From 36b3bd1009e5cbd8545b6abbb5988c00d7274c15 Mon Sep 17 00:00:00 2001
From: Marius Peter <dev@marius-peter.com>
Date: Thu, 13 Nov 2025 16:14:07 +0100
Subject: Factor out average-crop-requirement-nutrient-values.

---
 models/crop-requirement.rkt | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

(limited to 'models')

diff --git a/models/crop-requirement.rkt b/models/crop-requirement.rkt
index 4faa6bb..23740e7 100644
--- a/models/crop-requirement.rkt
+++ b/models/crop-requirement.rkt
@@ -143,3 +143,20 @@
   (query-exec (current-conn)
               (delete #:from crop_requirements
                       #:where (= id ,id))))
+
+
+;; Helpers
+
+(define (average-crop-requirement-nutrient-values mix)
+  (define average-values
+    (for/fold ([acc (hash)]) ([pair (in-list mix)])
+      (define crop-requirement (car pair))
+      (define percentage (/ (cdr pair) 100))
+      (for/fold ([acc acc])
+                ([nv (in-list (get-crop-requirement-values crop-requirement))])
+        (match-define (cons n v) nv)
+        (hash-update acc n
+                     (λ (old) (+ old (* v percentage)))
+                     (λ () (* v percentage))))))
+  (for/list ([(n v) (in-hash average-values)])
+    (cons n v)))
-- 
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