Feat: 인증 객체 및 유틸 구현 (#49)

Author: joyewon0705

src/main/java/com/back/global/security/CurrentUser.java

@@ -0,0 +1,64 @@
+package com.back.global.security;
+
+import com.back.domain.user.entity.User;
+import com.back.domain.user.repository.UserRepository;
+import com.back.global.exception.CustomException;
+import com.back.global.exception.ErrorCode;
+import lombok.RequiredArgsConstructor;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.context.SecurityContextHolder;
+import org.springframework.stereotype.Component;
+
+import java.util.Optional;
+
+/**
+ * SecurityContext에 저장된 인증 정보를 바탕으로
+ * 현재 로그인한 사용자 정보를 가져오는 유틸 클래스
+ */
+@Component
+@RequiredArgsConstructor
+public class CurrentUser {
+    private final UserRepository userRepository;
+
+    /**
+     * 현재 사용자가 인증된 상태인지 확인
+     */
+    public boolean isAuthenticated() {
+        Authentication auth = SecurityContextHolder.getContext().getAuthentication();
+        return auth != null
+                && auth.isAuthenticated()
+                && auth.getPrincipal() instanceof CustomUserDetails;
+    }
+
+    public Long getUserId() { return getDetails().getUserId(); }
+
+    public String getUsername() { return getDetails().getUsername(); }
+
+    public String getRole() { return getDetails().getRole(); }
+
+    public String getEmail() { return getUserFromDb().getEmail(); }
+
+    public String getProvider() { return getUserFromDb().getProvider(); }
+
+    public String getProviderId() { return getUserFromDb().getProviderId(); }
+
+    public String getStatus() { return getUserFromDb().getUserStatus().name(); }
+
+    /**
+     * SecurityContext에서 CustomUserDetails 추출
+     */
+    private CustomUserDetails getDetails() {
+        Authentication auth = SecurityContextHolder.getContext().getAuthentication();
+        if (auth != null && auth.getPrincipal() instanceof CustomUserDetails details) {
+            return details;
+        }
+        throw new CustomException(ErrorCode.UNAUTHORIZED);
+    }
+
+    /**
+     * DB에서 현재 사용자 엔티티 조회
+     */
+    private User getUserFromDb() {
+        return userRepository.findById(getDetails().getUserId()).orElseThrow(() -> new CustomException(ErrorCode.USER_NOT_FOUND));
+    }
+}