improve price formatting

1 files changed, 25 insertions, 1 deletions

diff --git a/lib/string.fnl b/lib/string.fnl
index 6538827..3e6134e 100644
--- a/lib/string.fnl
+++ b/lib/string.fnl
@@ -43,4 +43,28 @@
       (.. (trim (must (luna.utf8.sub str 1 len))) (or ellipsis "...")))
     ""))
 
-{: letters : empty? : split : ends-with : trim : truncate}
+(fn insert [str substr pos]
+  (.. (str:sub 1 pos) substr (str:sub (+ 1 pos))))
+
+(fn format-price [price]
+  (var price-str (tostring price))
+  (local dot-position (price-str:find "%."))
+  (local price-len (if dot-position
+                     (- (pick-values 1 dot-position) 1)
+                     (# price-str)))
+  (var cursor (- price-len 3))
+  (while (< 0 cursor)
+    (set price-str (insert price-str " " cursor))
+    (set cursor (- cursor 3)))
+  price-str)
+
+(fn test-format-price []
+  (assert (= (format-price 5123450.50689140) "5 123 450.5068914"))
+  (assert (= (format-price 123450.50689140) "123 450.5068914"))
+  (assert (= (format-price 1450.50689140) "1 450.5068914"))
+  (assert (= (format-price 14350) "14 350"))
+  (assert (= (format-price 100) "100"))
+  (assert (= (format-price 0) "0"))
+  (assert (= (format-price 0.5) "0.5")))
+
+{: letters : empty? : split : ends-with : trim : truncate : format-price}