elisp/gilded-rose-test.el
new file mode 100644
index 00000000..6fd903f1
--- /dev/null
+++ b/elisp/gilded-rose-test.el
@@ -0,0 +1,68 @@
+(require 'ert)
+(require 'gilded-rose)
+
+(ert-deftest test-aged-brie-increases-quality ()
+  "Test that Aged Brie increases in quality."
+  (let ((item (make-item "Aged Brie" 2 0)))
+    (update-quality item)
+    (should (= (item-quality item) 1))))
+
+(ert-deftest test-aged-brie-max-quality ()
+  "Test that Aged Brie does not exceed max quality."
+  (let ((item (make-item "Aged Brie" 2 50)))
+    (update-quality item)
+    (should (= (item-quality item) 50))))
+
+(ert-deftest test-backstage-passes-increases-quality ()
+  "Test that Backstage passes increase in quality."
+  (let ((item (make-item "Backstage passes" 15 20)))
+    (update-quality item)
+    (should (= (item-quality item) 20))))
+
+(ert-deftest test-backstage-passes-quality-increases-by-2 ()
+  "Test that Backstage passes increase by 2 when sell-in is 10 or less."
+  (let ((item (make-item "Backstage passes" 10 20)))
+    (update-quality item)
+    (should (= (item-quality item) 22))))
+
+(ert-deftest test-backstage-passes-quality-increases-by-3 ()
+  "Test that Backstage passes increase by 3 when sell-in is 5 or less."
+  (let ((item (make-item "Backstage passes" 5 20)))
+    (update-quality item)
+    (should (= (item-quality item) 23))))
+
+(ert-deftest test-backstage-passes-quality-drops-to-0 ()
+  "Test that Backstage passes drop to 0 after sell-in date."
+  (let ((item (make-item "Backstage passes" 0 20)))
+    (update-quality item)
+    (should (= (item-quality item) 0))))
+
+(ert-deftest test-normal-item-decreases-quality ()
+  "Test that normal items decrease in quality."
+  (let ((item (make-item "Normal Item" 5 10)))
+    (update-quality item)
+    (should (= (item-quality item) 9))))
+
+(ert-deftest test-normal-item-quality-decreases-twice-after-sell-in ()
+  "Test that normal items decrease in quality by 2 after sell-in date."
+  (let ((item (make-item "Normal Item" 0 10)))
+    (update-quality item)
+    (should (= (item-quality item) 8))))
+
+(ert-deftest test-sulfuras-quality-unchanged ()
+  "Test that Sulfuras quality remains unchanged."
+  (let ((item (make-item "Sulfuras" 0 80)))
+    (update-quality item)
+    (should (= (item-quality item) 80))))
+
+(ert-deftest test-normal-item-quality-never-negative ()
+  "Test that normal items' quality never goes negative."
+  (let ((item (make-item "Normal Item" 0 0)))
+    (update-quality item)
+    (should (= (item-quality item) 0))))
+
+(ert-deftest simple-test ()
+  (should (= 1 1)))
+
+;; Run the tests
+(ert-run-tests-interactively t)
diff --git a/elisp/gilded-rose.el b/elisp/gilded-rose.el
new file mode 100644
index 00000000..5722fa86
--- /dev/null
+++ b/elisp/gilded-rose.el
@@ -0,0 +1,42 @@
+(defun make-item (name sell-in quality)
+  "Create an item with NAME, SELL-IN, and QUALITY."
+  (list :name name :sell-in sell-in :quality quality))
+
+(defun item-name (item)
+  "Return the name of ITEM."
+  (plist-get item :name))
+
+(defun item-sell-in (item)
+  "Return the sell-in value of ITEM."
+  (plist-get item :sell-in))
+
+(defun item-quality (item)
+  "Return the quality of ITEM."
+  (plist-get item :quality))
+
+(defun update-quality (item)
+  "Update the quality of the ITEM according to the Gilded Rose rules."
+  (let ((quality (item-quality item))
+        (sell-in (item-sell-in item)))
+    (cond
+     ;; Aged Brie
+     ((string= (item-name item) "Aged Brie")
+      (setf (nth 2 item) (min 50 (1+ quality))))
+     
+     ;; Backstage passes
+     ((string= (item-name item) "Backstage passes")
+      (cond
+       ((> sell-in 10) (setf (nth 2 item) quality))
+       ((and (<= sell-in 10) (> sell-in 5)) (setf (nth 2 item) (min 50 (+ quality 2))))
+       ((and (<= sell-in 5) (> sell-in 0)) (setf (nth 2 item) (min 50 (+ quality 3))))
+       (t (setf (nth 2 item) 0))))
+     
+     ;; Sulfuras
+     ((string= (item-name item) "Sulfuras")
+      (setf (nth 2 item) quality)) ;; Sulfuras never changes
+
+
+     (defvar fork (make-item "fork" 10 10))
+     (update-quality fork)
+     (item-quality fork)
+(provide 'gilded-rose)