From a1dc85b2f7744a1dd7a5dfc4089fe94892ab9555 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoffer=20M=C3=BCller=20Madsen?=
 <christoffer@guava.space>
Date: Sat, 8 Apr 2017 20:33:00 +0200
Subject: [PATCH] add scaling of servings for recipes

---
 html.scm  | 10 +++---
 parse.scm | 91 ++++++++++++++++++++++++++++++++++++++-----------------
 2 files changed, 70 insertions(+), 31 deletions(-)

diff --git a/html.scm b/html.scm
index eecbde1..731a4a1 100644
--- a/html.scm
+++ b/html.scm
@@ -30,12 +30,14 @@
 (define recipe-as-html
   (lambda (recipe)
     (string-append "<h2>"
-                   (title recipe)
+                   (recipe-name recipe)
                    "</h2>"
-                   "<i>Ingredients</i><br>"
-                   (ingredients-as-html (ingredients recipe))
+                   "Servings: "
+                   (number->string (recipe-servings recipe))
+                   "<br><i>Ingredients</i><br>"
+                   (ingredients-as-html (recipe-ingredients recipe))
                    "<br><i>Steps</i><br>"
-                   (steps-as-html (steps recipe))
+                   (steps-as-html (recipe-steps recipe))
                    "<br>")))
 
 (define pretty-ingredient
diff --git a/parse.scm b/parse.scm
index b238ce7..0489244 100644
--- a/parse.scm
+++ b/parse.scm
@@ -1,16 +1,21 @@
-;; Predicates
-
-(define title
+(define recipe-name
   (lambda (recipe)
-    (car recipe)))
+    (cadr (assoc 'name recipe))))
 
-(define ingredients
+(define recipe-ingredients
   (lambda (recipe)
-    (car (cdr recipe))))
+    (cadr (assoc 'ingredients recipe))))
 
-(define steps
+(define recipe-steps
   (lambda (recipe)
-    (car (cdr (cdr recipe)))))
+    (cadr (assoc 'steps recipe))))
+
+(define recipe-servings
+  (lambda (recipe)
+    (if (recipe-specifies-servings? recipe)
+        (cadr (assoc 'servings recipe))
+        1)
+    ))
 
 (define ingredient-name
   (lambda (ingredient)
@@ -28,7 +33,28 @@
         ""
         (car (cdr ingredient)))))
 
-;;
+;; Predicates
+
+(define contains-ingredient?
+  (lambda (recipe search-ingredient)
+    (contains-ingredients? recipe (cons search-ingredient '()))))
+
+(define contains-ingredients?
+  (lambda (recipe search-ingredients)
+    (let ((ingredients (recipe-ingredients recipe)))
+      (cond [(null? search-ingredients) #t]
+            [(ingredient-by-name ingredients
+                                 (car search-ingredients))
+             (contains-ingredients? recipe
+                                    (cdr search-ingredients))]
+            [else #f])
+      )))
+
+(define recipe-specifies-servings?
+  (lambda (recipe)
+    (assoc 'servings recipe)))
+
+;; Searching and indexing
 
 (define ingredient-ref
   (lambda (ingredients n)
@@ -46,32 +72,43 @@
             [else (ingredient-by-name (cdr ingredients)
                                       search-name)]))))
 
-(define contains-ingredient?
-  (lambda (recipe search-ingredient)
-    (contains-ingredients? recipe (cons search-ingredient '()))))
-
-(define contains-ingredients?
-  (lambda (recipe search-ingredients)
-    (let ((ingredients (ingredients recipe)))
-      (cond [(null? search-ingredients) #t]
-            [(ingredient-by-name ingredients
-                                 (car search-ingredients))
-             (contains-ingredients? recipe
-                                    (cdr search-ingredients))]
-            [else #f])
-      )))
-
 (define recipes-by-ingredients
   (lambda (recipes search-ingredients)
     (filter (lambda (x) (contains-ingredients? x search-ingredients))
             recipes)))
 
 (define recipe-by-name
-  (lambda (recipes name)
+  (lambda (name recipes)
     (if (null? recipes)
         #f
         (let ((recipe (car recipes)))
-          (if (equal? (title recipe)
+          (if (equal? (recipe-name recipe)
                       name)
               recipe
-              (recipe-by-name (cdr recipes) name))))))
+              (recipe-by-name name (cdr recipes)))))))
+
+;; Manipulation
+
+(define scale-recipe
+  (lambda (recipe wanted-servings)
+    (let ([name (recipe-name recipe)]
+          [ingredients (recipe-ingredients recipe)]
+          [steps (recipe-steps recipe)]
+          [servings (recipe-servings recipe)])
+      (let ([new-name name]
+            [new-ingredients (map (lambda (ingr)
+                                    (list (* (/ (car ingr)
+                                                servings)
+                                             wanted-servings)
+                                          (cdr ingr)))
+                                  ingredients)]
+            [new-steps steps]
+            [new-servings wanted-servings])
+        (make-recipe new-name new-servings new-ingredients new-steps)
+      ))))
+
+;; Constructors
+
+(define make-recipe
+  (lambda (name servings ingredients steps)
+    `((name ,name) (servings ,servings) (ingredients ,ingredients) (steps ,steps))))