feat: add email verification

src/main/java/com/openisle/service/UserService.java

@@ -8,6 +8,7 @@ import org.springframework.security.crypto.password.PasswordEncoder;
 import org.springframework.stereotype.Service;
 
 import java.util.Optional;
+import java.util.Random;
 
 @Service
 @RequiredArgsConstructor
@@ -17,17 +18,33 @@ public class UserService {
 
     public User register(String username, String email, String password) {
         if (userRepository.findByUsername(username).isPresent() || userRepository.findByEmail(email).isPresent()) {
-            throw new RuntimeException("User already exists");
+            throw new IllegalStateException("User already exists");
         }
         User user = new User();
         user.setUsername(username);
         user.setEmail(email);
         user.setPassword(passwordEncoder.encode(password));
+        user.setVerified(false);
+        String code = String.format("%06d", new Random().nextInt(1000000));
+        user.setVerificationCode(code);
         return userRepository.save(user);
     }
 
+    public boolean verifyCode(String username, String code) {
+        Optional<User> userOpt = userRepository.findByUsername(username);
+        if (userOpt.isPresent() && code.equals(userOpt.get().getVerificationCode())) {
+            User user = userOpt.get();
+            user.setVerified(true);
+            user.setVerificationCode(null);
+            userRepository.save(user);
+            return true;
+        }
+        return false;
+    }
+
     public Optional<User> authenticate(String username, String password) {
         return userRepository.findByUsername(username)
+                .filter(User::isVerified)
                 .filter(user -> passwordEncoder.matches(password, user.getPassword()));
     }
 }