initial commit

app/Rules/LuhnValid.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace App\Rules;
+
+use Closure;
+use Illuminate\Contracts\Validation\ValidationRule;
+
+class LuhnValid implements ValidationRule
+{
+    /**
+     * Run the validation rule.
+     *
+     * @param  string  $attribute
+     * @param  mixed  $value
+     * @param  \Closure(string): \Illuminate\Translation\PotentiallyTranslatedString  $fail
+     */
+    public function validate(string $attribute, mixed $value, Closure $fail): void
+    {
+        if (!$this->passes($attribute, $value)) {
+            $fail('The :attribute is not a valid credit card number.');
+        }
+    }
+
+    public function passes($attribute, $value)
+    {
+        // Remove non-numeric characters
+        $cardNumber = preg_replace('/\D/', '', $value);
+
+        $sum = 0;
+        $shouldDouble = false;
+
+        // Process the digits from right to left
+        for ($i = strlen($cardNumber) - 1; $i >= 0; $i--) {
+            $digit = (int)$cardNumber[$i];
+
+            if ($shouldDouble) {
+                $digit *= 2;
+                if ($digit > 9) {
+                    $digit -= 9;
+                }
+            }
+
+            $sum += $digit;
+            $shouldDouble = !$shouldDouble;
+        }
+
+        // Return true if the total modulo 10 is 0
+        return ($sum % 10 === 0);
+    }
+}