implement registration validity checks

src/main/java/wtf/beatrice/releasehive/services/AccountServiceImpl.java

@@ -1,12 +1,17 @@
 package wtf.beatrice.releasehive.services;
 
+import org.apache.coyote.BadRequestException;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
 import org.springframework.security.authentication.AuthenticationManager;
 import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
 import org.springframework.security.crypto.password.PasswordEncoder;
 import org.springframework.stereotype.Service;
+import wtf.beatrice.releasehive.config.InternalConfiguration;
 import wtf.beatrice.releasehive.dtos.LoginUserDto;
 import wtf.beatrice.releasehive.dtos.RegisterUserDto;
+import wtf.beatrice.releasehive.exceptions.HiveException;
 import wtf.beatrice.releasehive.models.User;
 import wtf.beatrice.releasehive.repositories.UserRepository;
 
@@ -28,7 +33,37 @@ public class AccountServiceImpl implements AccountService {
     }
 
     @Override
-    public User register(RegisterUserDto userDto) {
+    public User register(RegisterUserDto userDto) throws BadRequestException {
+
+        if (userDto.getEmail() == null ||
+                userDto.getEmail().isEmpty() ||
+                userDto.getPassword() == null ||
+                userDto.getPassword().isEmpty() ||
+                userDto.getUsername() == null ||
+                userDto.getUsername().isEmpty()) {
+
+            throw new BadRequestException("Please provide a valid email, password, and username");
+        }
+
+        if(!userDto.getEmail().matches(InternalConfiguration.EMAIL_REGEX_RCF)) {
+            throw new BadRequestException("Invalid email format");
+        }
+
+        if(!userDto.getUsername().matches(InternalConfiguration.USERNAME_REGEX)) {
+            throw new BadRequestException("Username contains invalid characters");
+        }
+
+        if(!userDto.getPassword().matches(InternalConfiguration.PASSWORD_REGEX)) {
+            throw new BadRequestException("Invalid password format");
+        }
+
+        if (userRepository.findByEmail(userDto.getEmail()).isPresent()) {
+            throw new BadRequestException("An account already exists with this email");
+        }
+
+        if(userRepository.findByUsername(userDto.getUsername()).isPresent()) {
+            throw new BadRequestException("Username already in use");
+        }
 
         User user = new User();
         user.setUsername(userDto.getUsername());