Simplify logic of number_to_roman function

Author: paulbalandan

system/Helpers/number_helper.php

@@ -182,79 +182,36 @@ function format_number(float $num, int $precision = 1, ?string $locale = null, a
      */
     function number_to_roman(string $num): ?string
     {
+        static $map = [
+            'M'  => 1000,
+            'CM' => 900,
+            'D'  => 500,
+            'CD' => 400,
+            'C'  => 100,
+            'XC' => 90,
+            'L'  => 50,
+            'XL' => 40,
+            'X'  => 10,
+            'IX' => 9,
+            'V'  => 5,
+            'IV' => 4,
+            'I'  => 1,
+        ];
+
         $num = (int) $num;
+
         if ($num < 1 || $num > 3999) {
             return null;
         }
 
-        $_number_to_roman = static function ($num, $th) use (&$_number_to_roman) {
-            $return = '';
-            $key1   = null;
-            $key2   = null;
-
-            switch ($th) {
-                case 1:
-                    $key1 = 'I';
-                    $key2 = 'V';
-                    $keyF = 'X';
-                    break;
-
-                case 2:
-                    $key1 = 'X';
-                    $key2 = 'L';
-                    $keyF = 'C';
-                    break;
-
-                case 3:
-                    $key1 = 'C';
-                    $key2 = 'D';
-                    $keyF = 'M';
-                    break;
-
-                case 4:
-                    $key1 = 'M';
-                    break;
-            }
-            $n = $num % 10;
-
-            switch ($n) {
-                case 1:
-                case 2:
-                case 3:
-                    $return = str_repeat($key1, $n);
-                    break;
+        $result = '';
 
-                case 4:
-                    $return = $key1 . $key2;
-                    break;
-
-                case 5:
-                    $return = $key2;
-                    break;
-
-                case 6:
-                case 7:
-                case 8:
-                    $return = $key2 . str_repeat($key1, $n - 5);
-                    break;
-
-                case 9:
-                    $return = $key1 . $keyF; // @phpstan-ignore-line
-                    break;
-            }
-
-            switch ($num) {
-                case 10:
-                    $return = $keyF; // @phpstan-ignore-line
-                    break;
-            }
-            if ($num > 10) {
-                $return = $_number_to_roman($num / 10, ++$th) . $return;
-            }
-
-            return $return;
-        };
+        foreach ($map as $roman => $arabic) {
+            $repeat = (int) floor($num / $arabic);
+            $result .= str_repeat($roman, $repeat);
+            $num %= $arabic;
+        }
 
-        return $_number_to_roman($num, 1);
+        return $result;
     }
 }