feat(auth): add user registration endpoint

- Validate username, email and password on register
- Reject duplicate usernames and email addresses
- Create user with LOCAL credential and default USER role

Closes #3

src/main/java/com/onixbyte/deltaforceguide/controller/AuthController.java

@@ -1,6 +1,7 @@
 package com.onixbyte.deltaforceguide.controller;
 
 import com.onixbyte.deltaforceguide.domain.dto.LoginRequest;
+import com.onixbyte.deltaforceguide.domain.dto.RegisterRequest;
 import com.onixbyte.deltaforceguide.domain.dto.UserResponse;
 import com.onixbyte.deltaforceguide.security.annotation.RequiresAuth;
 import com.onixbyte.deltaforceguide.service.AuthService;
@@ -46,4 +47,11 @@ public class AuthController {
                 .header(HttpHeaders.SET_COOKIE, expiredCookie.toString())
                 .build();
     }
+
+    @Operation(description = "用户注册")
+    @PostMapping("/register")
+    public ResponseEntity<UserResponse> register(@Validated @RequestBody RegisterRequest request) {
+        var user = authService.register(request);
+        return authService.getUserResponseResponseEntity(user);
+    }
 }

src/main/java/com/onixbyte/deltaforceguide/domain/dto/RegisterRequest.java

@@ -0,0 +1,29 @@
+package com.onixbyte.deltaforceguide.domain.dto;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+import jakarta.validation.constraints.Email;
+import jakarta.validation.constraints.NotBlank;
+
+/**
+ * Registration request containing the new user account information.
+ *
+ * @author zihluwang
+ */
+@Schema(description = "注册请求")
+public record RegisterRequest(
+        @NotBlank(message = "用户名不能为空")
+        @Schema(description = "用户名", requiredMode = Schema.RequiredMode.REQUIRED)
+        String username,
+        @NotBlank(message = "邮箱不能为空")
+        @Email(message = "邮箱格式不正确")
+        @Schema(description = "邮箱", requiredMode = Schema.RequiredMode.REQUIRED)
+        String email,
+        @Schema(description = "昵称")
+        String nickname,
+        @Schema(description = "头像链接")
+        String avatarUrl,
+        @NotBlank(message = "密码不能为空")
+        @Schema(description = "密码", requiredMode = Schema.RequiredMode.REQUIRED)
+        String password
+) {
+}

src/main/java/com/onixbyte/deltaforceguide/manager/UserManager.java

@@ -1,7 +1,9 @@
 package com.onixbyte.deltaforceguide.manager;
 
 import com.onixbyte.deltaforceguide.domain.entity.User;
+import com.onixbyte.deltaforceguide.domain.entity.UserRole;
 import com.onixbyte.deltaforceguide.repository.UserRepository;
+import com.onixbyte.deltaforceguide.repository.UserRoleRepository;
 import org.springframework.stereotype.Component;
 import org.springframework.transaction.annotation.Transactional;
 
@@ -17,9 +19,11 @@ import java.util.Optional;
 public class UserManager {
 
     private final UserRepository userRepository;
+    private final UserRoleRepository userRoleRepository;
 
-    public UserManager(UserRepository userRepository) {
+    public UserManager(UserRepository userRepository, UserRoleRepository userRoleRepository) {
         this.userRepository = userRepository;
+        this.userRoleRepository = userRoleRepository;
     }
 
     /**
@@ -83,5 +87,42 @@ public class UserManager {
     public Optional<User> findByUsernameOrEmail(String principal) {
         return userRepository.findByUsernameOrEmail(principal);
     }
+
+    /**
+     * Checks whether a username is already registered.
+     *
+     * @param username the username to check
+     * @return true if the username is already taken
+     */
+    public boolean existsByUsername(String username) {
+        return userRepository.existsByUsername(username);
+    }
+
+    /**
+     * Checks whether an email address is already registered.
+     *
+     * @param email the email address to check
+     * @return true if the email address is already taken
+     */
+    public boolean existsByEmail(String email) {
+        return userRepository.existsByEmail(email);
+    }
+
+    /**
+     * Persists a new user together with an initial role assignment in a single transaction.
+     *
+     * @param user the user to persist, whose credentials are cascaded
+     * @param role the initial role name to assign
+     * @return the saved user
+     */
+    @Transactional
+    public User createWithRole(User user, String role) {
+        var saved = userRepository.save(user);
+        userRoleRepository.save(UserRole.builder()
+                .user(saved)
+                .role(role)
+                .build());
+        return saved;
+    }
 }
 

src/main/java/com/onixbyte/deltaforceguide/service/AuthService.java

@@ -2,12 +2,18 @@ package com.onixbyte.deltaforceguide.service;
 
 import com.onixbyte.deltaforceguide.client.TokenClient;
 import com.onixbyte.deltaforceguide.domain.dto.LoginRequest;
+import com.onixbyte.deltaforceguide.domain.dto.RegisterRequest;
 import com.onixbyte.deltaforceguide.domain.dto.UserResponse;
 import com.onixbyte.deltaforceguide.domain.entity.User;
+import com.onixbyte.deltaforceguide.domain.entity.UserCredential;
+import com.onixbyte.deltaforceguide.exeption.BadRequestException;
 import com.onixbyte.deltaforceguide.exeption.InternalServerErrorException;
 import com.onixbyte.deltaforceguide.manager.CookieManager;
+import com.onixbyte.deltaforceguide.manager.UserManager;
 import com.onixbyte.deltaforceguide.security.authentication.UsernamePasswordAuthentication;
 import com.onixbyte.deltaforceguide.shared.CookieName;
+import com.onixbyte.deltaforceguide.shared.CredentialProvider;
+import com.onixbyte.deltaforceguide.shared.Role;
 import org.jspecify.annotations.NonNull;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -15,6 +21,7 @@ import org.springframework.http.HttpCookie;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.ResponseEntity;
 import org.springframework.security.authentication.AuthenticationManager;
+import org.springframework.security.crypto.password.PasswordEncoder;
 import org.springframework.stereotype.Service;
 
 import java.time.Duration;
@@ -32,15 +39,21 @@ public class AuthService {
     private final AuthenticationManager authenticationManager;
     private final TokenClient tokenClient;
     private final CookieManager cookieManager;
+    private final UserManager userManager;
+    private final PasswordEncoder passwordEncoder;
 
     public AuthService(
             AuthenticationManager authenticationManager,
             TokenClient tokenClient,
-            CookieManager cookieManager
+            CookieManager cookieManager,
+            UserManager userManager,
+            PasswordEncoder passwordEncoder
     ) {
         this.authenticationManager = authenticationManager;
         this.tokenClient = tokenClient;
         this.cookieManager = cookieManager;
+        this.userManager = userManager;
+        this.passwordEncoder = passwordEncoder;
     }
 
     /**
@@ -66,6 +79,41 @@ public class AuthService {
         return authentication.getDetails();
     }
 
+    /**
+     * Registers a new user account with the LOCAL password provider and the default USER role.
+     *
+     * @param request the registration information
+     * @return the newly created {@link User}
+     */
+    public User register(RegisterRequest request) {
+        var username = request.username().trim();
+        var email = request.email().trim();
+
+        if (userManager.existsByUsername(username)) {
+            throw new BadRequestException("用户名已被注册。");
+        }
+        if (userManager.existsByEmail(email)) {
+            throw new BadRequestException("该邮箱已被注册。");
+        }
+
+        var now = LocalDateTime.now();
+        var user = User.builder()
+                .username(username)
+                .email(email)
+                .nickname(request.nickname())
+                .avatarUrl(request.avatarUrl())
+                .createdAt(now)
+                .updatedAt(now)
+                .build();
+        var credential = UserCredential.builder()
+                .provider(CredentialProvider.LOCAL)
+                .credential(passwordEncoder.encode(request.password()))
+                .build();
+        user.addCredential(credential);
+
+        return userManager.createWithRole(user, Role.ROLE_USER);
+    }
+
     @NonNull
     public ResponseEntity<UserResponse> getUserResponseResponseEntity(User user) {
         var currentTime = LocalDateTime.now();