complete story 11.2 with qa tests

app/Services/CaptchaService.php

@@ -0,0 +1,49 @@
+<?php
+
+namespace App\Services;
+
+class CaptchaService
+{
+    private const SESSION_KEY = 'captcha_answer';
+
+    /**
+     * Generate a new math captcha question.
+     *
+     * @return array{question: string, question_ar: string}
+     */
+    public function generate(): array
+    {
+        $num1 = rand(1, 10);
+        $num2 = rand(1, 10);
+        $answer = $num1 + $num2;
+
+        session([self::SESSION_KEY => $answer]);
+
+        return [
+            'question' => "What is {$num1} + {$num2}?",
+            'question_ar' => "ما هو {$num1} + {$num2}؟",
+        ];
+    }
+
+    /**
+     * Validate the user's captcha answer.
+     */
+    public function validate(mixed $answer): bool
+    {
+        $expected = session(self::SESSION_KEY);
+
+        if (is_null($expected)) {
+            return false;
+        }
+
+        return (int) $answer === (int) $expected;
+    }
+
+    /**
+     * Clear the current captcha from session.
+     */
+    public function clear(): void
+    {
+        session()->forget(self::SESSION_KEY);
+    }
+}